Dissertations / Theses: 'Chordates'

1

Coll-Lladó, Clara. "Evolution of muscle regulatory genes in chordates." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/16136.

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2

Boorman, Clive John. "Pitx in the evolution of chordate left- right asymmetry and the nasohypophysial placode." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250600.

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3

Whiting, James R. "The evolutionary consequences of genetic adaptation to parasitism." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/50591/.

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The processes driving and maintaining variable immune responses are poorly understood compared with other aspects of an organism’s ecology. This is particularly true from an evolutionary perspective, as the evolutionary relationships between immune responses and other traits and processes in nature remain inadequately explored. I investigated these associations in this thesis using the three-spined stickleback system as an evolutionary and immunological model. I combined sampling of wild individuals with genomic analyses to demonstrate phenotypic and genomic associations between immune responses and life history evolution across multiple populations. I also observe how experimental changes in daylength, a seasonal cue, modulate immune responses and increase parasite susceptibility in a controlled laboratory experiment. These findings occur independently of natural variation in parasite resistance. Stickleback are also a model for studies of speciation. I used sampling of wild hybrids to assess the significance of immune variation in postzygotic isolating mechanisms between diverging ecotypes; although my findings suggest a minor role. Finally, I demonstrate that genomic responses to parasitism and abiotic environmental variation are repeatable across independent, intercontinental adaptive radiation events in sticklebacks; conferring a repeatability of the evolutionary relationships of immune variation documented in this thesis. The findings within this thesis therefore provide novel insights into poorly explored or open areas of research regarding how variable immune responses evolve in nature.

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4

Vitale, Jessica. "The olfactory behaviour of spotted hyaenas (Crocuta crocuta) and sympatric mammals in the Okavango Delta, Botswana." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/48855/.

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Understanding the natural behaviour and coexistence of species is important for the conservation of intact ecosystems, and behavioural studies can enhance our knowledge of processes such as communication and competition. I investigated the social dynamics and scent-marking behaviour of spotted hyaenas (Crocuta crocuta), and the occurrence of interspecific olfactory eavesdropping among African mammals, within the Okavango Delta ecosystem of Botswana. First, social network analysis found that the hyaena population was comprised of five main clans that maintained territories but whose home ranges overlapped considerably. Scavenging at large carcasses involved associations between individuals from different clans and resulted in relative tolerance toward territorial intruders. Second, observations of communal latrine use found that latrines are likely involved in territorial advertisement by hyaena clans, and cyclical patterns of latrine growth and decline were linked to annual rainfall. Third, a translocation experiment showed that hyaena scats appear to be less important for hyaena communication than other cues associated with latrines, especially as hyaenas did not differ in their behaviour towards scat originating from latrines located in resident versus non-resident clan home ranges. Heterospecific mammals investigated, scent-marked, and were vigilant at hyaena latrines, suggesting a potential function for hyaena latrines in interspecific eavesdropping and/or communication. Fourth, a urine presentation experiment found that the investigation of sympatric predator urine by African mammals stimulated vigilance behaviour, suggesting that olfactory signals provide information about predation risk. Hyaenas exhibited context-specific differences in behaviour towards predator urine: they were more likely to investigate urine samples alongside indicators of predator activity (i.e. carrion odour, carcasses) and were most likely to exhibit vigilance at carcasses when exposed to urine from lions and wild dogs. This study greatly enhanced our understanding of spotted hyaena behaviour within the Okavango Delta, an important ecosystem for the conservation of African large predators. Furthermore, this study provided the first experimental evidence of the role of hyaena scats in intraspecific communication and interspecific olfactory eavesdropping at latrines. My research findings regarding the population’s clan structure and home ranges will form the foundation for subsequent investigation into human-wildlife conflict in the study area. Furthermore, the results from two scent experiments shed light on the potential importance of olfactory signals for mediating interspecific interactions among African mammals, particularly among large predators.

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5

Herrera, Úbeda Carlos. "Conservation of different mechanisms of Hox cluster regulation within chordates." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668561.

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In this thesis we have covered the importance of finding underlying conservation events to better understand the regulatory mechanisms of important development orchestrators like the Hox cluster. As an example of these non-evident conservation, we have shown two cases, as described below. The first case studied, after developing a software able to detect homologous long noncoding RNAs by means of microsynteny analyses, is the conservation of Hotairm1 in Chordata. For assessing the homology of this lncRNA, first we had to identify the lncRNA fraction within the B. lanceolatum transcriptome. With a reliable lincRNA dataset, we used our pipeline, LincOFinder, to identify orthologs between human and amphioxus through microsynteny. After the identification of Hotairm1 as one of the lincRNAs with conserved microsynteny, we used Xenopus as a proxy to analyse the homologies in the expression and the function. We had to proceed this way due to the difficulties associated with the inhibition of genes in B. lanceolatum, and the unavailability of expression patterns for Hotairm1 in the bibliography. After we successfully characterised Hotairm1 expression in amphioxus and Xenopus, we injected morpholino oligonucleotides to target and inhibit the splicing of Hotairm1 to promote an isoform imbalance. Through the phenotype obtained and the performing of qPCRs, we were able to deduct the mechanism of Hotairm1 and successfully relate this mechanism with the one described in human cells. With all the data obtained we were able to strongly suggest that the amphioxus Hotairm1 is homologous to the Xenopus and human Hotairm1, thus being conserved in most of the lineages within chordates. The second case studied was the conservation of the regulation of the Hox cluster mediated by Cdx. When analysing the B. floridae knockouts of Cdx and Pdx obtained using the TALEN technique, we found a severe phenotype of the developing larvae in Cdx-/- and a mild phenotype in Pdx-/-. The Cdx-/- phenotype consisted in the disruption of posterior gut development, as well as an underdevelopment of the postanal tail, coupled with a non-opening anus. When looking at changes in the expression of the Hox cluster in this Cdx-/- embryos, we found collinear misregulation of the expressed Hox genes, with the most anterior Hox cluster genes upregulated, and the most posterior ones downregulated. This is very similar to findings seen in triple morpholino knockdowns of the Cdx genes in Xenopus, indicating that in both, Xenopus and amphioxus, Cdx is regulating the Hox cluster through a homologous mechanism.

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6

Wetton, Jon. "Aspects of the biology of a house sparrow (Passer domesticus) colony." Thesis, University of Nottingham, 1990. http://eprints.nottingham.ac.uk/12023/.

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Morphological, biochemical and minisatellite DNA variation was investigated at the colour ringed Brackenhurst House Sparrow population. Measurements and blood samples were collected from 584 nestlings and 692 other birds between 1985 and 1989. Six loci (6PGD, IDH, PEPD2, PEPD3, PEPT and transferrin) which had been the subject of a previous report (Burke, 1984) were investigated by starch gel electrophoresis. All followed Mendelian inheritance patterns, were in Hardy Weinberg equilibria and displayed temporal stability in allele frequencies. No evidence was found of the previously reported segregation distortion at PEPD3 and transferrin but artefact bands were encountered when scoring the latter. Family groups identified by observing colour ringed adults during feeding visits were examined using both enzyme and minisatellite DNA markers. Z chromosome linkage of several fingerprint bands was implicated, though most segregate independently. The probability of detecting an extra-pair fertilization was estimated as 0.5454 using starch gels and 0.9998 by fingerprinting. 51 out of 420 nestlings from 144 broods possessed several bands absent from the attendants' fingerprints. All nestlings with multiple mismatches shared many bands with the attendant female but a number consistent with band sharing between unrelateds with the male, i.e. nonparentage, was the result of cuckoldry. 24% of broods and 37% of males were affected. A correlation between the presence of extra-pair offspring and poor hatching success was noted. Cuckoldry was twice as successful in broods which contained infertile eggs. Metric variation was examined in the confirmed families. Significant heritabilities were demonstrated for weight, tarsus and tail length but environmentally induced variance was considerable. Yearlings were smaller than full adults in plumage length. This may be due to levels of protein reserves at critical growth periods. Some evidence of assortative mating for tail length was found which was unrelated to age associated changes.

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7

Meng, Anming. "DNA fingerprinting and minisatellite variation of swans." Thesis, University of Nottingham, 1990. http://eprints.nottingham.ac.uk/13889/.

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Genetic variation in natural populations of four species of swans (Cygnus bewickii, Cygnus olor, Cygnus buccinator and Cygnus cygnus) has been investigated by examining minisatellite loci using human DNA fingerprinting probes pSPT19.6 and pSPT18.15. It has been found that swan minisatellites are highly variable. However, the degree of variation depends on the population structure and species. Bewick's Swans at Slimbridge have the highest degree of minisatellite variation, Whooper Swans at Caerlaverock come second, and then Mute Swans, and Trumpeter Swans in Montana. Comparative study of DNA fingerprints among populations and among species suggested that swan minisatellites are subject to specific as well as population differentiation, although the function of minisatellites remains an unsolved mystery. Hypervariable minisatellites of swans that are detected by DNA fingerprinting are stably inherited as codominant markers. DNA fingerprinting has been used to study mating behaviour of Mute and Whooper Swans in the wild The results showed that the Whooper swans were almost strictly monogamous and Mute Swans exhibited an adaptable reproductive system. A genomic library from Cygnus olor was constructed and dozens of minisatellites were isolated. Most of the cloned swan minisatellites were variable, some showed specific variation, and one (pcoMS6.1) detected RFLPs in PstI digests of Trumpeter Swans.

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8

Rahman, Abdul. "Life history evolution in three-spined stickleback." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/41732/.

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A main challenge in evolutionary ecology is to elaborate the main ecological factors that vary in a study system and analyse how those factors shape the phenotype of organisms in their natural environment. These ecological variables can have complex effects since most life history traits are correlated. Here I examined the effects of ecological factors on life history traits, and the relationship among life history traits of North Uist three-spined stickleback, Gasterosteus aculeatus (hereafter stickleback). Both abiotic and biotic factors that are commonly measured in aquatic systems, and are known to vary greatly between North Uist lochs, were examined. The traits analysed were body size, age and size at maturation, proportion of fish over one year old, and the fecundity rate. My results showed that there was strong variation in water chemistry and inter-specific competition among the lochs on North Uist. Lochs on the west side of the island were characterised by higher sodium and calcium ion concentrations, higher pH and conductivity, and increased inter-specific competition. As a result, western populations had a faster absolute growth rate, larger body size, and a higher proportion of older fish, indicative of a longer life span. Although western populations had a larger body size, they tended to mature later with a smaller gonadosomatic index. They also favoured a larger number of eggs, but with a smaller egg size. Variations within population showed that larger females had greater fecundity but small egg size. Both plasticity and evolution appear to have contributed to these life history variations. Overall, variation in life history of North Uist stickleback was largely related to measures of resources availability and interspecific competition, except for egg size which was mostly associated with variation in predator density.

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9

Cantryll-Stewart, Ricki. "A discernment of prey selection by the ancient Maya : white-tailed deer (Odocoileus virginianus) : pest, prey, or domesticate." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/50198/.

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This thesis investigates the demographics of paleo-populations of white-tailed deer (Odocoileus virginianus) as a means of testing the hypothesis that this species was domesticated or managed as a vital cultural and economic resource by the ancient Maya in Mesoamerica. To do so it employs a set of standardized bone measurements derived from a modern population and compares them with 1100 deer bone samples recovered by archaeologists from Maya sites dating from 450 B.C. to the late 16th century. These measurements were also applied to modern white-tailed deer specimens representing a discrete population from south eastern Florida of know age, and sex, for use as a baseline. The recorded measurements were used for side by side comparisons and to generate log ratios testing population stature and sexual dimorphism represented in the archaeological materials. Changes in deer stature and mortality profile over time are examined and tested against standard methods for the detection of herd management strategies, that may potentially reveal deer domestication or resource management. Pathologies common to white-tailed deer are identified and their potential for assessing the ontological age of mature deer is investigated. The results show variations in white-tailed deer stature over time and space, suggesting dynamic alterations in prey selection that may be reflective of changes in Maya social complexity.

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10

Dunn, Matthew Patrick. "Examination of the Leprecan gene family across the chordates : expression, regulation, and function /." Access full-text from WCMC, 2009. http://proquest.umi.com/pqdweb?did=1692100341&sid=1&Fmt=2&clientId=8424&RQT=309&VName=PQD.

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11

Marques, Carvalho João Emanuel. "Retinoic acid signaling in chordates : the evolutionary history of a morphogen-dependent signaling." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066083/document.

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L'une des caractéristiques les plus frappantes des animaux multicellulaires, aussi appelés les métazoaires, est leur étonnante diversité morphologique. Des études de type phylogénétique ont permis de mettre en relation cette abondance et cette variété observées au sein des formes de vie animale avec des différences au niveau de processus moléculaires, cellulaires, tissulaires et organiques. Parmi ces différences, celle affectant les programmes de développement apparaît comme un aspect clé de la diversité des métazoaires. Les programmes de développement reposent entre autres sur la mise en œuvre de communications entre cellules, ou entre milieu environnant et cellules, et ces communications sont assurées au niveau moléculaire par le déploiement de cascades d'activités protéiques nommées les voies de signalisation. Une des voies de signalisation essentielles au cours du développement de nombreux métazoaires est la voie de l'acide rétinoïque (AR). Le fonctionnement et les rôles de cette voie pendant le développement animal ont fait l'objet de nombreuses recherches, ces travaux ayant aboutis à des découvertes majeures. Néanmoins des analyses supplémentaires restent requises afin de mieux comprendre l'histoire évolutive de cette voie, du métabolisme de l'AR à la transmission de son signal, en passant par l'identification de ses gènes cibles, ses interactions avec d'autres voies de signalisation, et ses fonctions au cours du développement, le tout au sein du règne animal. Dans ce contexte, étudier cette voie chez un métazoaire tel que le céphalochordate amphioxus, qui possède une voie de signalisation de l'AR équivalente à celle des vertébrés, mais avec une redondance moléculaire moindre, représente une étape importante pour identifier l’architecture et les fonctions ancestrales de cette voie parmi les chordés.Chez l’amphioxus, la voie de signalisation de l'AR est étudiée depuis plus de 20 ans, mais peu de choses sont encore connues sur la régulation de la biodisponibilité de l'AR pendant le développement et sur la nature de ses gènes cibles et du réseau régulateur qu’ils définissent. Le but de mon travail de thèse a par conséquent été d’étudier ces deux aspects fondamentaux de la voie de signalisation de l'AR chez l'amphioxus. Au cours de mon projet de recherche, j’ai utilisé comme modèle d’étude l'amphioxus européen, Branchiostoma lanceolatum, pour lequel j’ai également mis en œuvre de nombreuses améliorations du système de culture ainsi que développer des techniques d’analyses in vivo, comme la microinjection d'ARNm dans des œufs
One of the most striking features of multicellular animals, the metazoans, is their amazing morphological diversity. Even though phylogenetic research has made remarkable progress towards revealing how the abundance and variety of animal life forms relates on the molecular, cellular, tissue, and organismal level, the alteration of developmental programs has been revealed as a key aspect in this process. During development, a rather limited number of signaling pathways has been shown to be instrumental for generating metazoan diversity. The retinoic acid (RA) signaling pathway is one of these instrumental signaling cascades. A significant amount of time and work has been used to characterize the functions and roles of RA signaling during development, although further work is required to better understand the evolutionary history of the RA signaling network, from metabolism to signal transduction passing by the interactions with other signaling cascades and its developmental functions and how they evolve with time. In this context, model organisms with representative, vertebrate-like RA signaling cascades, such as the cephalochordate amphioxus, will be an important case-study in order to identify the blueprint of an ancestral RA network.The amphioxus RA signaling pathway was initially studied about 20 years ago, even though not much is known about the bioavailability of RA during development. Moreover, the target genes of the RA signaling pathway and their hierarchical relationship during amphioxus development represent an interesting open question. Therefore, this work aimed at providing a detailed description of two fundamental aspects of the RA signaling pathway during amphioxus development: (1) the regulation of the bioavailability of RA in the developing embryo and (2) the target genes under the control of the RA signaling pathway together with their hierarchical regulatory relationship. To address these questions, the European amphioxus, Branchiostoma lanceolatum, was used as a model system.During my research project, not only these questions were fundamental, but also the implementation of amphioxus as a reliable model system and thus the establishment of multiple aquaculture improvements as well as in vivo techniques, such as the microinjection of mRNAs into amphioxus eggs. Furthermore, to characterize the bioavailability of RA during development of amphioxus, I focused on the study of the enzymes that mediate the catabolism of RA endogenously, the CYP26 subfamily proteins. I thus described the evolutionary diversification of CYP26 genes in deuterostomes as well as their expression, their function and the mechanisms that govern the feedback loop controlled directly by RA during amphioxus development.Additionally, to shed light on the target genes under the control of the RA signaling pathway during amphioxus development, I combined pharmacological treatments using retinoid-specific drugs with two different techniques of high throughput sequencing: RNAseq, that revealed the entire RNA profile and thus the genes being expressed at a given moment in time, and ATACseq (assay for transposase-accessible chromatin) that provided a global overview of accessible regions of the chromatin (i.e. open chromatin regions). By combining the data obtained by these techniques, I revealed a new set of genes that are under the control of the RA signaling pathway as well as new potential regulatory loops driving RAR-mediated expression. Moreover, I established a framework to characterize gene hierarchies during development that can be widely applied to other signaling pathways and organisms

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12

Marques, Carvalho João Emanuel. "Retinoic acid signaling in chordates : the evolutionary history of a morphogen-dependent signaling." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066083.

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L'une des caractéristiques les plus frappantes des animaux multicellulaires, aussi appelés les métazoaires, est leur étonnante diversité morphologique. Des études de type phylogénétique ont permis de mettre en relation cette abondance et cette variété observées au sein des formes de vie animale avec des différences au niveau de processus moléculaires, cellulaires, tissulaires et organiques. Parmi ces différences, celle affectant les programmes de développement apparaît comme un aspect clé de la diversité des métazoaires. Les programmes de développement reposent entre autres sur la mise en œuvre de communications entre cellules, ou entre milieu environnant et cellules, et ces communications sont assurées au niveau moléculaire par le déploiement de cascades d'activités protéiques nommées les voies de signalisation. Une des voies de signalisation essentielles au cours du développement de nombreux métazoaires est la voie de l'acide rétinoïque (AR). Le fonctionnement et les rôles de cette voie pendant le développement animal ont fait l'objet de nombreuses recherches, ces travaux ayant aboutis à des découvertes majeures. Néanmoins des analyses supplémentaires restent requises afin de mieux comprendre l'histoire évolutive de cette voie, du métabolisme de l'AR à la transmission de son signal, en passant par l'identification de ses gènes cibles, ses interactions avec d'autres voies de signalisation, et ses fonctions au cours du développement, le tout au sein du règne animal. Dans ce contexte, étudier cette voie chez un métazoaire tel que le céphalochordate amphioxus, qui possède une voie de signalisation de l'AR équivalente à celle des vertébrés, mais avec une redondance moléculaire moindre, représente une étape importante pour identifier l’architecture et les fonctions ancestrales de cette voie parmi les chordés.Chez l’amphioxus, la voie de signalisation de l'AR est étudiée depuis plus de 20 ans, mais peu de choses sont encore connues sur la régulation de la biodisponibilité de l'AR pendant le développement et sur la nature de ses gènes cibles et du réseau régulateur qu’ils définissent. Le but de mon travail de thèse a par conséquent été d’étudier ces deux aspects fondamentaux de la voie de signalisation de l'AR chez l'amphioxus. Au cours de mon projet de recherche, j’ai utilisé comme modèle d’étude l'amphioxus européen, Branchiostoma lanceolatum, pour lequel j’ai également mis en œuvre de nombreuses améliorations du système de culture ainsi que développer des techniques d’analyses in vivo, comme la microinjection d'ARNm dans des œufs
One of the most striking features of multicellular animals, the metazoans, is their amazing morphological diversity. Even though phylogenetic research has made remarkable progress towards revealing how the abundance and variety of animal life forms relates on the molecular, cellular, tissue, and organismal level, the alteration of developmental programs has been revealed as a key aspect in this process. During development, a rather limited number of signaling pathways has been shown to be instrumental for generating metazoan diversity. The retinoic acid (RA) signaling pathway is one of these instrumental signaling cascades. A significant amount of time and work has been used to characterize the functions and roles of RA signaling during development, although further work is required to better understand the evolutionary history of the RA signaling network, from metabolism to signal transduction passing by the interactions with other signaling cascades and its developmental functions and how they evolve with time. In this context, model organisms with representative, vertebrate-like RA signaling cascades, such as the cephalochordate amphioxus, will be an important case-study in order to identify the blueprint of an ancestral RA network.The amphioxus RA signaling pathway was initially studied about 20 years ago, even though not much is known about the bioavailability of RA during development. Moreover, the target genes of the RA signaling pathway and their hierarchical relationship during amphioxus development represent an interesting open question. Therefore, this work aimed at providing a detailed description of two fundamental aspects of the RA signaling pathway during amphioxus development: (1) the regulation of the bioavailability of RA in the developing embryo and (2) the target genes under the control of the RA signaling pathway together with their hierarchical regulatory relationship. To address these questions, the European amphioxus, Branchiostoma lanceolatum, was used as a model system.During my research project, not only these questions were fundamental, but also the implementation of amphioxus as a reliable model system and thus the establishment of multiple aquaculture improvements as well as in vivo techniques, such as the microinjection of mRNAs into amphioxus eggs. Furthermore, to characterize the bioavailability of RA during development of amphioxus, I focused on the study of the enzymes that mediate the catabolism of RA endogenously, the CYP26 subfamily proteins. I thus described the evolutionary diversification of CYP26 genes in deuterostomes as well as their expression, their function and the mechanisms that govern the feedback loop controlled directly by RA during amphioxus development.Additionally, to shed light on the target genes under the control of the RA signaling pathway during amphioxus development, I combined pharmacological treatments using retinoid-specific drugs with two different techniques of high throughput sequencing: RNAseq, that revealed the entire RNA profile and thus the genes being expressed at a given moment in time, and ATACseq (assay for transposase-accessible chromatin) that provided a global overview of accessible regions of the chromatin (i.e. open chromatin regions). By combining the data obtained by these techniques, I revealed a new set of genes that are under the control of the RA signaling pathway as well as new potential regulatory loops driving RAR-mediated expression. Moreover, I established a framework to characterize gene hierarchies during development that can be widely applied to other signaling pathways and organisms

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13

Hesp, Jon. "A study of the breeding biology of a pied flycatcher population in Wales." Thesis, University of Nottingham, 1993. http://eprints.nottingham.ac.uk/13454/.

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This study concerns a population of the Pied Flycatcher (Ficedula hypoleuca) living in nestboxes in an area of woodland in Mid-Wales. The occupants of 180 nestboxes were monitored during 1988 and 1989. In addition to behavioural observations and records of breeding performance, individual adults and pulli were caught and measured, and a blood sample taken. In the Pied Flycatcher, polygyny is a common mating strategy in which the two or more females mated to a single male nest in discrete territories up to 500m apart This behaviour has been interpreted in two ways, firstly as the result of female choice for the quality of the male or his territory, and secondly, as a consequence of male deception, by which already-mated males attract secondary females who suffer reduced breeding success as a result. In this population polygyny was a rare occurrence; only 3 of 240 breeding males were recognised to be polygynous. These males defended two adjacent nestboxes. The breeding success of the three secondary females was not unusually low. These results suggest that a model of male- or territory quality might better explain the situation in this population. The occurrence of extra-pair mating has being noted in a number of species, including the Pied Flycatcher. In this study it was found to account for 2.7% of the offspring screened by genetic fingerprinting. Another common method for detecting extra-pair paternity uses the heritability of a skeletal measurement.The results from the two methods are shown to be incompatible. A number of weaknesses with the heritability method are described and discussed. The increasing number of studies on the Pied Flycatcher throughout Europe reveal that the frequency of mating strategies such as polygyny and extra-pair mating differ from area to area This suggests that environmental factors may play a major part in determining the costs and benefits of such strategies.

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14

Lawal, Raman Akinyanju. "Signatures of selection and introgression in the genus Gallus." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/48629/.

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Here I investigate, using autosomal whole-genome sequence data, the signature of positive selection and/or introgression in the indigenous domestic village chickens from three countries (Ethiopia, Saudi Arabia, Sri Lanka), three fancy birds, three junglefowl species (red junglefowl Gallus gallus, grey junglefowl G. sonneratii, Ceylon Junglefowl G. lafayettii) and the Javan red junglefowl G. g. bankiva. All the new sequencing data were obtained from Illumina HiSeq 2000/2500 DNA sequencers with an individual bird depth of genome coverage ranging from 10 X to 30 X. The analyses in this thesis have been completed using the reference genome Galgal 4.0. For the detection of signatures of positive selection, this analysis excluded the three fancy birds and the grey junglefowl due to small sample size. Using the pool heterozygosity and SweeD composite likelihood selection signature methods, I identified two candidate selected regions shared between all the three indigenous domestic village chicken populations and the red junglefowl (chapter 2). These regions contain genes that are associated with the development of the central nervous system and adaptation to hypoxic environments. Five candidate regions were shared among the three indigenous village chicken populations, and they represent candidate domestication regions. Unique regions in each domestic chicken population were also identified. Functional genes have not been assigned to most of these regions but in those where the genes have been annotated, the gene function may be related to production and reproductive traits as well as adaptation to cold/hot temperatures and hypoxia. In chapter 3, I analysed only the Ceylon and green junglefowl whole genome sequences for the detection of candidate signatures of positive selection using both the pool heterozygosity and Tajima’s D. In both species, I identified candidate selected regions that contained genes which may be linked to adaptation to different environmental challenges e.g disease resistance, stress, thermoregulation and hypoxia. In the genome of green junglefowl, candidate selected regions associated with skeletal formation and ovarian follicle development were significantly detected. In chapter 4, I identified introgressed candidate regions from the grey and Ceylon junglefowls in domestic chicken (including the three indigenous chicken populations and fancy birds) using the ABBA – BABA four taxon method. Our result shows that, domestic chickens shared 75.8% of their genome with the red junglefowl, 4% with the grey junglefowl and 1.1% with the Ceylon junglefowl. I observed introgression in both directions, namely from the grey/Ceylon junglefowls into domestic chickens and vice versa. While from the grey junglefowl, introgression was present in all the domestic chicken populations as well as interestingly in the red junglefowl, for the Ceylon junglefowl, introgression was more restricted to the domestic chicken from Sri Lanka. From the ABBA – BABA analysis between the grey junglefowl and the domestic chicken, I also identified a single candidate introgressed region from the green junglefowl G. varius in two domestic birds from Sri Lanka. Future study should therefore consider investigating the genome-wide analysis of introgression from the green junglefowl into the domestic chicken. In chapter 5, I ended our introgression study by investigating if a distantly related subspecies of red junglefowl, the Javan red junglefowl Gallus gallus bankiva, has contributed to the gene pool of the domestic chicken. Alongside the three indigenous domestic chicken populations, I included the genome sequences of three domestic chickens sampled from the Java island of Indonesia. Our result shows a significant 10.6% genome admixture between the domestic chicken and the Javan red junglefowl. Overall, our results indicate that the genetic make-up of the domestic chicken is rather complex with multiple species and subspecies influences. These introgression events have contributed to the genetic diversity of these domesticates. Our results also support the geographic difference of introgression and indicate that these introgression events may have contributed to the adaptive traits of the domestic chicken. However, this requires further investigation.

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15

Modhara, Sunny. "Mathematical modelling of vascular development in zebrafish." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/29125/.

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The Notch signalling pathway is pivotal in ensuring that the processes of arterial specification, angiogenic sprouting and haematopoietic stem cell (HSC) specification are correctly carried out in the dorsal aorta (DA), a primary arterial blood vessel in developing vertebrate embryos. Using the zebrafish as a model organism, and additional experimental observations from mouse and cell line models to guide mathematical modelling, this thesis aims to better understand the mechanisms involved in the establishment of a healthy vasculature in the growing embryo. We begin by studying arterial and HSC specification in the zebrafish DA. Mathematical models are used to analyse the dose response of arterial and HSC genes to an input Notch signal. The models determine how distinct levels of Notch signalling may be required to establish arterial and HSC identity. Furthermore, we explore how Delta-Notch coupling, which generates salt-and-pepper patterns, may drive the average gene expression levels higher than their homogeneous levels. The models considered here can qualitatively reproduce experimental observations. Using laboratory experiments, I was able to isolate DA cells from transgenic zebrafish embryos and generate temporal gene expression data using qPCR. We show that it is possible to fit ODE models to such data but more reliable data and a greater number of replicates at each time point is required to make further progress. The same VEGF-Delta-Notch signalling pathway is involved in tip cell selection in angiogenic sprouting. Using an ODE model, we rigourously study the dynamics of a VEGF-Delta-Notch feedback loop which is capable of amplifying differences betwen cells to form period-2 spatial patterns of alternating tip and stalk cells. The analysis predicts that the feeback strengths of Delta ligand and VEGFR-2 production dictate the onset of patterning in the same way, irrespective of the parameter values used. This model is extended to incorporate feedback from filopodia, growing in a gradient of extracellular VEGF, which are capable of facilitating tip cell selection by amplifying the resulting patterns. Lastly, we develop a PDE model which is able to properly account for VEGF receptor distributions in the cell membrane and filopodia. Receptors can diffuse and be advected due to domain growth, defined by a constitutive law, in this model. Our analysis and simulations predict that when receptor diffusivity is large, the ODE model for filopodia growth is an excellent approximation to the PDE model, but that for smaller diffusivity, the PDE model provides valuable insight into the pattern forming potential of the system.

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Desta, Takele Taye. "Phenomic and genomic landscape of Ethiopian village chickens." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/53569/.

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This study involves two village chicken populations sampled from Horro and Jarso regions of Western and Eastern Ethiopia respectively. This study maps the phenomic and genomic landscape of the two chicken populations using morphological markers and a high density (600K) SNP array. Although the two chicken populations tend to display nondescript morphological characteristics, they show a subtle variation except for rare morph variants that have been in most instances scored on Jarso chickens. Morphological analysis uncovers a vast array of intrapopulation variation. Genetic diversity and population structure analyses assign the two chicken populations to two distinct genepools representing their population of origin. A high intrapopulation genetic diversity is uncovered, which shows a broad genetic base (high genetic diversity) of the two chicken populations. We hypothesized that a clearly evident genetic divergence observed between the two chicken populations may be attributed to difference in demographic history, origin (routes of introduction to Africa), breeding history of the two chicken populations and demographic structure of subsistence farmers. Absence of gene flow owing to their distant geographic location and ecological variation may have also contributed to this divergence. A population structure analysis performed on a random subset of the two Ethiopian chicken populations along with village chickens sampled from other African countries, Asia and Latin America, commercial populations and the junglefowl species reveals a unique genetic structure of Ethiopian chickens, which implicates the need for further study on the genetic landscape of the latter. To infer the extent of inbreeding we performed a run of homozygosity analysis (ROH). Our analysis indicates that ROH is more intense in Jarso than Horro chickens and in macrochromosomes than microchromosomes. The extensive ROH mapped in some chickens implicates the need to restructure the existing traditional breeding practice of subsistence farmers. Our analysis confirms the commonness of ROH in genic regions. For the first time, we detect twenty three putative uniparental disomy in twenty two Ethiopian village chickens. Signature of selection analysis detects divergently selected genomic regions in the two chicken populations indicating a considerable divergent selection imposed on the two populations. Genes involving in melanogenesis pathway are among those subjected to a divergent selection. However, some overlapping regions were also mapped in the two chicken populations implicating the ubiquitous impact of natural selection on genes regulating vital biological processes. A genome-wide association study performed on pigmentation (earlobe, plumage and shank) traits and variants of crest, comb and a lightly feathered shank maps a number of putative loci that may underlie variations in these traits. Our GWAS analysis on pigmentation traits produced a long list of loci than that have been known to involve in the genetic control of pigmentation in the chicken, with most of these have been mapped in the mouse. We also refined further the causative variants underlying a lightly feathered shank mutation. Our GWAS analysis map a number of putative novel loci that may underlie the genetic control of the traits analysed and this has laid a foundation for subsequent work that would involve targeted sequencing and a candidate gene approach. This study is the first of its kind in Africa that uses a large number of samples and a high density SNP array to unlock phenomic and genomic landscape of the true type village chickens.

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Dobson, Katharine L. "Descending control in sensitization of reflexes in the rat." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13110/.

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Electrical stimulation of the heel or toes evokes short latency polysynaptic reflexes in muscles of the ankle extensor medial gastrocnemius (MG), the ankle flexor tibialis anterior (TA) and the knee flexor biceps femoris (BF), the co-ordinated actions of which form an organized protective withdrawal response. Previous studies in the rabbit have shown that such reflexes are enhanced (sensitized) or inhibited by application of the chemogenic agent mustard oil (MO) to various areas of the body surface in a manner that reinforces the protective function of these responses. The organization of these ‘sensitization fields’ was strictly controlled by supraspinal pathways from the brain. The aim of the present experiments was therefore to extend these studies of the spatial organization of sensitization of withdrawal reflexes into the rat, the species most commonly used in pain research. Patterns of facilitation and inhibition of spinal reflexes were obtained and compared in decerebrate spinalized, decerebrate non-spinal, and Alfaxan- anaesthetized rats by applying mustard oil to sixteen different body locations including sites on the ipsilateral and contralateral hindlimbs as well as other off limb areas such as the snout and tail. It was found that in decerebrate spinalized animals, MO application to ipsilateral hindlimb sites enhanced but never inhibited reflex responses in the limb, whilst MO treatment to off limb sites was without effect. In contrast in anaesthetized animals the prevalent effect of MO was inhibition from treatment sites distributed across the entire animal. Reflexes in animals with an intact spinal cord (decerebrate or anaesthetized) were facilitated or inhibited by MO application to ipsilateral hindlimb sites in a way that resembled the modular organization of reflexes per se and previous sensitization studies in the rabbit. However clear differences were also observed in the effects of MO between the two species, including modulation of the heel-MG extensor response in spinalized animals, which in rabbit was inhibited by MO application to the ipsilateral toes whereas in the rat no inhibition by MO was found in spinalized animals. Sensitization of hindlimb reflexes by MO in the rat therefore seems to be influenced by descending inhibitory and facilitatory pathways. These influences were further investigated in subsequent studies. Whilst the predominant effect of spinalization was a loss of inhibition and an expansion of sensitization fields, in the toes-evoked TA reflex the reverse was noted with regard to MO treatment of distal ipsilateral sites. In this case, facilitation found in non-spinal animals did not occur in the equivalent spinalized cohort, and thereby implies that a descending facilitatory pathway is also implicated in the control of spinal reflex excitability in this model. In decerebrate rats, the noradrenergic α2-adrenoceptor antagonist RX 821002 or the serotonergic 5-HT3 receptor antagonist ondansetron were administered directly to the spinal cord (intrathecally, i.t.) either alone (dose-response studies) or as a single dose between two successive MO applications to one of three ipsilateral skin sites on the hindlimb (heel, metatarsophalangeal joints or flexion of the ankle). Cumulative i.t. doses of RX 821002 revealed the presence of tonic descending inhibition of all reflex responses as well as preventing MO-evoked inhibition (and possibly facilitation) of reflex responses suggesting the involvement of the α2-adrenoceptor subtype in mediating these effects in this model. On the other hand, cumulative i.t. ondansetron administration resulted in a decrease in the magnitude of reflex responses, thus indicating that 5-HT3 receptors are indeed implicated in tonic descending facilitation of spinal reflexes. In addition i.t. ondansetron revealed that potentiation (and possibly inhibition) of reflexes following an acute chemogenic insult appears to involve the actions of serotonin at 5-HT3 receptors in the spinal cord. These studies therefore show that the organization of sensitization of hindlimb reflexes in the rat are modulated by supraspinal influences that exist as a balance of descending facilitatory and inhibitory pathways, mediated at least in part by serotonergic 5-HT3 receptors and noradrenergic α2-adrenoceptors.

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Calatayud, Robert Sara. "Modular evolution of domain repeat proteins. Metal-binding and domain repeats of Metallothioneins in molluscs and chordates." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673942.

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Proteins are composed of domains, a well-defined region within a protein that constitutes a stable, independently folding, compact structural unit, and that usually performs a specific function. During protein evolution, domains have been used as a ‘modules’, and the vast majority of the current proteins show a modular organization in which two or more domains are combined. While the creation of multi-domain proteins through shuffling different domains has been studied extensively, the evolution of proteins made of tandem repeats of a same domain has been less investigated. It is known, for instance, that the fraction of proteins with domain repeats is higher in multicellular organisms than in unicellular organisms, or that proteins with domain repeats seem to be related with stress response functions or with the acquisition of high yielding capacity, but the origin, the genetic mechanisms and the evolutionary forces controlling the expansion of domains repeats in modular proteins are still poorly understood. To investigate the functional and structural evolution of modular proteins with domain repeats, we have chosen the Metallothioneins (MTs) as a case study. MTs are present across all the tree of life and due to their metal-binding ability have been involved in metal homeostasis and detoxification of many organisms. They are modular cysteine-rich proteins that bind metal ions through functionally and structurally independent domains that form metal-thiolate clusters. Many MTs are bi-modular proteins made of a tandem repetition of two similar (although not identical) metal-binding domains. There also are large multi-modular MTs that have expanded the number of their domain repeats, and therefore, their metal-binding capacity. Studying the evolution of metallothionein domains in several phyla can help us to understand, at some level, the evolvability of organisms to adapt to new environmental conditions. In our studies we have identified, analysed, characterized and compared many MTs from different groups of selected organisms (chordates and molluscs) in order to study their domain composition and arrangement, and to untangle the evolution of their modular organization.
Las proteínas están compuestas por dominios, una región bien definida dentro de una proteína que constituye una unidad estructural compacta, estable y que se pliega independientemente, y que normalmente realiza una función específica. Durante la evolución de las proteínas, los dominios se han utilizado como "módulos", y la gran mayoría de las proteínas actuales muestran una organización modular en la que se combinan dos o más dominios. Si bien la creación de proteínas de múltiples dominios mediante la combinación aleatoria de diferentes dominios se ha estudiado ampliamente, la evolución de proteínas compuestas de repeticiones en tándem de un mismo dominio se ha investigado menos. Se sabe, por ejemplo, que la fracción de proteínas con dominios repetidos es mayor en organismos multicelulares que en organismos unicelulares, o que las proteínas con dominios repetidos parecen estar relacionadas con funciones de respuesta al estrés o con la adquisición de una alta capacidad productiva, pero el origen, los mecanismos genéticos y las fuerzas evolutivas que controlan la expansión de las repeticiones de dominios en las proteínas modulares aún son poco conocidos. Para investigar la evolución funcional y estructural de las proteínas modulares con dominio repetido, hemos elegido las metalotioneínas (MT) como caso de estudio. Los MT están presentes en todo el árbol de la vida y, debido a su capacidad de unión a metales, han estado involucrados en la homeostasis de metales y la desintoxicación de muchos organismos. Son proteínas modulares ricas en cisteína que se unen a iones metálicos a través de dominios funcional y estructuralmente independientes que forman grupos de tiolatos metálicos. Muchos MT son proteínas bimodulares hechas de una repetición en tándem de dos dominios de unión a metales similares (aunque no idénticos). También hay grandes MT multimodulares que han ampliado el número de repeticiones de su dominio y, por lo tanto, su capacidad de unión a metales. El estudio de la evolución de los dominios de las metalotioneínas en varios filos puede ayudarnos a comprender, hasta cierto punto, la capacidad de evolución de los organismos para adaptarse a nuevas condiciones ambientales. En nuestros estudios hemos identificado, analizado, caracterizado y comparado muchos MT de diferentes grupos de organismos seleccionados (cordados y moluscos) para estudiar la composición y disposición de sus dominios y desentrañar la evolución de su organización modular.

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Chitheer, T. "Eco-evolutionary feedback in fish-zooplankton communities on the Scottish island of North Uist." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/51741/.

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‘Eco-evolutionary feedbacks’ occur when evolution of organismal traits causes environmental change that drives further evolution. Predator and prey interactions provide good examples of eco-evolutionary feedbacks. Here I examine the potential for eco-evolutionary feedbacks between three-spined sticklebacks (Gasterosteus aculeatus, hereafter ‘stickleback’) and their zooplankton prey in lochs (lakes) on the Scottish island of North Uist. Many lochs on the island were colonised by sticklebacks after the last glaciation, approximately 10,000-15,000 years ago. Previous work has shown that sticklebacks in different lochs have diverged greatly from each other in response to local environments. On the other hand, apart from several very old studies on the occurrence of some zooplankton species, there have been no previous in depth studies on the population dynamics of zooplankton on North Uist. I investigated first the diversity and abundance of zooplankton groups and the most common species across all North Uist lochs. Thirty-nine species were classified from three main groups (Rotifera, Cladocera and Copepoda). Species abundance in the presence of fish was relatively more even, while the abundance of zooplankton groups was not generally related to fish presence except for Cladocera in a subset of locations. The effects of predation on the life-history of zooplankton were also examined by comparing reproductive traits of the dominant cladoceran species (Bosmina and Daphnia) in lochs with and without fish. Cladocerans in lochs with fish have more rapid reproductive cycles and higher fecundity parameters, probably in response to the increased threat of predation. These effects remain evident in Bosmina after they have been raised through three generations in the laboratory, supporting the hypothesis that they have a genetic basis and are not a plastic response to predator presence. Life-history variables of cladocerans were also related to abiotic and biotic variation among lochs, including depth, pH, chlorophyll levels and the concentration of alkaline metals. I also demonstrate that stickleback have diversified greatly among lochs in functional trophic traits that determine the efficiency of feeding on different types of prey, which could affect total primary production and the structure of prey communities. Ancestral stickleback populations have adapted according to the type of habitat colonised. Fish feed on benthic prey in shallow lochs, which requires greater effort for successful foraging than that required by fish that feed on planktonic prey. I found that variation in stickleback trophic traits was related to both abiotic and biotic variation among lochs, including loch depth and the mean contributions of planktonic and benthic prey to diet. The results presented in this thesis suggest the possibility of eco-evolutionary feedbacks in these simple ecosystems on North Uist based on the significant responses in fish and zooplankton communities. The thesis also provides a basis for further studies on fish-zooplankton interactions on North Uist and contributes to the wider body of knowledge concerning the relevance of natural variation in shaping the foraging mechanisms of animals.

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Manenti, R. "DEVELOPMENT OF THE LARVAL PERIPHERAL NERVOUS SYSTEM IN THE ASCIDIAN CIONA INTESTINALIS: ROLE OF THE RETINOIC ACID AND FGF/WNT SIGNALLING PATHWAYS AND OF THE POU TRANSCRIPTION FACTORS." Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150061.

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The research presented in this document focuses on the development of the larval peripheral nervous system of the Tunicate Ciona intestinalis with two main aims: a) to understand how the interactions between Retinoic Acid (RA) and the FGF/WNT pathways control its development; b) to study the role played by transcription factors of the POU family in its differentiation. Within chordates, tunicates represent the sister group of vertebrates and their larvae have a typical chordate body plan. Notably, larval nervous system is formed by few cells whose organization mirrors that of vertebrates. For these reasons the species C. intestinalis, whose genome is completely sequenced, is a good animal model often used to understand the basic mechanisms of Chordate development. POU genes are an important family of transcription factors with several members that regulate the neural patterning and differentiation in both vertebrate and invertebrate embryos. C. intestinalis has only three genes coding for POU transcription factors: Ci-POU-2 Ci-POU-IV and Ci-POU-like. The gene Ci-POU-IV is specifically expressed in all peripheral nervous system (PNS) territories and in some cells of the central nervous system (CNS) during development. Since the expression of the two other genes was not previously studied in detail, a part of this research consisted in their characterization. Several experiments of in situ hybridization showed that the transcripts of Ci-POU-2 are present early during cleavage stages while Ci-POU-like gene expression is restricted to the lateral mesenchime cells of the larva and to their precursors during embryonic development. Thus the research was focused on the Ci-POU-IV gene. Its expression had been formerly studied by the research team of Prof. De Bernardi that discovered the existence of two alternative transcripts. In order to study the role that they play in neural differentiation Morpholino oligos were designed to perform gene knock-down experiments for the two different isoforms. The results from these experiments revealed that the expression of the serotonin rate-limiting synthesis enzyme, tryptophane hydroxylase (TPH), and glutamate transporter (vGlut) in the PNS neurons could be regulated by the product of the long transcript. To verify if the alternative transcripts were expressed in different PNS neuron populations in situ hybridizations were performed with a probe selective for the short isoform. These in situ hybridizations, compared to the whole expression profile of Ci-POU-IV, showed a lack of expression of the short form in the sensory epidermal neurons of the trunk. Moreover experiments were performed to understand the relationship between Ci-POU-IV and the Delta/Notch pathway. The latter has an important role in determining the cell to cell interactions in a number of taxa and to affect the neural or the epidermal fate of the PNS precursors. The Delta/Notch pathway was inhibited both using DAPT that inhibits the –secretase, responsible of the correct functioning of the pathway and electroporing the pFOG::VeSu(H)DBM construct that blocks the pathway activity. Embryos treated showed an abnormal development of epidermic sensorial neurons and the following in situ hybridizations for Ci-POU-IV pointed out an ectopic expression of the gene. Furthermore the study looked for the Ci-POU-IV targets in order to identify the genes regulated by Ci-POU-IV during the PNS differentiation. A bioinformatic approach was used. The possible consensus sequences were obtained by bibliographic research of those known for the POU IV family in both invertebrates and vertebrates. These sequences have been used to build a matrix that was employed to perform a bioinformatic research in the whole C. intestinalis genome with a software elaborated by the Lemaire team of the IBDML of Marseille. The search identified 19 possible targets of Ci-POU-IV; 8 regions, corresponding to 6 genes including TPH, have been preliminary selected. The activity of the selected regions is being evaluated. The second part of the thesis has been developed during a period of research with Dr. A. Pasini at the Institut de Biologie du Développent of Marseille. The aim was to identify the mechanisms with which RA and the FGF/WNT pathways act on antero-posterior differentiation of PNS during C. intestinalis embryonic development. In vertebrates it was already known that during the antero-posterior extension of the body axis these pathways antagonize each other to coordinate mesoderm and nervous system differentiation. For this reason the hypothesis that an analogous mechanism could occur in other Chordates, including tunicates was tested. Thus in C. intestinalis I performed in situ hybridizations for different genes potentially involved in this mechanism. I employed also the electroporation technique with specific constructs. In particular results showed that the expression of the gene Ci-Raldh that codes for Retinaldehyde dehydrogenase, the enzyme responsible of RA synthesis, is confined to the anterior part of the tail in tailbud stage embryos. To this region is limited also the expression of some gene responsive to RA such as Ci-Hox-1 and Ci-Cyp26. On the contrary, at the posterior extremity of the tail it is predictable the existence of a source of FGF and WNT signals as shown by the expression of Ci-FGF-8 and Ci-WNT-5. Moreover, embryos treated with RA showed Ci-Hox-1 up-regulation at throughout tail epidermis and the inhibition of the posterior Ci-Hox-12 expression. On the contrary, embryos treated with FGF showed an opposite situation with Ci-Hox-12 activation and Ci-Hox-1 inhibition. Moreover, quantifications of differentiated caudal epidermal neurons and meticulous analysis of their position along the tail have been performed in late stage embryos treated with RA, FGF, their respective inhibitors and an inhibitor of the enzyme Ci-Cyp26, responsible for RA catabolism. This showed significant alterations in both the number of neurons and their position. In particular RA treatment increased the oveall number of caudal epidermal neurones but causes the loss of the most posterior ones; on the contrary FGF treatment induced a decrease in the number of neurons but maintained the posterior ones. Treatment with FGF and Ci-Cyp26 inhibitors mimicks the effects of RA while treatment with RA synthesis inhibitor mimicks the effect of FGF. On the whole a complex picture of antagonistic interactions, both direct and indirect has been revealed posing interesting questions from an evolutionary point of view.

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Vandenberghe, Amanda. "Characterization of the troponin I gene of the ascidian Ciona intestinalis, evidence for mRNA 5' leader trans-splicing in the chordates." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0032/MQ64472.pdf.

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Campo-Paysaa, Florent. "Evolution du développement chez les Chordés : une histoire d'acide rétinoïque, de gènes hox et de microARNs." Thesis, Lyon, École normale supérieure, 2011. http://www.theses.fr/2011ENSL0653.

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Le but de toute étude en biologie évolutive du développement est l’étude des mécanismes développementaux à l’origine des diversifications morphologiques. Dans ce contexte, j’ai décidé de me focaliser sur l’émergence des Vertébrés au cours de l’évolution, par la mise en œuvre d’études comparatives entre différents modèles de Deutérostomiens. Le travail réalisé durant ma thèse est subdivisé en trois projets: (i) j’ai abordé le lien entre l’évolution du cerveau chez les Chordés et les modifications de la signalisation à l’acide rétinoïque (AR) au cours du développement. En particulier, j’ai examiné les rôles de l’AR au cours du développement du cerveau chez la lamproie Lampetra fluviatilis, et j’ai comparé les résultats obtenus chez cette espèce aux mécanismes développementaux agissant chez l’amphioxus, un Chordé invertébré, et chez les modèles gnathostomes classiques. Les données obtenues lors de ces analyses comparatives ont permis une meilleure compréhension de l’évolution de la régionalisation cérébrale chez les Vertébrés. (ii) j’ai étudié l’évolution des séquences régulatrices présentes au sein des clusters de gènes hox, connus pour agir dans la régionalisation du système nerveux des Chordés. L’identification d’éléments non-codants conservés ainsi que d’éléments de réponse à l’AR (RARE) potentiels dans des clusters hox de Chordés, combinée à la caractérisation de RAREs in vivo en cellules murines a permis une vision intégrée de l’évolution du contrôle des gènes hox par l’AR, chez les Chordés. (iii) j’ai analysé l’évolution des microARNs chez les Chordés en comparant les répertoires microARN chez plusieurs espèces de Deutérostomiens. Cette étude a permis d’émettre de nouvelles hypothèses quant à l’émergence des microARNs chez les animaux. Toutes ces analyses ont abordé différents aspects de l’évolution des Chordés avec pour objectif la proposition d’une vision intégrée des mécanismes moléculaires à l’origine de l’émergence des Vertébrés
The aim of the evolutionary developmental biology is to study the developmental mechanisms at the base of morphological diversification. In this context, I decided to focus my attention on the emergence of vertebrates during evolution by carrying out comparative analyses in several deuterostome models. The work carried out during of my thesis can be subdivided into three major projects: (i) I addressed the link between brain evolution and modifications in retinoic acid (RA) signaling during chordate development. In particular, I investigated the roles of RA signaling in brain development in a jawless vertebrate, the lamprey Lampetra fluviatilis, and compared the results with developmental mechanisms in the invertebrate chordate amphioxus and classical developmental model systems in jawed vertebrates. Data obtained from these comparative studies provided insights into the evolution of brain patterning in vertebrate evolution. (ii) I investigated the evolution of the regulatory landscape of hox gene clusters that are known to be fundamental for the patterning of the chordate central nervous system. The identification of conserved non-coding elements and putative RA response elements (RAREs) in hox clusters of different chordate species combined with the in vivo characterization of functional RAREs in mouse F9 cells provided an integrated view of the evolution of RA-dependent hox cluster regulation in chordates. (iii) I studied the roles of microRNAs (miRNAs) in chordate evolution by comparing the miRNA complements of different deuterostome species. This analysis provided novel insights about the general mechanisms of miRNA emergence in animals and highlighted species-specific miRNA complement amplifications in different deuterostome lineages. In sum, these studies have tackled different aspects of chordate evolution from an evo-devo perspective, aiming at an integrated view of the molecular mechanisms underlying vertebrate diversification

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Osborne, Peter Wayne. "Evolution of Chordate ParaHox Gene Regulation." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504446.

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Dehal, Paramvir Singh. "Comparative evolutionary analysis of chordate genomes /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.

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Pickup, Nicola Jane. "Cis-regulatory evolution in a chordate genome." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497071.

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Braun, Katrin. "Comparative study on the nervous system of Tunicata to elucidate tunicate phylogeny and character transformations." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19930.

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Tunicata umfasst 3000 marine Arten, mit sehr unterschiedlichen Lebensstrategien. Als eines der drei großen Taxa innerhalb der Chordata, stellt die Evolution der Tunikaten eine Schlüsselkomponente bei der Aufklärung der Evolution der Chordaten und Cranioten dar. Dafür ist ein Verständnis der Merkmalstransformationen innerhalb der Tunikaten notwendig. Leider sind die internen Verwandtschaftsverhältnisse der fünf großen Tunikatentaxa in verschiedenen molekularphylogenetischen Studien widersprüchlich. Bisher gibt es nur wenige morphologische phylogenetische Analysen. Ein Schwerpunkt dieser Arbeit liegt auf der Untersuchung neuroanatomischer Merkmale, da das Nervensystem wahrscheinlich phylogenetische Informationen enthält. Durch das Anwenden moderner morphologischer Methoden, wie hochauflösende konfokale Laserscan- und Elektronenmikroskopie (REM und TEM), und 3d Rekonstruktionen basierend auf lichtmikroskopischen Schnitten, wurde die Verfügbarkeit neuroanatomischer Daten wesentlich verbessert. Die Ergebnisse zeigen, dass die Variation neuroanatomischer Merkmale größer ist als bisher angenommen und dass sich die Gehirnanatomie und die Verteilung von Neurotransmittern in den zwei Stadien der Thaliaceen unterscheidet. Neue unabhängige Merkmale des Nervensystems wurden in einer Matrix kodiert. Ergänzt mit traditionellen in der Tunikatentaxonomie verwendeten Merkmalen, entstand die bisher umfangreichste morphologische Datenmatrix, die 116 Merkmale für insgesamt 54 Arten umfasst. Die kladistische Analyse ergab monophyletische Tunicata, in denen die Appendicularia die Schwestergruppe der übrigen Tunikaten bildet. Ascidiacea ist monophyletisch, während „Thaliacea“ paraphyletisch ist. Zusätzlich wurde eine kombinierte phylogenetische Analyse basierend auf den morphologischen Daten und 18S rDNA-Sequenzen durchgeführt. Eine stufenweise stärkere Gewichtung phänotypischer Merkmale zeigt, dass die morphologischen Daten das Ergebnis der kladistischen Analyse stark beeinflussen.
Tunicata comprises 3000 marine species with diverse life-history strategies. As one of the three major chordate taxa, the evolution of tunicates plays a key role to elucidate chordate and craniate evolution. Therefore, a broader understanding of character transformations within tunicates is essential, but the interrelationships of the five main tunicate subtaxa in previous molecular phylogenetic analyses were contradictory. Morphological phylogenetic analyses are rare. In this comparative study emphasis was given to neuroanatomical characters, as the nervous system probably contains phylogenetic information. Applying modern morphological techniques like high-resolution confocal laser scanning microscopy and electron microscopy (SEM and TEM), serial sectioning for light microscopy, and digital 3d reconstruction, the number of available tunicate neuroanatomical data was considerably increased. It was revealed that the variation of neuroanatomical characters is higher than previously assumed, a specific pattern of serotonin-like immunoreactive cells in ascidians is present, and that brain anatomy and distribution of neurotransmitters in the two thaliacean life-cycle stages differs. Novel independent characters of the central nervous system were coded in a matrix for a cladistic analysis. Including traditional morphological from tunicate literature this effort resulted in the largest morphological data matrix to date, containing 116 phenotypic characters and 54 species. The cladistic analysis resulted in monophyletic Tunicata, with Appendicularia the sister taxon to the remaining tunicates. Furthermore, the monophyly of Ascidiacea is supported, whereas “Thaliacea” are paraphyletic. An additional phylogenetic analysis combining morphological and 18S rDNA-sequence data was performed. A reevaluation of this dataset with a successively increased weighting of the phenotypic data showed that morphological data strongly influence the outcome of the cladistic analysis.

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Godin, Isabelle. "Etude des catécholamines chordales chez les embryons d'Amphibiens anoures." Bordeaux 1, 1986. http://www.theses.fr/1986BOR10536.

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Godin, Isabelle. "Etude des catécholamines chordales chez les embryons d'amphibiens anoures." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375979398.

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Garstang, Myles Grant. "The evolution and regulation of the chordate ParaHox cluster." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/11788.

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The ParaHox cluster is the evolutionary sister of the Hox cluster. Like the Hox cluster, the ParaHox cluster is subject to complex regulatory phenomena such as collinearity. Despite the breakup of the ParaHox cluster within many animals, intact and collinear clusters have now been discovered within the chordate phyla in amphioxus and the vertebrates, and more recently within the hemichordates and echinoderms. The archetypal ParaHox cluster of amphioxus places it in a unique position in which to examine the regulatory mechanisms controlling ParaHox gene expression within the last common ancestor of chordates, and perhaps even the wider Deuterostomia. In this thesis, the genomic and regulatory landscape of the amphioxus ParaHox cluster is characterised in detail. New genomic and transcriptomic resources are used to better characterise the B.floridae ParaHox cluster and surrounding genomic region, and conserved non-coding regions and regulatory motifs are identified across the ParaHox cluster of three species of amphioxus. In conjunction with this, the impact of retrotransposition upon the ParaHox cluster is examined and analyses of transposable elements and the AmphiSCP1 retrogene reveal that the ParaHox cluster may be more insulated from outside influence than previously thought. Finally, the detailed analyses of a regulatory element upstream of AmphiGsx reveals conserved mechanisms regulating Gsx CNS expression within the chordates, and TCF/Lef is likely a direct regulator of AmphiGsx within the CNS. The work in this thesis makes use of new genomic and transcriptomic resources available for amphioxus to better characterise the genomic and regulatory landscape of the amphioxus ParaHox cluster, serving as a basis for the improved identification and characterisation of functional regulatory elements and conserved regulatory mechanisms. This work also highlights the potential of Ciona intestinalis as a ‘living test tube' to allow the detailed characterisation of amphioxus ParaHox regulatory elements.

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Roca, Marianne. "The spindle assembly checkpoint in Phallusia mammillata embryos." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS500.

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Le point de contrôle du fuseau mitotique (Spindle Assembly Checkpoint : SAC) retarde l’anaphase jusqu’à ce que tous les chromosomes soient attachés correctement aux microtubules. Le SAC permet ainsi d’éviter des erreurs de ségrégation des chromosomes aboutissant à des cellules filles aneuploïdes (i.e. avec un nombre anormal de chromosomes). L’aneuploïdie, délétère pour les cellules, peut entrainer des problèmes de développement et est observée dans les cancers. Cependant, chez certaines espèces, le SAC n’est pas efficace au cours de la phase précoce du développement embryonnaire. J’ai mis en évidence que chez l’ascidie P. mammillata, un organisme marin du groupe des chordés, le SAC devient efficace au 8ème cycle cellulaire et son efficacité augmente dans les cycles suivants. J’ai démontré qu’en partie ventrale l’identité des cellules antérieures induisait la présence d’un SAC plus efficace mais que d’autres facteurs modulaient aussi l’efficacité du SAC. J’ai étudié les mécanismes moléculaires impliqués dans les variations de l’efficacité du SAC au cours du développement. Mes expériences ont révélé la présence des composants du SAC tout au long de l’embryogenèse. Cependant, j’ai pu montrer que les protéines du SAC ne se localisent pas au niveau des kinétochores lorsque le SAC est inefficace au début du développement mais qu’elles s’y localisent bien dans l’ovocyte en méiose et dans l’embryon plus tardif, lequel se caractérise par un SAC actif. Ma thèse a permis de montrer que P. mammillata est un organisme expérimental de grand intérêt pour l’étude du SAC au cours de l’embryogenèse
During mitosis, progression through anaphase must take place only when all chromosomes are correctly attached to spindle microtubules to avoid chromosome mis-segregation and the generation of aneuploid cells (i.e. with an abnormal chromosome number). Embryos containing aneuploid cells can exhibit developmental defects and lethality. Furthermore, cancer cells are often aneuploid. To prevent such deleterious aneuploidy, a control mechanism, the spindle assembly checkpoint (SAC), delays metaphase-anaphase transition until all chromosomes are properly attached to spindle microtubules. However, the SAC is not efficient during early development in some species. During my thesis, I analyzed the activity of the SAC during the development of the marine chordate P. mammillata. I showed that in P. mammillata embryos, the SAC becomes efficient at the 8th cell cycle and its efficiency increases progressively in the following cell cycles. Although, I demonstrated that patterning of the embryo along the anteroposterior axis influences SAC efficiency, my experiments suggest that additional parameters modulate SAC efficiency. I searched the molecular mechanisms, which control SAC efficiency during development. I collected evidence showing that SAC components are present in oocytes and all post-fertilization stages. I found that SAC proteins localize at kinetochores during meiosis and at later stages when there is an efficient SAC while they do not accumulate on unattached kinetochores in early SAC deficient embryos. My thesis work establishes P. mammillata as a valuable experimental organism to study SAC regulation during embryogenesis

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Furlong, Rebecca Felicity. "Were vertebrates octoploid? : a molecular phylogenic analysis of chordate evolution." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272243.

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Coppola, Ugo. "Evolutionary and developmental survey of genes involved in chordate pigmentation." Thesis, Open University, 2018. http://oro.open.ac.uk/53927/.

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The pigmentation represents one of the most interesting topics in animal life because it is a decisive factor for the evolutionary success and the conquest of new ecological niches. Through the combination of developmental biology and comparative genomics, some aspects of pigmentary dynamics have been studied. Given Rabs regulate a plethora of trafficking steps, the members belonging to this family are central to the transport of molecules involved in pigmentation. Moreover, comprehending the evolution of Rab family is relevant to understand the establishment of eukaryotic cellular organization and for its implication in many human pathologies. For the first time, I reconstructed the evolutionary scenario of Rab family in eleven species of metazoans, spanning from cnidarians to human. Phylogeny, intron code and synteny conservation prompted me to depict Rab evolution, with a special focus on chordates that exhibit a highly dynamic evolutionary pattern. I clarified the evolution of Rab32/38 subfamily, fundamental in regulation of trafficking related to melanogenesis. It has been clarified the evolutionary history of Rab32/38 genes in deuterostomes and the expression pattern in key species as zebrafish and amphioxus, demonstrating how events as whole-genome duplications have influenced their role during embryogenesis. In order to find new genes involved in pigmentation, I analyzed a Kelch-like member in ascidian Ciona robusta (Cr-Klhl21). My results point at this gene as a marker of pigmented cells, with a dynamic expression profile during embryogenesis: from middle tailbud stage, it is expressed specifically in the otolith. Moreover, Cr-Klhl21 shows an intricate regulatory scenario with the possible intervention of a transcription factors combination (Cr-Mitf, Cr-msxb, Cr-Dmrt). This work contains first data about a Kelch-like member in ascidians, providing new insights in pigmentation or pigment cell specification. This encourages further analyses on its gene regulatory network and possible function.

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Bonnet, Nadia Yukiji Koto. "Taxonomia e filogenia de ascidiidae (Chordata, Tunicata)." reponame:Repositório Institucional da UFPR, 2010. http://hdl.handle.net/1884/24079.

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Resumo: A família Ascidiidae faz parte da ordem Phlebobranchia e é formada por organismos solitários, com musculatura principalmente do lado direito do corpo e nos sifões, tentáculos simples, lâmina dorsal completa, faringe sem pregas, fendas faríngeas retilíneas e tubo digestivo do lado esquerdo do corpo, com as gônadas associadas ao mesmo. Tradicionalmente, há três gêneros em Ascidiidae: Ascidia Linnaeus, 1767, Phallusia Savigny, 1816 e Ascidiella Roule, 1883. Os três compartilham os caracteres acima descritos, sendo que Phallusia possui ainda aberturas acessórias ao tubérculo dorsal e Ascidiella apresenta papilas sustentando os vasos longitudinais da faringe sem projetar-se no lúmen da faringe. Devido ao fato de que as aberturas acessórias de Phallusia só são conspícuas com a retirada da faringe, historicamente espécies de Ascidia e Phallusia vêm sendo confundidas. Assim, o objetivo geral do trabalho é fazer uma revisão taxonômica de algumas espécies de Ascidiidae, com a redescrição completa das mesmas, além de testar a validade filogenética do gênero Ascidia. Foram observados 344 exemplares, de 26 espécies diferentes, sob microscópio esteroscópico. As estruturas internas foram evidenciadas com corante Hematoxilina de Harris e desenhos de espécies novas feitos em câmara clara. Posteriormente, os dados morfológicos foram utilizados na reconstrução de Ascidia, tendo como grupos-externos espécies de Ascidiella, Phallusia, Rhodosoma e Ciona. A matriz foi criada em NDE e a análise rodada em PAUP* 4.0b10, com busca heurística, TBR, sem limite de árvores, caracteres não-ordenados, pesagem implícita de caracteres, olapsamento dos ramos com comprimento zero e a história dos caracteres foi traçada em ACCTRAN. Apesar dos baixos índices de consistência encontrados, pode-se afirmar que Ascidiidae constitui um táxon filogeneticamente válido, porém Ascidia não forma um ramo monofilético, com Phallusia e Ascidiella inseridos no clado. Além do mais, Phallusia tampouco apresenta monofilia, tendo mais de uma origem ao longo da evolução. Estes resultados devem ser contrastados com outros gerados por sistemática molecular em busca de congruências, e, se houver a corroboração da hipótese aqui proposta, pode-se inferir que Ascidiidae atualmente é composta por um único gênero – Ascidia –, havendo a necessidade de realizar uma revisão da classificação da família.

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Lotufo, Tito Monteiro da Cruz. ""Ascidiacea (Chordata: Tunicata) do litoral tropical brasileiro"." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-21052002-125049/.

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Embora tenham sido muito estudadas em diversos pontos do globo, as ascídias do litoral brasileiro são pouco conhecidas. A maior parte do litoral brasileiro está incluída na região tropical, para qual as informações são mais escassas. Com o intuito de se conhecer a fauna de ascídias do litoral tropical brasileiro foram realizadas diversas coletas em diferentes pontos desta região, abrangendo desde a zona entremarés até o infralitoral raso. Outro objetivo do presente trabalho foi o de organizar as informações já existentes a partir de revisão bibliográfica e visitas a algumas instituições que continham coleções representativas. Foram realizadas ao todo 61 coletas em pontos distribuídos entre os estados do Rio de Janeiro, Espírito Santo, Bahia, Alagoas, Pernambuco, Paraíba, Rio Grande do Norte e Ceará. Os animais foram coletados, examinados e identificados até o nível de espécie. Para cada espécie se procurou fazer um extensa revisão taxonômica, tanto a partir da literatura como do exame de tipos depositados em diferentes instituições. O presente trabalho inclui listas sinonímicas, descrições e comentários para cada espécie estudada, com fotografias para a maior parte. Foram adicionadas ainda chaves dicotômicas para todos os táxons, em todas as categorias. Até a realização deste trabalho, 90 espécies de ascídias haviam sido registradas no litoral brasileiro, das quais 54 estão listadas para o estado de São Paulo. Com a realização das campanhas de coletas foram identificadas 67 espécies que, juntamente com uma revisão criteriosa da literatura e o exame de vários tipos e outros exemplares de outras regiões do mundo, fizeram com que a lista atualizada inclua 98 espécies. Estas espécies estão distribuídas entre as 2 ordens e 3 subordens da classe, com um total de 31 gêneros incluídos em 14 dentre as 23 famílias propostas atualmente. Como resultado imediato foram registradas 9 novas ocorrências para o litoral brasileiro, com a descrição de 1 gênero e 10 espécies novas. Além disso, 8 espécies tiveram sua situação alterada por sinonimia ou separação. Juntamente com outros dados da literatura, as tabelas de ocorrências foram submetidas a uma análise de agrupamento e uma análise de endemicidade por parcimônia. As análises evidenciaram um padrão de distribuição semelhante àquele observado para outros grupos bentônicos sésseis, com a divisão da região estudada em duas províncias, a Província Brasileira e a Província Paulista.
Although ascidians are well known in many regions of the globe, information about the group on Brazilian coast are very scanty. Most of the Brazilian coastline is included on the tropical region, which is the poorest known. In order to obtain an inventory of ascidians species on the Brazilian tropical coast, surveys were conducted in different points, ranging from the intertidal to the shallow subtidal depths. Another goal of the present work was to organize all available information through a revision of bibliography and visits to institutions that held representative collections. 61 visits were conducted in places along the coast of the states of Rio de Janeiro, Espírito Santo, Bahia, Alagoas, Pernambuco, Paraíba, Rio Grande do Norte e Ceará. Specimens were collected, examined and identified to the species level. An extensive taxonomic revision was made for every species, by means of literature as well as examination of types and other specimens deposited in different institutions. The present work includes synonymy lists, descriptions, pictures and remarks for each species studied. Keys for all taxa an every category were also included. Up to the present work, 90 species of ascidians had been recorded for Brazil, of which 54 are listed to the State of São Paulo. The surveys revealed a total of 67 species, expanding the list to 98 Brazilian species. Those species are distributed in 2 orders and 3 suborders of the class, with a total of 31 genera included in 14 of the 23 families currently accepted. As an immediate result, were registered 9 new records for Brazilian coast, along with the description of 1 new genus and 10 new species. Furthermore, 8 species have had its taxonomic situation altered by synonymy or separation. The present results, together with data from literature generated tables which were submitted to cluster analysis and a parsimony analysis of endemycity. These analyses revealed a distribution pattern similar to others observed for different benthic taxa. The region studied comprises two provinces, Brazilian Province and Paulista Province.

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Anselmi, Chiara. "Cyclical neurogenesis and neurodegeneration in the colonial tunicate Botryllus schlosseri." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425901.

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In this work, we studied the nervous and sensory system of the colonial ascidian Botryllus schlosseri during the development of embryos, buds, and in adult individuals belonging to young and old colonies. B. schlosseri is a colonial ascidian in which individuals (blastozooids) are organized in star-shaped systems. In a colony, sexual and asexual reproductions are coordinated and cyclical. Moreover, three generations of zooids coexist: adults (filter-feeding individuals), their buds (primary buds), and the budlets (secondary buds) produced by buds. Cyclically, during a phase called takeover, adult zooids are reabsorbed by the colony and are replaced in physiological activities by their buds that become adults. Cuncurrently, budlets mature into buds and produce a new generation of budlets. We first reviewed historical studies concerning B. schlosseri with the intent of characterizing the colony life cycle and bud development. We then compared nervous system formation in two different developmental pathways, embryogenesis and blastogenesis. Since B. schlosseri has internal fertilization and development, we developed a method for culturing embryos in vitro. Using a combination of in vivo, confocal, histological observations, and 3D reconstructions based on serial sections, we described the embryonic development and drafted a timetable. Next, we sequenced transcriptomes of embryos and buds at several stages and illuminated the strict temporal relationship between morphogenetic events and the expression pattern of genes associated with the nervous system during the formation of the larval brain, its degeneration at metamorphosis, the adult brain formation in embryo and bud, and its degeneration at takeover. We also studied the nervous system in adult individuals belonging to colonies of different ages. We observed that the number of brain cells changes throughout the adult zooid life following a specific trend. Transmission electron microscopy and TUNEL assays on adult brains showed that apoptosis is involved in neurodegeneration and the number of immunocytes contacting or infiltrating the brain increase in number during the adult life. Changes in brain cell number parallel changes in sensory cell number. We developed two novel behavioural experiments for B. schlosseri, which showed that zooid ability to respond to mechanical stimuli parallels changes in the number of brain and sensory cells. Then we compared adult individuals belonging to young and old colonies and found that aging influences both nervous system morphology and behaviour. We analysed differentially expressed genes in brains of individuals belonging to young and old colonies and found that the old colonies exhibit a gene pattern associated with several human neurodegenerative diseases, such as the Alzheimer’s disease. Finally, we studied, the coronal organ, a mechanoreceptor located on the tentacles, in the oral siphon. We analysed its cytodifferentiation during asexual reproduction and we documented the mechanosensorial impairment caused by gentamicin at morphological and behavioural level. In mammals gentamicin can destroy both hair cells and their innervating neurons. The pre-treatment with fenofibrate, a gentamicin protector, followed by a treatment with gentamicin, resulted in no significant effect on animal behaviour. These results support the hypothesis of homology between vertebrate hair cells and tunicate coronal sensory cells. In conclusion, the research presented here shows that B. schlosseri can be considered a useful model species for analysing the development of the central nervous system and sensory system, as well as its degeneration as caused by drugs, metamorphosis, takeover and aging. Additionally, the species’ different developmental pathways allow for interesting evolutionary comparisons, at both the morphological and molecular level, that can help improve scientific understanding of the origin of the animal phenotype.
Nel presente lavoro, ho studiato il sistema nervoso e sensoriale dell'ascidia coloniale Botryllus schlosseri durante lo sviluppo dell’embrione, delle gemme e degli individui adulti appartenenti a colonie giovani e meno giovani. In B. schlosseri, gli individui (blastozooidi) sono organizzati in sistemi a forma di stella. La colonia è composta, oltre che da zooidi adulti, da gemme e gemmine che si sviluppano tramite riproduzione asessuata, o blastogenesi, rispettivamente dagli zooidi adulti e dalle gemme. Ciclicamente, durante una fase chiamata takeover (rappresentante il momento di cambio di generazione), gli zooidi adulti vengono progressivamente riassorbiti dalla colonia e sostituiti nelle loro attività fisiologiche dalle loro gemme che diventano quindi i nuovi adulti della colonia. Inoltre, durante questa fase di cambio generazionale, le gemmine maturano in gemme producendo a loro volta una nuova generazione di gemmine. Nella vita di una colonia, riproduzione sessuata e asessuata sono coordinate e cicliche. Inizialmente, ho rivisto gli studi storici riguardanti B. schlosseri con lo scopo di caratterizzare il ciclo di vita della colonia e lo sviluppo delle gemme. Ho poi confrontato la formazione del sistema nervoso nei due diversi percorsi di sviluppo che caratterizzano B. schlosseri: l'embriogenesi e la blastogenesi. Poiché la fecondazione e lo sviluppo embrionale in questa specie avvengono all’interno del corpo del genitore, ho sviluppato un metodo per coltivare gli embrioni in vitro. Integrando le osservazioni in vivo, al microscopio confocale, l’istologia e ricostruzioni 3D basate su sezioni seriali, ho descritto lo sviluppo embrionale nel tempo. Successivamente, grazie al sequenziamento di embrioni e gemme nelle diverse fasi di sviluppo, ho studiato la stretta relazione temporale presente tra gli eventi morfogenetici e il pattern di espressione dei geni associati al sistema nervoso durante la formazione del cervello nell’embrione, la sua degenerazione alla metamorfosi, la formazione del cervello adulto nella gemma, e la sua degenerazione durante il takeover. Inoltre, ho studiato il sistema nervoso durante la vita degli individui adulti e appartenenti a colonie di diversa età. A riguardo, ho osservato che il numero di cellule cerebrali cambia durante tutta la vita dello zooide adulto seguendo uno specifico trend. La microscopia elettronica a trasmissione e le analisi TUNEL sui cervelli adulti hanno dimostrato che l'apoptosi è coinvolta nella neurodegenerazione e il numero di immunociti che contattano o si infiltrano nel cervello aumentano di numero durante la vita adulta. Questi cambiamenti nel numero di cellule cerebrali sono accompagnati anche da simili variazioni nel numero di cellule sensoriali. Inoltre, ho sviluppato due nuovi esperimenti comportamentali dimostrando che la capacità degli zooidi di rispondere a stimoli meccanici è in stretta relazione con il numero di cellule cerebrali e sensoriali. In seguito, ho confrontato la morfologia del sistema nervoso ed eseguito esperimenti comportamentali in individui adulti appartenenti sia a colonie giovani sia a quelle meno giovani, rilevando che l'invecchiamento influenza entrambi questi aspetti. Infine, ho analizzato i geni differentemente espressi nei cervelli di individui appartenenti a colonie giovani e vecchie scoprendo che le vecchie colonie mostrano un modello genetico associato a diverse malattie neurodegenerative umane, come il morbo di Alzheimer. Infine, ho studiato l'organo coronale, un meccanorecettore situato sui tentacoli del sifone orale, ritenuto omologo alle cellule capellute dei vertebrati. Ho analizzato il suo citodifferenziamento durante la riproduzione asessuata e documentato il deterioramento meccanosensoriale a livello morfologico e comportamentale causato dalla gentamicina. Nei mammiferi, la gentamicina può distruggere sia le cellule capellute che i neuroni sensoriali associati. Il pre-trattamento con fenofibrato, una sostanza che protegge rispetto all’azione della gentamicina, seguito da un trattamento con gentamicina, non produceva alcun effetto significativo sul comportamento animale. Questi risultati supportano l'ipotesi dell'omologia tra cellule capellute dei vertebrati e cellule sensoriali coronali tunicate. In conclusione, la ricerca qui presentata mostra che B. schlosseri può essere considerato una specie modello utile per analizzare lo sviluppo del sistema nervoso centrale e del sistema sensoriale, così come la sua degenerazione causata da farmaci, metamorfosi, takeover e invecchiamento. Inoltre, i diversi percorsi di sviluppo della specie consentono interessanti confronti evolutivi, sia a livello morfologico che molecolare, che possono aiutare a comprendere l'origine del fenotipo animale.

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36

Virata, Michael J. "A novel invertebrate chordate model for Alzheimer's disease using the ascidian ciona intestinalis." Diss., [La Jolla, Calif.] : [San Diego] University of California, San Diego ; San Diego State University, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3372801.

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Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2009.
Title from first page of PDF file (viewed October 22, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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Gostling, Neil J. "Evolution of the chordate nervous system, and the role of the Zic gene family." Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408337.

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Bassham, Susan Lee. "Molecular embryology of a larvacean urochordate, Oikopleura dioica, and the origin of chordate innovations." Thesis, view abstract or download file of text, 2002. http://wwwlib.umi.com/cr/uoregon/fullcit?p3055666.

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Thesis (Ph. D.)--University of Oregon, 2002.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 125-138). Also available for download via the World Wide Web; free to University of Oregon users.

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39

Li, Younan. "Analysis of CREs of ETS1/2 Target Genes in the Basal Chordate Ciona Intestinalis." Thesis, The University of Arizona, 2012. http://hdl.handle.net/10150/244408.

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Fibroblast growth factor (FGF) signaling and downstream activation of the transcription factor ETS1/2 specify the heart cell lineage in the basal chordate Ciona intestinalis. Based on our previous work, 144 candidate FGF/ETS1/2 dependent heart genes have been identified from the Ciona genome. The expression of a large subset of these genes has been verified in the heart precursor lineage using in-situ techniques. Using an bio-informatic approach, we identified candidate enhancers for some of these target genes. We then tested these predicted enhancers through reporter analysis. Our results indicate that the Ets1/2 binding site GGAW and the co-motif ATTA are required for heart lineage enhancer activity. This work can help us understand the conserved, primary role of FGF/Ets in chordate heart lineage specification.

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Friis, Thor-Einar. "The ancient gene C12orf29 : an exploration of its role in the chordate body plan." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61288/2/Thor-Einar_Friis_Thesis.pdf.

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The sheep (Ovis aries) is commonly used as a large animal model in skeletal research. Although the sheep genome has been sequenced there are still only a limited number of annotated mRNA sequences in public databases. A complementary DNA (cDNA) library was constructed to provide a generic resource for further exploration of genes that are actively expressed in bone cells in sheep. It was anticipated that the cDNA library would provide molecular tools for further research into the process of fracture repair and bone homeostasis, and add to the existing body of knowledge. One of the hallmarks of cDNA libraries has been the identification of novel genes and in this library the full open reading frame of the gene C12orf29 was cloned and characterised. This gene codes for a protein of unknown function with a molecular weight of 37 kDa. A literature search showed that no previous studies had been conducted into the biological role of C12orf29, except for some bioinformatics studies that suggested a possible link with cancer. Phylogenetic analyses revealed that C12orf29 had an ancient pedigree with a homologous gene found in some bacterial taxa. This implied that the gene was present in the last common eukaryotic ancestor, thought to have existed more than 2 billion years ago. This notion was further supported by the fact that the gene is found in taxa belonging to the two major eukaryotic branches, bikonts and unikonts. In the bikont supergroup a C12orf29-like gene was found in the single celled protist Naegleria gruberi, whereas in the unikont supergroup, encompassing the metazoa, the gene is universal to all chordate and, therefore, vertebrate species. It appears to have been lost to the majority of cnidaria and protostomes taxa; however, C12orf29-like genes have been found in the cnidarian freshwater hydra and the protostome Pacific oyster. The experimental data indicate that C12orf29 has a structural role in skeletal development and tissue homeostasis, whereas in silico analysis of the human C12orf29 promoter region suggests that its expression is potentially under the control of the NOTCH, WNT and TGF- developmental pathways, as well SOX9 and BAPX1; pathways that are all heavily involved in skeletogenesis. Taken together, this investigation provides strong evidence that C12orf29 has a very important role in the chordate body plan, in early skeletal development, cartilage homeostasis, and also a possible link with spina bifida in humans.

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Cone, Angela C. "Characterization of an individual neural crest-like cell lineage in the invertebrate chordate Ciona intestinalis." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3316226.

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Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2008.
Title from first page of PDF file (viewed September 4, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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Knegt, Leonardo Victor de. "Chiroptera (Chordatta: Mammalia) capturados em Belo Horizonte, Minas Gerais, 1999 a 2003." Universidade Federal de Minas Gerais, 2003. http://hdl.handle.net/1843/BUOS-8C4EWV.

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After a literature survey, it was found that, to date, the Chiroptera in Belo Horizonte were represented by three families (Phyllostomidae, Vespertilionidae and Molossidae), 18 genera and 24 species. With the aim of increasing knowledge of bat species present in the municipality as well as their distribution in urban and some characteristics of their reproductive cycle, a survey was conducted between 1999 and 2003. The study area, located at an altitude of 852.3 m above the sea level, 19 ° 56'S latitude and 43 ° 57 'The longitude was divided using the nine Regional Administrative City Hall. For the collection of species, there were two catches Regional home, one dry and one rainy season, and a search for possible shelter in a house of the Regional.
Após um levantamento bibliográfico, pôde-se verificar que, até o momento, os Chiroptera estavam representados em Belo Horizonte por três famílias, (Phyllostomidae, Molossidae e Vespertilionidae), 18 gêneros e 24 espécies. Com o objetivo de ampliar o conhecimento das espécies de morcegos presentes no Município, bem como sua distribuição na zona urbana e algumas características de seu ciclo reprodutivo, foi realizada uma pesquisa entre os anos de 1999 e 2003. A área de estudo, localizada a uma altitude de 852,3m do nível do mar, a 19°56S de latitude e 43°57 O de longitude, foi subdividida utilizando-se as nove Regionais Administrativa da Prefeitura. Para o levantamento de espécies, foram realizadas duas capturas em casa Regional, sendo uma estação seca e uma na chuvosa, bem como uma busca em possíveis abrigos em casa uma das Regionais.

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43

Thompson, Helen. "The development of cilia on the Ciona intestinalis embryo and the evolution of chordate left-right asymmetry." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558332.

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Most multicellular organisms have body plans that exhibit an element of symmetry; either radial or bilateral symmetry. Bilateral symmetry refers to organisms which have a single plane of symmetry with each side a mirror image of the other. Although externally these species appear symmetrical, internally, the organs are positioned in an asymmetric manner. This left-right axis is the last axis established after the A-P axis and D- V axis and recent research has analysed how this asymmetry is established. In the mouse it has been shown that monocilia on the organiser region, the mouse ventral node, rotate and generate a leftward fluid flow across the node. This flow, termed nodal flow, is essential for the left-sided localised expression of nodal, lefty and pitx2 and subsequent asymmetric patterning of organs. Nodal flow is highly conserved in the vertebrates but, although the conservation of asymmetric gene expression extends into the invertebrates, whether this is established through directional flow remains unknown. This research has investigated the extent of nodal flow conservation in a basal chordate, the urochordate, Ciona intestinalis. Here I have shown, through Electron Microscopy and immunofluorescence, that cilia are present, at the posterior of each cell of the Ciona intestinal is embryo, at the time point indicative to a role in the establishment of left-right asymmetry. They do not appear to be homologous to the cilia of the mouse ventral node because they are not motile and have a disorganised microtubule structure. However, the cilia may still have an important role in the development of left-right asymmetry in a sensory capacity or provide the site for H+/K +-ATPase channels already known to be involved in Ciona intestinal is left-right asymmetry.

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44

Holland, Linda Zimmerman. "Evolution of the chordate body plan : amphioxus (Branchiostoma floridae) as a stand-in for the ancestral vertebrate /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3035901.

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45

Sato, Goki. "Gene structure and expression of an ancestral vertebrate olfactory receptor gene from invertebrate chordate amphioxus Branchiostoma belcheri." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/149115.

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46

Ricci, Lorenzo. "A new model to study alternative developments : asexual propagation and regeneration in the basal chordate Botryllus schlosseri." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066683.

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Chez l’ascidie coloniale Botryllus schlosseri, en plus de l’embryogénèse existent deux voies de développement aboutissant à la production de la même structure : l’organisme adulte ou zooide. Ces développements alternatifs ont lieu lors de processus biologiques distincts : le bourgeonnement palléal (BP) et le bourgeonnement vasculaire (BV). Le BP est un processus de multiplication asexuée présentant une ontogénèse stéréotypée. En revanche, le BV est un phénomène régénératif, induit dans les vaisseaux sanguins de la colonie par l’ablation de tous les zooides et bourgeons palléaux. Mes travaux de recherche ont eu pour objectif de caractériser les bases moléculaires et cellulaires régissant le BP et le BV chez B. schlosseri. L’étude de gènes marqueurs des lignées méso-, endo- et ectodermiques a révélé l’existence de territoires présomptifs pour chacune de ces lignées, dès les premiers stades du BV et du BP, et suggéré l’existence d’un programme unique aux deux processus. Les lignées neurales et musculaires ont été étudiées plus en détail lors du BP, indiquant un double rôle potentiel, neuro- et myo-génétique, au tube dorsal, une structure jusqu’à présent uniquement associée au système nerveux. Une caractérisation morphologique poussée a mené à l’identification de stades précoces stéréotypés du BV lors de la régénération. Enfin, l’analyse de transcriptomes de différents stades du BP et de la régénération ont initié l’étude non biaisée des bases moléculaires du bourgeonnement chez Botryllus. L’objectif à long terme de ces travaux est de décrypter les bases moléculaires et génétiques facilitant, chez les métazoaires, l’évolution de voies de développement alternatives
In addition to embryogenesis, the colonial ascidians Botryllus schlosseri evolved two alternative developmental pathways leading to the same final structure: the adult body, or zooid. These non-embryonic ontogenesis occur during distinct biological processes: palleal budding (PB) and vascular budding (VB). PB is a process of asexual propagation, with a very stereotyped morphogenesis. Conversely, VB is a purely regenerative phenomenon, induced in the vascular system of the colony by the ablation of all zooids and palleal buds. My research work followed the objective to characterize the molecular and cellular basis of both PB and VB in B. schlosseri. The study of meso-, endo- and ectodermal lineage marker genes revealed the existence of presumptive territories of these lineages in the early palleal and vascular buds and that a single developmental program was launched in both VB and PB. Neural and muscle fates were studied in more detail for PB, indicating a potential double function, both neuro- and myo-genic for the dorsal tube, a structure so far associated with the nervous system only. A detailed morphological description of VB allowed to identify stereotyped stages during early regeneration. Eventually, a transcriptomic characterization of early VB and PB processes initiated an unbiased study of the molecular basis underlying the budding phenomenon in Botryllus. The overall goal of these research works is to unravel the molecular and genetic basis that facilitated, in Botryllus and globally in metazoan, the evolution of alternative developmental pathways

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47

Ricci, Lorenzo. "A new model to study alternative developments : asexual propagation and regeneration in the basal chordate Botryllus schlosseri." Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066683.

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Chez l’ascidie coloniale Botryllus schlosseri, en plus de l’embryogénèse existent deux voies de développement aboutissant à la production de la même structure : l’organisme adulte ou zooide. Ces développements alternatifs ont lieu lors de processus biologiques distincts : le bourgeonnement palléal (BP) et le bourgeonnement vasculaire (BV). Le BP est un processus de multiplication asexuée présentant une ontogénèse stéréotypée. En revanche, le BV est un phénomène régénératif, induit dans les vaisseaux sanguins de la colonie par l’ablation de tous les zooides et bourgeons palléaux. Mes travaux de recherche ont eu pour objectif de caractériser les bases moléculaires et cellulaires régissant le BP et le BV chez B. schlosseri. L’étude de gènes marqueurs des lignées méso-, endo- et ectodermiques a révélé l’existence de territoires présomptifs pour chacune de ces lignées, dès les premiers stades du BV et du BP, et suggéré l’existence d’un programme unique aux deux processus. Les lignées neurales et musculaires ont été étudiées plus en détail lors du BP, indiquant un double rôle potentiel, neuro- et myo-génétique, au tube dorsal, une structure jusqu’à présent uniquement associée au système nerveux. Une caractérisation morphologique poussée a mené à l’identification de stades précoces stéréotypés du BV lors de la régénération. Enfin, l’analyse de transcriptomes de différents stades du BP et de la régénération ont initié l’étude non biaisée des bases moléculaires du bourgeonnement chez Botryllus. L’objectif à long terme de ces travaux est de décrypter les bases moléculaires et génétiques facilitant, chez les métazoaires, l’évolution de voies de développement alternatives
In addition to embryogenesis, the colonial ascidians Botryllus schlosseri evolved two alternative developmental pathways leading to the same final structure: the adult body, or zooid. These non-embryonic ontogenesis occur during distinct biological processes: palleal budding (PB) and vascular budding (VB). PB is a process of asexual propagation, with a very stereotyped morphogenesis. Conversely, VB is a purely regenerative phenomenon, induced in the vascular system of the colony by the ablation of all zooids and palleal buds. My research work followed the objective to characterize the molecular and cellular basis of both PB and VB in B. schlosseri. The study of meso-, endo- and ectodermal lineage marker genes revealed the existence of presumptive territories of these lineages in the early palleal and vascular buds and that a single developmental program was launched in both VB and PB. Neural and muscle fates were studied in more detail for PB, indicating a potential double function, both neuro- and myo-genic for the dorsal tube, a structure so far associated with the nervous system only. A detailed morphological description of VB allowed to identify stereotyped stages during early regeneration. Eventually, a transcriptomic characterization of early VB and PB processes initiated an unbiased study of the molecular basis underlying the budding phenomenon in Botryllus. The overall goal of these research works is to unravel the molecular and genetic basis that facilitated, in Botryllus and globally in metazoan, the evolution of alternative developmental pathways

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VASCONCELOS, Rebeca Ferreira Lemos. "Produção de biomassa de Chlorella vulgaris (Chordat) para extração de óleo." Universidade Federal Rural de Pernambuco, 2012. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6441.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Currently there is much debate about the production of biodiesel and ethanol, and new technologies studied for obtaining oil, for example, microalgae, which are one of the most effective systems for conversion of solar energy into organic compounds. These compounds are mostly carbohydrates, proteins and lipids. The major difficulty in the production of biofuels through the harvesting of algae is therefore still quite expensive methods such as centrifugation, flocculation, sedimentation and filtration. This study aims to evaluate the effect of different flocculants in obtaining the biomass of Chlorella vulgaris (Chordat). The experimental design was completely randomized, with four bioassays, in which the first three comprised four treatments and three repetitions each composed of different treatments molalitys (0.1 M, 0.3 M, 0.5 M and 0.9 M) for flocculating agents sodium hydroxide, ferric chloride and aluminum polychloride. Subsequently fourth bioassay was performed which consisted of three treatments and three replications, where treatments consisted of different flocculating agents (sodium hydroxide, poly aluminum chloride and ferric chloride), in the same molar concentration (0.5 M). For experimentation microalgae of the species C. vulgaris were primed in experimental units, transparent materials with a volume of 2000 mL, reaching the seventh day the exponential phase of their growth curve obtained in previous tests. From the seventh day was started with a flocculation concentration algal average 1085 x 104 cel. mL-1, with a temperature of 22 ± 2 ° C and pH 7.0, constant aeration and light intensity of 2000 lux. Was added in experimental units 1 ml of standard solutions of flocculating agents then microalgae were subjected to moderate stirring continuously for 30 seconds. The pH variation data were interpreted by Analysis of Variance (ANOVA) followed by Tukey's test for comparison of means at the level of 5%. Analysis of the data verified that all treatments were different (P <0.05), but the use of sodium hydroxide as the flocculating agent obtained best results, we can conclude that where sodium hydroxide is the most suitable for flocculating agent quickly raise the pH of the culture (11.00 ± 0.37), thus leading to cell clumping and settling in a short time, and greater weight of biomass compared to other treatments.
Atualmente existe muita discussão sobre a produção de Biodiesel e etanol, sendo estudadas novas tecnologias para a obtenção de óleo, como por exemplo, as microalgas, que são um dos mais eficientes sistemas de transformação de energia solar em compostos orgânicos. Esses compostos são em sua maioria carboidratos, proteínas e lipídeos. A grande dificuldade para a produção de biocombustíveis através das algas é a colheita, pois ainda são métodos bastante onerosos, como a centrifugação, floculação, sedimentação, e filtração. Este trabalho tem como objetivo avaliar o efeito dos diferentes floculantes na obtenção da biomassa da Chlorella vulgaris (Chordat). O delineamento experimental adotado foi o inteiramente casualizado, composto por quatro bioensaios, nos quais os três primeiros compreendiam quatro tratamentos e três repetições cada, sendo os tratamentos compostos por diferentes molalidades (0,1M, 0,3M, 0,5M e 0,9M) para os agentes floculantes hidróxido de sódio, cloreto férrico e policloreto de alumínio. Posteriormente foi realizado o quarto bioensaio o qual era composto por três tratamentos e três repetições, onde os tratamentos consistiram em diferentes agentes floculantes (hidróxido de sódio, policloreto de alumínio e cloreto férrico), na mesma concentração molar (0,5M). Para a experimentação as microalgas da espécie C. vulgaris foram condicionadas em unidades experimentais, materiais transparentes com volume útil de 2000 mL, atingindo no sétimo dia a fase exponencial de sua curva de crescimento obtida em testes anteriores. A partir do sétimo dia deu-se início a floculação com uma concentração algal média de 1085 x 104 cel. mL-1, com temperatura de 22±2°C e pH 7,0, aeração constante e intensidade luminosa de 2000 lux. Foi adicionado nas unidades experimentais 1 mL de soluções padrão dos agentes floculantes, em seguida as microalgas foram submetidas a agitação moderada constante durante 30 segundos. Os dados da variação de pH foram interpretados por meio da análise de variância (ANOVA) seguido pelo teste Tukey para comparação de médias ao nível de 5%,. Após análise dos dados verificou-se que todos os tratamentos foram diferentes (P<0,05), porém a utilização do hidróxido de sódio como agente floculante obteve melhor resultado, onde podemos concluir que o hidróxido de sódio é o agente floculante mais indicado por elevar mais rapidamente o pH da cultura (11,00±0,37), ocorrendo assim a aglutinação e a decantação das células em um curto espaço de tempo, e maior peso da biomassa em relação aos outros tratamentos.

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49

Jimenez-Mejia, Jorge Hernan. "The loading and function of the mitral valve under normal, pathological and repair conditions : an in vitro study /." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-11102006-003456/.

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Thesis (Ph. D.)--Biomedical Engineering, Georgia Institute of Technology, 2007.
Ajit Yoganathan, Committee Chair ; Thomas Vassiliades, Committee Member ; Joseph Gorman, Committee Member ; Marc Levenston, Committee Member ; John N. Oshinski, Committee Member.

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Borges, Juliana Novo, Helena Lúcia Carneiro Santos, Martha Lima Brandão, Everton Gustavo Nunes dos Santos, Daniele Ferreira de Miranda, Daniel de Almeida Balthazar, José Luis Luque, and Cláudia Portes Santos. "Molecular and morphological characterization of Contracaecum pelagicum (Nematoda) parasitizing Spheniscus magellanicus (Chordata) from Brazilian waters." Colégio Brasileiro de Parasitologia Veterinária, 2014. https://www.arca.fiocruz.br/handle/icict/9984.

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Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Avaliação e Promoção da Saúde Ambiental. Curso de Pós-Graduação em Biodiversidade e Saúde. Rio de Janeiro, RJ, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Avaliação e Promoção da Saúde Ambiental. Rio de Janeiro, RJ, Brasil.
Universidade Federal Rural do Rio de Janeiro. Curso de Pós-Graduação em Parasitologia Veterinária. Seropédica, RJ, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Avaliação e Promoção da Saúde Ambiental. Rio de Janeiro, RJ, Brasil / Universidade Federal Rural do Rio de Janeiro. Curso de Pós-Graduação em Parasitologia Veterinária. Seropédica, RJ, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Avaliação e Promoção da Saúde Ambiental. Rio de Janeiro, RJ, Brasil.
Fundação Jardim Zoológico da Cidade do Rio de Janeiro. Rio de Janeiro, RJ, Brasil.
Universidade Federal Rural do Rio de Janeiro. Departamento de Parasitologia Animal. Seropédica, RJ, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Avaliação e Promoção da Saúde Ambiental. Rio de Janeiro, RJ, Brasil.
Foram determinadas três novas sequências da região do Citocromo c-oxidase da subunidade II do DNA mitocondrial (cox-2 mtDNA) de Contracaecum pelagicum, parasito de Spheniscus magellanicus, pinguim Magalhães, de águas brasileiras. As sequências apresentaram 99 e 98% de similaridade com sequências de C. pelagicum da Argentina depositadas no GenBank da mesma região genética com forte suporte estatístico inferido pela arvore filogenética. Estudos morfológicos e ultraestruturais realizados confirmaram a identidade genética.
Three new sequences of Mitochondrial cytochrome c-oxidase subunit 2 (mtDNA cox-2) from C. pelagicum parasite of Spheniscus magellanicus, the Magelanicus penguin, were determined from Brazilian waters. The sequences presented 99 and 98% of similarity with C. pelagicum sequences from Argentina, deposited on GenBank for the same genetic region and with a strong statistical support inferred from the phylogenetic tree. The morphological and ultrastructural studies that were carried out confirmed the genetic analysis.

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Dissertations / Theses on the topic 'Chordates'

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