Tesi sul tema "Evolution (Biology)"
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Karlberg, Olof. "Mitochondrial Evolution : Turning Bugs into Features". Doctoral thesis, Uppsala University, Molecular Evolution, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4216.
Testo completoThe bacterial origin of mitochondria from an ancient endosymbiosis is now widely accepted and the mitochondrial ancestor is generally believed to belong to the bacterial subdivision α-proteobacteria. The high fraction of mitochondrial proteins encoded in the nucleus has commonly been explained with a massive transfer of genes from the genome of the ancestral mitochondrion.
The aim of this work was to get a better understanding of the mitochondrial origin and evolution by comparative genomics and phylogenetic analyses on mitochondria and α-proteobacteria. To this end, we sequenced the genomes of the intracellular parasites Bartonella henselae and Bartonella quintana, the causative agents of cat-scratch disease and trench fever, and compared them with other α-proteobacteria as well as mitochondrial eukaryotes.
Our results suggest that the adaptation to an intracellular life-style is coupled to an increased rate of genome degradation and a reduced ability to accommodate environmental changes. Reconstruction of the α-proteobacterial ancestor and phylogenetic analyses of the mitochondrial proteome in yeast revealed that only a small fraction of the proteins used for mitochondrial functions could be traced to the α-proteobacteria. Furthermore, a substantial fraction of the mitochondrial proteins was of eukaryotic origin and while most of the genes of the α-proteobacterial ancestor have been lost, many of those that have been transferred to the nuclear genome seem to encode non-mitochondrial proteins.
Klasson, Lisa. "Genome Evolution in Maternally Inherited Insect Endosymbionts". Doctoral thesis, Uppsala University, Department of Evolution, Genomics and Systematics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5885.
Testo completoSymbiosis is a widely common phenomenon in nature and has undoubtedly contributed to the evolution of all organisms on earth. Symbiotic associations can be of varying character, such as parasitic or mutualistic, but all imply a close relationship. To study the evolution of genomes of insect endosymbionts, we have sequenced the genomes of the mutualist Buchnera aphidicola from the aphid Schizaphis graminum (Sg) and the reproductive manipulator Wolbachia pipientis strain wRi from Drosophila simulans that show strikingly different evolutionary patterns.
The comparison between the genome of B.aphidicola (Sg) and the genome of B.aphidicola from the aphid Acyrthosiphon pisum (Ap), that are believed to have diverged 50 million years ago, revealed a perfect gene order conservation and loss of only 14 genes in either of the lineages. In contrast, the rate of nucleotide turnover is very fast probably due to relaxed selection and loss of DNA repair genes. The genomic stasis observed in Buchnera was attributed to the loss of repeats and of the gene recA.
In striking contrast to the genomes of B.aphidicola, a vast amount of repeats were found in the genome sequence of W.pipientis strain wMel. The comparison between the genomes of W.pipientis strain wRi and W.pipientis strain wMel shows that a lot of rearrangements have occurred since their divergence. The massive amount of repeats might stem from relaxed selection pressure but possibly also from selection to create variability via recombination.
Comparisons between pairs of genomes from closely related bacteria showed that the stability of gene order and content is connected to an intracellular lifestyle and indicated that homologous recombination between repeats is an important mechanisms for causing intrachromosomal rearrangements. Our studies show that the lifestyle of a bacterium to a great extent shapes the evolution of their genetic material and future capabilities to adapt to new environments.
Jansson, Liselotte. "Evolution of signal form". Doctoral thesis, Stockholm : Zoologiska institutionen, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-189.
Testo completoRanjard, Louis. "Computational biology of bird song evolution". e-Thesis University of Auckland, 2010. http://hdl.handle.net/2292/5719.
Testo completoTam, Kwok-hin, e 談國軒. "Biology students' conceptions of evolution: aphenomenography". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31961940.
Testo completoSjöstrand, Joel. "Reconciling gene family evolution and species evolution". Doctoral thesis, Stockholms universitet, Numerisk analys och datalogi (NADA), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-93346.
Testo completoArters evolution kan i många fall beskrivas med ett träd, vilket redan Darwins anteckningsböcker från HMS Beagle vittnar om. Detta gäller också homologa gener; en gen i en ancestral art kan – genom genduplikationer, genförluster, lateral gentransfer (LGT) och artbildningar – ge upphov till en genfamilj spridd över samtida arter. Att från sekvenser från nu levande arter rekonstruera genfamiljens framväxt – genträdet – är icke-trivialt på grund av genetisk rekombination och sekvensevolution. Genträdet är emellertid av biologiskt intresse, i synnerhet för att det möjliggör antaganden om funktionellt släktskap mellan nutida genpar. Denna avhandling behandlar biologiskt välgrundade sannolikhetsmodeller för genfamiljsevolution. Dessa modeller tar hjälp av artevolutionens starka inverkan på genfamiljens historia, och ger väsentligen upphov till en förlikning av genträd och artträd. Genom Bayesiansk inferens baserad på Markov-chain Monte Carlo (MCMC) visar vi att våra metoder presterar bättre genträdsskattningar än traditionella ansatser som inte tar artträdet i beaktning. Mer specifikt beskriver vi en modell som omfattar genduplikationer, genförluster, en relaxerad molekylär klocka, samt sekvensevolution, och visar att metoden ger högkvalitativa skattningar på både syntetiska och biologiska data. Vidare presenterar vi två utvidgningar av detta ramverk som möjliggör (i) genträdsskattningar med tidpunkter för duplikationer, samt (ii) probabilistiska ortologiskattningar – d.v.s. att två nutida gener härstammar från en artbildning. Slutligen presenterar vi en modell som inkluderar LGT utöver ovan nämnda mekanismer. De beräkningsmässiga svårigheter som LGT ger upphov till löses med ett intrikat ramverk av dynamisk programmering och numeriska metoder för differentialekvationer. Vi tillämpar metoden för att skatta LGT- och duplikationsraten hos två bakteriella dataset där LGT förmodas ha spelat en central roll. Vi visar också att traditionella metoder – där genträd skattas och förlikas med artträdet i separata steg – tenderar att ge sämre genträdsskattningar, och därmed överskatta antalet LGT-händelser.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 5: Manuscript.
Tam, Kwok-hin. "Biology students' conceptions of evolution : a phenomenography /". Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2226677X.
Testo completoHearn, David John. "Growth form evolution in Adenia (Passifloraceae) and a model of the evolution of succulence". Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280706.
Testo completoChung, Hattie. "Genome evolution in structured systems". Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493565.
Testo completoSystems Biology
Tuch, Brian B. "Evolution of fungal transcription circuits". Diss., Search in ProQuest Dissertations & Theses. UC Only, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3297786.
Testo completoVan, der Walt Eric. "Experimental investigations of mastrevirus molecular biology and evolution". Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/4346.
Testo completoIncludes bibliographical references (leaves 138-161).
This dissertation describes three major sets of experiments, all of which involved the construction and use of various reciprocal chimaeric MSV constructs. First, chimaeric viruses were used in genetic complementation-type experiments to investigate the biological significance of interactions between the two virion-sense open reading frames (ORFs) of MSV, their products, and the rest of the genome. Six chimaeric MSV constructs were made by reciprocally exchanging the ORFs encoding movement protein (MP) and coat protein (CP) individually, and in pairs, between MSV-Kom and MSV-Set, which share just 78% overall nucleotide identity. Analysis of symptomatology and infection efficiency of chimaeras and wild-type parental viruses revealed evidence of functionally relevant specific interactions between MSV MP and CP.
Eriksson, Joakim. "Evolution and Development of the Onychophoran Head and Nervous System". Doctoral thesis, Uppsala universitet, Institutionen för geovetenskaper, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3387.
Testo completoLi, Yang. "Understanding lineage-specific biology through comparative genomics". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:23398cc7-8bbe-4f5a-8cd9-1104591400cc.
Testo completoGoodier, Sarah. "Evolution of the African Tigerfish (Genus Hydrocynus) : phylogeographic insights into drainage evolution". Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/10453.
Testo completoAquatic species,notably fish, can reveal details of drainage evolution, especially where their evolutionary relationships can be reconstructed using phylogeographic methods. In this study, the mitochondrial DNA sequence diversity of the characiform genus, Hydrocynus, which is widespread across tropical Africa, is reconstructed using a phylogenetic framework and divergences are dated using the cytochrome b (cyt) region.
Ober, Karen Ann. "The evolution of arboreal carabid beetles". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/289746.
Testo completoSinger, Gregory A. C. "Non-random neutral evolution". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6336.
Testo completoWilliams, Elizabeth Jane Bulkeley. "The evolution of genomic anatomy : linkage, expression and rates of evolution". Thesis, University of Bath, 2002. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268398.
Testo completoMathis, Robert Austin. "Intra-tumor heterogeneity and evolution". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113432.
Testo completoThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
Although the treatment of cancer is a major focus of biomedical research, many cancers are extremely hard to treat. Tumors likely resist treatment because each tumor is heterogeneous, and can evolve. Although tumor evolution has long been appreciated, it remains incompletely understood. In this thesis, I will explore two questions related to cancer heterogeneity and evolution: how evolution can affect plastic phenotypes, and the role of purifying selection in cancer evolution. Different cell states or phenotypes have been observed within tumors, and they are associated with treatment resistance and metastasis. The observation that these phenotypes are plastic leads to a conundrum: how can selection act on such an unstable phenotype? We determined that plasticity, in the form of cell state bias, varies widely across clones in a tumor. These different biases are heritable, with each cell faithfully passing its differentiation bias to its daughters. Simulations revealed that this makes plasticity an evolvable phenotype--- in a changing environment, an optimal state bias will be selected. The second question explored in this thesis is the role of purifying selection in cancer evolution. It is widely thought that tumor evolution is dominated by positive selection. We posited that, as in the evolution of species, purifying selection would prevent the fixation of deleterious mutations in tumors. Through computational analysis of tumor genomes, we determined that purifying selection acts to remove deleterious mutations. Genes under purifying selection must be important to tumors in vivo, as only mutations in these genes would be problematic. Consistent with this prediction, most genes under purifying selection in tumors were essential in cancer cell lines. To find genes essential to tumors but not generally cell-essential, we developed a method to find genes under increased purifying selection in one tumor type over others. This revealed a number of pathways under selection in melanomas, but not other tumor types, such as DNA damage pathways. By seeking genes important to tumors, but not generally essential, our analysis revealed potential therapeutic targets. Purifying selection offers an unprecedented view into which genes are essential to tumors in vivo, a finding predominantly inaccessible through experimentation.
by Robert Austin Mathis.
Ph. D.
Hudson, Corey M. "Informatic approaches to evolutionary systems biology". Thesis, University of Missouri - Columbia, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3577951.
Testo completoThe sheer complexity of evolutionary systems biology requires us to develop more sophisticated tools for analysis, as well as more probing and biologically relevant representations of the data. My research has focused on three aspects of evolutionary systems biology. I ask whether a gene’s position in the human metabolic network affects the degree to which natural selection prunes variation in that gene. Using a novel orthology inference tool that uses both sequence similarity and gene synteny, I inferred orthologous groups of genes for the full genomes of 8 mammals. With these orthologs, I estimated the selective constraint (the ratio of non-synonymous to synonymous nucleotide substitutions) on 1190 (or 80.2%) of the genes in the metabolic network using a maximum likelihood model of codon evolution and compared this value to the betweenness centrality of each enzyme (a measure of that enzyme’s relative global position in the network). Second, I have focused on the evolution of metabolic systems in the presence of gene and genome duplication. I show that increases in a particular gene’s copy number are correlated with limiting metabolic flux in the reaction associated with that gene. Finally, I have investigated the proliferative cell programs present in 6 different cancers (breast, colorectal, gastrointestinal, lung, oral squamous and prostate cancers). I found an overabundance of genes that share expression between cancer and embryonic tissue and that these genes form modular units within regulatory, proteininteraction, and metabolic networks. This despite the fact that these genes, as well as the proteins they encode and reactions they catalyze show little overlap among cancers, suggesting parallel independent reversion to an embryonic pattern of gene expression.
Baldwin, Maude Wheeler. "Evolution of sweet taste perception in hummingbirds". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467228.
Testo completoBiology, Organismic and Evolutionary
Vårdal, Hege. "From Parasitoids to Gall Inducers and Inquilines : Morphological Evolution in Cynipoid Wasps". Doctoral thesis, Uppsala universitet, Systematisk zoologi, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3975.
Testo completoWilson, Christopher William. "Mechanism and evolution of mammalian hedgehog signaling". Diss., Search in ProQuest Dissertations & Theses. UC Only, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3378515.
Testo completoPuhr, RoseMary Allyson. "Evolution of the Sparse inflorescence1 lineage in grasses". Thesis, California State University, Long Beach, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1523069.
Testo completoAuxin is a phytohormone that has long been known to control many aspects of plant growth and development. The YUCCA (YUC) gene family is a large group of genes that catalyze auxin biosynthesis and have been shown to be critical for vegetative growth and inflorescence development in grasses. There is genetic redundancy present with Arabidopsis YUCs, but in Zea mays (maize), a single gene knockout of ZmSPI1 causes a severe inflorescence phenotype. Since Oryza sativa (rice), another grass species, does not show an inflorescence phenotype when OsYUC1/SPI1 is knocked down, SPI1 appears to have undergone an evolutionary shift in function within the grass family. This study shows that SPI1 expression in PACMAD (Panicoideae, Arundinoideae, Chlorodoideae, Micrairoideae, Aristidoideae, and Danthoniodeae subfamilies) clade grasses Sorghum bicolor and Setaria italica occurs at sites of inflorescence branching and is consistent with maize, but in BEP (Bambusoideae, Ehrhartoideae, and Pooideae subfamilies) clade grasses rice and Brachypodium distachyon SPI1 shifts from localized expression to more generalized expression and potentially becomes weaker. Artificial microRNA (amiRNA) knockdowns of SPI1 expression in Brachypodium did not show a phenotype when expression was reduced to 28.01% (+/- 6.39%) of wild type. In rice and Brachypodium, other YUC genes were shown to be expressed in the inflorescence by quantitative RT-PCR (qPCR), suggesting YUC proteins are more redundant in BEP grasses such as B. distachyon and O. sativa, than in maize and potentially its relatives.
Stireman, John Oscar. "The ecology and evolution of tachinid-host associations". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/289745.
Testo completoWhitehead, Joanne. "Genomic Imprinting in Development and Evolution". Doctoral thesis, Uppsala universitet, Zoologisk utvecklingsbiologi, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4491.
Testo completoMaxwell, Erin. "Evolution of avian ossification sequences". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21942.
Testo completoLe temps de formation et la séquence d'événements du développement embryonnaire jouent un rôle important dans la forme adulte et dans l'évolution. La séquence selon laquelle les os se forment dans l'embryon devrait donc contenir des informations capables de révéler l'histoire évolutionnaire. Cependant, les facteurs qui influencent la séquence d'ossification et les séquences elles-mêmes sont mal compris et rarement étudiés. Dans cette thèse, je décris le développement squelettique embryonnaire chez Meleagris gallopavo, Sterna hirundo, Somateria mollissima, Anas platyrhynchos, Cairina moschata, Dromaius novaehollandiae, Rhea americana et Struthio camelus pour la première fois dans la littérature scientifique, en me concentrant sur l'ossification. Une variabilité intraspécifique entre les séquences d'ossification a été observée chez toutes espèces, mais le niveau de polymorphisme était généralement bas. Les spécimens d'espèces sauvages n'ont pas montré plus de variabilité dans la séquence d'ossification que ceux incubés dans les conditions constantes du laboratoire. Les os membraneux n'ossifient pas toujours avant les os de cartilage, et les os dérivés de la crête neurale ne se forment pas toujours avant les éléments dérivés du mésoderme paraxial. Ceci suggère que les facteurs qui contrôlent la séquence d'ossification sont complexes et que plus qu'une facteur peuvent y jouer un rôle. Afin d'examiner les séquences dans un contexte phylogénetique, je les ai convertis en une forme facile à analyser (‘paires d'événements') et ai utilisé les caractères de séquence d'ossification pour la reconstruction phylogénetique. Bien que cette technique présente des problèmes liés à un manque d'indépendence logique et biologique, c'est un outil efficace pour examiner la conservation et la divergence des séquences d'ossification à différents niveaux de rélation phylogénetique. J'ai aussi reconstruit les changements$
Omilian, Angela Ruggieri. "Features of Daphnia genome evolution". [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3243783.
Testo completoTitle from PDF t.p. (viewed Nov. 18, 2008). Source: Dissertation Abstracts International, Volume: 67-12, Section: B, page: 6862. Adviser: Michael Lynch.
Subramanian, Ayshwarya. "Inferring tumor evolution using computational phylogenetics". Research Showcase @ CMU, 2013. http://repository.cmu.edu/dissertations/275.
Testo completoRicono, Angela. "Ecology and Evolution of Common Milkweed". W&M ScholarWorks, 2018. https://scholarworks.wm.edu/etd/1550154023.
Testo completoEastman, Jonathan Michael. "On the role of historical constraint in evolution an emphasis in salamander evolution /". Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Dissertations/Spring2010/j_eastman_040310.pdf.
Testo completoAhmad, Syed Farhan. "High Scale Genomic Applied to B chromosome biology". Botucatu, 2019. http://hdl.handle.net/11449/183111.
Testo completoAbstract: One of the biggest challenges in chromosome biology is to understand the occurrence and complex genetics of extra, non-essential karyotype elements, commonly known as supernumerary B chromosomes (Bs). Bs are present in diverse species of eukaryotes and their molecular characterization remains elusive for years. A distinguished feature that makes them different from the normal chromosomes (called A chromosomes) is their way of inheritance in irregular fashion. Over the last decades, their genetic composition, function and evolution have remained an unresolved query, although a few successful attempts have been made to address these phenomena. The non-Mendelian inheritance and unpairing/non-recombining abilities make the B chromosomes immensely interesting for genomics studies, thus arising different questions about their genetic composition, survival, maintenance and role inside the cell. This study aims to uncover these phenomena in different species. Here, we sequenced the genomes of three model organisms including fish species Astyanax mexicanus and Astyanax correntinus, and grasshopper Abracris flavolineata with (B+) and without Bs (B-) to identify the B-localized sequences, called B chromosome blocks (“B-blocks”). We established approaches for this analysis that comprised of steps such as comparative genomics analysis and annotation of B chromosomal genes and DNA repeat types. The next generation sequencing (NGS) analyses identified thousands of genes fragments as well as... (Complete abstract click electronic access below)
Doutor
Winge, Per. "The evolution of small GTP binding proteins in cellular organisms. Studies of RAS GTPases in arabidopsis thaliana and the Ral GTPase from Drosophila melanogaster". Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-169.
Testo completoSmall GTP binding proteins function as molecular switches which cycles between GTP-bound ON and GDP-bound OFF states, and regulate a wide variety of cellular processes as biological timers. The first characterized member of the small GTPase family, the mutated oncogene p21 src, later known as Harvey-Ras, was identified in the early 1980s (Shih, T. Y. et al. 1980). In the following years small Ras-lik GTPases were found in several organisms and it was soon discovered that they took part in processes, such as signal transduction, gene expression, cytoskeleton reorganisation, microtubule organisation, and vesicular and nuclear transport. The first Rho (Ras homology) gene was cloned in 1985 from the sea slug Aplysia (Madaule, P. et al. 1985) and because of their homology to Ras it was first suspected that they could act as oncogenes. Later studies have shown that even though they participate in processes such as cell migration and motility they are not mutated in cancers.
The first indications that Rho was a signaling protein regulating the actin cytoskeleton, came from experiments where activated forms of human RhoA was microinjected into 3T3 cells (Paterson, H. F. et al. 1990). Another Rho-like GTPase Rac1 (named after Ras-related C3 botulinum toxin substrate) was later shown to regulate actin cytoskeletal dynamics as well, suggesting that Rho-family members cooperate in controlling these processes (Ridley, A. J. et al. 1992). The Rac GTPase was also implicated in regulating the phagocytic NADPH oxidase, which produce superoxide for killing phagocytized microorganisms (Abo, A. et al. 1991). Thus, it soon became clear that Rac/Rho and the related GTPase Cdc42 (cell division cycle 42) had central functions in many important cellular processes.
There are at least three types of regulators for Rho-like proteins. The GDP/GTP exchange factors (GEFs) which stimulates conversion from the GDPbound form to the GTP-bound form. GDP dissociation inhibitors (GDIs) decrease the nucleotide dissociation from the GTPase and retrieve them from membranes to the cytosol. GTPase activating proteins (GAPs) stimulates the intrinsic GTPase activity and GTP hydrolysis. In addition there are probably regulators that dissociate GDI from the GTPase leaving it open for activation by the RhoGEFs.
Ras and Rho-family proteins participate in a coordinated regulation of cellular processes such as cell motility, cell growth and division. The Ral GTPase is closely related to Ras and recent studies have shown that this GTPase is involved in crosstalk between both Ras and Rho proteins (Feig, L. A. et al. 1996; Oshiro, T. et al. 2002). Ral proteins are not found in plants and they appear to be restricted to animalia and probably yeast. During a screen for small GTPases in Drosophila melanogaster I discovered in 1993 several new members of the Ras-family, such as Drosophila Ral (DRal), Ric1 and Rap2. The functions of Ral GTPases in Drosophila have until recently been poorly known, but in paper 2 we present some of the new findings.
Rho-like GTPases have been identified in several eukaryotic organisms such as, yeast (Bender, A. et al. 1989), Dictyostelium discoideum (Bush, J. et al. 1993), plants (Yang, Z. et al. 1993), Entamoeba histolytica (Lohia, A. et al. 1993) and Trypanosoma cruzi (Nepomuceno-Silva, J. L. et al. 2001). In our first publication, (Winge, P. et al. 1997), we describe the cloning of cDNAs from RAC-like GTPases in Arabidopsis thaliana and show mRNA expressions pattern for five of the genes. The five genes analyzed were expressed in most plant tissues with the exception of AtRAC2 (named Arac2 in the paper), which has an expression restricted to vascular tissues. We also discuss the evolution and development of RAC genes in plants. The third publication, (Winge, P. et al. 2000), describe the genetic structure and the genomic sequence of 11 RAC genes from Arabidopsis thaliana. As most genomic sequences of the AtRACs we analyzed came from the Landsberg erecta ecotype and the Arabidopsis thaliana genome was sequenced from the Columbia ecotype, it was possible to compare the sequences and identify new polymorphisms. The genomic location of the AtRAC genes plus the revelation of large genomic duplications provided additional information regarding the evolution of the gene family in plants. A summary and discussion of these new findings are presented together with a general study of small Ras-like GTPases and their evolution in cellular organisms. This study suggests that the small GTPases in eukaryots evolved from two bacterial ancestors, a Rab-like and a MglA/Arp-like (Arf-like) protein. The MglA proteins (after the mgl locus in Myxococcus xanthus) are required for gliding motility, which is a type of movement that take place without help of flagella.
The second publication describes experiments done with the Drosophila melanogaster DRal gene and its effects on cell shape and development. Ectopic expression of dominant negative forms of DRal reveals developmental defects in eye facets and hairs, while constitutive activated forms affects dorsal closure, leaving embryos with an open dorsal phenotype. Results presented in this publication suggest that DRal act through the Jun N-terminal kinase (JNK) pathway to regulate dorsal closure, but recent findings may point to additional explanations as well. The results also indicate a close association between processes regulated by Rac/Rho and Ral proteins in Drosophila.
Kaliszewska, Zofia. "Evolution of Parasitism in the Lycaenidae (Lepidoptera)". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845507.
Testo completoBiology, Organismic and Evolutionary
Pond, Sergei L. "Modeling evolution of protein coding DNA sequences". Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289906.
Testo completoRalph, David Allen. "Evolution of cytoplasmic genomes /". The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487267546981989.
Testo completoVice, President Research Office of the. "Evolution Revolution". Office of the Vice President Research, The University of British Columbia, 2007. http://hdl.handle.net/2429/2683.
Testo completoNamkoong, Bumjin. "The Molecular Determinants of Cranial Skeletal Development and Evolution". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845478.
Testo completoBiology, Molecular and Cellular
Lagomarsino, Laura Penelope. "The Systematics and Evolution of Neotropical Bellflowers (Campanulaceae: Lobelioideae)". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845502.
Testo completoBiology, Organismic and Evolutionary
Cutter, Asher Damon. "Breeding system evolution and sex ratio in Caenorhabditis". Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280510.
Testo completoReed, Robert Dale Jr. "The evolution of pattern formation in butterfly wings". Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/290156.
Testo completoFrenkel, Evgeni Mikhailovich. "Competition and Coexistence in Yeast Experimental Evolution". Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493568.
Testo completoBiophysics
Sjölund, Johan. "Evolutionsteorin i skolan : gymnasieelevers uppfattningar om biologisk evolution". Thesis, Umeå University, Mathematics, Technology and Science Education, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1096.
Testo completoEtt generellt problem i dagens svenska gymnasieskola är att elever ofta använder vardagliga förklaringar istället för vetenskapliga när de ska förklara naturvetenskapliga teorier och begrepp. När elever ska förklara orsaken till att biologisk evolution sker, uppkommer olika alternativa idéer, idéer som inte är förenliga med vetenskapliga förklaringar. Denna studie beskriver vilka alternativa idéer som elever ger när de skriftligt besvarar en uppgift innehållande ett evolutionsbiologiskt fenomen. De förklaringar eleverna ger på uppgiften diskuteras och utvecklas i intervjuer, för att öka kunskapen och förståelsen för vilka uppfattningar gymnasieelever har om biologisk evolution. Den vanligaste alternativa idén som framkommer när den skriftliga uppgiften löses är att evolution drivs för att ett behov finns(giraffen behöver utvecklas för att klara sig). Andra förekommande alternativa idéer är inlärning (giraffen sträcker på sig och därför blir halsen längre) och anpassning (giraffen anpassar sig till en ny omgivning). Fem begrepp är centrala för att förstå helheten i evolutionsteorin; variation, överlevnad, ärftlighet, reproduktion och anpassning. Variation visar sig vara ett nyckelbegrepp för elevens förmåga att frångå en alternativ idé om evolution och uppnå en högre grad av vetenskaplighet i sin förklaring.
Nygren, Kristiina. "Evolutionary Consequences of Reproductive Strategies : Testing Theory on Sex and Reproductive Gene Evolution in the Fungal Model Neurospora". Doctoral thesis, Uppsala universitet, Evolutionsbiologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-152953.
Testo completoMerkin, Jason Jay. "The evolution of mRNA splicing in mammals". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89945.
Testo completoTitle as it appears in MIT commencement exercises program, June 6, 2014: The evolution of mRNA splicing in mammalian tissues Cataloged from PDF version of thesis.
Includes bibliographical references (pages 167-172).
In this thesis, I describe investigations into the evolution of splicing in mammals. I first investigate a small class of alternative splicing events, tandem splice sites, and show how they are used to introduce and remove coding sequence in a species-specific manner. I then describe the generation and analysis of a large RNA-seq dataset from 9 matched tissues in 5 species, with the aim to investigate the evolution of splicing in mammals. I first investigate the evolution of exons that predate the most ancient divergence of species studied, finding that their splicing is frequently poorly conserved. For a subset of these exons, I identify unique regulatory properties and provide evidence linking alternative splicing to phosphorylation potential of proteins. I then consider sources of novel exons, in these species. I use these and other published data to identify one way in which splicing of novel exons impacts the biology of the cell. I also present evidence implicating genomic indels in exon creation and splicing variation.
by Jason Jay Merkin.
Ph. D.
Moniz, de Sa Mario. "The evolution of angiosperm actin genes". Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/10062.
Testo completoBelda, Cuesta Eugeni. "Genome evolution and systems biology in bacterial endosymbionts of insects". Doctoral thesis, Universitat de València, 2010. http://hdl.handle.net/10803/57466.
Testo completoEn esta tesis doctoral, el proceso de reducción genómica característico de bacterias endosimbiontes de insectos ha sido estudiado utilizando diferentes aproximaciones computacionales basadas en la genómica comparada y la biología de sistemas. Por un lado, las dinámicas de reordenaciones genómicas han sido estudiadas en un subconjunto de 31 genomas completos de γ-proteobacterias que incluyen 5 genomas completos de endosimbiontes bacterianos de insectos, revelando una aceleración significativa de las tasas de reordenaciones en estos genomas en etapas iniciales del proceso de reducción. Posteriormente, el genoma de Sodalis glossinidius, el endosimbionte secundario de la mosca tsétsé, fue re-anotado con el objetivo de evaluar el impacto de los procesos de inactivación génica y proliferación de elementos genéticos móviles en etapas tempranas del proceso de reducción, asi como su impacto sobre las capacidades funcionales de la bacteria en el contexto ecológico de su coexistencia con el endosimbionte primario ancestral Wigglesworthia glossinidia. Finalmente, el proceso completo de reducción genómica en S. glossinidius ha sido estudiado a través de la reconstrucción de su red metabólica a diferentes etapas de este proceso y su análisis funcional mediante Análisis de Balance de Flujos, evaluando la robustez de las redes frente a sucesos de deleción asi como las dinámicas evolutivas de genes esenciales y no esenciales en base a su presencia en redes mínimas evolucionadas a partir de la red funcional. Este análisis permitió identificar sucesos de inactivación génica con efectos drásticos sobre las capacidades funcionales del sistema como los genes implicados en la biosíntesis de arginina y glicógeno, y especialmente la inactivación de la enzima fosfoenolpiruvato carboxilasa, asi como una disminución progresiva de la robustez de las redes frente a diferentes sucesos mutacionales asociada al proceso de pérdida génica. Finalmente, simulaciones de evolución reductiva sobre la red funcional bajo diferentes condiciones de entorno ha permitido definir conjuntos de genes esenciales y delecionables en base a su presencia o ausencia en las redes mínimas producto de las simulaciones, revelando una mayor conservación a nivel de secuencia y un uso de codones más optimizado en genes esenciales frente a genes cuya pérdida no afecta a la funcionalidad del sistema.
McDougall, Carmel. "Comparative biology of Pomatoceros lamarckii and Dix evolution in annelids". Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497051.
Testo completoLee, Mi-Hye. "Molecular biology and evolution of [beta]-globin genes in monotremes /". Title page, table of contents and summary only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phl479.pdf.
Testo completoNylander, Johan A. A. "Bayesian Phylogenetics and the Evolution of Gall Wasps". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3996.
Testo completoBranham, Marc A. "The evolution of Lampyridae, with special emphasis on the origin of photic behavior and signal system evolution (Coleoptera: Lampyridae) /". The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486402957196158.
Testo completo