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Auswahl der wissenschaftlichen Literatur zum Thema „Embryonic stages“
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Zeitschriftenartikel zum Thema "Embryonic stages"
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Chang, Kai-Hsin, Angelique M. Nelson, Hua Cao, Linlin Wang, Betty Nakamoto, Carol B. Ware und Thalia Papayannopoulou. „Definitive-like erythroid cells derived from human embryonic stem cells coexpress high levels of embryonic and fetal globins with little or no adult globin“. Blood 108, Nr. 5 (01.09.2006): 1515–23. http://dx.doi.org/10.1182/blood-2005-11-011874.
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Human embryonic stem cells are a promising tool to study events associated with the earliest ontogenetic stages of hematopoiesis. We describe the generation of erythroid cells from hES (H1) by subsequent processing of cells present at early and late stages of embryoid body (EB) differentiation. Kinetics of hematopoietic marker emergence suggest that CD45+ hematopoiesis peaks at late D14EB differentiation stages, although low-level CD45- erythroid differentiation can be seen before that stage. By morphologic criteria, hES-derived erythroid cells were of definitive type, but these cells both at mRNA and protein levels coexpressed high levels of embryonic (ϵ) and fetal (γ) globins, with little or no adult globin (β). This globin expression pattern was not altered by the presence or absence of fetal bovine serum, vascular endothelial growth factor, Flt3-L, or coculture with OP-9 during erythroid differentiation and was not culture time dependent. The coexpression of both embryonic and fetal globins by definitive-type erythroid cells does not faithfully mimic either yolk sac embryonic or their fetal liver counterparts. Nevertheless, the high frequency of erythroid cells coexpressing embryonic and fetal globin generated from embryonic stem cells can serve as an invaluable tool to further explore molecular mechanisms.
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Merchan, Jaime A., Francisco S. Del Campo und J. Rueda. „Sensorineural Interactions in Embryonic Stages“. Acta Oto-Laryngologica 101, sup429 (Januar 1986): 11–15. http://dx.doi.org/10.3109/00016488609122724.
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Niva, Cintia C., und Miriam Becker. „Embryonic external morphogenesis of Rhammatocerus conspersus (Bruner) (Orthoptera: Acrididae: Gomphocerinae) and determination of the diapausing embryonic stage“. Anais da Sociedade Entomológica do Brasil 27, Nr. 4 (Dezember 1998): 557–83. http://dx.doi.org/10.1590/s0301-80591998000400010.
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The grasshopper Rhammatocerus conspersus (Bruner) (Orthoptera: Acrididae: Gomphocerinae) is an occasional pest in pasturelands of Rio Grande do Sul State. It is a univoltine species with an embryonic diapause. Nymphal and adult stages occur during the warmer months (November-March). Eggs were dissected periodically for characterization of embryonic external morphogenesis in 1994 and 1995. Ten embryonic stages were illustrated. Two diapausing stages were verified in R. conspersus: one at 25% and another at 50% of total embryonic development.
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Prokop, A., und G. M. Technau. „The origin of postembryonic neuroblasts in the ventral nerve cord of Drosophila melanogaster“. Development 111, Nr. 1 (01.01.1991): 79–88. http://dx.doi.org/10.1242/dev.111.1.79.
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Embryonic and postembryonic neuroblasts in the thoracic ventral nerve cord of Drosophila melanogaster have the same origin. We have traced the development of threefold-labelled single precursor cells from the early gastrula stage to late larval stages. The technique allows in the same individual monitoring of progeny cells at embryonic stages (in vivo) and differentially staining embryonic and postembryonic progeny within the resulting neural clone at late postembryonic stages. The analysis reveals that postembryonic cells always appear together with embryonic cells in one clone. Furthermore, BrdU labelling suggests that the embryonic neuroblast itself rather than one of its progeny resumes proliferation as a postembryonic neuroblast. A second type of clone consists of embryonic progeny only.
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Boag, Brian, und Gregor Yeates. „Post-embryonic growth of longidorid nematodes“. Nematology 4, Nr. 8 (2002): 883–89. http://dx.doi.org/10.1163/156854102321122494.
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AbstractTo investigate changes in body size of Longidoridae during growth, we used published dimensions of stages to calculate volumes of the juvenile and adult stages of 33 species. A consistent increase in body volume between the juvenile stages was found with proportionally more growth occurring between the smaller stages. In species where three, rather than four, juvenile stages are present, the ultimate size of adults was correspondingly smaller. In the Heteroderidae, greatest growth occurs in later stages and this indicates different adaptations to plant parasitism. Analysis of further groups of free-living and parasitic nematodes is required to increase understanding of body growth and life histories, both within and between families.
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Kimmel, Charles B., William W. Ballard, Seth R. Kimmel, Bonnie Ullmann und Thomas F. Schilling. „Stages of embryonic development of the zebrafish“. Developmental Dynamics 203, Nr. 3 (Juli 1995): 253–310. http://dx.doi.org/10.1002/aja.1002030302.
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Praskova, E., E. Voslarova, Z. Siroka, L. Plhalova, S. Macova, P. Marsalek, V. Pistekova und Z. Svobodova. „Assessment of diclofenac LC50 reference values in juvenile and embryonic stages of the zebrafish (Danio rerio)“. Polish Journal of Veterinary Sciences 14, Nr. 4 (01.12.2011): 545–49. http://dx.doi.org/10.2478/v10181-011-0081-0.
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Assessment of diclofenac LC50 reference values in juvenile and embryonic stages of the zebrafish (Danio rerio) The aim of the study was to compare the acute toxicity of diclofenac to juvenile and embryonic stages of the zebrafish (Danio rerio). Acute toxicity tests were performed on the aquarium fish Danio rerio, which is one of the model organisms most commonly used in toxicity testing. The tests were performed using a semi-static method according to OECD guideline No. 203 (Fish, acute toxicity test). Embryo toxicity tests were performed in zebrafish embryos (Danio rerio) in compliance with OECD No. 212 methodology (Fish, short-term toxicity test on embryo and sac-fry stages). The results were subjected to a probit analysis using the EKO-TOX 5.2 programme to determine 96hLC50 and 144hLC50 (median lethal concentration, 50% mortality after a 96 h or 144 h interval, respectively) values of diclofenac. The statistical significance of the difference between LC50 values in juvenile and embryonic stages of Danio rerio was tested using the Mann-Whitney non-parametric test implemented in the Unistat 5.1 programme. The LC50 mean value of diclofenac was 166.6 ± 9.8 mg/L in juvenile Danio rerio, and 6.11 ± 2.48 mg/L in embryonic stages of Danio rerio. The study demonstrated a statistically higher sensitivity to diclofenac (P<0.05) in embryonic stages compared to the juvenile fish.
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Sharma, Adita, Tanushri Ghorai, Shivendra Kumar und P. P. Srivastava. „Differential impact of monsoon and late monsoon season on embryonic development of Amur Carp (Cyprinus carpio haematopterus)“. emergent Life Sciences Research 08, Nr. 02 (2022): 72–76. http://dx.doi.org/10.31783/elsr.2022.827276.
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The embryonic development of Amur carp (Cyprinus carpio haematopterus) throughout the monsoon and post-monsoon seasons is compared in this research work. During the regular and late breeding seasons, the study identifies the most critical features of the monsoon season that affect Amur carp embryonic development. The effects of temperature changes on embryonic development were evaluated by observing the morphological characteristics of the embryos and identifying the embryonic stages that eventually determined the impacts of temperature changes on embryonic development. According to present study, the development stages of eggs in the regular season are shorter than in the late monsoon season. Initially, eggs grow at the same time, but late monsoon eggs require more time to develop.
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Ikeda, Wataru, Hiroyuki Nakanishi, Jun Miyoshi, Kenji Mandai, Hiroyoshi Ishizaki, Miki Tanaka, Atushi Togawa et al. „Afadin“. Journal of Cell Biology 146, Nr. 5 (06.09.1999): 1117–32. http://dx.doi.org/10.1083/jcb.146.5.1117.
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Afadin is an actin filament–binding protein that binds to nectin, an immunoglobulin-like cell adhesion molecule, and is colocalized with nectin at cadherin-based cell–cell adherens junctions (AJs). To explore the function of afadin in cell–cell adhesion during embryogenesis, we generated afadin−/− mice and embryonic stem cells. In wild-type mice at embryonic days 6.5–8.5, afadin was highly expressed in the embryonic ectoderm and the mesoderm, but hardly detected in the extraembryonic regions such as the visceral endoderm. Afadin−/− mice showed developmental defects at stages during and after gastrulation, including disorganization of the ectoderm, impaired migration of the mesoderm, and loss of somites and other structures derived from both the ectoderm and the mesoderm. Cystic embryoid bodies derived from afadin−/− embryonic stem cells showed normal organization of the endoderm but disorganization of the ectoderm. Cell–cell AJs and tight junctions were improperly organized in the ectoderm of afadin−/− mice and embryoid bodies. These results indicate that afadin is highly expressed in the ectoderm- derived cells during embryogenesis and plays a key role in proper organization of AJs and tight junctions of the highly expressing cells, which is essential for proper tissue morphogenesis.
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Cheng, Yu-Rong, Ching-Yi Lin und Jr-Kai Yu. „Embryonic and post-embryonic development in the parasitic copepod Ive ptychoderae (Copepoda: Iviidae): Insights into its phylogenetic position“. PLOS ONE 18, Nr. 3 (07.03.2023): e0281013. http://dx.doi.org/10.1371/journal.pone.0281013.
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Parasitic copepods are frequently discovered in many marine animals, and they exhibit great species diversity with remarkable morphological adaptations to their parasitic lifestyle. Similar to their free-living relatives, parasitic copepods usually develop through complex life cycle, but they eventually transform into a modified adult form with reduced appendages. Although the life cycle and distinct larval stages have been described in a few species of parasitic copepods, particularly those infecting commercially valuable marine animals (such as fishes, oysters, and lobsters), very little is known about the developmental process of the species that transformed into extremely simplified adult body plan. This paucity also causes some difficulties when investigating the taxonomy and phylogeny of this kind of parasitic copepods. Here we describe the embryonic development and a series of sequential larval stages of a parasitic copepod, Ive ptychoderae, which is a vermiform endoparasite living inside the hemichordate acorn worms. We devised laboratory regimes that enable us raising large quantity of embryos and free living larvae, and obtaining post-infested I. ptychoderae samples from the host tissues. Using defined morphological features, the embryonic development of I. ptychoderae can be categorized into eight stages (1-, 2-, 4-, 8-, 16- cell stages, blastula, gastrula, and limb bud stages) and the post-embryonic development comprises six larval stages (2 naupliar and 4 copepodid stages). Based on the comparisons of morphological characters in the nauplius stage, our results provide evidence to support that the Ive-group is more closely related to the Cyclopoida, which represents one of the two major clades that contain many highly transformed parasitic copepods. Thus, our results help to resolve the problematic phylogenetic position of the Ive-group in previous study based on analysis using 18S rDNA sequences. Combining with more molecular data, future comparative analyses on the morphological features of copepodid stages will further refine our understanding of the phylogenetic relationships of parasitic copepods.
Dissertationen zum Thema "Embryonic stages"
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Jawdat, Razan S. „Investigating the role of mitochondria at the preimplantation stages of human embryonic development“. Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10047392/.
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Mitochondria are the major energy producers in cells in the form of ATP. Proteins required for mitochondrial function are encoded by both mitochondrial (mtDNA) and nuclear DNA (nDNA) necessitating compatibility between the two genomes. Good quality oocytes containing an optimal number of mitochondria and sufficient levels of ATP produce higher quality blastocysts. Recent data suggests an elevated level of mtDNA may be associated with aneuploidy in blastocysts. In this study, preimplantation embryo development was investigated in relation to mtDNA template number and aneuploidy. ATP levels were measured in blastocysts and linked to aneuploidy. To investigate possible nDNA/mtDNA mismatch, DNA from couples with repeated miscarriage or repeated implantation failure (RM/RIF) was compared with DNA from couples with no history of infertility but who had preimplantation genetic diagnosis (PGD) for monogenic disorders. DNA from both groups was genotyped using SNP arrays. Sequencing of the mitochondrial genome and a set of 53 nuclear-encoded genes important in mitochondrial function was also performed. Further sequencing of the selected nuclear genes in embryos from the PGD group was used to identify variants in the nuclear and mitochondrial genomes associated with poor embryo development. Our data showed that arrested embryos that were euploid had more mtDNA than arrested embryos that were aneuploid. Aneuploidy in blastocysts resulted in variability in ATP levels. When aneuploidy was present in more than ten chromosomes, ATP was almost undetectable. From the sequencing analysis, significantly more couples with RM/RIF (5/12) had partners from the same mtDNA haplogroup compared with the PGD group of couples (1/11). Yet, SNP data analysed by identity by state (IBS) showed no significant differences between partners in couples based on their nDNA even when the HLA region was considered separately. Within the PGD group, the presence of the T haplogroup in the male partner was associated with a smaller percentage of embryos developing to blastocysts. Analysis of embryos from these couples suggested a link with SNPs in nuclear genes (specifically COQ9 and PPARGC1a) encoding mitochondrial proteins which may contribute to poor embryo development due to a disturbance in the electron transport chain or mitochondrial biogenesis respectively. Determining the mitochondrial haplogroups of both parents is a useful tool to investigate potential mismatch between the nuclear and mitochondrial genomes in embryos which may influence their development.
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Ghosh, Samiran. „Identification of low temperature resistant embryonic stages for improving seed production in muga silkworm, antheraea assama, westwood for cold preservation of eggs“. Thesis, University of North Bengal, 2018. http://ir.nbu.ac.in/handle/123456789/2697.
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Lamoureux, Denis Oswald. „Development of the embryonic dentition in Xenopus laevis, Daudin, descriptive and experimental studies between stages 54 and 61“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq21589.pdf.
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Allan-Wojtas, Paula. „Ultrastructural characteristics of yolk in the chicken egg. Mechanisms for yolk absorption and its digestion by the yolk sac at different stages of embryonic development“. Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6930.
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An ultrastructural study using electron microscopy was undertaken of yolk and yolk sac to elucidate digestive mechanisms and to gather evidence to further substantiate the belief that intracellular digestion of yolk takes place in yolk sac epithelial cells during incubation. Initial work focused on the ultrastructure yolk in unincubated eggs using transmission electron microscopy of thin sections of yolk which had been fixed using conventional and novel fixatives. The next phase of the study involved the ultrastructural comparison of granules from sub-blastodermic fluid from 9 day old embryos, and extracellular yolk attached to the yolk sac of 15 day old embryos with the granules from yolk of unincubated eggs. The third phase of the study was the ultrastructural description of yolk sacs at 3 ages (3 days, 8 days and 15 days of incubation). A transport system for yolk lipid and its digestion products to the embryo was demonstrated ultrastructurally using the Imidazole-buffered Osmium Tetroxide protocol of Angermuller and Fahimi (1982) which enhanced lipid staining. We observed no ultrastructural changes in extracellular yolk granules and matrix particles at any age studied. Granules and matrix particles are taken up by endocytosis, and ultrastructural changes of yolk granules occur in epithelial cells, in acid phosphatase-containing vacuoles (which we have identified as secondary lysosomes), which are part of the functioning intracellular digestive system. We have ultrastructurally demonstrated the transport of lipids, which becomes more evident in 13 day old embryos. On the basis of the above evidence we conclude that yolk is digested in epithelial cells of the yolk sac, and the digestion products enter the blood sinuses and travel in the bloodstream to deliver nutrients to the developing embryo. (Abstract shortened by UMI.)
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Pinho, Sandra Isabel da Rocha Lourenco de. „Regulation of pluripotent states in human embryonic stem cells“. Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5884.
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A growing array of mouse and human pluripotent stem cell lines has been derived from the early embryo as well as from adult cells reprogrammed by ectopic expression of transcription factors – i.e. induced pluripotent stem (iPS) cells. These cell lines share the expression of key pluripotency markers and are able to self-renew and to generate differentiated progenies when induced. Their relationship to each other and whether they correspond to different pluripotent states with distinct developmental capacities and affiliations in vivo remains unclear, however. Profiling chromatin in a particular cell line has proven to be a valuable signature for cell identity and developmental stage. One approach has been to assay the timing of DNA replication across a panel of loci, as an indicator of chromatin accessibility. Of interest, this replication timing profiling was capable of discriminating pluripotent mouse ES (mES) cells from cells with a more restricted differentiation capacity. In this study, I have addressed whether distinct pluripotent states could be reliably discriminated at the chromatin level. In particular, I characterised the replication timing profile of a number of human ES (hES) cell lines alongside mES and mouse epiblast-derived stem (mEpiS) cell lines. I showed that mES cells have a steady and mostly early-replicating profile, regardless of their genetic background. In contrast, the profile of undifferentiated H1, H7 and H9 hES cell lines harboured an increased proportion of late-replicating loci during S-phase. Moreover, hES cell replication profile greatly varied between cultures and cell lines; a level of replication timing variability also observed among mEpiS cells, as opposed to mES cells. These results highlighted that hES and mEpiS cells share a common unstable or transitional state: primed on the verge of differentiation. This view was, however, further challenged by exploring how hES cell cultures could be modulated towards an ES-like versus epiblast-like state under different conditions. In particular, extensive and dynamic shifts of replication timing, from late to early, were consistently observed at many target loci in hES and hiPS cells upon increased Smad2/3 and p300 histone acetyltransferase activity. Importantly, these alterations were reversible and associated with differential gene expression profiles and functional properties of hES cells. Collectively, these data revealed the existence of distinct but interchangeable pluripotent hES cell states and proposed a key role for TGF-β/Activin signalling and the HAT p300 in modulating the balance between a naive versus primed state in hES cell cultures.
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Cho, Ting-yin. „Conversion from mouse embryonic to extra-embryonic endoderm stem cells reveals distinct differentiation capacities of pluripotent stem cell states“. Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607991.
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Autio, Matias. „Investigating the regulation of distinct epigenetic states in human embryonic stem cells“. Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11046.
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Accumulating evidence suggest that pluripotency – the ability to generate all somatic cell types – is not a fixed state. Pluripotent cell populations encompass a heterogeneous group of cells with different phenotypic and functional properties in equilibrium. At least two phases of pluripotency, immature and primed for differentiation, have been identified during early mouse development, and these are typified by the two distinct stem cell populations – mouse embryonic (mES) and epiblast-‐derived (mEpiS) stem cells – isolated from epiblast layers of pre-‐ and post-‐implantation embryo, respectively. Many lines of human ES (hES) cells have also been established in vitro from the inner cell mass of pre-‐ implantation blastocysts yet the precise in vivo lineage affiliation of these cells remains largely unresolved. Profiling chromatin in a particular cell line has proven to be a valuable signature for cell identity and developmental stage. One approach has been to assay the timing of DNA replication during S-‐phase of the cell cycle across a panel of loci, as an indicator of chromatin accessibility. This replication timing profiling was notably capable of discriminating pluripotent mES cells from cells with a more restricted differentiation capacity. This study sought to address whether distinct pluripotent states could be reliably discriminated at the chromatin level. In particular, the replication timing profiles of a number of hES cell lines were characterised and compared to those of mES and mEpiS cell lines derived from different genetic backgrounds. Profiles of undifferentiated H1, H7 and H9 hES cell lines typically harboured an increased proportion of late-‐replicating loci during S-‐ phase when compared to mES cells, which were confirmed to have a steady and mostly early-‐replicating profile regardless of their genetic background. Moreover, hES cell replication profile greatly varied between cultures and cell lines; a level of replication timing variability also observed among mEpiS cells, as opposed to mES cells. These results highlight that hES and mEpiS cells most likely share a common unstable epigenetic state or transitional state primed on the verge of differentiation. The epigenetic state of hES cell lines was further interrogated by analysing cells grown under two different culture conditions, both however similarly relying on TGF-‐β/Activin signalling. Results demonstrated that hES cells could adopt distinct yet reversible epigenetic signatures while retaining their pluripotency. In particular, extensive and dynamic shifts of replication timing, from late-‐to-‐early, were consistently observed at many target loci in hES cells as well as in human induced pluripotent cells (iPS) cells, upon increased SMAD2/3-‐associated P300/CBP histone acetyltransferase (HAT) activity. This was accompanied by fluctuations in the expression of NANOG and REX1 (also known as ZFP42), and a change in hES cell’s functional properties, as judged by their responsiveness to differentiation-‐inducing signals. Interestingly, inhibiting P300/CBP HAT activity by curcumin treatment in undifferentiated hES cells was sufficient to revert back to a late-‐replicating profile associated with a histone hypoacetylated state. Stable knockdown of P300 in hES cell cultures, however, resulted in a gradual loss of the pluripotent identity through differentiation or apoptosis, preventing further analysis of effects on replication timing. Collectively, these data strongly support the view that different but interchangeable pluripotent states exist within hES cell cultures and suggest a role for P300/CBP HAT activity in determining distinct epigenetic states in hES cells. As mentioned above, REX1 was also significantly upregulated in H1 hES cells upon culture condition change. REX1 is a developmental stage-‐specific marker that is expressed in the ICM of both mouse and human embryos, as well as in pluripotent mES, hES and iPS cells. However, its function in hES cells remains largely unclear. Human ES cells overexpressing REX1 were here generated to investigate the role of REX1 in regulating hES cell pluripotent identity. These cells expressed similar levels of key pluripotency markers than their normal counterparts and remained capable of self-‐renewing and differentiating into the three germ layers in vitro. Interestingly, however, upon withdrawal of exogenous Activin A, REX1 overexpressing hES cells in contrast to control cells retained a comparatively high level of OCT4 and stained positive for alkaline phosphatase, a known marker of undifferentiated hES cells. Taken together, these results point to a possible role for REX1 in sustaining hES cell self-‐renewal ability.
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Lange, Léa. „Influences environnementales précoces et plasticité phénotypique : étude d’un modèle amphibien avec soins parentaux prénataux, l’Alyte accoucheur“. Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS016.
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L’Alyte accoucheur (Alytes obstetricans) est une espèce d’amphibien où les soins parentaux sont réalisés par le mâle exclusivement. En effet, après l’accouplement, durant lequel le mâle participe activement à l’émission des oeufs, il attache sa ponte autour des articulations de ses membres postérieurs et la porte ainsi pendant tout le développement embryonnaire. Les amphibiens sont très sensibles à l’environnement abiotique, notamment aux conditions hydriques et thermiques. Pour éviter les températures extrêmes, ils peuvent thermoréguler comportementalement, par exemple en sélectionnant des refuges aux conditions microclimatiques favorables. Les Alytes accoucheurs ont montré une sélection de leurs refuges sur la base de leurs propriétés hydriques et thermiques. Les stades de développement précoces sont particulièrement sensibles à la température. Les parents peuvent alors réaliser des comportements parentaux pour en limiter les effets. Un effet phénologique paternel a été observé chez les Alytes accoucheurs, dont les mâles favorisent des températures plus élevées lorsqu’ils portent des oeufs. Les comportements parentaux sont cependant coûteux pour les adultes. Les Alytes accoucheurs ont présenté des performances de locomotion diminuées pendant le port des oeufs, ce qui pourrait induire une diminution de l’aptitude. De plus, les comportements parentaux influencent fortement le développement des jeunes. L’environnement thermique rencontré pendant le stade embryonnaire, et donc pendant la période de soins parentaux chez l’Alyte accoucheur, a eu des effets à court terme et des effets persistants sur la phénologie. L’environnement thermique rencontré pendant le stade larvaire peut également être déterminant. Chez l’Alyte accoucheur, l’environnement thermique postnatal a induit un basculement vers un développement pluriannuel lors d’un développement à 16°C, avec un hivernage au stade têtard, alors qu’il a été annuel lors d’un développement à 20°C et 24°C. L’environnement thermique postnatal a également impliqué des modifications morphologiques, physiologiques et comportementales. Enfin, une implication de la physiologie, et notamment de la fréquence cardiaque, a été observée tout au long du développement embryonnaire et larvaire des jeunesThe common Midwife toad (Alytes obstetricans) is a species of amphibian in which parental care is performed exclusively by the male. Indeed, after mating, during which the male actively helps the female for the emission of the eggs, he attaches the clutch around the joints of his hind limbs and thus carries it throughout embryonic development. Amphibians are very sensitive to the abiotic environment, especially to hydric and thermal conditions. To avoid extreme temperatures, they can behaviourally thermoregulate, for example by selecting refuges with favourable microclimatic conditions. The common Midwife toad has shown a selection of their refuges based on their hydric and thermal properties. The early stages of development are particularly sensitive to temperature. Parents can then carry out parental care to limit the effects. A paternal phenological effect has been observed in common Midwife toad, whose males favour higher temperatures when they carry eggs. Parental care is costly for adults, however. The common Midwife toad exhibited decreased locomotion performances during egg carrying, which could lead to decreased fitness. In addition, parental care strongly influences the development of young. The thermal environment encountered during the embryonic stage, and therefore during the period of parental care in the common Midwife toad, had both short-term and persistent effects on the phenology. The thermal environment encountered during the larval stage can also be decisive. In the common Midwife toad, the postnatal thermal environment induced a switch to multi-year development during development at 16 ° C, with overwintering at the tadpole stage, whereas it was annual during development at 20 ° C and 24 ° C. The postnatal thermal environment has also involved morphological, physiological, and behavioural changes. Finally, an involvement of physiology, and in particular heart rate, has been observed throughout the embryonic and larval development of the young
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Pinnock, Howard A. „A proposed framework for an embryonic environmental review process for Jamaica“. Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43268.
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Jamaica is faced with a number of serious environmental problems. Perhaps the most promising approach to address these problems is to subject development proposals to a process of environmental review while they are in the central government's planning approval process. Jamaica has never had such an environmental review process. In this thesis an attempt was made to develop the framework for an environmental review process that can be integrated into the Jamaican planning approval process.
Guided by case studies of the environmental review processes in three U.S. states and Puerto Rico, as well as an analysis of Jamaica's unique conditions as they affect the implementation of an environmental review process, an attempt was made to synthesize a framework for an environmental review process that can be both implementable and effective in Jamaica. In addition, an attempt was made to suggest some general strategies for achieving the implementation of the environmental review process.
A simple yet potentially effective EIA framework was developed. However, the necessary preconditions for effective implementation, i.e., political support, do not exist in Jamaica. Unless the environment becomes a major issue in Jamaica's political economy, it is unrealistic to expect the implementation of an effective process.Master of Urban and Regional Planning
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McKenna, Erin N. „Embryonic policies the stunted development of in vitro fertilization in the United States, 1975-1992 /“. Connect to this title online, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1143490658.
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Fabiola, Müller, Hrsg. The embryonic human brain: An atlas of developmental stages. 3. Aufl. Hoboken, N.J: Wiley-Liss, 2006.
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Fabiola, Müller, Hrsg. The embryonic human brain: An atlas of developmental stages. New York: Wiley-Liss, 1994.
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O'Rahilly, Ronan. The embryonic human brain: An atlas of developmental stages. 2. Aufl. New York: Wiley-Liss, 1999.
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Amy, Francis, Hrsg. Should the government fund embryonic stem cell research? Detroit: Greenhaven Press, 2009.
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Catholic Church. United States Conference of Catholic Bishops. On embryonic stem cell research: A statement of the United States Conference of Catholic Bishops. Washington, D.C: USCCB Pub., 2008.
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United States. Congress. Senate. Special Committee on Aging. Exploring the promise of embryonic stem cell research: Hearing before the Special Committee on Aging, United States Senate, One Hundred Ninth Congress, first session, Washington, DC, June 8, 2005. Washington: U.S. G.P.O., 2005.
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Alternative methods for deriving stem cells: Hearing before a Subcommittee on of the Committee on Appropriations, United States Senate, One Hundred Ninth Congress, first session, special hearing, July 12, 2005, Washington, DC. Washington: U.S. G.P.O., 2006.
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United States. Congress. Senate. Committee on Appropriations. Subcommittee on Departments of Labor, Health and Human Services, Education, and Related Agencies. Stem cells research, 2005: Hearing before a Subcommittee of the Committee on Appropriations, United States Senate, One Hundred Ninth Congress, first session, special hearing, October 19, 2005, Washington, DC. Washington: U.S. G.P.O., 2006.
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Can Congress help fulfill the promise of stem cell research?: Joint hearing before the Committee on Health, Education, Labor, and Pensions and the Subcommittee on Labor, Health and Human Services, Education, and Related Agencies of the Committee on Appropriations, United States Senate, One Hundred Tenth Congress, first session on examining stem cell research, focusing on ongoing federal support of both embryonic and non-embryonic stem cell research and scientific progress, including recent findings on amniotic fluid stem cells, January 19, 2007. Washington: U.S. G.P.O., 2007.
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Die genetische Veränderung des Erbgutes menschlicher Embryonen: Chancen und Grenzen im deutschen und amerikanischen Recht. Frankfurt am Main: P. Lang, 2009.
Den vollen Inhalt der Quelle findenBuchteile zum Thema "Embryonic stages"
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Campos-Ortega, José A., und Volker Hartenstein. „Stages of Drosophila Embryogenesis“. In The Embryonic Development of Drosophila melanogaster, 9–84. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-662-02454-6_3.
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Campos-Ortega, José A., und Volker Hartenstein. „Stages of Drosophila Embryogenesis“. In The Embryonic Development of Drosophila melanogaster, 9–102. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-22489-2_2.
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Bomsel-Helmreich, Ondine. „Heteroploidy and Embryonic Death“. In Ciba Foundation Symposium - Preimplantation Stages of Pregnancy, 246–69. Chichester, UK: John Wiley & Sons, Ltd., 2008. http://dx.doi.org/10.1002/9780470719435.ch12.
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Tarkowski, Andrzej K. „Embryonic and Postnatal Development of Mouse Chimeras“. In Ciba Foundation Symposium - Preimplantation Stages of Pregnancy, 183–93. Chichester, UK: John Wiley & Sons, Ltd., 2008. http://dx.doi.org/10.1002/9780470719435.ch9.
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Gates, Allen H. „Rate of Ovular Development as a Factor in Embryonic Survival“. In Ciba Foundation Symposium - Preimplantation Stages of Pregnancy, 270–93. Chichester, UK: John Wiley & Sons, Ltd., 2008. http://dx.doi.org/10.1002/9780470719435.ch13.
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Helluy, Simone, und Barbara Beltz. „Stages in the Embryonic Development of the American Lobster with Special Emphasis on Its Nervous System“. In Frontiers in Crustacean Neurobiology, 530–36. Basel: Birkhäuser Basel, 1990. http://dx.doi.org/10.1007/978-3-0348-5689-8_66.
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Downing, Gregory J. „A Researcher’s Guide to Federally Funded Human Embryonic Stem Cell Research in the United States“. In Human Embryonic Stem Cells, 27–37. Totowa, NJ: Humana Press, 2003. http://dx.doi.org/10.1007/978-1-59259-423-8_2.
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de Boer, P., F. A. van der Hoeven und M. P. Cuijpers. „Genetic Constitution of Early Stage Pig Embryos and Embryo Mortality“. In Embryonic Mortality in Farm Animals, 207–15. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-5038-2_17.
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Durzan, D. J. „Physiological States and Metabolic Phenotypes in Embryonic Development“. In Cell and Tissue Culture in Forestry, 405–39. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-4484-8_22.
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Bibliowicz, Abel Mordechai. „The Anti-Jewish Strand—The Embryonic Stage Summary“. In Jews and Gentiles in the Early Jesus Movement, 93–101. New York: Palgrave Macmillan US, 2013. http://dx.doi.org/10.1057/9781137281104_9.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Embryonic stages"
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Larin, Kirill V., Irina V. Larina und Mary E. Dickinson. „Early Mammalian Embryonic Imaging at Different Developmental Stages with Optical Coherence Tomography“. In Frontiers in Optics. Washington, D.C.: OSA, 2009. http://dx.doi.org/10.1364/fio.2009.fthv2.
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Rennie, Monique Y., Michael Danilchik, Kent L. Thornburg und Sandra Rugonyi. „Hemodynamic Forces Regulate Collagen Deposition in the Embryonic Chicken Outflow Tract“. In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14299.
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Alterations in blood flow at early embryonic stages can lead to detrimental remodeling and heart defects, but these structural adaptations are not well understood. We hypothesize that deposition of collagens will be increased as shear stress is increased — leading to a stiffer wall. To test this hypothesis a suture (OTB) was tightened around the outflow tract (OFT) of stage HH18 chick embryos for 24 hours to reduce cross sectional area of the lumen. Sham and OTB embryos were immunostained for collagen I, III, VI and XIV, imaged with confocal microscopy, and staining was quantified by grayscale analysis. Changes in fibril collagens I and III were not observed, however deposition of collagens VI and XIV increased in a degree-of-constriction dependent manner. The observed increase in collagen VI and XIV deposition suggests they play a key role in structural adaptation to increased hemodynamic pressure.
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Young, Jonathan M., Eric M. Beecher, Benjamen A. Filas, Larry A. Taber und Renato Perucchio. „FEM Voxel Modeling of the Tubular Embryonic Chick Heart for Finite Strain Analysis“. In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192756.
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Significant progress has been made in the study of the developmental biomechanics of the embryonic chick heart through the use of the finite element method (FEM) [1, 2, 3]. Our work focuses on the geometry of the Hamburger-Hamilton stages 9–12 embryonic chick heart, approximately the time when the heart begins to function and undergoes drastic morphological changes, such as c-looping. Our objective is to devise a method for building an accurate 3D solid FEM mesh used for nonlinear analysis of the myocardium (MY) and cardiac jelly (CJ). The models are based on the extraction of voxels from optical coherence tomography (OCT) images of an arrested developing heart. To alleviate the problem of jagged edges introduced by the hexahedral voxel structure, we present a method for geometric smoothing and mesh coarsening. The performance of the voxel and smoothed models are tested given physiological loading conditions (pressure, biological growth, muscle contraction), to ascertain which model should be used for modeling the c-looping process.
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Fernandes, Tiago G., Maria Margarida Diogo, Ana Fernandes-Platzgummer, Claudia Lobato da Silva und Joaquim M. S. Cabral. „Effect of hypoxia on proliferation and neural commitment of embryonic stem cells at different stages of pluripotency“. In 2011 1st Portuguese Meeting in Bioengineering - the Challenge of the XXI Century (ENBENG 2011). IEEE, 2011. http://dx.doi.org/10.1109/enbeng.2011.6026039.
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Hassan, H. J., A. Leonardi, C. Chelucci, R. Guerriero, P. M. Mannucci und C. Peschle. „EXPRESSION IN ONTOGENESIS OF HUMAN BLOOD COAGULATION FACTORS“. In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644610.
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We have analyzed the expression of several blood coagulation factors (IX, VIII, X, fibrinogen chains) and inhibitors (antithrombin III, protein C) in human embryonic and fetal livers, obtained from legal abortions at 6-11 week post-conception. The age was established by morphologic staging and particularly crown-rump lenght measurement.Total cellular RNA was isolated from partially purified hepatocytes or total liver homogenate using the guanidine isothiocyanate method. Poly(A)+ RNA was selected by oligodT cellulose chromatography. The size and the number of the embryonic and fetal transcripts are equivalent to those observed in adult liver, as evaluated by Northern blot analysis of total or poly(A)+ RNA hybridized to human cDNA probes.The level of coagulation factor transcripts in embryonic and fetal liver was evaluated by dot hybridization of total RNA (0.5-10 ug), as compared to RNA extracted from normal adult liver biopsies. The expression of blood coagulation factors in embryos is generally reduced for all factors, but at a different degree. In 5-11 wk liver, the level of factor IX is 5-10% of that observed in adults, while fibrinogen, protein C, antithrombin III RNA level rises from 25 to 50% and factor X is expressed at a level comparable to that observed in adult liver.We conclude that during these stages of development blood coagulation factors are expressed according to three different time, curves, possibly due to the effect of different types of regulatory mechanisms.
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Liu, Aiping, Ruikang Wang, Kent Thornburg und Sandra Rugonyi. „Wall Motion Influences Flow Pattern in the Outflow Tract of the Chick Embryonic Heart Tube“. In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19484.
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The outflow tract (OFT) of the chick embryonic heart offers a good model system to study the association between blood flow dynamics and cardiac morphogenesis in early heart development. At early stages, the chick heart is a looped tube without valves. The OFT, the distal region of the heart, functions as a primitive valve [1]. The OFT is a slightly curved tube with three-layered wall (Fig. 1 (A) and (B)): the myocardium, an external muscle layer that actively contracts; the endocardium, an inner endothelial layer that directly contacts blood; in between the cardiac jelly, an extracellular matrix layer. The OFT undergoes complex morphogenesis, eventually leading to the development of semilunar valves, and this morphogenesis is sensitive to blood flow dynamics.
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Young, Jonathan M., Larry A. Taber und Renato Perucchio. „Biomechanics of Early Cardiac Development: A Nonlinear Explicit FE Model of C-Looping in the Embryonic Chick Heart“. In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19525.
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C-looping is the morphomechanical process through which the initially straight embryonic heart tube (HT) reconfigures into a doubly bent, twisted, swollen, c-shaped tube [1] between stages HH10− and HH12 [2]. According to the biomechanical hypotheses proposed by Taber [3], the ventral and rightward bending of the heart tube are intrinsic to the initially straight HT, and are caused by actin polymerization within myocardial cells. The torsion and rotation of the HT are due to a rightward oriented force generated by the elongation of the left omphalomesenteric vein (OV) and a dorsally oriented force due to tension in the splanchnopleure (SPL) [4]. In order to numerically test these biomechanical hypotheses, the standard stiffness-based nonlinear finite element formulation (standard FE) has been modified to include growth-based deformation to simulate c-looping [5]. However, due to numerical difficulties, such an approach can represent only the initial stages of c-looping and does not include SPL contact, or the merger (fusion) of the OV, which contributes to the elongation of the caudal heart tube [6]. To overcome these modeling difficulties, we propose the use of the explicit finite element formulation (explicit FE) as an alternative technique for modeling c-looping.
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Tanguay, Robert L., Lisa Truong, Tatiana Zaikova und James E. Hutchison. „Rapid In Vivo Assessment of the Nano/Bio Interface“. In ASME 2013 2nd Global Congress on NanoEngineering for Medicine and Biology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/nemb2013-93153.
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Recent advances in nanoscience offer great promise for the nanomedicine sector. These advances in the nanotechnology field will undoubtedly increase both human and environmental exposures to engineered nanomaterials. Whether these exposures pose a significant risk remains uncertain. Despite recent collective progress there remain gaps in our understanding of the nanomaterials physiochemical properties that drive or dictate biological compatibility. The development and implementation of rapid relevant and efficient testing strategies to assess these emerging materials prior to large-scale exposures could help advance this exciting field. I will present a powerful approach that utilizes a dynamic in vivo zebrafish embryonic assay to rapidly define the biological responses to nanomaterial exposures. Early developmental life stages are often uniquely sensitive to environmental insults, due in part to the enormous changes in cellular differentiation, proliferation and migration required to form the required cell types, tissues and organs. Molecular signaling underlies all of these processes. Most toxic responses result from disruption of proper molecular signaling, thus, early developmental life stages are perhaps the ideal life stage to determine if nanomaterials perturb normal biological pathways. Through automation and rapid throughput approaches, a systematic and iterative strategy has been deployed to help elucidate the nanomaterials properties that drive biological responses.
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Dorokhovich, Galina Pavlovna, und Liudmila Mikhailovna Erofeeva. „Morphological Characteristics of the Vascular and Nervous Components of the Male Sex Gland in Humans at Different Stages of Embryonic Development“. In All-Russian scientific conference with International Participation. Publishing house Sreda, 2022. http://dx.doi.org/10.31483/r-102186.
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Taimusova, E. N. „The influence of various environmental factors on the state of the reproductive system and the main stages of embryonic development of productive animals“. In ACTUAL PROBLEMS OF ECOLOGY AND ENVIRONMENTAL MANAGEMENT. Federal State Budgetary Educational Institution of Higher Education St. Petersburg State University of Veterinary Medicine, 2022. http://dx.doi.org/10.52419/3006-2022-3-92-94.
Der volle Inhalt der QuelleBerichte der Organisationen zum Thema "Embryonic stages"
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Browdy, Craig, und Esther Lubzens. Cryopreservation of Penaeid Shrimp Embryos: Development of a Germplasm Cryo-Bank for Preservation of High Health and Genetically Improved Stocks. United States Department of Agriculture, August 2002. http://dx.doi.org/10.32747/2002.7695849.bard.
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The objectives of the project were to develop a successful protocol for cryopreservation of penaeid germ plasm in order to preserve a pathogen-free broodstock nucleus for commercial exploitation of marine shrimp in aquaculture. The critical parameters to be characterized in the project were: 1. Determination of chill sensitivity and chill tolerant embryonic stages, including a full description and time course study of embryonic developmental stages. 2. Development of protocols for loading and removal of cryoprotectant agents (CPAs) from embryos; determination of optimal concentrations and duration of loading. 3. Characterization of the toxicity of the selected CP As and 4. Establishing optimal cooling and thawing procedures. Studies were performed on two penaeid species: Litopenaeus vannamei (in the USA) and P. semisulcatus (in Israel). The effect of incubation temperature on embryonic development rate and hatching success was studied in L. vannamei, showing that spawns maybe maintained at temperatures ranging from 24°C to 30°C, without compromising hatchability. Embryonic development extends from 12 hr to 19 hr at 30°C and 24°C, respectively. Studies showed that advanced embryonic developmental stages were chill tolerant in the two studied species, but P. semisulcatus could better endure lower temperatures than L. vannamei. A large number of experiments were performed to determine the optimal CP As, their concentration and duration of loading. Permeating (e.g. glycerol, methanol, DMSO, 1,2- propanediol, ethylene glycol, glucose) and non-permeating CPAs (sucrose, PVP, polyethylene glycol) were tested and several combinations of permeating and non-permeating CP As, on fertilized eggs (embryos), nauplii and protozoeae. In general, nauplii tolerated higher CPA concentrations than eggs and nauplii were also more permeable to radiolabeled methanol. Chlorine treatment intended to remove the chitinous envelop from eggs, did not increase dramatically the permeation of radiolabled methanol into eggs. Cooling eggs, nauplii or protozoeae to cryogenic temperatures, by either vitrification or slow cooling protocols, did not result in full survival of thawed samples, despite exhaustive attempts testing various protocols and CP As. Results seemed more encouraging in freezing of nauplii in comparison to eggs or protozoeae. Successful preliminary results in cryopreservation of spermatozoa of P. vannamei, will facilitate preservation of genetic specific to some extent.
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Funkenstein, Bruria, und Cunming Duan. GH-IGF Axis in Sparus aurata: Possible Applications to Genetic Selection. United States Department of Agriculture, November 2000. http://dx.doi.org/10.32747/2000.7580665.bard.
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Many factors affect growth rate in fish: environmental, nutritional, genetics and endogenous (physiological) factors. Endogenous control of growth is very complex and many hormone systems are involved. Nevertheless, it is well accepted that growth hormone (GH) plays a major role in stimulating somatic growth. Although it is now clear that most, if not all, components of the GH-IGF axis exist in fish, we are still far from understanding how fish grow. In our project we used as the experimental system a marine fish, the gilthead sea bream (Sparus aurata), which inhabits lagoons along the Mediterranean and Atlantic coasts of Europe, and represents one of the most important fish species used in the mariculture industry in the Mediterranean region, including Israel. Production of Sparus is rapidly growing, however, in order for this production to stay competitive, the farming of this fish species has to intensify and become more efficient. One drawback, still, in Sparus extensive culture is that it grows relatively slow. In addition, it is now clear that growth and reproduction are physiological interrelated processes that affect each other. In particular sexual maturation (puberty) is known to be closely related to growth rate in fish as it is in mammals, indicating interactions between the somatotropic and gonadotropic axes. The goal of our project was to try to identify the rate-limiting components(s) in Sparus aurata GH-IGF system which might explain its slow growth by studying the ontogeny of growth-related genes: GH, GH receptor, IGF-I, IGF-II, IGF receptor, IGF-binding proteins (IGFBPs) and Pit-1 during early stages of development of Sparus aurata larvae from slow and fast growing lines. Our project was a continuation of a previous BARD project and could be divided into five major parts: i) obtaining additional tools to those obtained in the previous project that are necessary to carry out the developmental study; ii) the developmental expression of growth-related genes and their cellular localization; iii) tissue-specific expression and effect of GH on expression of growth-related genes; iv) possible relationship between GH gene structure, growth rate and genetic selection; v) the possible role of the IGF system in gonadal development. The major findings of our research can be summarized as follows: 1) The cDNAs (complete or partial) coding for Sparus IGFBP-2, GH receptor and Pit-1 were cloned. Sequence comparison reveals that the primary structure of IGFBP-2 protein is 43-49% identical to that of zebrafish and other vertebrates. Intensive efforts resulted in cloning a fragment of 138 nucleotides, coding for 46 amino acids in the proximal end of the intracellular domain of GH receptor. This is the first fish GH receptor cDNA that had been cloned to date. The cloned fragment will enable us to complete the GH - receptor cloning. 2) IGF-I, IGF-II, IGFBP-2, and IGF receptor transcripts were detected by RT-PCR method throughout development in unfertilized eggs, embryos, and larvae suggesting that these mRNAs are products of both the maternal and the embryonic genomes. Preliminary RT-PCR analysis suggest that GH receptor transcript is present in post-hatching larvae already on day 1. 3) IGF-1R transcripts were detected in all tissues tested by RT-PCR with highest levels in gill cartilage, skin, kidney, heart, pyloric caeca, and brain. Northern blot analysis detected IGF receptor only in gonads, brain and gill cartilage but not in muscle; GH increased slightly brain and gill cartilage IGF-1R mRNA levels. 4) IGFBP-2 transcript were detected only in liver and gonads, when analyzed by Northern blots; RT-PCR analysis revealed expression in all tissues studied, with the highest levels found in liver, skin, gonad and pyloric caeca. 5) Expression of IGF-I, IGF-II, IGF-1R and IGFBP-2 was analyzed during gonadal development. High levels of IGF-I and IGFBP-2 expression were found in bisexual young gonads, which decreased during gonadal development. Regardless of maturational stage, IGF-II levels were higher than those of IGF-L 6) The GH gene was cloned and its structure was characterized. It contains minisatellites of tandem repeats in the first and third introns that result in high level of genetic polymorphism. 7) Analysis of the presence of IGF-I and two types of IGF receptor by immunohistochemistry revealed tissue- and stage-specific expression during larval development. Immunohistochemistry also showed that IGF-I and its receptors are present in both testicular and ovarian cells. Although at this stage we are not able to pinpoint which is the rate-limiting step causing the slow growth of Sparus aurata, our project (together with the previous BARD) yielded a great number of experimental tools both DNA probes and antibodies that will enable further studies on the factors regulating growth in Sparus aurata. Our expression studies and cellular localization shed new light on the tissue and developmental expression of growth-related genes in fish.
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Halevy, Orna, Zipora Yablonka-Reuveni und Israel Rozenboim. Enhancement of meat production by monochromatic light stimuli during embryogenesis: effect on muscle development and post-hatch growth. United States Department of Agriculture, Juni 2004. http://dx.doi.org/10.32747/2004.7586471.bard.
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The original objectives were: A. To determine the critical embryonic age for monochromatic green light stimulation. B. To follow the ontogeny of embryos exposed to monochromatic green light vs. darkness. C. To investigate the effects of monochromatic green light illumination on myoblast and fiber development in the embryo. D. To investigate the stimulatory effect of light combinations during embryo and post-hatch periods on growth and meat production. E. To evaluate the direct effect of monochromatic green light on cultured embryonic and adult myoblasts. The overall purpose of this study was to investigate the effect of monochromatic light stimuli during incubation period of broilers on muscle development and satellite cell myogenesis. Based on previous studies (Halevy et al., 1998; Rozenboim et al., 1999) that demonstrated the positive effects of green-light illumination on body and muscle growth, we hypothesized that monochromatic light illumination accelerates embryo and muscle development and subsequently enhances muscle growth and meat production. Thus, further decreases management costs. Under the cooperation of the laboratories at the Hebrew University of Jerusalem and University of Washington we have conducted the following: 1. We have established the critical stage for exposure to green monochromatic light which has the maximal effect on body and muscle growth (Objective A). We report that embryonic day 5 is optimal for starting illumination. The optimal regime of lighting that will eliminate possible heat effects was evaluated by monitoring egg core temperature at various illumination periods. We found that intermitted lighting (15 min. on; 15 min. off) is optimal to avoid heat effects. 2. We have evaluated in detail gross changes in embryo development profile associated to green light stimuli vs. darkness. In addition, we have investigated the stimulatory effect of light combinations during embryo and post-hatch periods on body and muscle growth (Objective B,D). 3. We have studied the expression profile of muscle regulatory proteins during chicken muscle cell differentiation in cultures using newly developed antibodies. This study paved the way for analyzing the expression of these proteins in our photo stimulation experiments (Objective C). 4. We have studied the pattern ofPax7 expression during myogenesis in the posthatch chicken. Experimental chick pectoralis muscles as well adult myoblast cultures were used in this study and the results led us to propose a novel model for satellite cell differentiation and renewal. 5. The effects of monochromatic green light illumination during embryogenesis have been studied. These studies focused on fetal myoblast and satellite cell proliferation and differentiation at pre- and posthatch periods and on the effects on the expression of muscle regulatory proteins which are involved in these processes. In addition, we have analyzed the effect of photo stimulation in the embryo on myofiber development at early posthatch (Objective C). 6. In follow the reviewers' comments we have not conducted Objective E. The information gathered from these studies is of utmost importance both, for understanding the molecular basis of muscle development in the posthatch chicks and for applied approach for future broiler management. Therefore, the information could be beneficial to agriculture in the short term on the one hand and to future studies on chick muscle development in the embryo and posthatch on the other hand.
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Kuwayama, Mikio. Search for a New Partnership in Trade and Investment between Latin America and Asia-Pacific. Inter-American Development Bank, November 2001. http://dx.doi.org/10.18235/0010390.
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Although interregional cooperation in trade and investment between Latin America and Asia-Pacific has been on the agendas of countries in both regions for some time, initiatives have been few, with meager results. The lack of tangible results is related to the economic asymmetries between the two regions and a purely inter-industrial nature of bi-regional trade. The incipient drive in bi-regional trade up to the Asian crisis was triggered by the economic boom of East Asia on the one hand, and growth recovery, economic reforms and integration, on the other. Now, coupled with the slowdown of the US economy and the standstill of Japanese economy, the sustained impulse of these factors is uncertain. The present economic relations between the two regions do not reflect the potential for interregional trade and investment that exists in an increasingly globalized world. The current low level of economic interaction, especially in the aftermath of the economic crises experienced in each region in recent years, calls for joint actions in the economic sphere. Given the embryonic stage and limited country coverage of ongoing consultations on bilateral free trade agreements, the recently created Forum for East-Asia Latin America Cooperation (FEALAC) should address the issues of market access and bi-regional economic integration, and promote concrete integration initiatives.
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Uni, Zehava, und Peter Ferket. Enhancement of development of broilers and poults by in ovo feeding. United States Department of Agriculture, Mai 2006. http://dx.doi.org/10.32747/2006.7695878.bard.
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The specific objectives of this research were the study of the physical and nutritional properties of the In Ovo Feeding (IOF) solution (i.e. theosmostic properties and the carbohydrate: protein ratio composition). Then, using the optimal solution for determining its effect on hatchability, early nutritional status and intestinal development of broilers and turkey during the last quarter of incubation through to 7 days post-hatch (i.e. pre-post hatch period) by using molecular, biochemical and histological tools. The objective for the last research phase was the determination of the effect of in ovo feeding on growth performance and economically valuable production traits of broiler and turkey flocks reared under practical commercial conditions. The few days before- and- after hatch is a critical period for the development and survival of commercial broilers and turkeys. During this period chicks make the metabolic and physiological transition from egg nutriture (i.e. yolk) to exogenous feed. Late-term embryos and hatchlings may suffer a low glycogen status, especially when oxygen availability to the embryo is limited by low egg conductance or poor incubator ventilation. Much of the glycogen reserve in the late-term chicken embryo is utilized for hatching. Subsequently, the chick must rebuild that glycogen reserve by gluconeogenesis from body protein (mostly from the breast muscle) to support post-hatch thermoregulation and survival until the chicks are able to consume and utilize dietary nutrients. Immediately post-hatch, the chick draws from its limited body reserves and undergoes rapid physical and functional development of the gastrointestinal tract (GIT) in order to digest feed and assimilate nutrients. Because the intestine is the nutrient primary supply organ, the sooner it achieves this functional capacity, the sooner the young bird can utilize dietary nutrients and efficiently grow at its genetic potential and resist infectious and metabolic disease. Feeding the embryo when they consume the amniotic fluid (IOF idea and method) showed accelerated enteric development and elevated capacity to digest nutrients. By injecting a feeding solution into the embryonic amnion, the embryo naturally consume supplemental nutrients orally before hatching. This stimulates intestinal development to start earlier as was exhibited by elevated gene expression of several functional genes (brush border enzymes an transporters , elvated surface area, elevated mucin production . Moreover, supplying supplemental nutrients at a critical developmental stage by this in ovo feeding technology improves the hatchling’s nutritional status. In comparison to controls, administration of 1 ml of in ovo feeding solution, containing dextrin, maltose, sucrose and amino acids, into the amnion of the broiler embryo increased dramatically total liver glycogen in broilers and in turkeys in the pre-hatch period. In addition, an elevated relative breast muscle size (% of broiler BW) was observed in IOF chicks to be 6.5% greater at hatch and 7 days post-hatch in comparison to controls. Experiment have shown that IOF broilers and turkeys increased hatchling weights by 3% to 7% (P<0.05) over non injected controls. These responses depend upon the strain, the breeder hen age and in ovo feed composition. The weight advantage observed during the first week after hatch was found to be sustained at least through 35 days of age. Currently, research is done in order to adopt the knowledge for commercial practice.
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Hansen, Peter J., und Amir Arav. Embryo transfer as a tool for improving fertility of heat-stressed dairy cattle. United States Department of Agriculture, September 2007. http://dx.doi.org/10.32747/2007.7587730.bard.
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The overall objective of the current proposal is to develop procedures to improve the pregnancy rate achieved following transfer of fresh or cryopreserved embryos produced in the laboratory into heat-stress recipients. The overall hypothesis is that pregnancy rate in heat-stressed lactating cows can be improved by use of embryo transfer and that additional gains in pregnancy rate can be achieved through development of procedures to cryopreserve embryos, select embryos most likely to establish and maintain pregnancy after transfer, and to enhance embryo competence for post-transfer survival through manipulation of culture conditions. The original specific objectives were to 1) optimize procedures for cryopreservation (Israel/US), 2) develop procedures for identifying embryos with the greatest potential for development and survival using the remote monitoring system called EmbryoGuard (Israel), 3) perform field trials to test the efficacy of cryopreservation and the EmbryoGuard selection system for improving pregnancy rates in heat-stressed, lactating cows (US/Israel), 4) test whether selection of fresh or frozen-thawed blastocysts based on measurement of group II caspase activity is an effective means of increasing survival after cryopreservation and post-transfer pregnancy rate (US), and 5) identify genes in blastocysts induced by insulin-like growth factor-1 (IGF-1) (US). In addition to these objectives, additional work was carried out to determine additional cellular determinants of embryonic resistance to heat shock. There were several major achievements. Results of one experiment indicated that survival of embryos to freezing could be improved by treating embryos with cytochalasin B to disrupt the cytoskeleton. An additional improvement in the efficacy of embryo transfer for achieving pregnancy in heat-stressed cows follows from the finding that IGF-1 can improve post-transfer survival of in vitro produced embryos in the summer but not winter. Expression of several genes in the blastocyst was regulated by IGF-1 including IGF binding protein-3, desmocollin II, Na/K ATPase, Bax, heat shock protein 70 and IGF-1 receptor. These genes are likely candidates 1) for developing assays for selection of embryos for transfer and 2) as marker genes for improving culture conditions for embryo production. The fact that IGF-1 improved survival of embryos in heat-stressed recipients only is consistent with the hypothesis that IGF-1 confers cellular thermotolerance to bovine embryos. Other experiments confirmed this action of IGF-1. One action of IGF-1, the ability to block heat-shock induced apoptosis, was shown to be mediated through activation of the phosphatidylinositol 3-kinase pathway. Other cellular determinants of resistance of embryos to elevated temperature were identified including redox status of the embryo and the ceramide signaling pathway. Developmental changes in embryonic apoptosis responses in response to heat shock were described and found to include alterations in the capacity of the embryo to undergo caspase-9 and caspase-3 activation as well as events downstream from caspase-3 activation. With the exception of IGF-1, other possible treatments to improve pregnancy rate to embryo transfer were not effective including selection of embryos for caspase activity, treatment of recipients with GnRH.and bilateral transfer of twin embryos. In conclusion, accomplishments achieved during the grant period have resulted in methods for improving post-transfer survival of in vitro produced embryos transferred into heat-stressed cows and have lead to additional avenues for research to increase embryo resistance to elevated temperature and improve survival to cryopreservation. In addition, embryo transfer of vitrified IVF embryos increased significantly the pregnancy rate in repeated breeder cows.
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Hansen, Peter J., Zvi Roth und Jeremy J. Block. Improving oocyte competence in dairy cows exposed to heat stress. United States Department of Agriculture, Januar 2014. http://dx.doi.org/10.32747/2014.7598163.bard.
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Original Objectives. The overall goal is to develop methods to increase pregnancy rate in lactating dairy cows exposed to heat stress through methods that minimize damage to the oocyte and embryo caused by heat stress. Objectives were as follows: (1) examine the protective effects of melatonin on developmental competence of oocytes exposed to elevated temperature in vitro; (2) test whether melatonin feeding can improve developmental competence of oocytes in vivo and, if so, whether effects are limited to the summer or also occur in the absence of heat stress; and (3) evaluate the effectiveness of improving fertility by facilitating follicular turnover in the summer and winter. Revised Objectives. (1) Examine protective effects of melatonin and follicular fluid on developmental competence of oocytes exposed to elevated temperature in vitro; (2) examine the protective effects of melatonin on developmental competence of embryos exposed to elevated temperature in vitro; (3) evaluate effectiveness of improving fertility by administering human chorionicgonadotropin (hCG) to increase circulating concentrations of progesterone and evaluate whether response to hCG depends upon genotype for four mutations reported to be related to cow fertility; and (4) identify genes with allelic variants that increase resistance of embryos to heat shock. Background. The overall hypothesis is that pregnancy success is reduced by heat stress because of damage to the oocyte and cleavage-stage embryo mediated by reactive oxygen species (ROS), and that fertility can be improved by provision of antioxidants or by removing follicles containing oocytes damaged by heat stress. During the study, additional evidence from the literature indicated the potential importance of treatment with chorionicgonadotropin to increase fertility of heat- stressed cows and results from other studies in our laboratories implicated genotype as an important determinant of cow fertility. Thus, the project was expanded to evaluate hCG treatment and to identify whether fertility response to hCG depended upon single nucleotide polymorphisms (SNP) in genes implicated as important for cow fertility. We also evaluated whether a SNP in a gene important for cellular resistance to heat stress (HSPA1L, a member of the heat shock protein 70 family) is important for embryonic resistance to elevated temperature. Major conclusions, solutions & achievements. Results confirmed that elevated temperature increases ROS production by the oocyte and embryo and that melatonin decreases ROS. Melatonin reduced, but did not completely block, damaging effects of heat shock on the oocyte and had no effect on development of the embryo. Melatonin was protective to the oocyte at 0.1-1 μM, a concentration too high to be achieved in cows. It was concluded that melatonin is unlikely to be a useful molecule for increasing fertility of heat-stressed cows. Treatment with hCG at day 5 after breeding increased first-service pregnancy rate for primiparous cows but not for multiparous cows. Thus, hCG could be useful for increasing fertility in first-parity cows. The effectiveness of hCG depended upon genotype for a SNP in COQ9, a gene encoding for a mitochondrial-function protein. This result points the way to future efforts to use genetic information to identify populations of cows for which hormone treatments will be effective or ineffective. The SNP in HSPA1L was related to embryonic survival after heat shock. Perhaps, genetic selection for mutations that increase cellular resistance to heat shock could be employed to reduce effects of heat stress on fertility. Implications, both scientific and agricultural. This project has resulted in abandonment of one possible approach to improve fertility of the heat-stressed cow (melatonin therapy) while also leading to a method for improving fertility of primiparous cows exposed to heat stress (hCG treatment) that can be implemented on farms today. Genetic studies have pointed the way to using genetic information to 1) tailor hormonal treatments to cow populations likely to respond favorably and 2) select animals whose embryos have superior resistance to elevated body temperatures.
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Funkenstein, Bruria, und Shaojun (Jim) Du. Interactions Between the GH-IGF axis and Myostatin in Regulating Muscle Growth in Sparus aurata. United States Department of Agriculture, März 2009. http://dx.doi.org/10.32747/2009.7696530.bard.
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Growth rate of cultured fish from hatching to commercial size is a major factor in the success of aquaculture. The normal stimulus for muscle growth in growing fish is not well understood and understanding the regulation of muscle growth in fish is of particular importance for aquaculture. Fish meat constitutes mostly of skeletal muscles and provides high value proteins in most people's diet. Unlike mammals, fish continue to grow throughout their lives, although the size fish attain, as adults, is species specific. Evidence indicates that muscle growth is regulated positively and negatively by a variety of growth and transcription factors that control both muscle cell proliferation and differentiation. In particular, growth hormone (GH), fibroblast growth factors (FGFs), insulin-like growth factors (IGFs) and transforming growth factor-13 (TGF-13) play critical roles in myogenesis during animal growth. An important advance in our understanding of muscle growth was provided by the recent discovery of the crucial functions of myostatin (MSTN) in controlling muscle growth. MSTN is a member of the TGF-13 superfamily and functions as a negative regulator of skeletal muscle growth in mammals. Studies in mammals also provided evidence for possible interactions between GH, IGFs, MSTN and the musclespecific transcription factor My oD with regards to muscle development and growth. The goal of our project was to try to clarify the role of MSTNs in Sparus aurata muscle growth and in particular determine the possible interaction between the GH-IGFaxis and MSTN in regulating muscle growth in fish. The steps to achieve this goal included: i) Determining possible relationship between changes in the expression of growth-related genes, MSTN and MyoD in muscle from slow and fast growing sea bream progeny of full-sib families and that of growth rate; ii) Testing the possible effect of over-expressing GH, IGF-I and IGF-Il on the expression of MSTN and MyoD in skeletal muscle both in vivo and in vitro; iii) Studying the regulation of the two S. aurata MSTN promoters and investigating the possible role of MyoD in this regulation. The major findings of our research can be summarized as follows: 1) Two MSTN promoters (saMSTN-1 and saMSTN-2) were isolated and characterized from S. aurata and were found to direct reporter gene activity in A204 cells. Studies were initiated to decipher the regulation of fish MSTN expression in vitro using the cloned promoters; 2) The gene coding for saMSTN-2 was cloned. Both the promoter and the first intron were found to be polymorphic. The first intron zygosity appears to be associated with growth rate; 3) Full length cDNA coding for S. aurata growth differentiation factor-l I (GDF-II), a closely related growth factor to MSTN, was cloned from S. aurata brain, and the mature peptide (C-terminal) was found to be highly conserved throughout evolution. GDF-II transcript was detected by RT -PCR analysis throughout development in S. aurata embryos and larvae, suggesting that this mRNA is the product of the embryonic genome. Transcripts for GDF-Il were detected by RT-PCR in brain, eye and spleen with highest level found in brain; 4) A novel member of the TGF-Bsuperfamily was partially cloned from S. aurata. It is highly homologous to an unidentified protein (TGF-B-like) from Tetraodon nigroviridisand is expressed in various tissues, including muscle; 5) Recombinant S. aurata GH was produced in bacteria, refolded and purified and was used in in vitro and in vivo experiments. Generally, the results of gene expression in response to GH administration in vivo depended on the nutritional state (starvation or feeding) and the time at which the fish were sacrificed after GH administration. In vitro, recombinantsaGH activated signal transduction in two fish cell lines: RTHI49 and SAFI; 6) A fibroblastic-like cell line from S. aurata (SAF-I) was characterized for its gene expression and was found to be a suitable experimental system for studies on GH-IGF and MSTN interactions; 7) The gene of the muscle-specific transcription factor Myogenin was cloned from S. aurata, its expression and promoter activity were characterized; 8) Three genes important to myofibrillogenesis were cloned from zebrafish: SmyDl, Hsp90al and skNAC. Our data suggests the existence of an interaction between the GH-IGFaxis and MSTN. This project yielded a great number of experimental tools, both DNA constructs and in vitro systems that will enable further studies on the regulation of MSTN expression and on the interactions between members of the GHIGFaxis and MSTN in regulating muscle growth in S. aurata.