Dissertations / Theses on the topic 'Mice – Embryology'
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1
Poirier, Luc. "The degradation of the stem-loop binding protein at the late 2-cell stage of mouse embryogenesis /." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80351.
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The efficient processing of replication-dependent histone mRNA requires the Stem-Loop Binding Protein (SLBP). SLBP is also involved in regulating histone mRNA half-life, their nucleocytoplasmic transport, and their translation. Unlike somatic cells, where SLBP protein accumulates only in S-phase, SLBP protein is present throughout the first two embryonic cell cycles in mice. We report here that in late 2-cell mouse embryos there is a substantial, proteasome-dependent decrease in SLBP throughout the cell. Based on chromosome morphology, the degradation of SLBP protein in late 2-cell embryos is most likely a late G2-phase event. The degradation of SLBP protein is not simply a zygotic clock event, but requires development to the late 2-cell stage. Furthermore, SLBP protein degradation in 2-cell mouse embryos requires cyclin-dependent kinase (Cdk) activity, DNA replication, and zygotic genome activation. A model for SLBP protein degradation is proposed based on observations made in both early mouse embryos and somatic cells.
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Joyce, Bradley. "Elucidating the molecular mechanisms underlying cell movements during early embryogenesis." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589616.
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The anterior visceral endoderm (AVE) is a specialised subpopulation of the visceral endoderm (VE), a single layer simple epithelium that surrounds the extra-embryonic ectoderm and epiblast of the egg cylinder stage embryo. Initially induced at the distal tip of the egg cylinder, AVE cells undergo a stereotypic migration towards the prospective anterior, stopping at the interface between the underlying epiblast and extra-embryonic ectoderm (ExE). Previous research has shown that membrane enrichment of Dvl2 is present in the VE overlying the epiblast (Epi-VE). In this thesis I confirm the presence of planar cell polarity (pep) signalling in this region by assaying the subcellular localisation of additional core pep proteins Vangl2 and Daaml. I show that null embryos of the Nodal antagonist Lefty1 exhibit ectopic membrane enrichment of Dvl2 and a previously unreported AVE over-migration phenotype. Furthermore, using pharmacological inhibition of Nodal signalling I show that the TGF~ protein Nodal modulates pep signalling in the YE. Utilising DIe and confocal microscopy I perform detailed time-lapse analyses of the VE to quantify the dynamic cell behaviour and topology. Using this assay I show that wild-type embryos exhibit dynamic cell movement, which is regionally restricted to the Epi-VE. Analysis of Leftyl-/- and ROSA26lyn-Celsr-l mutants, both of which exhibit disrupted pep signalling and AVE over-migration phenotypes, indicates that normal VE dynamics and topology are disrupted. The results of this quantitation indicate that these mutants exhibit increased cell migration and neighbour exchange across the YE. These data show that regional restriction of movement is lost and results in the AVE over-migration phenotypes observed. Together these results show that regionally restricted pep signalling in the VE acts to modulate cell behaviour and topology, which in turn determines the regional restriction and normal end-point of AVE migration.
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Chan, Siu-yuen. "Effects of prostaglandins on peri-implantation development of mouse embryos /." [Hong Kong : University of Hong Kong], 1989. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12730191.
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McClellan, Kelly Anne. "Murine oocyte loss occurs during fetal development." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79047.
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Recently, the timing of oocyte loss during murine development has been brought into question as authors using mouse vasa homologue (MVH) as a germ cell marker did not observe a loss of oocytes during fetal life. Instead the major loss was observed in the days following birth, after chromosome pairing has occurred.In this study the controversy was addressed by establishing a new and reliable method to quantify murine oocytes in meiotic prophase, as well as to determine the gestation age and meiotic prophase stage of oocyte loss. Earlier limitations were overcome through the use of Germ Cell Nuclear Antigen-1 (GCNA-1) antibody as a germ cell specific marker, and the novel addition of a cytospin centrifugation step to the method. Progress through meiotic prophase was examined in chromosome spread preparations where meiotic stages were assessed using an antiserum against synaptonemal complex (SC) proteins. Quantification was accomplished by counting the number of GCNA-1 immunoreactive cells in chromosome spread preparations and estimated in histological sections using the ratio estimation model. (Abstract shortened by UMI.)
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Fuku, Eiji. "Studies on the preservation of mammalian embryos in the supercooled state." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60523.
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Firstly, exposure of compacted morulae (CM) and early blastocysts (EB) to methanol (M) or glycerol (G) for 1 h at room temperature followed by culture in standard culture medium showed that the embryos tolerated up to 12 to 24% methanol or 24 to 48% glycerol. Next, the effects of stage of embryo (CM vs EB), preservation temperature and concentration of 1:1 M:G on embryo survival were tested. EB survived longer than CM under all conditions. Increased concentrations of cryoprotectants (M and G) increased the survival of supercooled embryos, but survival was decreased with the storage temperature. Replacing G with propanediol (P) significantly increased blastocyst survival at lower temperatures.Exposure for 1 h to $>$ 0.6 M of sucrose or trehalose at room temperature suppressed growth in culture, but dehydration in up to 0.4M sucrose before supercooling (in M:P) increased survival at $-$5 or $-$10$ sp circ$C, survival increasing with dehydration.
Finally, demi-embryos and intact embryos were cultured to the blastocyst stage, stored at $-$5$ sp circ$ for 48 h, then cultured for 24 h and transferred into pseudopregnant recipients.
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Chia, Gloryn Le Bin. "Investigating the role of Oct4 during lineage specification in the physiological context of mouse embryonic development." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607990.
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Yu, Hing-Sing. "Studies on the toxicity and teratogenicity of cadmium on mouse pre-embryos in vitro and in vivo with special reference to their subsequent development /." [Hong Kong] : University of Hong Kong, 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1221579X.
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Fu, Germaine 1976. "Mouse oocytes and embryos with or without the H10 gene : linker histone subtypes and development performance." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33399.
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H1 histones are potentially significant to nuclear reprogramming during the oocyte-to-embryo transition. One characteristic distinguishing the H1 subtypes is that the somatic H1 histones are found primarily in dividing cells, whereas the H10 subtype is predominantly found in differentiated cells. The H1 complement in mouse oocytes and preimplantation embryos from wild-type and H10-/- animals was investigated.Immunocytochemistry of wild-type cells demonstrated that H10 was predominant in oocytes while somatic H1 began accumulating in the 2-cell embryo. In H10-/- cells H10 was not detected, but, surprisingly, somatic H1 was detected beginning at the 1-cell stage. Radiolabeling of wild-type and H10-/- cells revealed that somatic H1 synthesis intensified after meiotic maturation, and therefore prior to its detection in embryos. The functional study found that loss of H10 impaired oogenesis but enhanced embryogenesis. The patterns of H1 immunodetection and synthesis are integrated, and the significance of H1 composition in development is discussed.
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McLay, David W. "Developmental regulation and molecular nature of an activity in murine oocytes that transfers histones onto sperm DNA." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38235.
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At fertilization, the remodelling of the sperm nucleus into the male pronucleus is critical for normal development. Morphological and functional changes to the nucleus are underpinned by biochemical changes in the chromatin composition, most notably the removal of sperm specific protamines and assembly of histones onto the paternal DNA. This exchange is controlled by oocyte factors, as exemplified in Xenopus by nucleoplasmin. Though mammalian factors remain unidentified, a functional assay based on antibodies recognizing core histones has been developed to test the activity in oocytes that transfers histones onto sperm DNA, named histone transfer activity (HTA). The assay was applied to growing and maturing murine oocytes to determine when during oogenesis HTA develops, and to probe potential regulatory mechanisms. Fully-grown oocytes develop HTA upon maturation, in a protein-synthesis dependent manner. Large, growing oocytes also develop HTA upon entry into M-phase. Small growing meiotically incompetent oocytes, ones that do not spontaneously enter M-phase, do not develop HTA, though this can be overcome by culture of oocytes to meiotic competence, or by treatment with strontium to induce intracellular calcium oscillations. Taken together these findings form a model of how HTA develops throughout oogenesis. Finally, an attempt is made to identify a potential mammalian HTA factor. Transcripts for two remodelling factors, mNAP and Npm3, are identified in the murine oocyte, and injection of anti-sense oligonucleotides reveals that Npm3 plays a significant role in the deposition of histories and the remodelling of sperm chromatin at fertilization. Combined with the findings of the HTA assay, the data forms a testable model of how Npm3 may be regulated throughout oogenesis.
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Cheong, Wan-yee Ana, and 張韻怡. "A study on the embryotrophic action of the complement component-3 derivative (iC3b) in the preimplantation mouse embryo development." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B44231994.
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Fung, Chun-kit. "An investigation on the effects of glutamine in culture meida on the preimplantation mouse embryo /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21629821.
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Moase, Connie E. (Connie Evelyn). "Histopathology of, and retinoic acid effects in, biochemically identified splotch-delayed mouse embryos." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66099.
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Chan, Siu-yuen, and 陳小圓. "Effects of prostaglandins on peri-implantation development of mouse embryos." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B30257256.
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Fung, Chun-kit, and 馮俊傑. "An investigation on the effects of glutamine in culture meida on the preimplantation mouse embryo." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31222560.
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余慶聲 and Hing-Sing Yu. "Studies on the toxicity and teratogenicity of cadmium on mouse pre-embryos in vitro and in vivo with special reference to theirsubsequent development." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31231457.
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Alexandrova, Stoyana. "In vivo behaviour of embryonic stem cells in early mouse embryo development." Thesis, University of Cambridge, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708686.
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Xu, Jiasen. "A study of embryotrophic mechanism of human oviductal cells on mouse embryo development in vitro." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22926197.
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Tse, Pui-keung, and 謝沛強. "An investigation on the conversion of C3 to embryotrophic iC3b in the human oviductal cell-mouse embryo co-culture system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B45010936.
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Macdonald, Karen Beth. "The genetics and embryopathology of exencephaly in SELH/Bc mice." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27983.
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This project was the first study of the genetics and embryo-pathology of exencephaly in a partially inbred mouse stock, SELH/Bc. Exencephaly was found in 17% of SELH fetuses. Analysis of day 8-9 gestation embryos indicated that SELH embryos were collectively normal in general development, but delayed in neural tube closure relative to overall or general development compared to two normal strains of mice, ICR/Be and SWV/Bc. Exencephaly was observed to be caused by a failure of fusion of the cranial neural folds in the mesencephalon region in SELH.
All SELH embryos appeared to be abnormal in their pattern of cranial neural tube closure. They fail to make initial contact at the prosencephalon/mesencephalon junction region of the cranial neural folds (the first fusion in the cranial neural folds in normal embryos). SELH embryos, fused their anterior neural folds via an alternate (possibly passive) mechanism compared to normal strains of mice (SWV/Bc, and ICR/Be), by fusing the folds in a "zipper-like" fashion from the rostral base of the prosencephalon. This closure of the neural tube in genetically liable embryos by an abnormal sequence of events suggests a new model for anterior neural tube closure failure.
Liability to exencephaly appeared to be fixed in the SELH stock. Of the 53 SELH males tested, all produced exencephaly. SELH animals were found to be heterogeneous in the frequency of exencephaly they produced, indicating that there are still genes segregating in the stock which affect the ability of embryos to complete anterior neural tube closure. Exencephaly in SELH does not appear to be caused by an autosomal dominant, sex-linked dominant or recessive, or simple autosomal recessive single gene, although F2, BCl, and BC2 exencephaly frequencies (after an outcross to ICR/Be) suggest that only a small number of genes are involved. A marked excess of female exencephalics was observed in SELH, F2, BCl, and BC2 fetuses.Medicine, Faculty of
Medical Genetics, Department of
Graduate
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Tian, Xiao Ying. "The study of Chinese herbal medicine in embryonic development of mice." HKBU Institutional Repository, 2009. http://repository.hkbu.edu.hk/etd_ra/1071.
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Mohamed, Othman. "Identification of multiple roles for Wnt signaling during mouse development." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85087.
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Signaling molecules play essential roles in communication between cells. Wnt signaling molecules are critical for embryonic development of several organisms. I examined the involvement of Wnt signaling during two major developmental processes, namely embryo implantation and formation of the embryonic body axes. Using RT-PCR analysis, I showed that multiple Wnt genes are expressed in the blastocyst at the time of implantation. Moreover, expression of Wnt 11 requires both estrogen produced by the mother and the uterine environment. Using a transgenic approach, I showed that beta-catenin-regulated transcriptional activity, which is a major transducer of Wnt signaling, is activated in the uterus specifically at the site of implantation in an embryo-dependent manner. These results introduce Wnts as candidate signaling factors that may mediate the communication between the embryo and uterus that initiates implantation.Wnt/beta-catenin signaling triggers axis formation in Xenopus and zebrafish embryos. I showed that, during embryonic development, beta-catenin-regulated transcriptional activity is first detected in the prospective primitive streak region prior to gastrulation. This demarcates the posterior region of the embryo. This activity then becomes restricted to the elongating primitive streak and to the node. In Xenopus embryos, beta-catenin participates in the formation of the organizer through the activation of the homeodomain transcription factors Siamois and Twin. I obtained evidence that a Siamois/Twin-like binding activity exists in mouse embryos and is localized in the node. These results strongly suggest that, as the case in Xenopus and zebrafish, the Wnt/beta-catenin pathway is involved in establishing embryonic body axes.
Furthermore, using the transgenic mouse line that I generated for these studies, I mapped the transcriptional activity of beta-catenin during mouse embryonic development. These results revealed when and where this activity, and presumably Wnt signaling, is active during the development of several organs and embryonic structures.
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Dann, Jeremiah J. "Immunological characterization and histone kinase activity of cyclin B1 and Cdk1 at G1 and G2/M phase of the cell division cycle in one-cell mouse embryos." Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1306852.
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Cyclin B1 is a cell cycle protein typically associated with the regulation of cellular division (mitosis). Previous studies in this laboratory involving preimplantation mouse embryos found that cyclin B1, or a cyclin B 1-related protein, were present at both G1 and G2/M phase of the cell cycle. Not only was cyclin Bi detected during G1 phase in this study, it was found to be present in higher concentrations at G1 phase through the first three cell cycles. These findings were unexpected, because most of the literature suggests that cyclin B1 is normally degraded during G1 phase. Using immunoprecipitation and immunoblot techniques, a more detailed study of cyclin B1 expression was inititated. Using two different primary antibodies direct against cyclin B1, a 48.97 kDa protein band, which is believed to be cyclin B1, was detected at both G1 and G2/M phases in 1-cell mouse embryos. Using another antibody directed against Cdk1, the kinase that forms a complex with cyclin B1 in order to direct the G2/M transition, a 37 kDa protein band was also detected at both G1 and G2/M phases in 1-cell mouse embryos. In order to determine whether cyclin B1 was present as a complex with Cdk1, immunoblotting with the anti-Cdk1 antibody. Again, a 37kDa protein band was detected at both G1 and G2/M phases. Finally, in order to determine whether the cyclin B1/Cdk1 complex exists in its active form, histone kinase assays were performed using anti-cyclin B1 immunoprecipitates. Kinase activity was detected in immunoprecipitates collected from G2/M phase 1-cell embryos, but no kinase activity was detected from immunoprecipitates collected from G1 phase 1-cell embryos. These data indicate that cyclin B1 and Cdk1 are present and exist as a complex in both G1 and G2/M phases of 1-cell mouse embryos, although the complex only appears to be active at the G2/M phase.Department of Biology
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Trowbridge, Amanda J. "Expression of SNAP23 and Rab3A in mouse oocytes and fertilized eggs and their role in cortical granules exocytosis." Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1307377.
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The proteins and molecular machinery mediating the release of cortical granule (CG) contents from fertilized embryos is not completely understood. The process of vesicle fusion involves linking chaperones prior to vesicle to membrane contact. Rab3A, a member of a low-molecular weight GTP-binding protein superfamily has been detected in mouse embryos from the unfertilized meiotic II stage to the 2-cell. It is believed to positively regulate the final step of CG exocytosis by binding to Rabphillin, calcium ions (Ca2+), and phospholipids. SNAP23 a member of soluble NSF [N-ethylmaleimidesensitive factor] attachment protein receptors (SNAREs) binds together with parts of the Rab3A-rabphilin3A complex and is believed to be involved in the Ca2+-dependent exocytosis of non-neuronal systems. In this study we observed the mRNA expression for SNAP23 and Rab3A in pre-Meiotic I, post-Meiotic I unfertilized eggs (pre-MI UFE and post-MI UFE), and fertilized eggs (FE) utilizing RT-PCR. The products were analyzed in 2% agarose gel stained with ethidium bromide. Density analysis using a globin external standard showed that the levels of mRNA transcripts declined from the UFE to the FE in both genes, SNAP23 and Rab3A. Immunofluorescence was used for the detection and localization of Rab3A protein within the pre-MI and post-MI UFE and FE mouse egg. Eggs were stained with anti-Rab3A primary antibody and lens culinaris agglutinin (LCA) conjugated to FITC. Rab3A showed punctate staining in pre- and post-MI UFEs on small vesicles assumed to be CGs and in FEs on vesicles of a larger size. Uniform cytoplasmic expression was also seen, throughout the cells cortical and subcortical regions in each stage (pre- and post-MI UFEs and FEs), but with decreasing intensity as the eggs matured. This cytoplasmic stain may represent inactive Rab3A in the cytosol. The LCA stain showed punctate expression of cortical granules with localization within the cortical region and the plasma membrane. The addition of information on SNAP23 and Rab3A will aid in the process of studying CG exocytosis as well as in understanding the temporal and spatial development pathways involved in stimulating the cortical reaction.Department of Biology
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Tolle, Michelle D. "In vivo Dilantin treatment alters expression levels and nuclear localization of cyclins A and B1 during mouse preimplantation embryo development." Muncie, IN : Ball State University, 2009. http://cardinalscholar.bsu.edu/677.
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Hurtubise, Patricia. "Intracellular signalling during murine oocyte growth." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31239.
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During the growth phase of oogenesis, mammalian oocytes increase several hundred-fold in volume. Although it is known that ovarian granulosa cells send growth promoting signals, neither these external signals nor the transduction pathways that become activated in the oocyte are known. Therefore, the presence and the activity of candidate signaling pathways in growing murine oocytes were investigated. By immunoblotting, the MAP kinases, ERK1 and ERK2, as well as their activating kinase MEK, were detected in oocytes at all stages of growth. However, using a phospho-specific anti-ERK antibody, no immunoreactive species were detectable in isolated granulosa cells or oocytes at any stage of growth, except metaphase II. Phosphorylated ERK was also present, although in smaller quantities, in oocyte-granulosa cell complexes at the later stages of growth. Furthermore, when ovarian sections were stained with an anti-ERK antibody, the protein was found to be highly concentrated in the cytoplasm of oocytes at all stages of growth, with lower levels in the nucleus. Another member of the MAP kinase family, Jun kinase (JNK), was investigated. By immunoblotting, JNK was detected in growing oocytes. Experiments using an anti-JNK antibody on ovary sections revealed the protein to be uniformly distributed in non-growing and growing oocytes with no evidence of preferential nuclear localization. These results imply that an interaction between the oocyte and the granulosa cells may be required to generate phosphorylated ERK. They also imply that growth signals probably are not relayed through ERK, but do not exclude a role for Jun kinase in mediating oocyte growth.
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O'Leary, Debra Alison. "Characterisation of gene structure and function of the ETS transcription factor Gabpα in mouse." Monash University, Centre for Functional Genomics and Human Disease, 2003. http://arrow.monash.edu.au/hdl/1959.1/9445.
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Yan, Jin 1972. "The mechanisms of hydroxyurea induced developmental toxicity in the organogenesis stage mouse embryo /." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115897.
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Hydroxyurea was used as a model teratogen to investigate the role of oxidative stress and stress-response pathways in mediating developmental toxicity. When administered to pregnant mice during early organogenesis, hydroxyurea induced fetal death and growth retardation, as well as external and skeletal malformations. The malformed fetuses displayed hindlimb, vertebral column, and tail defects. Hydroxyurea treatment enhanced the production of 4-hydroxynonenal, a lipid peroxidation end product, in malformation sensitive regions of the embryo. Depletion of glutathione, a major cellular antioxidant, specifically enhanced hydroxyurea-induced malformations and elevated the region-specific production of 4--hydroxynonenal protein adducts in the embryo, without affecting the incidence or extent of hydroxyurea-induced fetal death or growth retardation. The major proteins modified by 4-hydroxynonenal were involved in energy metabolism. Thus, oxidative stress is important in the induction of malformations by hydroxyurea.Exposure to hydroxyurea stimulated the DNA binding activity of activator protein 1 (AP-1), an early response redox-sensitive transcription factor. Activated AP-1 was composed mainly of c-Fos heterodimers. Glutathione depletion did not change the effects of hydroxyurea on AP-1/c-Fos DNA binding activities despite an augmentation of the incidence of embryo malformations. Mitogen-activated protein kinases (MAPKs) activate AP-1 in response to stress by post-transcriptional phosphorylation of AP-1 proteins. Hydroxyurea treatment dramatically enhanced the activation of stress-responsive p38 MAPKs and JNKs (c-Jun N-terminal protein kinases). Selectively blocking p38 MAPKs enhanced the incidence of fetal death, whereas selective inhibition of JNKs specifically elevated the limb defects induced by hydroxyurea. Thus, activation of stress-response pathways impacts on the response of the embryo to a teratogenic insult.
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Ringvall, Maria. "Functions of Heparan Sulfate During Mouse Development : Studies of Mice with Genetically Altered Heparan Sulfate Biosynthesis." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4244.
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Junior, Antonio Euclides Pereira de Souza. ""Acetato de medroxiprogesterona administrado em período pré-natal induz hipospádia em machos e virilização em fêmeas de camundongos"." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/5/5153/tde-17022006-105731/.
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A fertilização in vitro tem sido associada com um aumento na incidência das hipospádias, e alguns hormônios esteróides usados em seus protocolos têm sido implicados neste processo. Para testar essas hipóteses em um modelo animal, descrevemos neste trabalho as alterações morfológicas ocorridas no tubérculo genital de camundongos, expostos à progesterona durante a vida intrauterina. Foi administrado acetato de medroxiprogesterona por via subcutânea no período pré-natal em animais normais e animais desprovidos de receptores androgênicos (Tfm). A progesterona induziu a formação de hipospádia nos animais do sexo masculino, virilização nos do sexo feminino e não causou alterações nos animais TfmIn vitro fertilization (IVF) has been associated with an increase incidence of hypospadias. IVF protocols require the maternal use of progesterone which may be a factor in causing hypospadias. To test these hypotheses in an animal model, we describe the effects of maternal progesterone exposure on genital development in mice. Medroxyprogesterone acetate (MPA) was administered by subcutaneous injection during the pre-natal period to wild type mice and animals knockout to androgen receptors (Tfm mice). Progesterone caused hypospadias in male mice fetuses, a virilizing effect in the female mice genitalia and didn't have any effect in Tfm animals
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Nowacka, Lidia. "Muscle gene transfer studies of a 27-BP segment of the troponin I fast gene IRE enhancer." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111563.
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The fast-skeletal-muscle-fiber-specific expression of the troponin I(fast) (TnIfast) gene is driven by an Intronic Regulatory Element (IRE) located within the first intron of the gene. The IRE is a 148 bp transcriptional enhancer that contains several known and suspected cis-regulatory elements. These include the E-box, the closely-spaced MEF2 site and CACT box, the CACC site, and the CAGG element. Previous loss-of-function studies performed using the quail TnIfast IRE suggest that its activity depended on the MEF2 and CACT elements. The goal of my thesis research was to determine whether the MEF2 and CACT sites were not only necessary, but also sufficient, to support IRE activity. I prepared head-to-tail multimers of a 27-bp IRE segment that consisted largely of the near-adjacent MEF2 and CACT elements and did not contain any other known/suspected elements. These multimers were cloned upstream of a reporter gene consisting of the minimal promoter of the quail TnIfast gene linked to sequences encoding human placental alkaline phosphatase. The transcriptional capabilities of the constructs were assessed by gene transfer into the mouse soleus muscle in vivo by intramuscular injection/electroporation, and histochemical analysis of reporter enzyme plap expression including quantitative microdensitometry. I found that expression of these constructs was readily detectable and that it was markedly reduced by prior mutation of the CACT and, especially, of the MEF2 sites. These data indicate that the short DNA segment containing MEF2 and CACT elements is sufficient to drive expression in skeletal muscle and confirms the functional importance of these specific elements.Although constructs containing the wild-type IRE 27-bp region were expressed, there was little preferential expression in fast fibers, in contrast to expression driven by the complete 148-bp IRE. Thus my results indicate that the MEF2 and CACT elements are not sufficient to drive fast fiber-type-specific expression, and suggest that additional elements outside of the 27-bp region tested are also necessary for fiber-type-specificity.
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Gnanabakthan, Naveen. "Understanding the basis of 5-Bromo-2'-deoxuridine teratogen specificity in organogenesis stage mouse embryos." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112624.
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5-Bromo-2'-deoxyuridine (BrdU), a thymidine analogue, is genotoxic and teratogenic. The exposure of mouse embryos to BrdU at doses that cause malformations induces oxidative stress and an embryonic stress response characterized by an increase in c-Fos dependent AP-1 DNA binding. The goal of this thesis was to test the hypothesis that development is disturbed at sites where BrdU is incorporated into DNA, triggering oxidative stress and c-Fos induction. Gestation day 9 CD-1 mice were treated with BrdU and embryos were obtained for immunolocalization of BrdU, 8-oxoguanine, a biomarker for oxidative stress, and c-Fos. BrdU incorporation into DNA was dispersed throughout the embryo. In contrast, the staining for 8-oxoguanine and c-Fos were highest in the neuroepithelium. BrdU incorporation was not affected by the pre-administration of N-acetyl-cysteine (NAC), an anti-oxidant, although both 8-oxoguanine and c-Fos staining were decreased. Thus, the response of the embryo to insult is tissue specific.
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Sucré, Elliott. "Mise en place des ionocytes au cours de l'embryogenèse du loup dicentrarchus labrax. émergence de la fonction osmorégulatrice et adaptation précoce aux variations de salinité." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20148.
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Le Loup ou Bar Dicentrarchus labrax est une espèce euryhaline dont les femelles pondent généralement en eau de mer. Pendant son cycle de vie, des migrations vers les estuaires et les lagunes, peuvent exposer très tôt les jeunes stades à des variations de salinité. Les mécanismes de l'osmorégulation sont bien connus chez les prélarves, les larves et les adultes de D. labrax en eau de mer (EM, 38) et en eau de mer diluée (EMD, 5), cependant les possibilités d'osmorégulation et leurs mécanismes sont inconnus chez les embryons. Le but de cette étude a été d'évaluer la mise en place de la fonction osmorégulatrice chez les embryons de D. labrax.Tout d'abord le développement embryonnaire des différents sites osmorégulateurs a été décrit, en se focalisant sur le tube digestif, en incluant le pharynx et les premières fentes branchiales. La formation de ces structures débute au stade 12 somites (S) et a été décrite jusqu'à l'ouverture de la bouche, 5 jours après l'éclosion.En second lieu, le lieu et la cinétique d'apparition des premières cellules osmorégulatrices, les « ionocytes » ont été recherchés. Ces cellules ont été identifiées au stade 12S sur la membrane de la vésicule vitelline et au niveau des premières fentes branchiales et du tube digestif primitif au stade 14S. La fonctionnalité de ces cellules a été étudiée grâce à des immunomarquages des principales protéines transmembranaires impliqués dans l'osmorégulation [l'ATPase Na+/K+ (NKA), le cotransporteur Na+/K+/2Cl- (NKCC) et le canal à chlore (CFTR)], et avec une étude ultrastructurale. Des ionocytes potentiellement fonctionnels sont présents à partir du stade 25S au niveau de la membrane de la vésicule vitelline et du tube digestif primitif, mais les ionocytes des premières fentes branchiales ne sont pas totalement fonctionnels à l'éclosion. L'existence d'un phénomène de boisson passive qui permettrait la régulation hydrique chez D. labrax est envisagé.Finalement, l'osmorégulation embryonnaire existant en EM et en EMD a été étudiée. Des mesures nanoosmométriques des fluides embryonnaires indiquent une capacité à hyper- et hypo-osmoréguler. Cependant, en EMD, des analyses en qRT-PCR et des immunomarquages de NKA, NKCC et CFTR révèlent que les mécanismes de l'hyper-osmorégulation peuvent limiter les pertes ioniques mais ne sont pas suffisamment efficaces pour permettre une acclimatation totale à l'EMD à ce stade très précoceThe European sea bass Dicentrarchus labrax is a euryhaline species which usually spawns in seawater. Due to its life cycle that includes migrations to lagoon and estuaries, young stages can be exposed early to salinity variations. Osmoregulatory patterns are well known in prelarvae, larvae and adults D. labrax in seawater (SW, 38) and in dilute seawater (DSW, 5), but the possibility and mechanisms of embryonic osmoregulation are still unknown. The goal of this study was to investigate the occurence of the omoregulatory function in the embryos of D. Labrax.First, the embryonic development of the different osmoregulatory sites was described, focusing on the digestive system including the pharynx and the first gill slits. The formation of these structures is initialized at stage 12 somites (S) and was described throughout the opening of the mouth five days after hatching.Secondarily, the time and the location of the occurrence of the first osmoregulatory cells, the ionocytes were followed. These cells were identified at stage 12S on the yolk sac membrane and at stage 14S in the first gill slits and in the posterior primitive gut. The functionality of these cells was studied, using immunostaining of the main ionic transporters involved in osmoregulation [the Na+/K+ ATPase (NKA), the Na+/K+/2Cl- cotransporter (NKCC) and the chloride channel (CFTR)], and through ultrastructural investigations. Potentially functional ionocytes are present from stage 25S in the yolk sac membrane and in the gut, but gill slits ionocytes are not fully functional at hatching. Passive drinking is suspected to regulate water balance in D. labrax.Finally, the embryonic osmoregulation in SW and DSW was investigated. Nanoosmometry measurements of the embryonic fluids demonstrated some capabilities of hyper- and hypo-osmoregulation. However, in DSW, qRT-PCR and imunostaining of NKA, NKCC and CFTR, reveal that hyper-osmoregulatory mechanisms can only limit ion loss but are not efficient enough to allow a full acclimation at this early life stage
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Baroux, Célia. "Etude del'embryogenèse d'Arabidopsis thaliana : mise en oeuvre d'une technologie de transactivation pour une expression ciblée ou une dérégulation systématique de gènes." Perpignan, 2000. http://www.theses.fr/2000PERP0389.
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Dans le but de contribuer à l'étude de l'embryogenèse d'Aabidopsis thaliana, deux nouvelles approches ont été initiées au moyen du système de transactivation pOp/LhG4 (Moore et al. , 1998), et évaluées. Ce système à deux composants place le gène d'intérêt sous le contrôle du promoteur pOp synthétique, transcriptionnellement actif qu'en présence de l'Activateur (transactivation)This work describes the initiation and evaluation of two novel approaches for studying embryodevelopment in Arabidopsis thaliana using the two components pOp/LhG4 expression system which allows a genetic transcriptional control on transgene expression(Moore et al. 1998)
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Meissirel, Claire. "Contribution de l'élimination sélective à la mise en place des connexions corticales au cours du développement." Lyon 1, 1994. http://www.theses.fr/1994LYO1T010.
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Galland, Rachel. "Mise en évidence d'un gène de glutathion S-transférase exprimé au cours des stades précoces de l'embryogenèse somatique de la chicorée." Lille 1, 2001. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2001/50376-2001-235-236.pdf.
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Chez le Cichorium hybride "474" (Cichorium intybus var. Sativum x Cichorium endivia var. Latifolia), l'embryogenèse somatique est directe et d'origine unicellulaire. De plus, la première division embryogène peut être retardée par l'addition de glycérol dans le milieu lors de la phase d'induction et synchronisée lors du transfert des tissus dans un milieu d'expression dépourvu de glycérol. Ces trois caractéristiques, spécifiques du modèle chicorée, facilitent l'étude des mécanismes inducteurs précoces de l'embryogenèse somatique. Au cours de cette étude, nous avons utilisé la technique de "differential display" (DD RT-PCR) afin de mettre en évidence des modifications dans l'expression des gènes au cours des stades précoces de l'embryogenèse somatique de la chicorée. Nous avons comparé les populations d'ARNm accumulés dans les fragments foliaires placés en conditions d'embryogenèse somatiques pendant 0, 1, 2, 3, 4 et 7 jours. Un ADNc partiel présentant de fortes homologies avec des GSTs de plantes inductibles par l'auxine a ainsi été isolé. Il s'accumule fortement dans les fragments foliaires du génotype embryogène "474", mais pas chez le génotype non embryogène Pévèle. La séquence complète de cet ADNc, nommé CHI-GST1, a été reconstituée après amplification de la partie 5' par RACE-PCR. Des expériences d'hybridation in situ et d'immunolocalisation nous ont permis de localiser les transcrits et le produit du gène CHI-GST1 dans les tissus foliaires. Les résultats obtenus suggèrent l'existence de plusieurs isoformes de GSTs chez la chicorée dont une serait spécifique des cellules réactivées et des cellules embryonnaires.
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Quirin, Magali. "Etude fonctionnelle des facteurs de transcription Jun et Tel lors de la mise en place de l'axe dorso-ventral chez l'embryon d'oursin Paracentrotus lividus." Paris 6, 2011. http://www.theses.fr/2011PA066564.
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Rajjou, Loïc. "Analyse protéomique de la germination des graines et de la mise en place des mécanismes précoces de défense chez Arabidopsis thaliana." Pau, 2006. http://www.theses.fr/2006PAUU3005.
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Les graines occupent une place privilégiée en étant le moyen le plus répandu de multiplication de végétaux. Cest à ce titre que les graines suscitent un si grand intérêt de le part du monde agricole, industriel et scientifique. La formation et le développement de la graine sont des étapes clés dans la vie de la plante. Au cours de la maturation, de nombreux processus métaboliques interviennent. La graine accumule des réserves qui seront mobilisées lors de la germination puis acquiert une forte tolérance à la dessiccation. La germination débute lors de la réhydratation de la graine mature sèche et s'achève à la sortie de la radicule. L'utilisation de l'alpha-amanitine, inhibiteur de la transcription, a permis de mieux caractériser le rôle des ARNm et des protéines stockés et néosynthétisés dans les graines en germination. Chez Arabidopsis la germination a lieu malgré la présence de fortes concentrations en cet inhibiteur transcriptionnel. De plus, des phénomènes d'oxydation des protéines prennent place au cours de la maturation et de la germination des graines d'Arabidopsis. Ce stress oxydatif tend à s'accumuler au cours du vieillissement des graines. L'analyse protéomique de plusieurs lots de graines différentiellement vieilles à permis de mettre en évidence plusieurs marqueurs de qualité germinative. Dans le cycle de vie des plantes, la graine et la plantule sont les stades les plus vulnérables, étant très sensibles aux conditions de l'environnement. Les travaux réalisés au cours de cette étude ont permis de mieux comprendre la mise en place des mécanismes précoces de défense des plantes dès le stade de la germination ce qui est d'importance capitale en agricultureSeed is the most widespread plant multiplication system. The agricultural, industrial and scientific worlds are very interested by seed biology. The formation and the development of seed constitute key stages in the plant life. During seed maturation, many metabolic processes are involved. Seed acquires a strong tolerance to the desiccation and accumulates reserves in order to mobilize them during germination. By definition, germination sensu stricto incorporates those events that start with the uptake of water by the non-dormant quiescent dry seed stop with the protusion of the radicle and the elongation of the embryonic axis. To investigate the role of stored and neosynthetized mRNAS and proteins in seed germination, we examined the effect of alpha-amanitin, a transcriptional inhibitor. Arabidopsis seed germination occured in spite of the absence of transcription. Increased cellular levels of reactive oxygen species are known to occur during seed development and germination. This oxidative stress tends to increase during seed aging. Proteomic analysis of differential aged seeds highlights several germinative quality markers. In the plant life cycle, seeds and seedlings are the most vulnerable stages, particularly susceptible to environmental conditions. Toward a characterization of early plant defense mechanisms was assessec by physiological measurements and proteomics during seed germination what is fundamental importance in agriculture
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Bihan, Réjane. "Mécanismes moléculaires mis en jeu par les protéines Hox et Pbx au cours de la mise en place du tractus génital femelle chez la souris." Rennes 1, 2005. http://www.theses.fr/2005REN1S142.
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La spécification des différentes identités régionales du tractus génital femelle de souris est notamment contrôlée par les protéines Hox et Pbx. Afin de mieux comprendre les mécanismes moléculaires mis en jeu par ces protéines au cours de ces processus, les profils d'expression de ces gènes ainsi que les localisations tissulaire et subcellulaire de ces protéines ont été déterminés de façon extensive. Par ailleurs, un nouveau partenaire de Pbx1 a été identifié. Cette protéine possédant de multiples doigts de zinc a été appelée ZFPIP (pour Zinc Finger Protein Interacting with Pbx). Des données récentes indiquent que les protéines Hox coopèrent directement ou indirectement avec certaines protéines à doigt de zinc pour établir les identités positionnelles. ZFPIP pourrait selon un mode indirect participer à un tel mécanisme. Des expériences ultérieures visant à tester cette hypothèse sont nécessaires et sont actuellement à l'étude.
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Serre-Barioz, Claire-Marie. "Mise en place et évolution de la matrice extracellulaire dans le foie embryonnaire de poulet." Grenoble 1, 1988. http://www.theses.fr/1988GRE10068.
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Luxey, Maëva. "Caractérisation du rôle d'ephrineB1 et ephrineB2 dans la mise en place du système sensori-moteur chez la souris." Toulouse 3, 2011. http://www.theses.fr/2011TOU30243.
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Le système sensori-moteur permet à un organisme d'interagir avec le monde extérieur par le biais des neurones sensoriels et de réagir à ces informations par le biais des neurones moteurs. La motricité dépend de la connexion stéréotypique des neurones moteurs avec leurs muscles cibles. Ces motoneurones se situent dans la corne ventrale de la moelle épinière et se regroupent en unités fonctionnelles appelées colonnes motrices. Chaque colonne contient des neurones ayant la même identité et allant innerver des tissus cibles périphériques. Cette topographie semble importante pour une innervation correcte car à chaque groupe de motoneurones donné correspond un seul muscle cible. En parallèle, les neurones sensoriels du ganglion rachidien dorsal (DRG) émettent aussi des prolongements pour aller innerver les muscles mais aussi l'épiderme. Cette croissance axonale motrice et sensorielle se fait grâce à un système de guidance moléculaire. De récentes études ont montré que ces molécules de guidance établissaient une interaction entre les motoneurones et les neurones sensoriels permettant une innervation précise. De plus, plusieurs études suggèrent un potentiel rôle du système vasculaire, mis en place plus tôt, dans l'agencement du réseau nerveux à travers certaines de ces protéines. Les récepteurs Eph et leurs ligands, les ephrines constituent l'une de ces familles de molécules de guidance axonale. La signalisation bidirectionnelle qui résulte de leur liaison, est impliquée dans de nombreux processus développementaux chez les Vertébrés et les Invertébrés. Bien que le rôle des Eph/ephrine A ait été bien établi dans la mise ne place du système sensori-moteur in vivo, peu de choses sont connues à propos de l'implication des Eph/ephrine de classe B et de leurs cibles moléculaires dans ce processus développemental. Mes travaux de thèse ont permis de caractériser le rôle de deux membres de la famille des ephrineBs dans la mise en place du système sensori-moteur. En particulier, nous avons montré qu'ephrineB2 jouait un rôle autonome dans la position du soma des motoneurones dans le tube neural, en corrélation avec une modification dans le choix de l'innervation dorso/ventrale. De plus, nous avons également mis en évidence le rôle non autonome d'ephrineB1 sur les axones afin de permettre leur fasciculation. Cette fonction semble passer par une action répulsive de la signalisation au niveau du cône de croissance, en agissant sur la dynamique des microtubules. En effet, des expériences en culture cellulaire ont montré un lien direct entre la signalisation EphB2/ephrineB1et la dynamique de microtubules individuels. De plus, afin de tester la potentielle implication du système vasculaire dans l'innervation, en particulier à travers l'expression de molécules de guidance, nous avons généré une lignée transgénique de souris surexprimant ephrineB2 spécifiquement dans les cellules endothéliales. Au cours de ces deux dernières années, un certain nombre d'études a montré que l'expression des récepteurs Eph et ephrines est augmentée après une lésion dans le système nerveux ou dans certaines pathologies tumorales. Ces résultats suggèrent que cette voie de signalisation pourrait jouer un rôle significatif dans la réparation après une lésion nerveuse ainsi que dans l'angiogenèse tumorale. Ces travaux récents soulignent l'importance de nos études visant à comprendre le rôle et les mécanismes moléculaires de la signalisation Eph/ephrine dans le développement du système sensori-moteurThe sensori-motor system allows an organism to interact with the environnement through sensory neurons and respond to this information via motor neurons. Motricity depends on the stereotypical connection of motor neurons with their target muscles. These neurons are located in the ventral horn of the spinal cord and are grouped into functional units called motor columns. Each column contains neurons with the same identity that innervate the same peripheral target tissues. This topography appears to be important for proper nerve supply for each group of neurons is given a single muscle target. Simultaneously, the sensory neurons of the spinal dorsal ganglion (DRG) also emit extensions to innervate the muscles but also the epidermis. The motor and sensory axonal growth is achieved through a system of guidance molecules. Recent studies have shown that these guidance molecules establishe an interaction between motor neurons and sensory neurons allowing a specific innervation. In addition, several studies suggest a potential role of the vascular system, established earlier, in the arrangement of the nervous system through some of these proteins. Eph receptors and their ligands, ephrins are one of the families of axon guidance molecules. Bidirectional signaling resulting from their binding is involved in many developmental processes in Vertebrates and Invertebrates. Although the role of Eph / ephrin A has been well established in the establishment of sensori-motor system in vivo, little is known about the involvement of Eph / ephrin B class and their molecular targets in this developmental process. During my PhD, we characterized the role of two family members of the ephrin B in the establishment of sensori-motor system. In particular, we showed that ephrinB2 plays an independent role in the position of the soma of motor neurons in the neural tube, in connection with a change in the choice of dorso/ventral innervation. In addition, we also highlighted the non-autonomous role of ephrineB1 to allow axon fasciculation. This function seems to go through a repellent signaling at the growth cone, by acting on microtubule dynamics. Indeed, experiments in cell culture have shown a direct link between EphB2/ephrineB1 signaling and individual microtubule dynamics. In addition, to test the potential involvement of the vascular system in innervation, especially through the expression of guidance molecules, we generated a transgenic line of mice overexpressing ephrineB2 specifically in endothelial cells. During the past two years, a number of studies showed that the expression of Eph receptors and ephrins is increased after injury in the nervous system or in tumors. These results suggest that this signaling pathway could play a significant role in repair after nerve injury as well as in tumor angiogenesis. These recent studies highlight the importance of our studies aimed at understanding the role and molecular mechanisms of Eph / ephrin signaling in the development of the sensori-motor system
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Deschamps, Claire. "Etude de l'expression de la molécule de guidage éphrine-A5 dans le cerveau de souris au cours du développement : implication dans la mise en place de la voie mésostriatale." Poitiers, 2010. http://theses.edel.univ-poitiers.fr/2010/Deschamps-Claire/2010-Deschamps-Claire-These.pdf.
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Le fonctionnement du système nerveux dépend de la mise en place d'un réseau complexe de connexions neuronales au cours du développement embryonnaire et postnatal. Comprendre comment ces réseaux neuronaux s'établissent est un axe majeur de la neurobiologie du développement. Au-delà de son importance fondamentale, la compréhension des mécanismes cellulaires et moléculaires du guidage axonal représente un enjeu capital pour appréhender les situations pathologiques consécutives à des troubles lésionnels ou dégénératifs du système nerveux, compte tenu de l'importance des mécanismes développementaux dans la réparation des circuits neuronaux adultes. Au sein de l'équipe Physiopathologie des Troubles Neurodégénératifs et Adaptatifs de l’unité CNRS UMR 6187, le Pr. Afsaneh Gaillard a récemment réussi à reconstruire la voie nigrostriée dans un modèle murin de la maladie de Parkinson, par greffe de cellules embryonnaires issues du mésencéphale ventral. Afin d'identifier les mécanismes moléculaires mis en jeu, nous nous sommes attachés à étudier les mécanismes de guidage axonal des neurones dopaminergiques issus du mésencéphale ventral vers leur région cible, le striatum, pendant l’embryogenèse chez la souris. De précédentes études ont suggéré l'implication du couple de molécules de guidage éphrine-A5/EphA5 en se basant sur l'expression de leurs ARNm respectivement mis en évidence dans le striatum et dans le mésencéphale ventral. Cependant, aucune implication fonctionnelle n'a été démontrée. Ainsi, nous sommes-nous tout d'abord attachés à décrire, in vivo, l'expression de la protéine éphrine-A5 par immunohistochimie dans le système nerveux central de la souris au cours du développement, avant d'émettre l'hypothèse de l'implication de l'interaction éphrine-A5/EphA5 dans la mise en place de la voie mésostriatale. Nous avons notamment détecté à proximité des axones dopaminergiques, pendant l'embryogenèse et le développement post-natal, l'expression de la protéine éphrine-A5 dans le thalamus, dans le télencéphale ventral selon un gradient décroissant rostro-caudal et ventro-dorsal, et dans le striatum. Nous avons montré, in vitro par immunocytochimie et in vivo par immunohistochimie, qu'une proportion de neurones dopaminergiques exprime la protéine réceptrice EphA5. De plus, nous avons observé, par stripe assay, que la protéine purifiée éphrine-A5 exerce un effet répulsif sur la majorité des projections dopaminergiques. Chez l'embryon dont le gène codant pour éphrine-A5 a été invalidé, nous avons mis en évidence, par western blot, une diminution de l’expression de la tyrosine hydroxylase, marqueur des neurones catécholaminergiques, dans le mésencéphale ventral. L'ensemble de ces résultats suggèrent que les éphrines-A, et plus particulièrement éphrine-A5, participent au guidage axonal et à la mise en place topographique des connexions dopaminergiques mésostriatales. Ce travail nous a amenés à proposer un nouveau modèle de guidage axonal des connexions dopaminergiques mésostriatales chez la souris, dans lequel l'interaction répulsive éphrine-A5/EphA5 participerait au maintien de la trajectoire rostro-ventrale de la voie mésostriatale et à la distribution topographique des projections dans le striatumNervous system activity depends on the establishment of a complex network of neuronal connections during embryonic and postnatal development. Understanding how these neural networks are established is a major focus of developmental neurobiology. Beyond its fundamental importance and given the significance of developmental mechanisms in the repair of adult neural circuits, elucidating the cellular and molecular mechanisms of axon guidance is necessary to understand the pathological conditions resulting from lesions or degenerative disorders of the nervous system. In the “Physiolopathologie des Troubles Neurodégénératifs et Adaptatifs” CNRS UMR 6187 laboratory, Prof. Afsaneh Gaillard managed to restore the nigrostriatal pathway in a mouse model of Parkinson's disease by grafting embryonic cells from the ventral midbrain in the substantia nigra. This work suggests that guidance cues are present in the adult tissue and may help to repair this pathway. In order to identify the molecular mechanisms that may be involved in this pathological condition, we investigated the mechanisms of guidance of dopaminergic neurons arising from the ventral midbrain during embryogenesis and connecting onto the striatum. Previous studies have suggested the involvement of ephrin-A5/EphA5 guidance molecules. However, no functional role neither expression of these proteins have been demonstrated up to now. We then showed, using immunohistochemistry, that ephrin-A5 protein is widely expressed in the central nervous system of mice during development. We more particularly detected ephrin-A5 in the vicinity of midbrain dopaminergic axons in the thalamus, the ventral forebrain and the striatum. Moreover, we showed, that a proportion of dopaminergic neurons express the receptor protein EphA5. In addition, we observed, in stripe assay, that the purified protein ephrin-A5 has a repellent effect on dopaminergic projections. Finally, the study of ephrin-A5 knock-out mouse embryos exhibited a decrease of tyrosine hydroxylase (used as marker for midbrain dopaminergic neurons) expression in the substantia nigra. Overall, this study suggests that ephrins-A and particularly ephrin-A5 may participate in the axon guidance of the dopaminergic mesostriatal pathway. This led us to propose a new model of axon guidance of dopaminergic mesostriatal connections in mice, in which the repulsive interaction between ephrin-A5, expressed in the microenvironnement of dopaminergic fibers, and EphA5, expressed on midbrain dopaminergic neurons, participate in the maintenance of the rostro-ventral trajectory of this pathway and in the topographic distribution of dopaminergic projections onto the striatum
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Boukhatmi, Hadi. "Mise en place de l'identité des muscles au cours de la spécification des myoblastes chez la drosophile." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1777/.
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La formation des muscles squelettiques au cours de l'embryogenèse de la drosophile est un modèle d'étude du contrôle génétique de la différentiation cellulaire. La formation de chaque muscle comprend quatre étapes successives: spécification d'un groupe promusculaire, sélection d'un progéniteur (PC) à partir de ce groupe, division asymétrique de ce progéniteur pour donner des cellules fondatrices de muscles (FC) ; fusion de chaque FC avec des myoblastes compétents (FCM), suivie de la différenciation musculaire. Chaque muscle squelettique est composé d'une fibre. Chaque muscle présente des propriétés spécifiques de taille, forme, position, attachement, et patron d'innervation. Ces propriétés sont groupées sous le terme d'identité musculaire. Cette identité est conférée par l'expression dans chaque PC/FC d'une combinatoire de Facteurs de Transcription identitaires (FTi). Notre laboratoire étudie ce processus, en utilisant comme point d'entrée l'expression et les rôles du FTi Collier (Col) au cours du développement d'un muscle dorso-latéral, le muscle DA3 (Dorsal Acute 3). Au cours de la première partie de ma thèse, j'ai étudié la régulation transcriptionnelle de col durant les phases de spécification des groupes promusculaires et de sélection du PC à l'origine du muscle DA3. Partant de prédictions bioinformatiques j'ai caractérisé le module cis régulateur (CRM) de col actif durant ces phases (CRM précoce). Un CRM " tardif ", actif du stade progéniteur à la complétion de la formation du muscle DA3, avait été préalablement caractérisé dans l'équipe. Afin de déterminer plus précisément les fenêtres temporelles d'activité des deux CRM mésodermiques de col, j'ai mis au point un nouveau gène rapporteur comportant un intron permettant de détecter les transcrits primaires. Ceci m'a permis de montrer que les CRM précoce et tardif reproduisent ensemble l'expression endogène de col. La caractérisation du CRM précoce de col m'a aussi permis de suivre le destin des FCM du groupe promusculaire Col dans les embryons tardifs et de montrer que ces FCM contribuent uniquement à des muscles dorsaux-latéraux. Au cours de la deuxième partie de ma thèse, j'ai caractérisé le rôle, inconnu jusqu'alors, du FT à domaine LIM-Homeodomaine Tailup (Tup)/Islet1 dans la myogenèse. J'ai d'abord montré que Tup est spécifiquement exprimé dans les 4 muscles les plus dorsaux. L'analyse de mutants m'a permis de montrer qu'en absence de Tup, le muscle dorsal DA2 exprime Col et est transformé en muscle dorso-latéral de type DA3. J'ai ensuite montré que le PC du DA2 est à l'origine de la FC DA2 et d'un précurseur musculaire adulte (AMP). Ce PC est sélectionné à partir du groupe promusculaire Col quand les cellules de ce groupe expriment encore le FT à homéodomaine Tinman/NKx2. 5. Tin active tup dans le PC DA2. Tup, en retour, réprime col et cette répression permet de distinguer les identités musculaires DA2 et DA3. En conclusion, mes travaux de thèse m'ont permis de proposer un nouveau modèle permettant de relier le processus de spécification des progéniteurs au contrôle temporel et spatial de l'expression des FTi. Une vision dynamique de ce processus de spécification permet de mieux comprendre le programme identitaire propre à chaque muscle. L'analyse des interactions entre Tin, Tup, et Col au cours de la formation des muscles dorsaux révèle de nouveaux parallèles avec les interactions entre Nkx2. 5, Islet, EBF au cours de la formation des muscles pharyngaux chez les chordésThe somatic musculature of the Drosophila embryo is a classical model to study the regulatory processes that generate cellular diversity. Muscle formation is a multistep process: the first step is the specification, within the mesoderm, of a group of competent cells, called promuscular cluster. The second step is the selection of a progenitor cell (PC) from this cluster. Asymmetric division of each PC then generates muscle founder cells (FC). Finally, each FC undergoes a fusion process with fusion competent myoblasts (FCM) to generate a muscle fiber. Each muscle is formed of a single multinucleate fiber. Each Drosophila muscle has a specific identity, as it can be distinguished by its position, shape, orientation, attachment, and innervation pattern. Muscle identity reflects the expression by each PC/FC of a specific combination of identity Transcription Factors (iTF). In the laboratory, we study the control of muscle identity, using as entry point, the expression and requirement of the iTF Collier (Col) during development of a dorso-lateral (DA3) muscle. I started my PhD by characterizing col transcriptional regulation during early steps of DA3 muscle formation. Starting from computational predictions, I identified an early col cis regulatory module (Early CRM) responsible for col activation in a promuscular cluster. A late col CRM, active from the PC stage, had previously been characterized in the laboratory. To determine with more precision the temporal windows of activity of each of these CRM, I designed a novel intron-containing reporter gene in order to detect primary transcripts. This allowed me to show that the late and the early CRMs together reproduce precisely the endogenous col expression pattern. Characterization of the early mesodermal col CRM also allowed to do lineage experiments and determine the fate of FCMs that transiently express Col at the promuscular stage. I found that these myoblasts contribute mostly to dorso-lateral muscles. During the second part of my thesis, I described a new role of the LIM-homeodomain TF Tailup/Islet1 (Tup) in specifying dorsal muscles. I first showed that Tup is specifically expressed in the four dorsal muscles. In tup null mutants, on one hand, the dorsal musculature is severely disorganized and, on the other hand, the dorsal DA2 muscle ectopically expresses Col and is transformed into a dorso-lateral DA3-like muscle. I showed that the DA2 PC is singled out from the Col promuscular cluster when cells of this cluster still express (transitorily) the homeodomain TF Tinman/Nkx2. 5 (Tin). The DA2 PC gives rise to the DA2 FC and a (dorso-lateral) adult muscle precursor (AMP). Tup activation by Tin in the DA2 PC is required to repress col and establish a DA2 instead of DA3 identity. In conclusion, my work allowed to propose a model which connects a temporal sequence of transcriptional regulation of iTFs to the specification of muscle PC identity and final muscle pattern. It provides a novel, dynamic view of how muscle identity is specified. These findings also provide novel parallels with the specification of pharyngeal muscles in vertebrates
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Glaser, Juliane. "Functional characterization of the imprinted Liz/Zdbf2 locus in mice : from the early embryo to adult physiology." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS243.
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L’empreinte parentale est un mécanisme de régulation épigénétique qui réduit l’expression d’environ 120 gènes à une seule dose parentale. L’expression monoallélique dépend de marques différentielles de méthylation de l’ADN, établies dans l’ovocyte et le spermatozoïde et maintenues après fécondation dans l’individu en développement. Chez les mammifères, les gènes soumis à empreinte sont essentiels au développement embryonnaire et à certaines fonctions comportementales et physiologiques après la naissance. Définir les mécanismes de régulation et la fonction des gènes soumis à empreinte est une question cruciale en biologie du développement et en pathologie. Mon travail de thèse a concerné l’étude fonctionnelle du locus Zdbf2 chez la souris. Zdbf2 est un gène exprimé paternellement, conservé chez l’humain, mais dont la fonction était inconnue. J’ai pu démontrer que l’activation de Zdbf2 dans le cerveau de souris pré-pubères dépend d’un signal épigénétique indélébile mis en place dès les premiers jours de développement embryonnaire. Cette programmation précoce de Zdbf2 assure une croissance normale du nouveau-né. Mes résultats indiquent de plus que la dose, mais pas l’origine parentale de Zdbf2 est essentielle. Ces découvertes ont été possibles par la création de divers modèles mutants avec des variations de la dose de Zdbf2 dans l’axe hypothalamo-hypophysaire. Ce travail met en lumière la fonction cruciale d’un gène soumis à empreinte, de sa régulation dans l’embryon précoce à son rôle sur la physiologie adulteGenomic imprinting refers to the epigenetic mechanism by which approximately 120 genes are expressed in a parent-of-origin manner. This parental asymmetry in gene expression is mediated through differential profiles of DNA methylation established in the oocyte and the sperm and maintained after fertilization in the developing individual. In mammals, imprinted genes are essential for normal embryo development as well as behavioral and physiological functions after birth. Clarifying the regulation and the function of those genes is thus fundamental in the field of developmental biology and health. During my PhD, I functionally characterized the imprinted Zdbf2 locus in mice. Zdbf2 is a paternally expressed gene, conserved from mouse to human, whose biological function was unknown. I revealed that Zdbf2 activation in the post-natal brain requires an indelible epigenetic signal that is established during the first days of embryogenesis. Additionally, I provided in vivo evidence that early programming of Zdbf2 is essential for proper growth after birth. By generating multiple CRISPR-mediated genetic mutants with varied doses of Zdbf2 in the hypothalamo-pituitary axis, I finally demonstrated that Zdbf2 is a growth-promoting gene, with a dose-sensitive effect and acting independently of its parental origin. Altogether, my work shed light onto the crucial function of a mammalian imprinted gene, from its regulation in the early embryo to its role in adult physiology
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Rouvre, Denis. "Caractérisation de l'activité foetale : mise en oeuvre d'un dispositif d'enregistrement et analyse des signaux Doppler multidimensionnels." Tours, 2006. http://www.theses.fr/2006TOUR4031.
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Dans cette thèse, nous avons développé des techniques numériques et un dispositif médical appelé Actifoetus (réalisé par la société Ultrasons Technologies) pour l’analyse automatique des rythmes fœtaux. La première étape de ce projet consiste à évaluer les différentes méthodes de traitement du signal en vue d’extraire les informations pertinentes suivantes : activité fœtale globale ; rythme cardiaque fœtal ; mouvements des membres supérieurs et inférieurs ; Mouvements dus à la mère ; mouvements pseudo respiratoires. La deuxième partie est consacrée à l’intégration de ces techniques de traitement de signal dans une électronique embarquée sur un appareil portable. Enfin, nous avons réalisé la validation clinique de l’appareil en milieu hospitalierIn this thesis, we developed numerical techniques and a medical device called Actifoetus (the device has been built by the company Ultrasons Technologies) to analyse automatically the foetal rhythms. The first step of this project was to evaluate the different methods of signal processing in order to extract the following pertinent informations : global foetal activity ; foetal heart rate ; foetal upper limbs movement ; foetal lower limbs movements ; Mothers movements ; pseudo-breathing movements. The second part of this work was to integrate these numerical signal processing techniques in an embedded electronic device. We also have validated the device in the Hospital of Tours
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Trávníčková, Jana. "Rôle de l'environnement sur la mise en place de l'hématopoïèse définitive." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONT3510.
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L’hématopoïèse est le processus de formation des cellules souches hématopoïétiques (CSH); elle est conservée au cours d’évolution. Durant l’hématopoïèse embryonnaire, deux vagues hématopoïétiques se succèdent, la vague primitive et la vague définitive. La vague primitive produit des macrophages, des neutrophiles et des érythrocytes. Au cours de la vague définitive, les CSH émergent du plancher de l’aorte dorsale par une transition endothélio-hématopoïétique ou TEH, dans une région appelée aorte-gonades-mesonephros (AGM).Ces dernières années, des études des organes hématopoïétiques chez les mammifères ont démontré que le microenvironnement joue un rôle crucial dans l’émergence et le devenir des CSH. Pendant ma thèse, je me suis intéressée au rôle du microenvironnement dans la mise en place de l’hématopoïèse définitive chez l’embryon de zebrafish. Dans l’AGM, j’ai caractérisé et évalué la contribution de différents acteurs dont deux populations en particulier, les macrophages et le système neuronal sympathique. Chacune de ces cellules joue un rôle spécifique durant la vague définitive de l’hématopoïèse. Les macrophages mobilisent des CSH de l’AGM afin de permettre leur intravasation et la colonisation des organes hématopoïétiques. Les catécholamines synthétisées par le système neuronal sympathique quant à elles contrôlent la TEH par l’activation des récepteurs beta2b et beta3 dans l’AGM.En conclusion, nous avons démontré que le microenvironnement influence l’hématopoïèse définitive chez le zebrafish par différents mécanismes. Ces travaux ont pour objectif d’améliorer la compréhension du mécanisme de genèse des CSH et potentiellement de permettre un jour la production de CSH in vitroHaematopoiesis is the process of haematopoietic stem cell (HSC) generation conserved in all vertebrates. During the embryonic development, two successive waves of haematopoiesis occur – the primitive and the definitive wave. The first one gives rise to erythrocytes, macrophages and neutrophils. During the second one, HSCs emerge from the ventral wall of dorsal aorta (DA) in the aorta-gonads-mesonephros (AGM) region by a process called endothelial-to-haematopoietic transition or EHT.In the last years, several studies performed in mammals have shown that the microenvironment plays a key role in haematopoiesis. During my thesis I have studied the role of the microenvironment in definitive haematopoiesis in the zebrafish embryo. I have described several cell components present in the AGM and evaluated their contribution to the haematopoiesis. I further analysed two of those players: macrophages and sympathetic nervous system. Each of them plays a specific role during the definitive wave of haematopoiesis. Macrophages mobilise nascent HSCs from the AGM to allow their intravasation and colonisation of haematopoietic organs. Catecholamines synthetized by sympathetic nervous system control EHT through the activation of beta2b and beta3 receptors in the AGM.In conclusion, we have shown that the microenvironment can substantially influence the definitive haematopoiesis in the zebrafish by distinct mechanisms. These findings would help to understand the mechanism of HSC generation and potentially to allow in vitro HSC production
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GAUTIER, JEAN. "Recherches sur le determinisme cellulaire et moleculaire de la mise en place de la symetrie bilaterale dans l'ovocyte et l'oeuf d'axolotl." Toulouse 3, 1988. http://www.theses.fr/1988TOU30004.
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Khan, Daulat Raheem. "Reprogrammation embryonnaire et somatique au moment de la mise en route du génome dans l’embryon bovin." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA11T060.
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Lors de la fécondation, le sperme et l'ovule s'unissent pour former un zygote totipotent. Initialement, le zygote est transcriptionnellement inactif. Au cours des premiers clivages a lieu la mise en route du génome embryonnaire (EGA) et le développement passe alors sous le contrôle de l’information embryonnaire (au stade 8-16-cellules chez le bovin). Cette transition d’un contrôle maternel à un contrôle embryonnaire est appelée « maternal to embryonic transition (MET) ». De la même façon, lors du transfert nucléaire (clonage), un noyau de cellule somatique placé dans un ovocyte énucléé devient totipotent. Ce processus est appelé «reprogrammation nucléaire somatique?». En fait, la reprogrammation nucléaire lors du clonage est équivalente à la MET, toutefois, le clonage est très peu efficace. Les objectifs de cette étude chez les bovins sont a) d'explorer le processus de reprogrammation lors de la MET dans des embryons fécondés in vitro (FIV) et b) d’estimer l'efficacité de la reprogrammation génique après le transfert nucléaire lors du clonage. Nous émettons l'hypothèse que l'acquisition d'un profil d'expression génique correct pourrait être prédictif d’un potentiel de développement à terme de l'embryon, et pourrait être évalué dès juste après l'activation du génome embryonnaire (EGA) chez les bovins. Nous avons développé notre travail selon deux axes a) des analyses globales d'expression génique utilisant une puce dédiée à l’EGA et b) l’analyse du profil d'expression de gènes candidats par qRT-PCR dans les embryons fécondés et clonés. Dans un premier temps nous avons optimisé le protocole d'amplification d'ARNm pour l'analyse du transcriptome de matériels rares. Puis nous avons fait l'analyse du transcriptome avant et après EGA d’embryons issus d’ovocytes prélevés sur des vaches phénotypées comme « bonnes » ou « mauvaises » donneuses d’embryons. En outre, ces ovocytes ont été maturés soit in vivo soit in vitro. Nos analyses montrent que l'effet individuel est plus important que l'effet « bonne ou mauvaise donneuse » ou même que l’effet « conditions de maturation ». Nous avons ensuite analysé les expressions géniques de 5 types d'embryons clonés ayant différents potentiels de développement à terme en fonction de la lignée cellulaire utilisée comme source de cellules donneuses. Globalement, leur expression génique est proche de celle de morulae FIV, mais quelques gènes présentent une expression différente. Ces gènes varient avec la lignée de cellules donneuses et leur nombre n’est pas lié à l’aptitude au développement à terme. L’analyse d’un lien éventuel entre leur nature et cette aptitude devra être poursuivie. Dans un deuxième temps, nous avons analysé les profils d'expression spatio-temporelle des transcrits et des protéines des gènes de pluripotence (OCT4, SOX2 et NANOG) et les niveaux d'ARNm de certains de leurs cibles dans les ovocytes et les embryons précoces chez le bovin. Les profils d'expression de ces gènes ont aussi été analysés dans des embryons clonés présentant différents potentiels de développement à terme. Nos résultats montrent que (1) la triade de gènes de pluripotence n'est probablement pas impliquée dans l’EGA bovine. (2) les transcrits et protéines de SOX2 et de NANOG sont restreints au lignage pluripotent plus tôt que ceux de OCT4, (3) les embryons à faible taux de développement à terme ont un taux de transcription plus élevé, néanmoins, l’équilibre précaire entre les gènes de pluripotence est maintenue. Cet équilibre pourrait permettre un développement normal in vitro, mais le taux de transcription plus élevé pourrait avoir des conséquences délétères sur le développement ultérieurIn natural fertilization, sperm and ovum unite to form a totipotent zygote. Initially, the zygote is transcriptionally inactive and after few cleavages (8-16-cell stage in bovine) embryonic genome activation (EGA) takes place and embryo shifts from maternal to embryonic control, the process called maternal to embryonic transition (MET). Likewise, in nuclear transplantation (cloning) a somatic cell nucleus achieves totipotency when placed in an enucleated oocyte, the process called “nuclear reprogramming”. In fact, nuclear reprogramming in cloning experiments is equivalent to MET; however, this process is afflicted with low efficiency. The objectives of this study in bovine were a) to explore the process of MET reprogramming of in vitro fertilized (IVF) embryos and b) to estimate the efficiency of gene reprogramming after nuclear transfer in animal cloning. We hypothesized that the acquisition of a proper gene expression pattern could herald development potential of the embryos, which could be assessed as early as morula stage or after embryonic genome activation (EGA) in bovine. Here, we opted for a study plan consisting of two axes a) global gene expression analysis using an EGA-dedicated microarray and b) candidate gene expression profiling through qRT-PCR in the fertilized and cloned bovine embryos. Firstly, we optimized the protocol of mRNA amplification for transcriptome analysis which generates antisens-RNA (aRNA). Then we did transcriptomic analysis of the 4-cell and morulae derived from two genotypes having better and two genotypes having poorer in vitro embryonic development potentials. In addition, these oocytes were either matured in vivo or in vitro. We observed that the effect of individual genotype was more important than the effect of the phenotypic category (poorer or better) or conditions of oocyte maturation. Furthermore, we explored the expression patterns of 5 types of cloned embryos having different full term developmental potentials depending upon the donor cell line used. Their genes expression patterns closely resembled to the IVF morulae, except for few genes which present differences. These genes vary with the cell line used as somatic cell donor for SCNT and the number of these deregulated genes did not increase with the poorer developmental potential of the cloned embryos. The analysis of an eventual correlation between the potential for embryonic development to term and nature of the deregulated genes should be addressed. Secondly, we charted quantitative and/or qualitative spatio-temporal expression patterns of transcripts and proteins of pluripotency genes (OCT4, SOX2 and NANOG) and mRNA levels of some of their downstream targets in bovine oocytes and early embryos. Furthermore, to correlate expression patterns of these genes with term developmental potential, we used cloned embryos, instead of gene ablation, having similar in vitro but different full term development rates. We chose these genes to be analysed since pluripotency genes are implicated in mouse embryonic genome activation (EGA) and pluripotent lineage specification. Moreover, their expression levels have been correlated with embryonic term development. Our findings affirm: first, the core triad of pluripotency genes probably is not implicated in bovine EGA since their proteins were not detected during pre-EGA phase, despite the transcripts for OCT4 and SOX2 were present. Second, an earlier ICM specification of SOX2 and NANOG makes them better candidates of bovine pluripotent lineage specification than OCT4. Third, embryos with low term development potential have higher transcription rates; nevertheless, precarious balance between pluripotency genes is maintained. This balance presages normal in vitro development but, probably higher transcription rate disturbs it at later stage that abrogates term development
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Verdier, Gaetan. "Mise en évidence du rôle du cytochrome P450 CYP 77A4 et de la protéine BODYGUARD dans la biosynthèse du polymère de cutine chez Arabidopsis thaliana." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4094.
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La cutine est un polymère d'acides gras oxydés et de glycérol propre aux plantes. Elle forme la matrice structurale de la cuticule qui recouvre l'épiderme des parties aériennes et joue un rôle vital pour les plantes en empêchant la dessiccation. La biosynthèse du polymère de cutine a été étudiée chez la plante modèle Arabidopsis thaliana. Des mutants perte-de-fonction pour la monooxygénase de type cytochrome P450 CYP77A4 ont été isolés. L'analyse de lignées transgéniques exprimant le gène rapporteur GUS sous le contrôle du promoteur de CYP77A4 a montré que le gène était exprimé essentiellement dans les organes floraux et les graines. L'analyse de la cutine dans divers organes a permis de démontrer que le gène était essentiel pour la synthèse d'un acide gras trihydroxylé en C18 présent dans les polyesters des embryons. Une méthode permettant la séparation de l'embryon et des téguments des graines en quantité suffisante pour analyser la cutine a été mise au point. Le profil de monomères des embryons mutants a montré que CYP77A4 est une époxygénase de la voie de biosynthèse des monomères de cutine en C18. L'étude de la physiologie des mutants a par ailleurs permis de démontrer que les acides gras trihydroxylés de la cuticule de l'embryon jouent un rôle important dans la germination de la graine en conditions de stress salin. Dans une deuxième étude, des mutants perte-de-fonction et des suexpresseurs pour le gène d'Arabidopsis BODYGUARD (BDG) codant une protéine de la superfamille des hydrolases à repliement α/β ont été caractérisés. L'analyse des polyesters dans ces lignées a permis de montrer que cette protéine jouait en fait un rôle dans la biosynthèse de la cutineCutin is a polymer of oxidized fatty acids and glycerol specific to plants. It forms the structural matrix of the waxy cuticle covering the epidermis of the aerial parts and plays a vital role in plants by preventing desiccation. Biosynthesis of cutin polymer was studied in the model plant Arabidopsis thaliana. Mutant loss-of-function monooxygenase type cytochrome P450 CYP77A4 were isolated. The analysis of transgenic lines expressing the GUS reporter gene under the control of the promoter of CYP77A4 showed that the gene was expressed mainly in floral organs and seeds. The analysis of various organs in the cutin demonstrated that the gene was essential for the synthesis of a C18 trihydroxy polyesters present in seed polyesters (9,10,18-trihydroxyoctadecenoic acid). A method for the separation of the embryo and seed coat allowing to analyze embryo polyesters was developed. The trihydroxy C18 fatty acid was found to be the major cutin embryo monomer. Profile of cutin monomers in mutant embryos showed that CYP77A4 is an epoxygenase in the biosynthetic pathway of C18 cutin monomers. The study of the physiology of the mutants also showed that the trihydroxy- fatty acids of the embryo cuticle play an important role in the germination of the seed under conditions of salt stress. In a second study, mutant loss-of-function and overexpressors for the Arabidopsis gene BODYGUARD encoding a protein of the α / β hydrolase fold superfamily have been characterized. Analysis of polyesters in these lines showed that this protein, whose role in the formation of the cuticle was not understood, plays in fact a role in cutin biosynthesis
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Xue, Zhi-Gang. "Recherches sur la différenciation du système nerveux periphérique chez les oiseaux : mise en évidence et propriétés des précurseurs de type autonome présents dans les ganglions sensoriels." Paris 13, 1987. http://www.theses.fr/1987PA132008.
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Pelton, Tricia Ann. "Expression and function of genes identifying pluripotent cell sub-populations in the early mouse embryo." Thesis, 2007. http://hdl.handle.net/2440/63569.
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Work presented in this thesis determined that K7 encoded a gene with considerable identity at both the DNA and protein level to a human gene of unknown function, termed KIA A0165.Thesis (Ph.D.) - University of Adelaide, School of Molecular and Biomedical Science, 2007