Finding biomarkers in non-model species: literature mining of transcription factors involved in b... more Finding biomarkers in non-model species: literature mining of transcription factors involved in bovine embryo development
Our laboratory has been working on bovine clones for many years. These clones were studied and se... more Our laboratory has been working on bovine clones for many years. These clones were studied and several cloned females were bred to obtain clone offsprings. All pregnancies were normal and calves developed as healthy individuals. The females were used for embryo collection after superovulation. The objective of this study was to compare the embryo recovery results between clone offspring and control animals. Altogether, 28 cows were used for this study (18 clone offspring and 10 controls). All the animals were born and raised in the same experimental farm, in the same time period and in the same rearing conditions. 90 flushes were performed to collect D9 to D21 embryos for research protocols. For early embryos on D9, a classical 3 way collection equipment (IMV, France) was used. To collect the late embryos D12-D21, the same equipment was modified so that larger embryos could be collected through the remaining larger hole (2 way collection) (Richard et al. 2015, Theriogenology 83, 110...
STUDY QUESTION Does oocyte maturation under lipolytic conditions have detrimental carry-over effe... more STUDY QUESTION Does oocyte maturation under lipolytic conditions have detrimental carry-over effects on post-hatching embryo development of good-quality blastocysts after transfer? SUMMARY ANSWER Surviving, morphologically normal blastocysts derived from bovine oocytes that matured under lipotoxic conditions exhibit long-lasting cellular dysfunction at the transcriptomic and metabolic levels, which coincides with retarded post-hatching embryo development. WHAT IS KNOWN ALREADY There is increasing evidence showing that following maturation in pathophysiologically relevant lipotoxic conditions (as in obesity or metabolic syndrome), surviving blastocysts of good (transferable) morphological quality have persistent transcriptomic and epigenetic alteration even when in vitro embryo culture takes place under standard conditions. However, very little is known about subsequent development in the uterus after transfer. STUDY DESIGN, SIZE, DURATION Bovine oocytes were matured in vitro in the ...
Embryo transfer in cattle is performed with blastocysts produced in vivo or in vitro using define... more Embryo transfer in cattle is performed with blastocysts produced in vivo or in vitro using defined media. However, outdated systems such as those that use serum and co-culture remain of interest for research purposes. Here, we investigated the effect of additional culture time on in vitro-produced embryos. Specifically, we compared embryos that formed a blastocoel at different times after fertilisation to those that stayed in culture for up to two additional days with respect to their development in vivo after temporary transfer to oestrus-synchronised recipients. A pre-transfer set (D6, D6+1, D6+2, D7, D7+1, D8) was examined using microarray analyses, and correlated with a post-transfer set that included two different days of transfer (D6-T6, D6+2-T8, D7+1-T8, D8-T8). All surviving conceptuses reached primitive-streak stages and filamentous sizes similarly to in vivo (D18) or in vitro controls (D7/T7). The recovery rate differed between D6 and D8 embryos that were immediately trans...
During the formation of a complex organism, cells divide, die, migrate, and differentiate. Biolog... more During the formation of a complex organism, cells divide, die, migrate, and differentiate. Biologists have established tools to observe those phenomena but also to change their course, which subsequently enables to infer causal relationships between various events occurring in different cell groups. More precisely, present approaches mostly rely on modifications of gene expression. For instance, cells are labeled with fluorescent proteins and tracked within the embryo,
In mammalian species, endometrial receptivity is driven by maternal factors independently of embr... more In mammalian species, endometrial receptivity is driven by maternal factors independently of embryo signals. When pregnancy initiates, paracrine secretions of the preattachment embryo are essential both for maternal recognition and endometrium preparation for implantation and for coordinating development of embryonic and extraembryonic tissues of the conceptus. This review mainly focuses on domestic large animal species. We first illustrate the major steps of preattachment embryo development, including elongation in bovine, ovine, porcine, and equine species. We next highlight conceptus secretions that are involved in the communication between extraembryonic and embryonic tissues, as well as between the conceptus and the endometrium. Finally, we introduce experimental data demonstrating the intimate connection between conceptus secretions and endometrial activity and how adverse events perturbing this interplay may affect the progression of implantation that will subsequently impact...
Apoptotic activity is a common physiological process which culminates at the blastocyst stage in ... more Apoptotic activity is a common physiological process which culminates at the blastocyst stage in the preimplantation embryo of many mammals. The degree of embryonic cell death can be influenced by the oocyte microenvironment. However, the prognostic significance of the incidence of apoptosis remains undefined. Prostaglandin E2 (PGE2) derived from prostaglandin G/H synthase-2 (PTGS2) activity is a well-known prosurvival factor that is mainly studied in oncology. PGE2 is the predominant PTGS2-derived prostaglandin present in the oocyte microenvironment during the periconceptional period. Using an in vitro model of bovine embryo production followed by transfer and collection procedures, we investigated the impact of periconceptional PGE2 on the occurrence of spontaneous apoptosis in embryos and on subsequent in vivo posthatching development. Different periconceptional PGE2 environments were obtained using NS-398, a specific inhibitor of PTGS2 activity, and exogenous PGE2. We assessed t...
Proceedings of the National Academy of Sciences of the United States of America, Dec 20, 2016
A major unresolved issue in the cloning of mammals by somatic cell nuclear transfer (SCNT) is the... more A major unresolved issue in the cloning of mammals by somatic cell nuclear transfer (SCNT) is the mechanism by which the process fails after embryos are transferred to the uterus of recipients before or during the implantation window. We investigated this problem by using RNA sequencing (RNA-seq) to compare the transcriptomes in cattle conceptuses produced by SCNT and artificial insemination (AI) at day (d) 18 (preimplantation) and d 34 (postimplantation) of gestation. In addition, endometrium was profiled to identify the communication pathways that might be affected by the presence of a cloned conceptus, ultimately leading to mortality before or during the implantation window. At d 18, the effects on the transcriptome associated with SCNT were massive, involving more than 5,000 differentially expressed genes (DEGs). Among them are 121 genes that have embryonic lethal phenotypes in mice, cause defects in trophoblast and placental development, and/or affect conceptus survival in mice...
We previously showed that the homeodomain transcription factor HOXB9 is expressed in mammalian oo... more We previously showed that the homeodomain transcription factor HOXB9 is expressed in mammalian oocytes and early embryos. However, a systematic and exhaustive study of the localization of the HOXB9 protein, and HOX proteins in general, during mammalian early embryonic development has so far never been performed. The distribution of HOXB9 proteins in oocytes and the early embryo was characterized by immunofluorescence from the immature oocyte stage to the peri-gastrulation period in both the mouse and the bovine. HOXB9 was detected at all studied stages with a dynamic expression pattern. Its distribution was well conserved between the two species until the blastocyst stage and was mainly nuclear. From that stage on, trophoblastic cells always showed a strong nuclear staining, while the inner cell mass and the derived cell lines showed important dynamic variations both in staining intensity and in intra-cellular localization. Indeed, HOXB9 appeared to be progressively downregulated in...
Rencontres Autour Des Recherches Sur Les Ruminants, 2003
RESUME-Chez les bovins, plus de 30 % des pertes embryonnaires observées après insémination artifi... more RESUME-Chez les bovins, plus de 30 % des pertes embryonnaires observées après insémination artificielle, semblent avoir une origine précoce, liée à la croissance exponentielle du trophoblaste. Durant cette phase d'élongation qui se produit entre le 13 ème et le 19 ème jour de gestation, se mettent en place entre l'embryon et l'utérus, des interactions physiologiques indispensables pour le maintien de la gestation. Nos travaux en cours portent sur l'identification de transcrits impliqués dans la croissance de l'embryon avant l'implantation. Dans le cadre de cette étude, nous avons utilisé un réseau sur filtre de nylon, comprenant 1920 inserts ordonnés provenant d'une banque d'ADNc établie à partir d'embryons bovins en début d'élongation (14 ème jour), pour comparer les profils d'expression de trophoblastes provenant d'embryons de taille croissante : ovoïde (10-18mm), tubulaire (50-60mm) et filamenteux (140-160mm). Une première analyse statistique fait apparaître des gènes jusqu'alors inconnus dont l'expression est différentielle entre ces stades.
Nodal activity in the left lateral plate mesoderm is a conserved sign of irreversible left-right ... more Nodal activity in the left lateral plate mesoderm is a conserved sign of irreversible left-right asymmetry at early somite stages of the vertebrate embryo. An earlier, paraxial nodal domain accompanies the emergence and initial extension of the notochord and is either left-sided, as in the chick and pig, or symmetrical, as in the mouse and rabbit; intriguingly, this interspecific dichotomy is mirrored by divergent morphological features of the posterior notochord (also known as the left-right organizer), which is ventrally exposed to the yolk sac cavity and carries motile cilia in the latter 2 species only. By introducing the cattle embryo as a new model organism for early left-right patterning, we present data to establish 2 groups of mammals characterized by both the morphology of the left-right organizer and the dynamics of paraxial nodal expression: presence and absence of a ventrally open surface of the early (plate-like) posterior notochord correlates with a symmetrical (in mi...
Projet transversal PHASE - Alimentation Humaine Ce projet est coordonné en commun par Isabelle Le... more Projet transversal PHASE - Alimentation Humaine Ce projet est coordonné en commun par Isabelle Le Huërou-Luron et Pascale Chavatte-Palmer Session: Atelier 5. Adaptation des animaux
In recent years, the aging of pipelines has been severe and has caused fatal accidents. The pipe ... more In recent years, the aging of pipelines has been severe and has caused fatal accidents. The pipe diameters are small, and the layouts are complex. Pneumatically driven mobile robots have become popular as inspection methods. Various types of robots have been studied, like earthworm-type robots, inchworm-type robots, and spiral-tube-type robots. Typically, they make periodic movements; however, they have challenges because they are driven by existing pneumatic valve technologies, which are limited to small mobile robots. Small pneumatic valves have low flow rates and limit the performance of pneumatic actuators. Therefore, we focused on the structure of the ball valve and periodic motion. Furthermore, in this paper, we developed the Compact Rotary Valve Mechanism for pneumatic mobile robots in pipe inspection, which generates periodic air pressure.
Proceedings of the National Academy of Sciences, 2013
Syncytins are envelope genes of retroviral origin that have been co-opted for a role in placentat... more Syncytins are envelope genes of retroviral origin that have been co-opted for a role in placentation and likely contribute to the remarkable diversity of placental structures. Independent capture events have been identified in primates, rodents, lagomorphs, and carnivores, where they are involved in the formation of a syncytium layer at the fetomaternal interface via trophoblast cell–cell fusion. We searched for similar genes within the suborder Ruminantia where the placenta lacks an extended syncytium layer but displays a heterologous cell-fusion process unique among eutherian mammals. An in silico search for intact envelope genes within the Bos taurus genome identified 18 candidates belonging to five endogenous retrovirus families, with one gene displaying both placenta-specific expression, as assessed by quantitative RT-PCR analyses of a large panel of tissues, and conservation in the Ovis aries genome. Both the bovine and ovine orthologs displayed fusogenic activity by conferrin...
ABSTRACT Pluripotency can be captured in vitro, providing that the culture environment meets the ... more ABSTRACT Pluripotency can be captured in vitro, providing that the culture environment meets the requirements that avoid differentiation while stimulating self-renewal. From studies in the mouse embryo, two kinds of pluripotent stem cells have been obtained from the early and late epiblast, embryonic stem cells (ESCs) and epiblast stem cells (EpiSCs), representing the naive and primed states, respectively. All attempts to derive convincing ESCs in ungulates have been unsuccessful, although all attempts were based on the assumption that the conditions used to derive mouse ESCs or human ESC could be applied in other species. Pluripotent cells derived in primates, rabbit, and pig strongly indicate that the state of pluripotency of these cells is, in fact, closer to EpiSCs than to ESCs, and thus depend on fibroblast growth factor (FGF) and Activin signaling pathways. Based on this observation, we have tried to derive EpiSC from the epiblast of bovine elongated embryos as well as ESCs from Day-8 blastocysts. We here show that the core transcription factors Oct4/Sox2/Nanog can be used as markers of pluripotency in the bovine since their expression was restricted to the developing epiblast after Day 8, and disappeared following differentiation of both the ESC-like and EpiSC-like cultures. Although FGF and Activin pathways are indeed present and active in the bovine, it is not sufficient/enough to maintain a long-term pluripotency ex vivo, as was reported for mouse and pig EpiSCs.
We determined if somatic cell nuclear transfer (SCNT) cloning is associated with WNT-related gene... more We determined if somatic cell nuclear transfer (SCNT) cloning is associated with WNT-related gene expression in cattle development, and if the expression of genes in the WNT pathway changes during the peri-implantation period. Extra-embryonic and endometrial tissues were collected at gestation days 18 and 34 (d18, d34). WNT5A,
Brachyury is a T-box-containing transcription factor involved in mesoderm formation during verteb... more Brachyury is a T-box-containing transcription factor involved in mesoderm formation during vertebrate gastrulation. To analyse whether the regulation of gastrulation varies as much as the timing of gastrulation does with respect to implantation, we isolated a bovine brachyury cDNA fragment. The amino acid sequence shows high similarity to mouse and human Brachyury and clear differences to other T-box genes. Whole-mount in situ hybridisation reveals a normal expression pattern except for a transiently reduced expression in the anterior part of the primitive streak. According to these results, gastrulation in mammals is implemented and regulated irrespective of implantation.
Finding biomarkers in non-model species: literature mining of transcription factors involved in b... more Finding biomarkers in non-model species: literature mining of transcription factors involved in bovine embryo development
Our laboratory has been working on bovine clones for many years. These clones were studied and se... more Our laboratory has been working on bovine clones for many years. These clones were studied and several cloned females were bred to obtain clone offsprings. All pregnancies were normal and calves developed as healthy individuals. The females were used for embryo collection after superovulation. The objective of this study was to compare the embryo recovery results between clone offspring and control animals. Altogether, 28 cows were used for this study (18 clone offspring and 10 controls). All the animals were born and raised in the same experimental farm, in the same time period and in the same rearing conditions. 90 flushes were performed to collect D9 to D21 embryos for research protocols. For early embryos on D9, a classical 3 way collection equipment (IMV, France) was used. To collect the late embryos D12-D21, the same equipment was modified so that larger embryos could be collected through the remaining larger hole (2 way collection) (Richard et al. 2015, Theriogenology 83, 110...
STUDY QUESTION Does oocyte maturation under lipolytic conditions have detrimental carry-over effe... more STUDY QUESTION Does oocyte maturation under lipolytic conditions have detrimental carry-over effects on post-hatching embryo development of good-quality blastocysts after transfer? SUMMARY ANSWER Surviving, morphologically normal blastocysts derived from bovine oocytes that matured under lipotoxic conditions exhibit long-lasting cellular dysfunction at the transcriptomic and metabolic levels, which coincides with retarded post-hatching embryo development. WHAT IS KNOWN ALREADY There is increasing evidence showing that following maturation in pathophysiologically relevant lipotoxic conditions (as in obesity or metabolic syndrome), surviving blastocysts of good (transferable) morphological quality have persistent transcriptomic and epigenetic alteration even when in vitro embryo culture takes place under standard conditions. However, very little is known about subsequent development in the uterus after transfer. STUDY DESIGN, SIZE, DURATION Bovine oocytes were matured in vitro in the ...
Embryo transfer in cattle is performed with blastocysts produced in vivo or in vitro using define... more Embryo transfer in cattle is performed with blastocysts produced in vivo or in vitro using defined media. However, outdated systems such as those that use serum and co-culture remain of interest for research purposes. Here, we investigated the effect of additional culture time on in vitro-produced embryos. Specifically, we compared embryos that formed a blastocoel at different times after fertilisation to those that stayed in culture for up to two additional days with respect to their development in vivo after temporary transfer to oestrus-synchronised recipients. A pre-transfer set (D6, D6+1, D6+2, D7, D7+1, D8) was examined using microarray analyses, and correlated with a post-transfer set that included two different days of transfer (D6-T6, D6+2-T8, D7+1-T8, D8-T8). All surviving conceptuses reached primitive-streak stages and filamentous sizes similarly to in vivo (D18) or in vitro controls (D7/T7). The recovery rate differed between D6 and D8 embryos that were immediately trans...
During the formation of a complex organism, cells divide, die, migrate, and differentiate. Biolog... more During the formation of a complex organism, cells divide, die, migrate, and differentiate. Biologists have established tools to observe those phenomena but also to change their course, which subsequently enables to infer causal relationships between various events occurring in different cell groups. More precisely, present approaches mostly rely on modifications of gene expression. For instance, cells are labeled with fluorescent proteins and tracked within the embryo,
In mammalian species, endometrial receptivity is driven by maternal factors independently of embr... more In mammalian species, endometrial receptivity is driven by maternal factors independently of embryo signals. When pregnancy initiates, paracrine secretions of the preattachment embryo are essential both for maternal recognition and endometrium preparation for implantation and for coordinating development of embryonic and extraembryonic tissues of the conceptus. This review mainly focuses on domestic large animal species. We first illustrate the major steps of preattachment embryo development, including elongation in bovine, ovine, porcine, and equine species. We next highlight conceptus secretions that are involved in the communication between extraembryonic and embryonic tissues, as well as between the conceptus and the endometrium. Finally, we introduce experimental data demonstrating the intimate connection between conceptus secretions and endometrial activity and how adverse events perturbing this interplay may affect the progression of implantation that will subsequently impact...
Apoptotic activity is a common physiological process which culminates at the blastocyst stage in ... more Apoptotic activity is a common physiological process which culminates at the blastocyst stage in the preimplantation embryo of many mammals. The degree of embryonic cell death can be influenced by the oocyte microenvironment. However, the prognostic significance of the incidence of apoptosis remains undefined. Prostaglandin E2 (PGE2) derived from prostaglandin G/H synthase-2 (PTGS2) activity is a well-known prosurvival factor that is mainly studied in oncology. PGE2 is the predominant PTGS2-derived prostaglandin present in the oocyte microenvironment during the periconceptional period. Using an in vitro model of bovine embryo production followed by transfer and collection procedures, we investigated the impact of periconceptional PGE2 on the occurrence of spontaneous apoptosis in embryos and on subsequent in vivo posthatching development. Different periconceptional PGE2 environments were obtained using NS-398, a specific inhibitor of PTGS2 activity, and exogenous PGE2. We assessed t...
Proceedings of the National Academy of Sciences of the United States of America, Dec 20, 2016
A major unresolved issue in the cloning of mammals by somatic cell nuclear transfer (SCNT) is the... more A major unresolved issue in the cloning of mammals by somatic cell nuclear transfer (SCNT) is the mechanism by which the process fails after embryos are transferred to the uterus of recipients before or during the implantation window. We investigated this problem by using RNA sequencing (RNA-seq) to compare the transcriptomes in cattle conceptuses produced by SCNT and artificial insemination (AI) at day (d) 18 (preimplantation) and d 34 (postimplantation) of gestation. In addition, endometrium was profiled to identify the communication pathways that might be affected by the presence of a cloned conceptus, ultimately leading to mortality before or during the implantation window. At d 18, the effects on the transcriptome associated with SCNT were massive, involving more than 5,000 differentially expressed genes (DEGs). Among them are 121 genes that have embryonic lethal phenotypes in mice, cause defects in trophoblast and placental development, and/or affect conceptus survival in mice...
We previously showed that the homeodomain transcription factor HOXB9 is expressed in mammalian oo... more We previously showed that the homeodomain transcription factor HOXB9 is expressed in mammalian oocytes and early embryos. However, a systematic and exhaustive study of the localization of the HOXB9 protein, and HOX proteins in general, during mammalian early embryonic development has so far never been performed. The distribution of HOXB9 proteins in oocytes and the early embryo was characterized by immunofluorescence from the immature oocyte stage to the peri-gastrulation period in both the mouse and the bovine. HOXB9 was detected at all studied stages with a dynamic expression pattern. Its distribution was well conserved between the two species until the blastocyst stage and was mainly nuclear. From that stage on, trophoblastic cells always showed a strong nuclear staining, while the inner cell mass and the derived cell lines showed important dynamic variations both in staining intensity and in intra-cellular localization. Indeed, HOXB9 appeared to be progressively downregulated in...
Rencontres Autour Des Recherches Sur Les Ruminants, 2003
RESUME-Chez les bovins, plus de 30 % des pertes embryonnaires observées après insémination artifi... more RESUME-Chez les bovins, plus de 30 % des pertes embryonnaires observées après insémination artificielle, semblent avoir une origine précoce, liée à la croissance exponentielle du trophoblaste. Durant cette phase d'élongation qui se produit entre le 13 ème et le 19 ème jour de gestation, se mettent en place entre l'embryon et l'utérus, des interactions physiologiques indispensables pour le maintien de la gestation. Nos travaux en cours portent sur l'identification de transcrits impliqués dans la croissance de l'embryon avant l'implantation. Dans le cadre de cette étude, nous avons utilisé un réseau sur filtre de nylon, comprenant 1920 inserts ordonnés provenant d'une banque d'ADNc établie à partir d'embryons bovins en début d'élongation (14 ème jour), pour comparer les profils d'expression de trophoblastes provenant d'embryons de taille croissante : ovoïde (10-18mm), tubulaire (50-60mm) et filamenteux (140-160mm). Une première analyse statistique fait apparaître des gènes jusqu'alors inconnus dont l'expression est différentielle entre ces stades.
Nodal activity in the left lateral plate mesoderm is a conserved sign of irreversible left-right ... more Nodal activity in the left lateral plate mesoderm is a conserved sign of irreversible left-right asymmetry at early somite stages of the vertebrate embryo. An earlier, paraxial nodal domain accompanies the emergence and initial extension of the notochord and is either left-sided, as in the chick and pig, or symmetrical, as in the mouse and rabbit; intriguingly, this interspecific dichotomy is mirrored by divergent morphological features of the posterior notochord (also known as the left-right organizer), which is ventrally exposed to the yolk sac cavity and carries motile cilia in the latter 2 species only. By introducing the cattle embryo as a new model organism for early left-right patterning, we present data to establish 2 groups of mammals characterized by both the morphology of the left-right organizer and the dynamics of paraxial nodal expression: presence and absence of a ventrally open surface of the early (plate-like) posterior notochord correlates with a symmetrical (in mi...
Projet transversal PHASE - Alimentation Humaine Ce projet est coordonné en commun par Isabelle Le... more Projet transversal PHASE - Alimentation Humaine Ce projet est coordonné en commun par Isabelle Le Huërou-Luron et Pascale Chavatte-Palmer Session: Atelier 5. Adaptation des animaux
In recent years, the aging of pipelines has been severe and has caused fatal accidents. The pipe ... more In recent years, the aging of pipelines has been severe and has caused fatal accidents. The pipe diameters are small, and the layouts are complex. Pneumatically driven mobile robots have become popular as inspection methods. Various types of robots have been studied, like earthworm-type robots, inchworm-type robots, and spiral-tube-type robots. Typically, they make periodic movements; however, they have challenges because they are driven by existing pneumatic valve technologies, which are limited to small mobile robots. Small pneumatic valves have low flow rates and limit the performance of pneumatic actuators. Therefore, we focused on the structure of the ball valve and periodic motion. Furthermore, in this paper, we developed the Compact Rotary Valve Mechanism for pneumatic mobile robots in pipe inspection, which generates periodic air pressure.
Proceedings of the National Academy of Sciences, 2013
Syncytins are envelope genes of retroviral origin that have been co-opted for a role in placentat... more Syncytins are envelope genes of retroviral origin that have been co-opted for a role in placentation and likely contribute to the remarkable diversity of placental structures. Independent capture events have been identified in primates, rodents, lagomorphs, and carnivores, where they are involved in the formation of a syncytium layer at the fetomaternal interface via trophoblast cell–cell fusion. We searched for similar genes within the suborder Ruminantia where the placenta lacks an extended syncytium layer but displays a heterologous cell-fusion process unique among eutherian mammals. An in silico search for intact envelope genes within the Bos taurus genome identified 18 candidates belonging to five endogenous retrovirus families, with one gene displaying both placenta-specific expression, as assessed by quantitative RT-PCR analyses of a large panel of tissues, and conservation in the Ovis aries genome. Both the bovine and ovine orthologs displayed fusogenic activity by conferrin...
ABSTRACT Pluripotency can be captured in vitro, providing that the culture environment meets the ... more ABSTRACT Pluripotency can be captured in vitro, providing that the culture environment meets the requirements that avoid differentiation while stimulating self-renewal. From studies in the mouse embryo, two kinds of pluripotent stem cells have been obtained from the early and late epiblast, embryonic stem cells (ESCs) and epiblast stem cells (EpiSCs), representing the naive and primed states, respectively. All attempts to derive convincing ESCs in ungulates have been unsuccessful, although all attempts were based on the assumption that the conditions used to derive mouse ESCs or human ESC could be applied in other species. Pluripotent cells derived in primates, rabbit, and pig strongly indicate that the state of pluripotency of these cells is, in fact, closer to EpiSCs than to ESCs, and thus depend on fibroblast growth factor (FGF) and Activin signaling pathways. Based on this observation, we have tried to derive EpiSC from the epiblast of bovine elongated embryos as well as ESCs from Day-8 blastocysts. We here show that the core transcription factors Oct4/Sox2/Nanog can be used as markers of pluripotency in the bovine since their expression was restricted to the developing epiblast after Day 8, and disappeared following differentiation of both the ESC-like and EpiSC-like cultures. Although FGF and Activin pathways are indeed present and active in the bovine, it is not sufficient/enough to maintain a long-term pluripotency ex vivo, as was reported for mouse and pig EpiSCs.
We determined if somatic cell nuclear transfer (SCNT) cloning is associated with WNT-related gene... more We determined if somatic cell nuclear transfer (SCNT) cloning is associated with WNT-related gene expression in cattle development, and if the expression of genes in the WNT pathway changes during the peri-implantation period. Extra-embryonic and endometrial tissues were collected at gestation days 18 and 34 (d18, d34). WNT5A,
Brachyury is a T-box-containing transcription factor involved in mesoderm formation during verteb... more Brachyury is a T-box-containing transcription factor involved in mesoderm formation during vertebrate gastrulation. To analyse whether the regulation of gastrulation varies as much as the timing of gastrulation does with respect to implantation, we isolated a bovine brachyury cDNA fragment. The amino acid sequence shows high similarity to mouse and human Brachyury and clear differences to other T-box genes. Whole-mount in situ hybridisation reveals a normal expression pattern except for a transiently reduced expression in the anterior part of the primitive streak. According to these results, gastrulation in mammals is implemented and regulated irrespective of implantation.
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Papers by Isabelle Hue