Project description:The aberrant gene expression in the uterine endometrium and embryo has been the major causes of pregnancy failure in cattle. Therefore, selecting cows having adequate endometrial receptivity and embryos of better developmental competence based on the gene expression could increase the number of calves produced by in each cow during its productive life time. We used endometrial and embryo biopsy technology in conjunction with the pregnancy outcome information to establish a direct link between the pre-transfer endometrial or in vivo derived embryo gene expression and pregnancy outcome after embryo transfer. Endometrial samples were collected from Simmental heifers at day 7 and 14 of the estrous cycle, one cycle prior to embryo transfer. In the next cycle, embryo biopsies consisting of 60-70% of inner cell mass and trophectoderm were transferred to the recipients at day 7 of the estrous cycle. The remaining 30-40% parts of the embryos were retained for analysis.Pregnancy diagnosis was performed at days 28 and 42 by ultrasonography and at day 56 by rectal palpation. Those heifers returned to heat at day 21 were considered as non pregnant or non receptive endometrium (NP) while those heifers ended up with successful pregnancy and calf delivery was considered as the calf delivery group or receptive endometrium (CD). Following this, the endometrial samples collected during the pre-transfer period and the embryo biopsies retained during embryo transfer were categorized based on the pregnancy outcome. Those endometrial biopsies collected at days 7 and 14 of the estrous cycle from heifers resulted in successful calf delivery were designated as CDd7 and CDd14, respectively and endometrial biopsies taken at days 7 and 14 of the estrous cycle from those subsequently resulted in no pregnancy were designated as NPd7 and NPd14, respectively. Similarly, the embryo biopsies were classified as those embryo biopsies resulted in successful calf delivery and those resulted in no pregnancy

Project description:The aberrant gene expression in the uterine endometrium and embryo has been the major causes of pregnancy failure in cattle. Therefore, selecting cows having adequate endometrial receptivity and embryos of better developmental competence based on the gene expression could increase the number of calves produced by each cow during its productive life time. We used endometrial and embryo biopsy technology in conjunction with the pregnancy outcome information to establish a direct link between the pre-transfer endometrial or in vivo derived embryo gene expression and pregnancy outcome after embryo transfer. Endometrial samples were collected from Simmental heifers at day 7 and 14 of the estrous cycle, one cycle prior to embryo transfer. In the next cycle, embryo biopsies consisting of 60-70% of inner cell mass and trophectoderm were transferred to the recipients at day 7 of the estrous cycle. The remaining 30-40% parts of the embryos were retained for analysis.Pregnancy diagnosis was performed at days 28 and 42 by ultrasonography and at day 56 by rectal palpation. Those heifers returned to heat at day 21 were considered as non pregnant or non receptive endometrium (NP) while those heifers ended up with successful pregnancy and calf delivery was considered as the calf delivery group or receptive endometrium (CD). Following this, the endometrial samples collected during the pre-transfer period and the embryo biopsies retained during embryo transfer were categorized based on the pregnancy outcome. Those endometrial biopsies collected at days 7 and 14 of the estrous cycle from heifers resulted in successful calf delivery were designated as CDd7 and CDd14, respectively and endometrial biopsies taken at days 7 and 14 of the estrous cycle from those subsequently resulted in no pregnancy were designated as NPd7 and NPd14, respectively. Similarly, the embryo biopsies were classified as those embryo biopsies resulted in successful calf delivery and those resulted in no pregnancy

Project description:Although somatic cell nuclear transfer (SCNT) cloning is more efficient in bovine than in all other species tested so far, there is a high rate of pregnancy failure that has been linked to structural and functional abnormalities of the placenta. We tested the hypothesis that these changes may originate from disturbed embryo-maternal interactions in the pre-implantation period. Therefore, we evaluated the transcriptome response of the endometrium to SCNT embryos (produced from five different donor cell cultures) as compared to embryos derived from in vitro fertilization (IVF). SCNT embryos and IVF embryos were cultured under identical conditions to the blastocyst stage (Day 8) and transferred to recipients. The recipients were slaughtered at day 18 of pregnancy and the uterus was recovered. Pregnancy was verified by the presence of at least one normally developed embryo. Transcriptome profiling of endometrium samples using a custom cDNA microarray covering transcripts expressed in the endometrium and/or oviduct epithelium revealed 58 transcripts that were differently abundant between endometrium samples from SCNT vs. IVF pregnancies. Prominent examples are NR2F2 (encoding the orphan nuclear receptor COUP-TFII) and GJA1 (encoding connexin 43). Both transcripts are known to play important roles in placentation and were significantly less abundant in endometrium from SCNT vs. IVF pregnancies. These findings suggest that placental failure in bovine clone pregnancies may originate from abnormal embryo-maternal communication already in the pre- or peri-implantation period. Endometrium transcriptome profiles may serve as a novel readout to evaluate SCNT embryos for their ability to induce pregnancy with a functional placenta. Keywords: response to different embryos Nineteen German Fleckvieh (Simmental) heifers were slaughtered at day 18 of pregnancy. Cycle-synchronized recipient heifers received either IVP or SCNT embryos at day 7 of the estrous cycle. Animals were slaughtered at day 18. Endometrial (intercaruncular) tissue samples were obtained from 10 pregnant animals after transfer of IVP embryos and from 9 pregnant animals after transfer of SCNT embryos.

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