Coprophagia in early life tunes expression of immune genes after weaning in rabbit ileum.

Coprophagia by suckling rabbits, i.e. ingestion of feces from their mother, reduces mortality after weaning. We hypothesized that this beneficial effect of coprophagia is immune-mediated at the intestinal level. Therefore, this study investigated immune development after weaning by analyzing the ileal transcriptome at day 35 and 49 in rabbits with differential access to coprophagia in early life. Rabbit pups had access between day 1 and 15 to (i) no feces (NF) or (ii) feces from unrelated does (Foreign Feces, FF) or (iii) feces from unrelated does treated with antibiotics (FFab). 350 genes were differentially expressed between day 35 and day 49 in suckling rabbits with access to coprophagia. These genes coded for antimicrobial peptides, a mucin, cytokines and chemokines, pattern recognition receptors, proteins involved in immunoglobulin A secretion and in interferon signaling pathway. Strikingly, prevention of coprophagia or access to feces from antibiotic-treated does in early life blunted immune development between day 35 et 49 in the ileum of rabbits. Thus, coprophagia might be crucial for the maturation of intestinal immunity in rabbits and could explain why this behavior improves survival.

Bovine Oviduct Epithelial Cells Dedifferentiate Partly in Culture, While Maintaining their Ability to Improve Early Embryo Development Rate and Quality.

There are convincing arguments to suggest that the success of early reproductive events is reliant on a satisfactory dialogue between gametes-embryo and the oviduct epithelium. The aim of this study was to develop and characterize an in vitro model to study these interactions. Cattle zygotes produced in vitro were cultured in either SOF or TCM-199 in the presence or absence of bovine oviduct cell monolayers (BOEC), under 20% or 5% O2 . The embryonic development rate and its quality (cell numbers, cryosurvival) were evaluated, as were the BOEC contents in 11 candidate transcripts (real-time PCR) at different time points. A BOEC co-culture did indeed increase the rate of development in both media under 5% O2 (41 vs 27% and 28 vs 10% of Day 8 blastocysts in SOF and TCM-199, respectively; p < 0.05). The effect of BOEC on the developmental rate was more pronounced under 20% O2 (35 vs 6% and 27 vs 4% of Day 8 blastocysts in SOF and TCM-199, respectively; p < 0.05). BOEC significantly increased the embryonic cell count in TCM-199 (122.5 ± 11.1 vs 70.3 ± 9.6; p < 0.05) and embryonic cryosurvival in both media. The expression levels of SOD, FGF2 and TGF-ß1 in BOEC remained steady during culture, although mRNA levels of OGP, C3, PGR and ESR2 were clearly reduced, suggesting a dedifferentiation of BOEC during culture. However, SSP1 and GPX4 transcripts were slightly increased during culture, this rise becoming significant by the end of the culture period. In conclusion, our co-culture system with bovine oviduct epithelial cells used for the development of bovine zygotes produced in vitro enhanced blastocyst formation and above all the quality of the resulting embryos, which was associated with specific transcriptomic changes.

Vitrification alters rabbit foetal placenta at transcriptomic and proteomic level.

Although numerous studies have demonstrated that cryopreservation alters gene expression, less is known about those embryos that implanted successfully and continued in gestation. To raise the question of the neutrality of this technique, we examine the effects of vitrification through gestation in rabbit before and after the implantation. We monitored the distribution of losses of 569 vitrified morulae, observing that embryos which reach the last pre-implantatory stage are able to implant. However, we found that not all implanted embryos had the ability to continue with their gestation. The results reveal that vitrification decreased foetus and maternal placenta weights at mid-gestation, but led to a higher offspring birth weight. A novel finding is that while no differences in gene expression were detected in pre-implantatory embryos at day 6, vitrification affects a gene and protein expression in the placenta at day 14. Our results for first time reveal strong evidence of modifications in implanted embryos subjected to vitrification, suggesting that the crucial step that vitrified embryos must overcome is the placenta formation. On the basis of these findings, our work leaves the question open as to whether the effects we observed that cause vitrification during foetal development could give rise to some type of physiological or metabolic alteration in adulthood.

[Use of an in vitro model in bovine to evidence a functional and molecular dialogue between preimplantation embryo and oviduct epithelial cells]. / Mise en évidence d'un dialogue moléculaire et fonctionnel entre l'embryon préimplantatoire bovin et l'oviducte grâce à un modèle in vitro.

Beyond being a pipe between ovary and uterus, the oviduct is an active player in different aspects of early reproductive processes, in particular in the transport of embryos to the site of implantation and the regulation of its early development. Different studies evidenced a communication between oviduct and early embryo at the molecular and functional levels. Since the study of these interactions is difficult in vivo, different in vitro systems have been developed to mimic the maternal milieu during early development. These systems allowed to confirm the action of the cells on the quality of early development (blastocyst rate and viability). In turn, the embryos are producing signals that are able to modify and adapt the activity of maternal cells.