Endometrial luminal epithelial cells sense embryo elongation in the roe deer independent of interferon-tau†

Comparative proteomics of ovaries elucidated the potential targets related to ovine prolificacy

Small Tail Han (STH) sheep, a unique Chinese breed, is recognized for its early maturity, year-round estrus, and prolificacy. However, the molecular mechanism of its high prolificacy has not been fully elucidated. The Proteomics approach is feasible and effective to reveal the proteins involved in the complex physiological processes of any organism. Given this, we performed the protein expression profiling of ovarian tissues during the luteal phase using polytocous STH sheep (litter size ≥2, three consecutive lambings) and monotocous STH sheep (litter size =1, three consecutive lambings) (PL vs. ML), and the follicular phase using polytocous STH sheep (litter size ≥2, three consecutive lambings) and monotocous STH sheep (litter size =1, three consecutive lambings) (PF vs. MF), respectively. Parallel Reaction Monitoring (PRM) was conducted to validate the differentially abundant proteins (DAPs). The tandem mass tag (TMT) quantitative proteomic results showed that a total of 5,237 proteins were identified, of which 49 and 44 showed differential abundance in the PL vs. ML and PF vs. MF groups, respectively. Enrichments analyses indicated that the DAPs including TIA1 cytotoxic granule-associated RNA-binding protein-like 1 (TIAL1), nicotinamide phosphoribosyltransferase (NAMPT), and cellular retinoic acid-binding protein 1 (CRABP1) were enriched at the luteal phase, while TIAL1, inhibin beta-a-subunit (A2ICA4), and W5PG55 were enriched at the follicular phase, potentially mediating reproductive processes in polytocous ewes. Furthermore, six DAPs were verified using PRM, confirming the accuracy of the TMT data acquired in this study. Together, our work expanded the database of indigenous sheep breeds and provided new ovarian candidate molecular targets, which will help in the study of the genetic mechanisms of ovine prolificacy.

Embryonic diapause in roe deer: A model to unravel embryo-maternal communication during pre-implantation development in wildlife and livestock species

An alarming number of large mammalian species with low reproduction rates is threatened with extinction. As basic knowledge of reproductive physiology is currently lacking in many species, increasing the understanding of reproductive physiology is imperative and includes the development of novel artificial reproduction technologies. Despite the relatively comprehensive knowledge on molecular mechanisms underlying reproduction in livestock species such as cattle, pregnancy failures are likewise far from understood. Contrary to other wildlife species, the European roe deer (Capreolus capreolus) displays a remarkably high pregnancy rate. In parts, cattle and roe deer exhibit comparable features of preimplantation embryo development. Therefore, understanding the high fertility rate in the roe deer holds a great potential for cross-species knowledge gain. As the only known species among the artiodactylae, the roe deer displays a long period of embryonic diapause. The preimplantation blastocyst reaches a diameter of 1 mm only at around 4 months compared to around 13 days post estrus in cattle. The expanded blastocyst survives in a uterine microenvironment that contains a unique set of yet unidentified factors that allow embryonic stem cells to proliferate at low pace without impairing their developmental potential. Upon reactivation, intimate embryo-maternal communication comparable to those reported in cattle is thought to occur. In this review, current knowledge, parallels and differences of reproductive physiology in cattle and roe deer are reviewed. The roe deer is proposed as a unique model species to (1) enhance our knowledge of fertility processes, (2) define factors that support embryo survival for an extended period, (3) advance knowledge on embryonic stem cells, and (4) unravel potential implications for the development of novel strategies for artificial reproductive technologies.