Periodic Reporting for period 1 - DIASTORE (Diapause-mediated cattle embryo storage)
Berichtszeitraum: 2024-03-01 bis 2025-08-31
Embryo transfer is an assisted reproductive technology employed in farm animals mainly to accelerate the genetic improvement by amplifying the offspring derived from high genetic merit individuals. In a nutshell, the technique consists in obtaining embryos from donor females of high genetic merit and transfer them into recipient females to expand the genetic traits harboured by the donor females. In cattle, the livestock species where this technology is implemented to a greater extent, ~1.5 M embryos are transferred every year in the countries reporting data to the International Embryo Transfer Society (IETS).
The embryos obtained often require to be stored before being transferred to the recipient females, as recipients must be oestrous synchronized and may not be available at the same time and location where the embryos are obtained. Such embryo storage currently relies on cryopreservation, a technique that requires liquid nitrogen and compromises embryo viability.
Embryonic diapause is the natural way to store embryos in several mammalian species, providing a plausible alternative to embryo cryopreservation in livestock animals. However, the conditions to induce diapause in livestock animals, where diapause does not occur naturally, remained unexplored. The objective of this project has been to develop a culture medium able to induce reversible diapause in cattle embryos.
The embryos obtained often require to be stored before being transferred to the recipient females, as recipients must be oestrous synchronized and may not be available at the same time and location where the embryos are obtained. Such embryo storage currently relies on cryopreservation, a technique that requires liquid nitrogen and compromises embryo viability.
Embryonic diapause is the natural way to store embryos in several mammalian species, providing a plausible alternative to embryo cryopreservation in livestock animals. However, the conditions to induce diapause in livestock animals, where diapause does not occur naturally, remained unexplored. The objective of this project has been to develop a culture medium able to induce reversible diapause in cattle embryos.
To develop a medium able to induce reversible diapause in cattle embryos, embryos were produced in vitro from oocytes collected from animals destined for human consumption. In vitro produced embryos were cultured in different media varying in their composition of nutrients and compounds involved in cell cycle regulation pathways. Diapause induction was tested by assessing a deceleration of embryonic growth, protein and DNA synthesis. Recovery from diapause was assessed by embryo survival, resumption of embryonic growth and the development of specific lineages by immunofluorescence. The results of the experiments performed have allowed to define a media composition able to induce a reversible diapause in cattle embryos that may be maintained in such medium for up to 7 days until diapause resumption.
Scientifically, the results constitute a breakthrough in the field of developmental biology, as diapause has not been induced before in embryos from any mammalian species where this process does not occur naturally. The product developed is applicable to the cattle industry, although no embryo transfers were performed to test the ultimate developmental ability of diapaused embryos.