Determination of sex and scrapie resistance genotype in preimplantation ovine embryos

Prenatal programming by testosterone of follicular theca cell functions in ovary

In mammalian ovaries, the theca layers of growing follicles are critical for maintaining their structural integrity and supporting androgen synthesis. Through combining the postnatal monitoring of ovaries by abdominal magnetic resonance imaging, endocrine profiling, hormonal analysis of the follicular fluid of growing follicles, and transcriptomic analysis of follicular theca cells, we provide evidence that the exposure of ovine fetuses to testosterone excess activates postnatal follicular growth and strongly affects the functions of follicular theca in adulthood. Prenatal exposure to testosterone impaired androgen synthesis in the small antral follicles of adults and affected the expression in their theca cells of a wide array of genes encoding extracellular matrix components, their membrane receptors, and signaling pathways. Most expression changes were uncorrelated with the concentrations of gonadotropins, steroids, and anti-Müllerian hormone in the recent hormonal environment of theca cells, suggesting that these changes rather result from the long-term developmental effects of testosterone on theca cell precursors in fetal ovaries. Disruptions of the extracellular matrix structure and signaling in the follicular theca and ovarian cortex can explain the acceleration of follicle growth through altering the stiffness of ovarian tissue. We propose that these mechanisms participate in the etiology of the polycystic ovarian syndrome, a major reproductive pathology in woman.

Early steps of cryopreservation of day one honeybee (Apis mellifera) embryos treated with low-frequency sonophoresis

Honeybees, major providers of pollination, are endangered in many areas. Embryo cryopreservation may be a very useful tool to maintain their genetic diversity. However, it is complex in insects, because embryos are chill sensitive and are surrounded by two protectant membranes, the chorion and vitelline. These membranes prevent penetration of cryoprotectant in the embryos. This study aimed to test different conditions of embryo preparation before cryopreservation, including low-frequency sonophoresis, a physical method of permeabilization, and passages through cryoprotectant solutions. Apis mellifera ligustica embryos were collected in artificial cell plugs 7.5 h after queens had been caged, in two different seasons (winter, spring) and were then incubated in vitro overnight (16.5 h). Embryos were individually sonicated and then incubated in three cryoprotectant baths (B1 = 10%, B2 = 20% and B3 = 40% of cryoprotectant) and quenched in liquid nitrogen. Artificial cell plugs and in vitro incubation device were efficient in producing future embryos hatching. Embryos stained ruby red with rhodamine B after sonophoresis treatment indicated that low-frequency ultrasound had permeabilized embryos. According to the treatment, different significant hatching rates were obtained after sonophoresis (up to 25%). After three cryoprotectant incubations, best hatching rates were obtained after 10 min in B1 and B2, and 40 s in B3. These results show that sonophoresis is an efficient tool to permeabilize the chorion and vitelline membrane of the day one honeybee embryo allowing a hatching rate of more than 20%. They also show that the season is an important variability factor.

Reproductive technologies and genomic selection in cattle

The recent development of genomic selection induces dramatic changes in the way genetic selection schemes are to be conducted. This review describes the new context and corresponding needs for genomic based selection schemes and how reproductive technologies can be used to meet those needs. Information brought by reproductive physiology will provide new markers and new improved phenotypes that will increase the efficiency of selection schemes for reproductive traits. In this context, the value of the reproductive techniques including assisted embryo based reproductive technologies (Multiple Ovaluation Embryo Transfer and Ovum pick up associated to in vitro Fertilization) is also revisited. The interest of embryo typing is discussed. The recent results obtained with this emerging technology which are compatible with the use of the last generation of chips for genotype analysis may lead to very promising applications for the breeding industry. The combined use of several embryo based reproductive technologies will probably be more important in the near future to satisfy the needs of genomic selection for increasing the number of candidates and to preserve at the same time genetic variability.