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Background The segregation of the hypoblast and the emergence of the pluripotent epiblast mark the final stages of blastocyst formation in mammalian embryos. In bovine embryos the formation of the hypoblast has been partially studied, and evidence shows that MEK signalling plays a limited role in the segregation of this lineage. Here we explored the role of different signalling pathways during lineage segregation in the bovine embryo using immunofluorescence analysis of NANOG and SOX17 as readouts of epiblast and hypoblast, respectively. Results We show that SOX17 starts to be expressed in 16–32-cell stage embryos, whereas NANOG is first detected from 8-cell stage. SOX17 is first co-expressed with NANOG, but these markers become mutually exclusive by the late blastocyst stage. By assessing the expression kinetics of NANOG/SOX17 we show that inhibition of MEK signalling can eliminate SOX17 expression in bovine blastocysts, without altering NANOG expression. Modulation of WNT, PKC and LIF did not affect NANOG expression in the epiblast when used in combination with the ERK inhibitor. Conclusions This study shows that SOX17 can be used as a reliable early marker of hypoblast in the bovine, and based on its expression profile we show that the hypoblast segregates in day 7 blastocysts. Furthermore, SOX17 expression is abolished using 1 μM of PD0325901, without affecting the NANOG population in the epiblast. Modulation of WNT, PKC and LIF are not sufficient to support enhanced NANOG expression in the epiblast when combined with ERK inhibitor, indicating that additional signalling pathways should be examined to determine their potential roles in epiblast expansion. Electronic supplementary material The online version of this article (10.1186/s12861-019-0193-9) contains supplementary material, which is available to authorized users.

Five Argentine Pampinta (dairy breed) and six Corriedale (dual-purpose breed) adult rams were used to study the effect of season on sexual behavior, plasma testosterone (T) and semen characteristics for a period of 1 year. Scrotal circumference (SC) and T concentrations were determined at 2-week intervals. Each ram was exposed monthly to three ovariectomized ewes in one 20-min test and the total number of mounts and successful matings were recorded. Semen collection was attempted from each ram twice weekly for six consecutive weeks during each season. In both breeds, SC varied seasonally showing the lowest mean values during winter and spring and in the Corriedale rams (32.8 ± 0.3 cm) was smaller (p < 0.05) than in Pampinta rams (34.4 ± 0.4 cm). No difference (p > 0.05) was recorded in T concentration between breeds and both breeds reached a peak in summer and autumn. Number of matings showed the maximal values in autumn in both breeds. Season had no significant effect on mass motility, sperm concentration and percentage of live sperm. Semen volume, percentage of progressive motility and total sperm per ejaculate were higher during summer and autumn than in other seasons of the year. Pampinta rams had the highest values (p < 0.05) of sperm concentration, total sperm per ejaculate and percentage of abnormal sperm. Results of this study show that sexual behavior, SC and T concentrations exhibit seasonal variation in Pampinta and Corriedale rams and that semen of superior quantity and quality is especially collected in both breeds during the summer and autumn.Additional key words: hormone, rams; semen quality; serving capacity. Resumen Variación estacional en el comportamiento sexual, testosterona plasmática y características seminales de carneros Pampinta Argentina y CorriedaleCinco carneros adultos Pampinta Argentina (raza lechera) y seis Corriedale (raza doble propósito) fueron utilizados para estudiar el efecto de la estación del año sobre el comportamiento sexual, testosterona plasmática (T) y caracterís-ticas seminales. La circunferencia escrotal (CE) y las concentraciones de T fueron determinadas cada dos semanas. Mensualmente, cada carnero fue expuesto a tres ovejas ovariectomizadas en una prueba de 20 min y se registró el número total de montas y apareamientos. La colección del semen fue intentada dos veces por semana por seis semanas consecutivas durante cada estación. En ambas razas los menores valores de CE fueron observados en invierno y primavera (Corriedale = 32,8 ± 0,3 cm; Pampinta = 34,4 ± 0,4 cm; p < 0,05). La concentración de T alcanzó un máximo en verano y otoño y el número de apareamientos fue máximo en otoño. La estación no tuvo efecto (p > 0,05) sobre la motilidad masal, la concentración espermática y el porcentaje de espermatozoides vivos. El volumen del eyaculado, el porcentaje de motilidad progresiva y el número total de espermatozoides fueron mayores en el verano y otoño. La raza del carnero tuvo un efecto (p < 0,05) sobre la concentración espermática, el número total de espermato...

ObjectivesThe use of induced pluripotent stem (iPS) cells as an alternative to embryonic stem cells to produce transgenic animals requires the development of a biotechnological platform for their generation. In this study, different strategies for the generation of bovine and porcine iPS cells were evaluated. Lentiviral vectors were used to deliver human factors OCT4, SOX2, KLF4 and c-MYC (OKSM) into bovine and porcine embryonic fibroblasts and different culture conditions were evaluated.ResultsProtocols based on the integrative lentiviral vector STEMCCA produced porcine iPS-like cells more efficiently than in bovine cells. The iPS-like cells generated displayed stem cell features; however, expression of exogenous factors was maintained along at least 12 passages. Since inactivation of the exogenous factors is still a major bottleneck for establishing fully reprogrammed iPS cells, defining culture conditions that support endogenous OKSM expression is critical for the efficient generation of farm animals’ iPS cells.Electronic supplementary materialThe online version of this article (10.1186/s13104-018-3627-8) contains supplementary material, which is available to authorized users.

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