Genes con efecto mayor sobre la fertilidad de ovejas. Revisión

Abstract

El estudio genético en razas de ovejas que naturalmente presentan altas tasas de ovulación (TO) y de prolificidad, ha permitido detectar la participación de varios genes. Entre ellos están los relacionados a lasuperfamilia del factor de crecimiento transformante B (BMPRIB, GDF9 y BMP-15), así como de otros genes con efecto mayor, tales como el “distal-less homeobox 3” (FecL), el receptor de estrógenos (ESR), el receptor de prolactina (PRLR) y el de las inhibinas (INHA y INHB). Sin embargo, las ovejas homocigotas para la mayoría de las variantes alélicas en BMP-15 o GDF9 son estériles, por lo que es importante el entendimiento de las bases genéticas y moleculares de estos polimorfismos, para su uso en programas racionales de mejoramiento genético con énfasis en la prolificidad. El polimorfismo en el gen de la melatonina (MTNR1) se ha asociado con la no estacionalidad reproductiva en ovejas. La selección en varias razas de ovejas para estas características ha reducido significativamente el anestro estacional, mostrando actividad reproductiva durante la primavera y el verano. Sin embargo, parece ser que estos genes en algunas razas pueden estar interactuando aditivamente, y una variante alélica en una raza puede no aparecer en otra, o bien dos al mismo tiempo, por lo que son variados los mecanismos genéticos que afectan la tasa ovulatoria y prolificidad.

Evaluation of the Precision Xtra meter for monitoring blood β-hydroxybutyrate concentrations in late-gestation ewes

“…13,17 Stress and concurrent diseases are also predisposing factors for ketosis, likely because they contribute to appetite suppression. 4 Placental transfer of ketones from ewes to fetal lambs was confirmed previously. 12 Although the significance of this finding is not known, low birth weight, weak and nonviable lambs, and poor milk availability are reported consequences in lambs of maternal ketosis.…”

“…12 Although the significance of this finding is not known, low birth weight, weak and nonviable lambs, and poor milk availability are reported consequences in lambs of maternal ketosis. 4…”

Fec, CA5A and CLSTN2 genes and their function during sheep ovulation: a review.

“…Ovulation rate is genetically regulated by the combined action of a group of genes with small effects and, in some cases, by the action of a gene with a larger effect. Genetic variants related to fertility in sheep are referred to as Fec, and the different alleles are assigned a letter or the initials of the breed in which the variant was discovered (Luna and Alonso, 2014).…”

“…The bone morphogenic protein gene (BMP15 or GDF9B), located on the X chromosome in sheep, is 1179 bp in length. The protein encoded by the BMP15 gene is a member of the TGF family of bone morphogenic proteins (Hanrahan et al, 2004), which acts through a series of signalling proteins (SMAD pathway) responsible for a wide range of physiological behaviours at the cellular level, including oocyte development and maturation, as BMP15 is expressed in secondary ovarian follicles, stimulating the growth and differentiation of granulosa cells through homotypic connexin-37 junctions, promoting the exchange of nutrients and signals with the oocyte (Luna and Alonso, 2014).…”

“…Expression of the BMP15 gene is a key factor in determining the rate of ovulation and fertility in mammals. In sheep, nucleotide changes in the BMP15 gene increase ovulation rate by at least 1.0 and litter size by 0.6 (Luna and Alonso, 2014). The following mutations have been reported Fec XI , FecX H , FecX G , FecX B , FecX L and FecX R , FecX O , FecX Gr , FecX Bar and a 17 base pair deletion in FecX R , as well as BMPR1B and FecX 2W gene, which increases the number of antral follicles (Feary et al, 2007;Albarella et al, 2015;Pineda et al, 2018;Hernández-Montiel et al, 2020).…”