Identification of Single-Nucleotide Polymorphism in the Progesterone Receptor Gene and Its Association With Reproductive Traits in Rabbits

Abstract

A total of 598 F 2 does from a cross between the high and low lines selected divergently for uterine capacity during 10 generations were used in a candidate gene analysis. The presence of major genes affecting the number of implanted embryos and uterine capacity has been suggested in lines divergently selected for uterine capacity. Uterine capacity is a main component of litter size. The progesterone receptor gene was tested as a candidate gene to determine whether polymorphisms explain differences in litter size and its components. Fragments of the promoter region and exons 1-8 were amplified and sequenced. One SNP was found in the promoter region, 2464G.A, three SNPs in the 59-UTR exon 1, and a silence SNP in exon 7. The first four SNPs were segregated in two haplotypes. The allele G found in the promoter region was found in 75% of the high-line parental animals and in 29% of the low-line parental animals. The GG genotype had 0.5 kits and 0.5 implanted embryos more than the AA genotype. At 48 hr of gestation, the difference in early embryo survival and embryonic stage of development was small. However, at 72 hr of gestation, the GG genotype had 0.36 embryos more than the AA genotype and also had a more advanced embryonic stage of development, showing a lower percentage of compacted morulae and a higher percentage of blastocysts. The difference in litter size between the GG and GA genotypes was similar to the difference found between homozygote genotypes; however, differences in implanted embryos, early embryo survival, and embryo development were not detected between the GG and GA genotypes.

Analysis of the oviductal glycoprotein 1 polymorphisms and their effects on components of litter size in rabbits

“…The F 2 population was created by reciprocal mating between two lines of rabbits, High (H) and Low (L), divergently selected for uterine capacity (UC) as described by Peiró et al. (2008).…”

“…Embryo survival (ES) was analysed as IE fitting OR as a covariate, foetal survival (FS) as LS fitting IE as a covariate, and prenatal survival (PS) as LS fitting OR as a covariate. Traits were analysed using the Bayesian approach extensively described in Peiró et al. (2008).…”

Exposure to high ambient temperatures alters embryology in rabbits

“…Percentage of total embryos (%TE) was the embryos which were recovered and was calculated for each female as TE OR Â 100 (Peiró et al 2008;Argente et al 2010). Embryos were classified as normal (NE) when they presented homogenous cellular mass and intact zona pellucida and mucin coat (Maurer 1978), using a binocular stereoscopy microscope (Leica Mz 9.5-600x).…”

“…All embryos can be found in the isthmic part of the oviduct at 24 hpc (Bourdage and Halbert 1988), while they are located between the ampulla and uterotubal junction at 48 hpc (Besenfelder et al 2000). We assumed that TE, %TE and %NE were different traits at 24 and 48 hpc, as previously has been presented by Peiró et al (2008) and Argente et al (2010).…”

A genomewide association study in divergently selected lines in rabbits reveals novel genomic regions associated with litter size traits

“…Approximately one‐half of the response in UC was obtained in the first two generations suggesting the presence of a major locus with large effect segregating in these populations (Argente, Blasco, Ortega, Haley, & Visscher, ; Blasco et al, ). Thus, a candidate gene strategy was carried out to characterize this locus by comparing polymorphisms and expression levels between the two UC lines of a some promising candidates (Argente et al, ; Ballester et al, ; Peiró et al, ). Some of these genes (progesterone receptor— PGR , hydroxysteroid (17‐beta) dehydrogenase 4 —HSD17B4 , and endoplasmic reticulum oxidoreductase 1— ERO1 ) showed different expression levels in the oviduct of the two UC line, remarkably overexpressed in the low UC line, but these result could not identify any putative causal mutations (Argente et al, ; Ballester et al, ; Peiró et al, ).…”