Interpretive Summary: Investigation of the oviductal glycoprotein 1 (OVGP1) gene associated with embryo survival and development in the rabbit
By: Jackie Walling
An article published in the May 2010 Journal of Animal Science investigated the association of the oviductal glycoprotein 1 (OVGP1) gene with embryo survival and development in the rabbit.
Managing litter size in meat rabbits can significantly reduce costs of production. Garcia et. al., formulated the study, “Investigation of the OVGP1 gene associated with embryo survival and development in the rabbit” and found that early prenatal survival in rabbits greatly influences litter size. Embryo survival and development prior to 96 hours of gestation could explain differences in litter sizes between two different rabbit lines selected for uterine capacity. Researchers studied the oviductal glycoprotein 1 (OVGP1) found in the oviducts of the rabbit and found two mutations: an SNP (single-nucleotide polymorphism, variation in a single nucleotide) causing a change in an amino acid and a triallelic microsatellite in the promoter region of the gene. The purpose of this article was to study the association of these two mutations with embryo survival and development at 48 and 72 hours of gestation.
Embryos from 172 rabbit reproductive tracts were examined at 48 hours gestation and 159 tracts at 72 hours. Additionally, researchers calculated the ovulation rate, fertilization rate, early embryo survival (EES), and embryonic stage of development at those times.
For analysis purposes, the SNP genotypes were designated CC, CG, and GG while the microsatellite was denoted by one of its possible alleles, (GT)14T(G)5. (It then had the possibilities of (GT)14T(G)5/(GT)14T(G)5, (GT)14T(G)5/-, or -/-)
A consensus for both 48 and 72 hours of gestation saw a high fertilization rate producing normal embryos likely to be found in the stage of a compact morula, the stage before a blastocyst. The detailed SNP and microsatellite results based off of Bayesian statistics can be found in the article. Concerning the SNP portion of the OVGP1, CC and GG genotypes had many similarities including ovulation and fertilization rates for both gestation periods. The CC genotype had less EES and a smaller percentage of early morulae than the GG genotype at 72 hours. When the genotypes CC and CG were compared, it was again 72 hours of gestation that brought about differences. The CG tended to have .5 more embryos and a greater EES than the CC genotype, but the stages of embryonic development were similar.
The same analyses were performed for the microsatellite genotypes with credible differences between the two possible homozygote genotypes. It was favorable for the (GT)14T(G)5 homozygote genotype to have a greater EES over the genotype homozygous for the absence of the (GT)14T(G)5 allele. The ovulation rate and percentage of early morulae were also greater at 48 hours indicating less embryonic development. At 72 hours, it was likely to see .5 more embryos and an increased percentage of early morulae. When this homozygote genotype was compared to the heterozygote genotype, slight differences were found in some measures while the stages of development remained similar for both gestations.
The authors conclude there is a likelihood for the OVPG1 gene to influence the variability of early embryo survival due to the SNP and triallelic microsatellite mutations. The GG genotype representing the SNP favored a greater EES and a lesser amount of development at the 72 hour mark. The microsatellite complemented those findings when the homozygote genotype for the (GT)14T(G)5 allele presented itself.
To view the full article "Investigation of the oviductal glycoprotein 1 (OVGP1) gene associated with embryo survival and development in the rabbit," visit the Journal of Animal Science.