Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 21, 2006
Publication Date: July 1, 2006
Citation: Vallet, J.L., Freking, B.A. 2006. An erythropoietin receptor (EPOR) gene polymorphism (SNP) alters EPOR mRNA in fetal liver of swine during early gestation [abstract]. Journal of Animal Science. 84 (Supplement 1):450. (Abstract #634) Technical Abstract: We previously reported that an EPOR gene C/T SNP was associated with litter size. The T allele created a putative GATA-1 site, which was predicted to increase EPOR gene expression. This experiment determined whether the SNP was associated with: (1) EPOR gene expression by the fetal liver or (2) maturation of the fetal blood supply during early gestation. CC and CT gilts were unilaterally hysterectomized-ovariectomized at 160 days of age, mated to boars of like genotype and slaughtered on days 25 (n = 13 CC, 13 CT), 30 (19, 25) and 40 (14, 15) of gestation. Numbers of corpora lutea (CL) and live fetuses were recorded. For CT gilts only, a blood smear was prepared for each fetus, the fetus was weighed and fetal liver and other tissues were collected. Percentage of nucleated blood cells was assessed on day 30 and 40 (all blood cells were nucleated on day 25). DNA was prepared from fetal tissues to determine EPOR genotype. Total RNA was prepared from fetal liver of one fetus of each genotype for each litter (day 25 and 30), and EPOR mRNA was measured using real time RT-PCR. Number of fetuses decreased (p < 0.01) between day 30 (11.7 +/ 0.4) and 40 (8.5 +/ 0.5), but did not differ between gilt genotypes. Percent nucleated cells decreased significantly between day 30 and 40, but were not affected by fetal genotype. Fetal liver EPOR gene expression was greater (p < 0.01) on day 30 compared to day 25 of gestation and a significant additive effect of genotype (p < 0.01) was observed (Day 25, 3.8 +/ 0.7, 4.6 +/ 0.7, 5.4 +/ 0.7; Day 30, 9.8 +/ 0.5, 10.3 +/ 0.5, 11.3 +/ 0.5 relative units; CC, CT and TT, respectively). Although these results do not indicate an effect of the SNP on litter size, uterine capacity affects litter size on day 40 or later, and the number of gilts on day 40 were likely inadequate. The SNP also did not affect maturation of the fetal blood supply. However, the T allele was associated with increased EPOR gene expression during early pregnancy as predicted, and thus could influence erythropoiesis and fetal survival.