Submitted to: Biology of Reproduction Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/24/1998
Publication Date: N/A
Technical Abstract: Erythropoietin (EPO), a 30.4 kDa glycoprotein, is required for erythropoiesis. In other species, EPO synthesis begins in the embryonic liver and subsequently synthesis is transferred to kidney cells, which are the primary site of EPO synthesis in adults (J Perinat Med 23:19, 1995). The current study was conducted to determine when EPO expression is first present in embryonic pig liver, and if ontogeny of this expression is influenced by uterine environment and breed. Livers were obtained from embryos of intact (INT) and unilaterally hysterectomized-ovariectomized (UHO) white crossbred and intact Meishan (ME) gilts on d 24, 30, and 40 of gestation (n = 6 gilts/treatment/day). A 294 bp cDNA was produced using RT-PCR with pig kidney total RNA and primers complementary to porcine EPO. The cDNA was cloned into a pCR2.1 vector and sequenced. Northern hybridization analyses were conducted using 10 ug of total embryonic liver RNA. Relative concentrations of mRNA were determined using densitometry an expressed as arbitrary absorbance units. Levels of embryonic liver EPO mRNA were highest on d 24 (p<.01) and on this day were similar in INT (.72 +/- .15) and UHO (.50 +/- .13), but INT EPO mRNA exceeded (p=.04) that present in ME (.39 +/- .11). EPO mRNA was detectable in only 50% of embryonic livers at d 30 or 40 and did not differ among treatments. Preliminary analyses indicate EPO expression in INT placentae at d 24 and 30 of pregnancy. These data indicate that porcine EPO mRNA is present in liver very early in gestation and is influenced by breed but not uterine environment. Decreases in liver EPO mRNA after d 24 may reflect an early transfer of EPO synthesis to extrahepatic tissues. The data further suggest the possibility that the porcine placenta is a source of embryonic EPO.