Submitted to: Animal Reproduction Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/24/2000
Publication Date: 4/30/2001
Citation: Klemcke, H.G., Vallet, J.L., Christenson, R.K., Pearson, P.L. 2001. Erythropoietin mRNA expression in pig embryos. Animal Reproduction Sciences. 66(1-2):93-108. Interpretive Summary: There are 30-50% fetal losses in pigs; when the uterine environment is artificially crowded, additional losses occur between days 25 and 40 of gestation. At this critical time period, one important body system that is undergoing rapid development is the cardiovascular system and its associated red blood cells. We have hypothesized that development of red blood cells, which are required to provide oxygen to fetuses, may be abnormal and constitute one cause of fetal death at this time. The hormone erythropoietin is required for red blood cell development. Hence, the current study was conducted to determine if the genetic message for erythropoietin, its messenger ribose nucleic acid (mRNA), was affected by age of gestation, pig breed, or a crowded uterine environment (unilateral hysterectomy-ovariectomy). Erythropoietin mRNA was present in the fetal liver, decreased with gestational age (days 24-40; term is 114 days), and was unaffected by pig breed or uterine environment. These results suggest that abnormal transcription (mRNA production) of liver erythropoietin is not a cause of fetal loss at days 24-40 of pig gestation.
Technical Abstract: A study was conducted to determine erythropoietin mRNA expression in liver and placental tissue of embryos at days 24, 30 and 40 of gestation. Effects of uterine environment and breed were investigated by examining three pig models: intact white crossbred gilts; white crossbred gilts that had undergone unilateral hysterectomy-ovariectomy prior to puberty and whose pregnant uterus constituted a crowded environment; and prolific intact Meishan gilts. A cDNA for porcine erythropoietin was developed via reverse transcription and polymerase chain reaction procedures and was cloned. This cDNA and primers specific for the 3' end of porcine erythropoietin were used to generate a 32P-labelled probe for Northern analyses. Expression of embryonic liver erythropoietin mRNA was highest on day 24, decreased by day 30 (P < 0.01) and was barely detectable by day 40 of gestation. No breed or uterine environment differences in expression were detected. Placental erythropoietin mRNA expression was inconsistent, but was present in 4 of the 53 placentae examined. These results indicate that at the gestational ages examined, the embryonic liver is one source of plasma erythropoietin and placental tissues may also contribute.