Submitted to: Developmental Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 1999
Publication Date: January 1, 2000
Citation: Wilson, M.E., Sonstegard, T.S., Smith, T.P., Fahrenkrug, S.C., Ford, S.P. 2000. Differential gene expression during elongation in the pig embryo. Developmental Genetics. 11(8):682-688.
Interpretive Summary: The long term objective of this research is to devise methods to optimize conceptus growth and survival in economically important pig breeds, thereby increasing conception rate, litter size, and industry productivity. Previous experiments have shown that ovulation rate and uterine size between Chinese and U.S. pig breeds is similar. In contrast, the Chinese pig is more prolific and embryos from these pig breeds elongate during preimplantaion with fewer trophectoderm cells. Thus far descriptions of elongation have been limited to histologic and immunofluorescent studies of cell morphology and gross biochemical evaluations. In order to better understand the pattern of gene expression during elongation, we applied differential RNA expression analysis to embryos pooled by developmental stage. Our findings strongly suggest that genes involved in regulating alternative splicing contribute to the morphogenetic process of elongation. The conserved nature of the elongation process in domestic livestock species leads us to believe that information obtained in these and future experiments will impact our understanding of conceptus-uterine interactions vital to embryo growth and survival.
On day 12-13 of gestation the preimplantation pig conceptus undergoes a dramatic morphologic change from an approximately 1 cm sphere to nearly 1 m long thread. This transformation, referred to as elongation, occurs in just 12 to 4 hours. Elongation is primarily the result of trophectodermal cell shape changes, as there is relatively little mitosis during this stage of development. Thus far descriptions if elongation have been limited to histologic and immunofluorescent studies of cell morphology and gross biochemical evaluations. We hypothesized that the changes in trophectoderm morphology likely involves significant changes in gene expression. Therefore, we used RNA arbitrarily primed-PCR (RAP-PCR) to characterize potential differential gene expression by trophectodermal cells during pig conceptus elongation. We found that the porcine heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 was shown to be differentially expressed by trophectodermal cells during elongation. We suggest that regulated alternative splicing may contribute to the morphogenetic process of elongation.