Department of Animal Biology, University of Illinois, Urbana, IL, USA.
PLoS One. 2012;7(9):e45463. doi: 10.1371/journal.pone.0045463. Epub 2012 Sep 19.
In organisms that provision young between fertilization and birth, mothers and their developing embryos are expected to be in conflict over embryonic growth. In mammalian embryos, the expression of Insulin-like growth factor II (IGF2) plays a key role in maternal-fetal interactions and is thought to be a focus of maternal-fetal conflict. Recent studies have suggested that IGF2 is also a focus of maternal-fetal conflict in placental fish in the family Poeciliidae. However, whether the expression of IGF2 influences offspring size, the trait over which mothers and embryos are likely to be in conflict, has not been assessed in a poeciliid. We tested whether embryonic IGF2 expression varied among four populations of a placental poeciliid that display large and consistent differences in offspring size at birth. We found that IGF2 expression varied significantly among embryonic stages with expression being 50% higher in early stage embryos than late stage embryos. There were no significant differences among populations in IGF2 expression; small differences in expression between population pairs with different offspring sizes were comparable in magnitude to those between population pairs with the same offspring sizes. Our results indicate that variation in IGF2 transcript abundance does not contribute to differences in offspring size among H. formosa populations.
在那些在受精和出生之间为幼体提供营养的生物中，母亲和她正在发育的胚胎应该会在胚胎生长上产生冲突。在哺乳动物胚胎中，胰岛素样生长因子 II（IGF2）的表达在母胎相互作用中起着关键作用，被认为是母胎冲突的焦点。最近的研究表明，IGF2 也是盘鱼科胎盘鱼类中母胎冲突的焦点。然而，IGF2 的表达是否会影响后代的大小，这是母亲和胚胎可能产生冲突的特征，在盘鱼科鱼类中尚未得到评估。我们测试了在具有出生时后代大小存在显著差异的四种胎盘鱼中，IGF2 的表达是否存在差异。我们发现，IGF2 的表达在胚胎阶段存在显著差异，早期胚胎的表达比晚期胚胎高 50%。IGF2 的表达在种群之间没有显著差异；在具有不同后代大小的种群对之间，表达上的微小差异与具有相同后代大小的种群对之间的差异相当。我们的结果表明，IGF2 转录物丰度的变化不会导致 H. formosa 种群之间后代大小的差异。
