Department of Zoology, Ohio Wesleyan University, Delaware, OH 43015, USA.
J Hered. 2011 May-Jun;102(3):352-61. doi: 10.1093/jhered/esr002. Epub 2011 Feb 21.
Matrotrophic fish in the genus Poeciliopsis (Poeciliidae) have a placenta-like structure used in postfertilization maternal provisioning of the developing embryo. To understand better the structure and function of the Poeciliopsis placenta, we derived cDNA libraries from the maternal follicular placenta of 2 matrotrophic Poeciliopsis sister species, P. turneri and P. presidionis. These species inherited their placenta from a common ancestor and represent one of 3 independent origins of placentas in Poeciliopsis. Expressed sequence tags (ESTs) were generated and putative function was determined using BLASTX homology searches and Gene Ontology (GO) annotation. Reverse transcription-polymerase chain reaction was used to verify placenta tissue expression of a putative candidate gene, alpha-2 macroglobulin. In total, 1956 (71.5% of the total submitted ESTs) and 924 (71.0% of the total submitted ESTs) unique transcripts were identified for the P. turneri and P. presidionis placenta, respectively. Homology search and GO annotation revealed putative genes whose products may be involved in specific transport functions of the maternal follicle. These putative genes are excellent candidates for future research on the evolution of the placenta. We discuss our results in light of the parent-offspring conflict theory of placental evolution and in terms of the Poeciliid placenta structure and function.
食籽鱼属（胎生鱂科）中的鱼类具有胎盘样结构，用于受精后母体为胚胎提供营养。为了更好地了解食籽鱼胎盘的结构和功能，我们从两种食籽的胎生鱂姐妹种，即 Poeciliopsis turneri 和 P. presidionis 的母体滤泡胎盘，构建了 cDNA 文库。这两个物种从共同的祖先那里继承了胎盘，代表了胎生鱂属中胎盘的 3 个独立起源之一。我们通过 BLASTX 同源性搜索和基因本体论（GO）注释生成了表达序列标签（EST），并确定了其可能的功能。我们使用逆转录聚合酶链反应（RT-PCR）来验证候选基因 alpha-2 巨球蛋白在胎盘组织中的表达。分别为 P. turneri 和 P. presidionis 胎盘鉴定到了 1956 个（总提交 EST 的 71.5%）和 924 个（总提交 EST 的 71.0%）独特的转录本。同源搜索和 GO 注释揭示了可能参与母体滤泡特定转运功能的候选基因。这些候选基因是未来研究胎盘进化的优秀候选基因。我们根据胎盘进化的亲代-后代冲突理论以及胎生鱂的胎盘结构和功能来讨论我们的结果。
