Yilmaz Ozlem, Patinote Amélie, Nguyen Thaovi, Bobe Julien
Fish Physiology and Genomics Institute, INRA UR1037, Rennes Cedex, France.
Department of Biological Sciences, University of Bergen, Bergen, Norway.
Fish Physiol Biochem. 2018 Dec;44(6):1509-1525. doi: 10.1007/s10695-018-0524-y. Epub 2018 Jun 7.
Scrutiny of the zebrafish (Danio rerio) genomic database confirmed eight functional vitellogenin (vtg) genes, each with one or two transcript variants, and the encoded Vtg polypeptides were structurally and functionally characterized in detail by in silico and experimental analyses. There were five type I (vtgs1, 4, 5, 6, and 7), two type II (vtg2 and vtg8), and one type III (vtg3) vtg gene(s) encoding three major types of Vtg protein based on subdomain structure (Vtg-I, Vtg-II, and Vtg-III, respectively). Among various tissues of mature zebrafish, transcripts of the eight vtg genes were detected by RNA-Seq only in liver and intestine, with liver being the main site of vtg expression. All vtg transcripts except vtg8 were also detected in mature female liver by RT-qPCR. The relative abundances of Vtg proteins and their variants were quantified by LC-MS/MS in the liver of mature females and in eggs. The Vtgs were generally several fold more abundant in eggs, but profiles of abundance of the 19 different forms of Vtg evaluated were otherwise similar in liver and eggs, suggesting that yolk protein composition is determined largely by hepatic Vtg synthesis and secretion. Based on transcript and protein levels, Vtg-I is, by far, the dominant type of Vtg in zebrafish, followed by Vtg-II and then Vtg-III. When relative abundances of the different forms of Vtg were evaluated by LC-MS/MS in egg batches of good versus poor quality, no differences in the proportional abundance of individual forms of Vtg, or of different Vtg types, attributable to egg quality were observed.
对斑马鱼（Danio rerio）基因组数据库的仔细研究证实了八个功能性卵黄蛋白原（vtg）基因，每个基因有一个或两个转录变体，并且通过计算机模拟和实验分析对编码的Vtg多肽进行了详细的结构和功能表征。基于亚结构域结构，有五个I型（vtgs1、4、5、6和7）、两个II型（vtg2和vtg8）和一个III型（vtg3）vtg基因，分别编码三种主要类型的Vtg蛋白（分别为Vtg-I、Vtg-II和Vtg-III）。在成熟斑马鱼的各种组织中，通过RNA测序仅在肝脏和肠道中检测到八个vtg基因的转录本，肝脏是vtg表达的主要部位。通过RT-qPCR在成熟雌性肝脏中也检测到了除vtg8之外的所有vtg转录本。通过LC-MS/MS对成熟雌性肝脏和卵中的Vtg蛋白及其变体的相对丰度进行了定量。Vtgs在卵中的丰度通常要高几倍，但在肝脏和卵中评估的19种不同形式的Vtg的丰度分布在其他方面相似，这表明卵黄蛋白组成在很大程度上由肝脏Vtg的合成和分泌决定。基于转录本和蛋白质水平，Vtg-I是迄今为止斑马鱼中占主导地位的Vtg类型，其次是Vtg-II，然后是Vtg-III。当通过LC-MS/MS评估优质和劣质卵批次中不同形式Vtg的相对丰度时，未观察到由于卵质量导致的单个Vtg形式或不同Vtg类型的比例丰度差异。
