Manchado Manuel, Infante Carlos, Asensio Esther, Cañavate Jose Pedro, Douglas Susan E
IFAPA Centro El Toruño, Junta de Andalucía Camino Tiro de pichón s/n, El Puerto de Santa María, Cádiz, Spain.
BMC Evol Biol. 2007 Jul 3;7:107. doi: 10.1186/1471-2148-7-107.
Ribosomal proteins (RPs) are key components of ribosomes, the cellular organelle responsible for protein biosynthesis in cells. Their levels can vary as a function of organism growth and development; however, some RPs have been associated with other cellular processes or extraribosomal functions. Their high representation in cDNA libraries has resulted in the increase of RP sequences available from different organisms and their proposal as appropriate molecular markers for phylogenetic analysis.
The development of large-scale genomics of Senegalese sole (Solea senegalensis) and Atlantic halibut (Hippoglossus hippoglossus), two commercially important flatfish species, has made possible the identification and systematic analysis of the complete set of RP sequences for the small (40S) ribosome subunit. Amino acid sequence comparisons showed a high similarity both between these two flatfish species and with respect to other fish and human. EST analysis revealed the existence of two and four RPS27 genes in Senegalese sole and Atlantic halibut, respectively. Phylogenetic analysis clustered RPS27 in two separate clades with their fish and mammalian counterparts. Steady-state transcript levels for eight RPs (RPS2, RPS3a, RPS15, RPS27-1, RPS27-2, RPS27a, RPS28, and RPS29) in sole were quantitated during larval development and in tissues, using a real-time PCR approach. All eight RPs exhibited different expression patterns in tissues with the lowest levels in brain. On the contrary, RP transcripts increased co-ordinately after first larval feeding reducing progressively during the metamorphic process.
The genomic resources and knowledge developed in this survey will provide new insights into the evolution of Pleuronectiformes. Expression data will contribute to a better understanding of RP functions in fish, especially the mechanisms that govern growth and development in larvae, with implications in aquaculture.
核糖体蛋白（RPs）是核糖体的关键组成部分，核糖体是细胞内负责蛋白质生物合成的细胞器。其水平会随生物体的生长发育而变化；然而，一些核糖体蛋白还与其他细胞过程或核糖体以外的功能相关。它们在cDNA文库中的高丰度导致了来自不同生物体的核糖体蛋白序列数量增加，并被提议作为系统发育分析的合适分子标记。
塞内加尔鳎（Solea senegalensis）和大西洋庸鲽（Hippoglossus hippoglossus）这两种具有重要商业价值的比目鱼物种的大规模基因组学发展，使得对小（40S）核糖体亚基的全套核糖体蛋白序列进行鉴定和系统分析成为可能。氨基酸序列比较显示，这两种比目鱼物种之间以及与其他鱼类和人类相比都具有高度相似性。EST分析表明，塞内加尔鳎和大西洋庸鲽分别存在两个和四个RPS27基因。系统发育分析将RPS27与它们在鱼类和哺乳动物中的对应物聚类到两个独立的进化枝中。使用实时PCR方法对鳎幼体发育过程中和组织中的八个核糖体蛋白（RPS2、RPS3a、RPS15、RPS27 - 1、RPS27 - 2、RPS27a、RPS28和RPS29）的稳态转录水平进行了定量。所有八个核糖体蛋白在组织中均表现出不同的表达模式，在脑中水平最低。相反，核糖体蛋白转录本在幼体首次摄食后协同增加，在变态过程中逐渐降低。
本研究中开发的基因组资源和知识将为鲽形目鱼类的进化提供新的见解。表达数据将有助于更好地理解鱼类中核糖体蛋白的功能，特别是控制幼体生长发育的机制，这对水产养殖具有重要意义。
