Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0371, USA.
J Exp Biol. 2010 Mar 1;213(5):749-58. doi: 10.1242/jeb.037242.
Growth rates in animals are governed by a wide range of biological factors, many of which remain poorly understood. To identify the genes that establish growth differences in bivalve larvae, we compared expression patterns in contrasting phenotypes (slow- and fast-growth) that were experimentally produced by genetic crosses of the Pacific oyster Crassostrea gigas. Based on transcriptomic profiling of 4.5 million cDNA sequence tags, we sequenced and annotated 181 cDNA clones identified by statistical analysis as candidates for differential growth. Significant matches were found in GenBank for 43% of clones (N=78), including 34 known genes. These sequences included genes involved in protein metabolism, energy metabolism and regulation of feeding activity. Ribosomal protein genes were predominant, comprising half of the 34 genes identified. Expression of ribosomal protein genes showed non-additive inheritance - i.e. expression in fast-growing hybrid larvae was different from average levels in inbred larvae from these parental families. The expression profiles of four ribosomal protein genes (RPL18, RPL31, RPL352 and RPS3) were validated by RNA blots using additional, independent crosses from the same families. Expression of RPL35 was monitored throughout early larval development, revealing that these expression patterns were established early in development (in 2-day-old larvae). Our findings (i) provide new insights into the mechanistic bases of growth and highlight genes not previously considered in growth regulation, (ii) support the general conclusion that genes involved in protein metabolism and feeding regulation are key regulators of growth, and (iii) provide a set of candidate biomarkers for predicting differential growth rates during animal development.
动物的生长速度受多种生物因素的控制，其中许多因素仍未得到很好的理解。为了确定建立双壳类幼虫生长差异的基因，我们比较了通过太平洋牡蛎（Crassostrea gigas）的遗传杂交实验产生的具有明显生长差异的表型（慢生长和快生长）的表达模式。基于对 450 万个 cDNA 序列标签的转录组分析，我们对通过统计分析鉴定的 181 个 cDNA 克隆进行了测序和注释，这些克隆被认为是差异生长的候选基因。在 GenBank 中找到了 43%（N=78）克隆的显著匹配，包括 34 个已知基因。这些序列包括参与蛋白质代谢、能量代谢和摄食活动调节的基因。核糖体蛋白基因占主导地位，占鉴定出的 34 个基因的一半。核糖体蛋白基因的表达表现出非加性遗传，即快速生长的杂种幼虫的表达与来自这些亲本家族的同系幼虫的平均水平不同。使用来自同一家庭的其他独立杂交实验，通过 RNA 印迹验证了四个核糖体蛋白基因（RPL18、RPL31、RPL352 和 RPS3）的表达谱。监测了 RPL35 的表达情况，直到早期幼虫发育结束，结果表明这些表达模式在发育早期（在 2 日龄幼虫期）就已经建立。我们的研究结果（i）提供了对生长机制基础的新见解，并强调了以前在生长调控中未被考虑的基因；（ii）支持了参与蛋白质代谢和摄食调节的基因是生长关键调节剂的一般结论；（iii）为预测动物发育过程中的差异生长速率提供了一组候选生物标志物。
