Transcriptome assembly and candidate genes involved in nutritional programming in Xiphophorus multilineatus

Nutritional programming takes place in early development. Variation in the quality and/or quantity of nutrients in early development can influence long-term health and viability. However, little is known about the mechanism of nutritional programming. The live-bearing fish Xiphophorus multilineatus, has the potential to be a new model for understanding these mechanisms, given evidence of both genetic and nutritional programming influences on juvenile growth rate. To study the molecular signatures of nutritional programming, we assembled a de novo transcriptome for X. multilineatus, and used RNA-Seq to profile gene expression in the brains of males reared in low and high quality juvenile environments. We found131 genes were differentially expressed, including metabolism and appetite master regulator agrp gene. Xiphophorus multilineatus were read in High Quality Juvenile Environment (HQJE:fish were housed individually after 14 days of age, and were fed Tetramin and brine shrimp, ad libitum) or Low Quality Juvenile Enviroment (LQJE; densities > 6 fish per liter, N = 23. Fish in this group were fed Tetramin once a day) . 2 biological replicates for each treatment were performed.

营养编程（nutritional programming）发生于个体发育早期。发育早期的营养物质质量和/或数量的变化，可对个体的长期健康与生存能力产生影响。然而，目前学界对营养编程的作用机制仍知之甚少。胎生鱼类多线剑尾鱼（Xiphophorus multilineatus）有望成为解析此类机制的新型模式生物，已有证据表明遗传与营养编程均可影响其幼体生长速率。为探究营养编程的分子特征，我们对多线剑尾鱼进行了从头转录组（de novo transcriptome）组装，并通过RNA测序（RNA-Seq）分析了在优质与劣质幼体环境中饲养的雄性个体脑部的基因表达谱。本研究共鉴定出131个差异表达基因，其中包括代谢与食欲的核心调控基因agrp。实验中将多线剑尾鱼饲养于优质幼体环境（HQJE：14日龄后单缸饲养，投喂 Tetramin 与卤虫，不限量投喂）或劣质幼体环境（LQJE：养殖密度>6尾/升，每组n=23；该组每日投喂一次 Tetramin）。每组均设置2个生物学重复。