肉鸡胚胎期肌肉发育基因表达谱及肉质性状形成的遗传调控网络研究

In the current poultry cultivation, there is an obvious contradictory, i.e. the fast-growing broilers superior to the indigenous broiler breeds in feed usage with bad meat quality, while the indigenous quality broilers are good in meat quality with a slow growing pace and low feed usage. However, the chicken muscle productivity and meat quality are directly related to the genetic regulation of muscle development. Previous studies reported the results of breast muscle gene expression profile of chicken after birth, but few report of gene expression profile of chicken muscle tissues, such as the breast mass, during embryonic muscle development. This study was designed to analyzed the breast muscle gene expression profiles at 3-5 key points at the ages of 7-14 days of two broiler breeds (White Plymouth Rock and Huainan Spotted-Brown Chicken) embryos in hatching with DNA microarray experiments, and try to find out the differences of gene expression, gene co-expression networks and their possible regulation pathways. The study aims at finding all the up-regulated or down-regulated genes that effecting the chicken mass and eating quality of breast muscles. In the study, the Bayesian Network inferred and Genetic Network Analysis approach will be used in combination with the published papers and knowledge to reveal the mutiple gene regulation network of fast-growing broilers and the interactions between genes. Finally, the major and/or dominant genes should be pointed out in the network and their possible roles to be considered for the fast adaptive development of broilers' muscle tissues. Therefore, we could finally resolve the genetic regulatory mechanism of the huge differences of muscle development and meat quality existing between the fast-growing broilers and the indigenous broilers from the point of view of system biology.

当前家禽生产中，肉鸡肉用品质与生长速度存在明显的矛盾：快大型鸡生长快，饲料利用率高，肉品质很差；地方小型优质鸡肉用品质优良，其生长速度慢、饲料利用率低，且鸡的产肉潜力和肉质与肌肉发育的遗传调控密切相关。此前有人对出生后鸡的胸肌组织做了基因表达谱研究，但尚未见胚胎期的研究。本项目利用基因芯片研究隐性白洛克和淮南麻黄鸡胚胎期第7-14天3-5个时间点胸肌组织生长发育的基因表达谱、基因共表达模式及信号转导通路，寻找快大型肉鸡相对地方鸡种显著上调和下调的基因，以及影响肌肉发育差异和肉质性状变差的差异表达基因。构建基于贝叶斯算法的基因调控互作网络，结合已有文献，利用遗传调控网络解析肌肉适应快速发育的多基因调控机理，以期至少找到在调控网络中起主导作用的几个关键基因，最终揭示这些基因在肉鸡胚胎期胸肌组织适应快速发育过程中的功能与作用，从系统生物学角度解析这两个鸡种肌肉发育和肉质性状差异的遗传调控机制。

本项目按照项目申请书的研究目标和计划任务书展开研究，经过课题组努力工作，主要采用基因芯片技术对单性别（雄性）的快大型肉鸡和地方型肉鸡的胚胎期胸部骨骼肌组织进行转录组水平的系统研究，获得了两种鸡胚胎期胸肌组织发育差异和快大型隐性白洛克肉鸡胚胎期胸肌快速发育的全基因组表达谱的重要信息，成功采取了两种鸡（雄性）的胚胎期胸肌组织样本，通过基因芯片实验和统计处理，我们成功获得雄性隐性白洛克肉鸡的和雄性鲁西斗鸡（根据基金委审核通过的项目计划任务书和有关专家建议修改了地方鸡种）的胸肌基因表达谱数据，本项目实验总共筛选得到了114个发生显著差异表达的基因（p<0.001，FDR≤0.018）。接着，我们选取了在基因芯片实验中12个差异表达的基因进行了荧光定量PCR实验，以期验证基因芯片差异表达数据的可靠性。通过GO富集分布分析，我们发现两种鸡胚胎期差异表达基因聚成6类，主要富集在核酸合成、离子运输和细胞分化等细胞内新陈代谢和细胞分化发育过程。最后，我们通过多次调试分析了基因差异表达情况，利用Bayesian Network Toolbox（BNT）成功构建了胚胎期106个基因的Bayesian Network互作网络和网络关键节点基因，该基因分子调控网络中涉及到25个重要节点基因，其中有3个核心节点基因，另1个为负反馈节点基因，以上这些结果均为进一步筛选与肌肉发育和肉质差异的特定基因及相关遗传调控机制奠定了基础。目前，课题组公开发表学术论文4篇，其中发表在SCI收录期刊的学术论文2篇、EI收录期刊的学术论文2篇，基本完成项目主要研究内容，达到了项目预期的研究目标。