蒙古羊尾椎性状分子遗传机理的研究

Mongolian sheep is local sheep breed which has relatively abundant variant of coccygeal vertebra ,in the initial investigation found that Hulunbeier sheep only 5 to 8 coccygeal vertebra, Sunite sheep coccygeal vertebra up to 20, Although the two cross can significantly change the size of the tail fat, not conform to the Mendelian inheritance patterns, it is a complex quantitative trait that is influenced by many factors. The molecular genetic mechanism of Mongolia sheep coccygeal vertebra trait is also not reported.Therefore, in this study, the cross-population between the Hulunbe and Sunite sheep, which were established in the early stage of the research group, were used as the experimental material to carry out the pooling-resequencing analysis of the extreme traits based on the family. The Bulked Segregant analysis method was used to locate funtional QTL for the extreme traits and then Verifing Causal mutation ,annotating the selected functional genes,investigating the expression level and location of the functional genes in the different stages of the embryo to study the important role in the development and form of coccygeal vertebra. Integrating the number of coccygeal vertebrae, Genome resequencing into gene expression data to find major gene that affected variation of coccygeal vertebrae, and to construct the molecular regulation network ，which will provide a scientific basis to clarify livestock coccygeal vertebra genetic variation law and the molecular mechanism.

蒙古羊是尾椎变异比较丰富的地方绵羊品种，前期研究发现蒙古系羊呼伦贝尔羊仅有5~8根尾椎，苏尼特羊尾椎最多达20根，二者杂交可以明显改变尾脂的大小，但不符合孟德尔遗传规律，是受多因素影响的复杂的数量性状，至今未见蒙古羊尾椎变异的分子遗传机理详细报道。因此，本研究以课题组建立的呼伦贝尔短尾羊X苏尼特羊杂交资源群体为试验材料，开展基于家系的极端性状混池重测序，采用集群分离分析的方法定位极端性状受选择的QTL区域，并进行位点的因果突变效应验证，注释受选择的功能基因，检测其在胚胎不同时期的表达水平和分布，研究对尾椎发育和形态建成的重要作用，整合尾椎数表型、基因组重测序和基因表达数据，发现影响尾椎变异的主效基因，构建尾椎变异的分子调控网络，为揭示家畜尾椎遗传变化规律和分子机理提供科学依据。

蒙古羊是尾椎变异比较丰富的地方绵羊品种，研究发现蒙古系呼伦贝尔羊与苏尼特羊杂交导血可以明显改变尾脂大小，但不符合孟德尔遗传规律，是受多因素影响的复杂的数量性状，至今未见蒙古羊尾椎变异的分子遗传机理详细报道。本研究首先对呼伦贝尔短尾羊 X 苏尼特羊杂交资源群体中不同尾椎数个体进行了基因组重测序，结合Fst与Pi的分析方法定位到2号、10号、12号染色体约90K的受选择区域，包含63个功能基因，富集分析表明其与脂肪密度、骨骼发育和脂肪沉积相关；其次对尾椎发育关键功能基因HOXb13全基因序列进行了PCR扩增和sanger测序，190份血液样本中发现了11个SNPs多态位点，关联分析表明，SNP3位点与尾长性状显著相关，SNP6位点与尾宽性状显著相关；同时，使用同期发情、人工输精孕周胎儿为研究材料，开展了短尾羊不同胎儿期尾脂比较转录组研究。75天胎儿与55天胎儿比较，鉴定出1850个差异基因，主要参与细胞增殖信号通路。95天胎儿与75天胎儿比较，鉴定出705个差异基因，主要参与脂肪酸合成相关信号通路。初生胎儿与95天胎儿比较，鉴定出2952个DEGs，主要参与能量代谢和细胞分化相关信号通路。根据转录组测序数据，短尾羊尾脂肪发育大致可分为脂肪形成、脂肪沉积和能量储存三个阶段；最后，整合基因组重测序、比较转录组以及关键功能基因表达定量检测数据，发现基因组受选择的63个基因中有35个在短尾羊尾脂发育过程中表达，并构建了短尾蒙古羊尾脂发育分子调控网络，确定了USP1、RELN、MBD5、PDE10A、API5为影响短尾蒙古羊尾脂发育的核心功能基因。