【作者】 王辉；

【导师】 徐鹏；

【作者基本信息】 河南师范大学 ， 水产学 水产养殖， 2021， 硕士

【摘要】 第二次全基因组复制发生在七鳃鳗和有颌脊椎动物分离之前,随后在硬骨鱼中又发生了第三次全基因组复制。这次全基因组复制大约发生在3.2亿年前,被认为是硬骨鱼特有的一次全基因组复制事件。全基因组复制增加了基因数目的多样性,为进化提供了丰富的原材料。在这些全基因组复制事件之后,硬骨鱼一些分支种的物种发生了特异的基因组复制和多倍化。如鲤科鱼类中的鲤鱼和金鱼。鲤科鱼类中发生了多次全基因组复制,鲤鱼与金鱼的祖先经历了同一次全基因组复制,因此它是一个研究多倍体形成机制及多倍体物种进化的良好材料。同时,鲤鱼也是我国乃至世界范围内主要的水产养殖对象,具有水产和基因组进化上的双重重要性。嗅觉系统作为基本感官,参与鱼类基本的生命活动,如摄食、繁殖、趋利避害等。胚胎阶段是神经系统发育的关键时期。嗅觉系统由大量的神经组成,且嗅觉系统发育未完全发育时,其已经能发挥部分功能。故可以在胚胎阶段观察嗅觉系统的早期发育。本研究中以异源四倍体鲤鱼为研究对象,通过生物信息学手段挖掘鲤鱼的基因组,鉴定了鲤鱼的4类嗅觉基因。共鉴定到49个OR基因和6个TAAR基因,分别在基因组上成簇分布。ORA基因家族包括7个基因,ORA1和ORA2、ORA3和ORA4、ORA5和ORA6分别形成基因对,且在进化树上其进化关系更近。Olf C基因家族包括7个基因。在斑马鱼中Olf C基因分布在17号和18号染色体上,以17号染色体居多,河豚中都分布在16号染色体上。鲤鱼中Olf C基因主要分布在A18和B18号染色体上,且成簇分布。对所有的嗅觉基因进行选择压力分析,发现所有的基因受到的选择压力强度都有放松。对处于不同发育阶段的胚胎进行转录组学研究,初步探究嗅觉系统在胚胎中的发育。对转录组数据进行过滤,发现大部分测序数据中的clean reads率达到97%以上,与参考基因组的比对率达到90%以上,表明测序数据的可靠性。同时,发现随着胚胎的发育,嗅觉基因在神经胚阶段后表达量和表达数目相对神经胚以前都有所提升。更多还原

【Abstract】 The second whole-genome duplication occurred before the divergence of the lamprey fish from the jawed vertebrates,followed by a third whole-genome duplication in the teleosts.This WGD occurred about320 million years ago and is thought to be a WGD event unique to bony fishes.WGD has increased the diversity of gene numbers and provided a rich source of raw material for evolution.Following these wholegenome duplication events,specific genome duplication and polyploidy occurred in some branches of bony fishes,like common carp and goldfish in Cyprinidae.Multiple whole-genome duplications have occurred in Cyprinidae fishes,and the WGD experienced by common carp occurred in its common ancestor with goldfish,making it a good material for studying the mechanism of polyploid formation and the evolution of polyploid species.Also,common carp is a major aquaculture fish in China and worldwide,and is both important in aquaculture and genomic evolution.As a basic sense,the olfactory system is involved in feeding,courtship,socialization and avoidance of harm.The olfactory system mainly relies on nerves to transmit information.In the early stage of embryonic development,the nervous system starts to develop and the olfactory system can already function partially when the development of the olfactory system is not fully completed.Therefore,the early development of the olfactory system can be observed in the embryonic stage.In this study,we identified four types of olfactory genes in allotetraploid common carp(Cyprinus carpio).A total of 49 OR genes and 6 TAAR genes were identified,which were distributed in clusters on common carp genome.The ORA gene family included 7 genes,ORA1 and ORA2,ORA3 and ORA4,ORA5 and ORA6 formed gene pairs,respectively,and their relationships were closer with each other in the evolutionary tree.the Olf C gene family included 7 genes.In zebrafish,Olf C genes are mainly distributed on chromosome 17 and 18,and in puffer fish,these genes are all distributed on chromosome 16 in cluster.In common carp,Olf C genes were mostly distributed on chromosomes A18 and B18,and were also distributed in clusters.Selection pressure analysis of all olfactory genes revealed that all genes were subjected to a relaxation in selection.Transcriptomic studies were performed on embryos at different developmental stages to initially explore the development of the olfactory system in the embryo.The transcriptomic data were filtered and it was found that the percent of clean reads in most of the sequencing data reached over 97% and the mapping rate reached over 90%,indicating the reliability of the sequencing data.Meanwhile,it was found that as the embryos developed,the expression of olfactory genes has increased after neurula compared to stages before neurula.更多还原