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鱼类DMRT家族两个基因的 克隆及其特征分析
Alternative TitleCloning and characterization of two DMRT genes from fish
夏伟
Subtype博士
Thesis Advisor桂建芳
2006-11-30
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
KeywordDmrt 性别决定 性别分化 内含子 生精细胞 Dmrt2b 石斑鱼 银鲫 斑马鱼 功能歧化
AbstractDMRT基因首先是作为与性别决定和分化相关的因子被发现的,随着越来越多物种的多个DMRT基因被克隆得到,DMRT基因明显构成了一个基因家族,除哺乳类DMRT8基因除外所有的DMRT基因有着一个共同的特征,就是都含有具DNA结合能力的在序列上高度保守的DM 结构域。但是随着越来越多成员基因的性质得到鉴定,我们也发现,并不是所有的DMRT基因都很古老并与性别分化有关,因此DMRT基因除了保守的特征之外,也在不断的改变自己以适应物种新的需求。所以在更多的物种中去描述已经发现的DMRT基因,以及发现和鉴定更多新的DMRT家族成员就显得很有意义。 本研究首先克隆了具有天然性反转现象石斑鱼的DMRT1基因,对其基因结构以及表达模式的分析使我们发现它具有两大不同于其它物种DMRT1基因的特征。第一,该基因的开放阅读框内不含内含子;第二,只在精子发生过程的生精细胞中表达。因此我们推测这种不含内含子的结构可能与更容易满足生精细胞对其基因表达产物的快速需求相关,同时进化分析的结果表明该基因与其它五种进化地位各不相同鱼类的DMRT1基因关系较近,比较有趣的是这几种鱼类之间虽然距离很远,但都具有性别反转或者性别决定容易受环境影响的现象。 其次,通过在斑马鱼和银鲫中研究terra基因的一个鱼类特有的重复拷贝-DMRT2b基因,我们发现这个基因虽然在胚胎发育过程有着重要的作用,但是不像其它大部分的直系同源基因那样由于受到很强的选择压力的控制而功能很少发生改变,DMRT2b除了与terra基因发生明显的功能分化之外,不同物种的DMRT2b基因之间也发生了明显的分歧。并且通过实验证实这种分歧除了涉及它们编码蛋白生化性质的改变之外,还可能是由于表达模式以及其作用发挥所依赖的分子环境改变的原因,从而为后续工作的开展给出了一些设想。
Other AbstractDMRT genes were first identified as transcription factors related to sex determination and sex differentiation, but as more and more different DMRT genes were identified from different species, DMRT genes obviously formed a gene family. Despite mammalian DMRT8, all those DMRT genes share a common feature of having a highly conserved DM domain, which has been shown to be responsible for their ability to binding DNA. But when the characters of different DMRT genes were well depicted gradually, we found that not all DMRT genes were involved in sex differentiation. So DMRT genes are not only conservative but also changeable to adapt to changing requirements. Thus it will be interesting to describe the existing DMRT genes in different species and to find and characterize new members of DMRT gene family. We first cloned the full-length cDNAs of DMRT1 gene from grouper, which is protogynous hermaphrodite and sex reversal species. Through analyzing its gene structure and expression profile, we found it has two major differences from other DMRT1 homologues. First, no introns were found in the ORF of grouper DMRT1 gene, and the second, this gene was strictly expressed in spermatogenic cells during spermatogenesis. So we postulate the intronless DMRT1 that is able to undergo rapid transcriptional turnover might be a significant gene for stimulating spermatogenesis in the protogynous hermaphroditic gonad. At the same time, phylogenetic analysis and substitution estimation revealed a closer relationship that the grouper DMRT1 is most closely related to the homologues from bream, pejerrey, tilapia, rice field eel, and wrasse, although these fishes are distantly related species from the evolutionary and taxonomic points. Interestingly, sex reversal and environmental sex determination have been commonly reported in these fish species. We also analyzed a fish specific new duplicated version of terra gene in crucian carp and zebrafish, and found that although this gene play essential roles during embryo development but unlike the orthologues of other genes, which are mostly conserved across species due to the strong purifying selective pressure on them, we observed that not only DMRT2b genes diverge from terra homologues functionally but also different DMRT2b homologues have experienced obvious functional divergence. And we also verified this divergence is not only due to the changing of their biochemical properties but also may be caused by changing of expression profiles and the molecular interactive environment. Accordingly we give a clear conception about the future work about this gene.
Pages113
Language中文
Document Type学位论文
Identifierhttp://ir.ihb.ac.cn/handle/342005/12012
Collection学位论文
Recommended Citation
GB/T 7714
夏伟. 鱼类DMRT家族两个基因的 克隆及其特征分析[D]. 水生生物研究所. 中国科学院水生生物研究所,2006.
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