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题名: 两种小型鱼类的某些基因组特征研究
作者: 游翠红
答辩日期: 2007-09-03
导师: 童金苟
授予单位: 中国科学院水生生物研究所
授予地点: 水生生物研究所
学位: 博士
关键词: 大鳞副泥鳅 ; 稀有鮈鲫 ; 性别决定,性别分化,遗传结构 ; 杂交 ; 雌核发育 ; 微卫星 ; Sox基因
其他题名: The studies on some genomic characters of two small fishes in China
摘要: 鱼类性别决定机制复杂,性染色体分化程度低,遗传和环境因子可能会对其性别产生作用。鱼类的天然杂交与遗传渐渗也是鱼类学家和生态学家一直关注的问题。本研究采用种间杂交、诱导雌核发育及人工转性等细胞遗传学方法,并结合性别相关基因Sox基因家族克隆研究以及微卫星标记的多态性研究,以我国所特有的小型实验鱼类、据报道具有雌性异配型性别决定的大鳞副泥鳅 (Paramisgurnus dabryanus)以及具有模式实验动物发展潜力的稀有鮈鲫(Gobiocypris rarus) 为研究对象,探讨性别决定的可能的染色体机制,以及鱼类的天然杂交等问题,为深入解析这两种小型鱼类的基因组特征以及保护利用鱼类资源提供新的证据。 进展主要包括两大方面。第一方面是关于大鳞副泥鳅的基因组特征:1)通过6对微卫星引物,研究了长江流域的6个地方样本和1个珠江流域样本共7个大鳞副泥鳅群体的遗传结构现状,发现其群体遗传多样性较低,群体间遗传分化明显,但分化水平仍属于地域上的分化。2)作为研究天然杂交的参照,将大鳞副泥鳅与其近缘种泥鳅进行了人工杂交,其正、反交杂种的性比均偏离预期值,杂种为三倍体,雌性不育;应用3个微卫星座位研究了来自野外的部分疑是大鳞副泥鳅和泥鳅杂种的样本,获得了自然界中两种泥鳅之间存在稀有的杂交现象的证据。3)采用红鲫异源精子和温度休克成功地诱导了大鳞副泥鳅减数分裂和有丝分裂雌核发育,并证实冷休克不能像热休克处理那样有效地、稳定地诱导大鳞副泥鳅有丝分裂雌核发育;通过统计雌核发育子一代和子二代的性比,基本证实了大鳞副泥鳅的雌性异配型性别决定类型,但目前还不能排除温度效应对大鳞副泥鳅性别发育的影响。4)从大鳞副泥鳅基因组中,通过扩增和克隆测序获得了18个Sox基因,其中6个哺乳动物Sox直系同源基因存在两个或以上的拷贝;对在两种泥鳅亲本及杂种性腺中表达的Sox基因进行了初步的RT-PCR及测序分析,推测Sox8和Sox9在大鳞副泥鳅及与泥鳅的杂种的性腺分化中发挥重要作用。 二是在稀有鮈鲫中,采用热休克诱导了其减数分裂雌核发育,并对雌核发育子一代应用雄激素进行转性,将转性后的子代进行自交获得子二代。通过统计子一代及子二代的性比,初步认为稀有鮈鲫性别决定机制复杂,其常染色体上的因子可能参与了性别决定。
英文摘要: Sex determination in fish is complex because the differentiation level of sex chromosomes is low. Both genetic and environmental factors may have influenced on the sex of fishes. Natural hybridization and genetic introgression in fish have also been concerned by ichthyologists and ecologists. Using such cytogenetic approaches as interspecific hybridization, gynogenesis, artificial sex reversal, together with the cloning of Sox genes and detection of microsatellite polymorphisms, this dissertation focuses on the possible chromosomal mechanisms for sex determination and natural hybridization in large scale loach, Paramisgurnus dabryanus, in which a female heterogamete sex determination was previously proposed, and also on sex determination of rare minnow Gobiocypris rarus, a potential Chinese model fish, in order to provide new evidence for further understanding and exploring the genomic characters of the two small experimental species native to China. The results would be useful for effective protection and utilization of the natural resources of fish. Two major achievements were obtained in this dissertation. First, some genomic characters were studied in large scale loach in the following aspects: 1) Genetic structure of seven populations (six from the Yangtze River system and one from the Pearl River system) of large scale loach was studied at six microsatellite loci, and the results showed that the populations exhibited low genetic diversity but significant genetic differentiation. The differentiation may be still at the level of population or geographical differentiation. 2) Artificial hybridization between large scale loach and its close-related species, pond loach M. anguillcaudatus, was performed as the positive references in the studies of their natural hybridization. The hybrids were triploids with female sterile, and the sex ratios of the reciprocal hybrids were significantly biased. Through the investigation on some wild samples at three microsatellite loci, evidence for rare hybridization between the two loach species was obtained from those individuals with ambiguous morphology. 3) Meiotic and mitotic gynogenesis were successfully induced in large scale loach by using heterogeneous sperms of red crucian carp and temperature shock, and the results showed that cold shocks could not stably induce mitotic gynogenesis as effectively as heat shocks. By scoring sex ratios of gynogenetic F1 and F2 progenies, a female heterogamete sex determination in large scale loach was generally confirmed, although temperature effects may not be excluded. 4) Eighteen Sox genes were cloned and characterized from the genomic DNA of large scale loach, and six of them were found to be orthologous to those of mammals and have two or more copies. With the preliminary RT-PCR analyses combined with sequencing Sox genes expressed in the gonad tissues of two loach species and their reciprocal hybrids, the results indicated that Sox9 and Sox8 would be important in sex differentiation of large scale loach and its hybrids with pond loach. Second, meiotic gynogenesis was induced in rare minnow, and some of the meiogens were subjected to artificial sex reversal by feeding androgens. F2 progenies were obtained by self-mating among the sex-reversed progenies. Based on the results from scoring sex ratios in the F1 and F2 progenies, a complex mechanism of sex determination in rare minnow was proposed, and factors on autosomal chromosomes might have influenced on its sex in this study.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ihb.ac.cn/handle/342005/12280
Appears in Collections:中科院水生所知识产出(2009年前)_学位论文

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Recommended Citation:
两种小型鱼类的某些基因组特征研究.游翠红[d].中国科学院水生生物研究所,2007.20-25
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