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鱼类性别决定机制是脊椎动物中最复杂的。同高等脊椎动物一样,鱼类性别决定的基础依然是遗传基因。鱼类的性别控制对于水产养殖有着十分重要的指导意义。目前用于生产实践的鱼类人工性别控制方法有很多,但大多数仍然处于探索与实验阶段,理论上的作用机理仍未研究透彻。文章旨在通过对鱼类性别决定机制、性别决定相关基因等方面国内外研究进展的阐述,为鱼类性别控制、调控养殖鱼类的经济性状如生长率和个体大小等,提供有益的参考资料。 相似文献
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动物从受精卵发育到具有不同性别特征的个体是一个奇妙而又严谨的过程,是人类长期以来试图揭示的自然现象。上世纪90年代初在人类Y染色体上发现了性别决定基因SRY[1],进而发现了一个新的Sox基因家族[2]。上述基因的发现,促进了以哺乳类为代表的动物性别决定和分化机制研究。由于鱼类在脊椎动物中的特殊进化地位、庞大的种类数量以及显著的社会经济价值,鱼类的性别决定研究一直受到遗传和发育学者的重视。尽管离最终阐明鱼类性别决定的机制还有距离,但近20多年来鱼类性别决定的遗传基础研究已取得不少重要进展。本文试图根据现有文献资料,… 相似文献
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鱼类性别在鱼类育种中非常重要,因为各种养殖对象的雌雄性别之间存在着生长速度、行为方式.生育时间、体色.外形和大小等方面的差异。鱼类育种者或养殖者力图按照生物性状或经济性状将雌雄分开,以期达到单性养殖的目的。本文将对鱼类的性别、性别控制以及未来的控制途径作一概述。 相似文献
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1891年,Henking(转自①)在一些半翅类中发现;有一对同源染色体在减数分裂中总是落在其它染色体之后。当时人们对这对染色体的作用还迷惑不解,因而他仿照数学家用“X”表示未知数的方法,把这对举动特殊的染色体称为X染色体。 相似文献
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The aim of this review is to present an overview of the sex differentiation and sex determination processes in eels in relation to the urgent need to provide scientific knowledge to better protect and manage the Anguilla genus. Indeed, the global decline of the three main temperate eel stocks, Anguilla anguilla, Anguillidae (Fisheries Management and Ecology, 2003, 10, 365); Anguilla japonica, Anguillidae (Casselman, Eel Biology, Springer Japan, 2003, 293) and Anguilla rostrata, Anguillidae (Tatsukawa, Eel Biology, Springer, Japan, 2003, 255), raises concerns about the necessity to better understand all stages of the life cycle of eels (Righton and Walker, Journal of Fish Biology, 2013, 83, 754). Little is known about the mechanisms involved in the production of males and females in this species with environmental sex determination. Previous reviews identifying the density of individuals as the major factor influencing sex determination were undertaken (Krueger and Oliveira, Environmental Biology of Fishes, 1999, 55, 381; Reviews in Fish Biology and Fisheries, 2005, 15, 37). Here, we review the current advances on the subject, focusing on the roles of early growth rate and interindividual relationships, which are mechanisms underpinned by density, as well as the sex differentiation process, and we question how this knowledge might influence global conservation measures. 相似文献
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Studies of thein vitro gonadal steroidogenesis in intersexual fishes, using labelled testosterone as precursor, showed large species variation.
The protogynousMonopterus albus produced predominantly 5α-reduced metabolites while the protandrousRhabdosargus sarba produced mainly 5β-reduced products. Both fishes synthesized 11-oxotestosterone; the synthesis of which appeared to mediate
mainly through adrenosterone inM. albus butvia 11β-hydroxytestosterone inR. sarba.
When the plasma levels of androstenedione, testosterone, 11-oxotestosterone, 11β-hydroxytestosterone, estrone and 17β-estradiol
among the male, intersexual and female phase of the same species were compared, available data showed that either there was
no obvious difference among the different sexual phases or the differences could be accounted for by the seasonal reproductive
activities of the animal.
Except for androstenedione, there are no marked changes in plasma testosterone, 11-oxotestosterone, 11β-hydroxytestosterone,
estrone and 17β-estradiol levels in the intersexual phase compared with the female and male, it is unlikely that these classical
sex steroids act as a primary trigger of natural sex reversal in these fishes; the role of androstenedione awaits further
elucidation.
Department of Zoology, University of Hong Kong 相似文献
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该研究测量和统计了人工养殖四指马鲅 (Eleutheronema tetradactylum) 的形态及性别比例,并观察其性腺的组织学和形态学特征。结果显示,当盐度为10.8~13.0、水温为28.0~30.7 ℃时,在228尾7月龄四指马鲅样本中检测到雄性、雌性和雌雄同体3种个体,其比例分别为85.53%、5.70%和8.77%;3种个体的体质量、全长、体长和体高等形态性状无明显差异。解剖学观察显示,雌雄同体性腺的两背内侧为精巢,呈白色,两腹外侧为卵巢,呈浅黄偏红色。组织学显示精巢侧已有成熟精子形成,为典型精巢的Ⅳ或Ⅴ期特征,卵巢侧具卵巢腔,主要为卵原细胞和早期Ⅱ时相卵母细胞,为典型卵巢的Ⅱ期特征,可判断四指马鲅为雄性先熟雌雄同体;其性逆转过程可分为早、中、晚3个阶段,主要组织结构变化特征为卵巢结构逐渐形成并发育成Ⅱ期卵巢,而精巢组织则逐渐退化消失,在整个性逆转过程均检测到精巢的细胞凋亡信号。
相似文献15.
Y. Nagahama 《Fish physiology and biochemistry》2005,31(2-3):105-109
We have used various genetic and molecular approaches to investigate the mechanisms of sex determination and gonadal sex differentiation
in fish. DMY was identified as the sex-determining gene of medaka. In tilapia, endogenous estrogens act as natural inducers of ovarian
differentiation, while DMRT1 may be important for testicular differentiation. The roles of these regulators in sex determination and gonadal sex differentiation
were ascertained using a gene or hormonal blockade strategy. 相似文献
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In a 7 months old foal with a male pseudohermaphroditism the cytogenetic investigation revealed a XO/XYY-mosaic with a centric fusion of the Y-chromosomes. 相似文献
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Morphology, endocrinology, and environmental modulation of gonadal sex differentiation in teleost fishes 总被引:1,自引:0,他引:1
Successful reproduction by an adult depends on the normal ontogenesis of the gonads, a complex process of cellular and histological
differentiation that starts early in life. This process is theoretically predetermined by genetic factors and includes sensitisation
of the bipotential gonads to endogenous endocrine factors prior to, during and even after commitment to maleness or femaleness.
However, young fish are relatively vulnerable to a host of environmental (physical and chemical) factors that can affect this
endogenous endocrine axis, disturbing or even overriding the putative developmental pathway. This sexually lability can be
exploited to our advantage for the production of monosex fish populations of the most valuable sex for food production or
aquarium fish trade. On the other hand, it represents also a potential path for undesirable influences from endocrine-disrupting
chemicals and climatic factors, particularly environmental temperature. This paper provides a detailed account of the early
histological process of gonadal sex differentiation, with special reference to gonochoristic species, and reviews the criteria
employed to positively identify ovarian and testicular differentiation. It also reviews the development of endocrine competence
and sensitivity of the differentiating gonads to exogenous influences in the context of the relative stability of genotypic
sex determination in various fish species. Sex differentiation in some species seems to be under strong genetic control and
may not require endogenous sex steroid production. Conversely, reliance on endogenous sex steroids for gonadal differentiation
is observed in other species and this phenomenon is apparently associated with a higher incidence of environment (mainly temperature)-labile
sex differentiation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献