鱼类性别决定机制的研究进展

鱼类的性别决定受多方面的调控，主要可分为基因型性别决定和环境型性别决定。文章阐述了鱼类性别决定机制方面的研究进展，近期的研究热点是性别决定的分子机制。     

鱼类性别决定机制及相关基因研究进展

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。     

人工雌核发育在鱼类遗传育种中的应用

阐述了鱼类人工雌核发育的基本原理,介绍了人工雌核发育在研究鱼类性别决定机制,养殖生产中的性别控制和鱼类性别遗传机制分析及选育新品种等方面的应用成果。     

鱼类性别遗传标记研究进展

鱼类的性别遗传机制正处于分化的初级阶段,其性别决定受环境因素和遗传因素的共同控制,其性别决定机制比较复杂.一直以来鱼类与性别连锁的遗传标记的研究备受到关注,近年来在分子标记方面的研究取得一些进展.本文从表型标记、蛋白质标记和DNA分子标记三方面对鱼类的性别决定和性别遗传标记研究现状进行综述,着重介绍鱼类DNA水平上的性别遗传标记的研究进展,为鱼类的性别标记及性别控制研究提供基础资料.     

雌雄同体鱼类性别分化及性转变研究进展

在脊椎动物中,鱼类具有多样的性别分化方式,大致可分为雌雄异体、雌雄同体以及单性生殖3类。一般情况下,鱼类性别决定后,性腺可分化为卵巢或精巢,并且在整个生命周期内保持不变。而在雌雄同体鱼类,其性别可以从雌性转变为雄性、雄性转变为雌性或者在雌雄两种性别间进行多次转变。雌雄同体鱼类具有多种性别转变形式,是研究脊椎动物性别决定与分化的理想模型。因此,本文从性腺发育组织学变化、性激素分泌、神经内分泌、性别决定与分化基因的分子调控等方面,综述了近年来雌雄同体鱼类性别分化与性转变相关的研究进展,为更深入地研究鱼类性别调控机制提供参考。     

鱼类的性别决定及性别控制

<正> 各种水域中的鱼类,除了少数种类以外,都有雌雄之分。研究鱼类的性别决定机制并进行人为的鱼类性别控制,对于水产养殖业的品种改良,增加经济效益具有重要的意义。     

水产养殖中鱼类性别决定的遗传基础及性别控制技术运用分析

在水产养殖期间,需合理控制鱼类性别比例,以此提升水产养殖收益,实现效益最大化,但对于部分鱼类而言,在自然生长期间将出现性别转变现象,为保障水产养殖效果,应做好鱼类性别控制.基于此,首先阐述了鱼类性别转变现象,分析鱼类性别决定的遗传基础,讨论环境因子对鱼类性别决定的影响,并以罗非鱼为例,探讨性别控制技术在水产养殖中的实际应用.     

近期我国鱼类性别人工控制的研究重点

有关鱼类性别决定与性控制的研究,在近二十年里已有快速的进展。本文在总结前人工作的基础上提出发展我国鱼类性别控制的战略思路与研究重点,仅供参考。     

TGF-β信号通路在鱼类性别决定与分化中的作用

脊椎动物性别分化和性腺发育的分子机制保守，但不同类群的最上游的性别决定基因却大不相同，尤其是鱼类，其性别决定基因表现出明显的多样性。性别决定包括环境性别决定和遗传性别决定，环境性别决定主要受温度、光照、激素和pH等的影响，而遗传性别决定一般由位于性染色体上的性别决定基因决定。转化生长因子-β(transforming growth factor β, TGF-β)信号通路参与介导了多种生物学过程，近年来很多研究表明，鱼类有多个性别决定基因都是TGF-β信号通路的成员，且该信号通路对于鱼类的性别分化也有重要的作用。本文总结了鱼类已报道的性别决定基因或候选基因，详细综述了TGF-β信号通路在鱼类性别决定与分化中的各种功能，并探讨了该信号通路参与鱼类性别决定的可能机制，这对认识TGF-β信号通路在鱼类性别决定、分化中的作用和性控育种有重要意义。     

鱼类的性别决定与人工控制

鱼类性别的人工控制是鱼类育种中一个十分重要的领域。本文概述了鱼类的性别决定机制及鱼类生理性别的表现方式,同时介绍了鱼类性别的多种人工控制方法,为育种单位的生产实践提供参考。     

鱼类性别决定的遗传基础研究概况

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,…     

Sex change in coral reef fish

Gonadal differentiation can take many forms in fish, ranging from gonochorism, where individuals directly develop as male or female and finally possess only testis or ovaries at sexual maturation, to hermaphroditism where the same individuals can produce mature male and female gametes at some time in their lives. Hermaphrodite fish are, thus, an excellent model for studying the plasticity of sex determination and differentiation in vertebrates. We have shown that sex steroids play a principal role in sex differentiation and sex change in fish. Our laboratory implements several fish models that undergo sex change from female to male or male to female or in both directions. In this review, we will briefly discuss recent advances in our understanding of the mechanism of sex change in coral reef fish.     

Patterns of sex ratio response to water temperature during sex determination in honmoroko Gnathopogon caerulescens

ABSTRACT:   The sex ratios of the offspring of males from broods of honmoroko Gnathopogon caerulescens that displayed thermolabile sex determination (TSD), and those from eggs collected from the wild, strongly suggest that the combination of parents plays an important supplementary role in TSD in this species. The proportion of females in all broods from eight pairings of fish captured in the field decreased significantly at 30°C compared to 20°C, and one brood was entirely female at the lower temperature. These results suggest that phenotypic males (XX-males) exist in nature, probably as a result of sex change from genetic females caused by TSD. Sex ratios in relation to water temperature fall into five patterns, two of which seem to result from normal pairings of XX-females and XY-males, and from pairings of XX-males and XX-females with non-thermosensitivity. Two other patterns are thought to result from the same types of pairing, but with thermosensitivity. The last pattern, which shows male bias at both low and high temperature, is not explained only by the combination of genotypic sex determination (XX/XY) and TSD. Fluctuating temperatures close to natural conditions showed little potential to masculinize broods laid in the field between April and early June. However, the sex ratios of fish spawned in early June showed male bias at low and high temperatures. The sex determination mechanism in G. caerulescens may involve the interaction between temperature and sex-determining genetic factors, and the relative importance of each component differs with breeding season.     

Morphology, endocrinology, and environmental modulation of gonadal sex differentiation in teleost fishes

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.     

A comparative analysis of chemically induced sex reversal in teleosts: challenging conventional suppositions

Environmental sex reversal (ESR) occurs when extreme environmental factors overpower predetermined sexual development. Scientific theory is beginning to acknowledge the potential roles of sex‐reversed individuals in influencing population dynamics and driving the evolution of sex‐determination mechanisms. ESR is a phenomenon that has been widely observed in fish and can be induced by exposing individuals to exogenous hormones. However, reports of the susceptibility of fish to hormonally induced ESR vary greatly – a concept we termed ‘inducibility’. It has been suggested that variation in inducibility can be attributed to biological differences among species of different taxonomic groups (i.e. phylogenetic effects are present). Here, we provide the first quantitative test of this theory, which was achieved by combining published data with phylogenetic trees, using phylogenetically controlled comparative analysis. Our results confirm that a great amount of variation exists in the reported inducibility of fish. However, species and taxonomic relationships were responsible for trivial portions of variation. Rather, we found that sampling (measurement) errors in combination with methodological differences across studies accounted for much more variation in inducibility than taxonomy did. Given that our analysis contains representatives from over 25% of all teleost orders, we conclude that inducibility is not a taxonomically constrained trait in teleosts. Therefore, we suggest that the sex‐determination mechanisms of most fish are uniformly plastic. Further, we propose that ESR occurs relatively regularly over evolutionary time in many teleost species, playing a vital role in the maintenance of homomorphic sex chromosomes in this taxonomic group.     

Molecular mechanisms of sex determination and gonadal sex differentiation in fish

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.     

Using machine learning algorithms to analyse the scute structure and sex identification of sterlet Acipenser ruthenus (Acipenseridae)

Sturgeons are valued as specialty black caviar, which is very expensive. Only females are used in the technology of caviar aquaculture. Universal method of sex determination has not yet been developed. Most of known methods are not sufficiently accurate, or used at a relatively late age, or difficult to use. Perfect early determination of sex is considered to be impossible. Because of the dark colour of most sturgeons and important morphological differences, which fish of almost all ages have, were overlooked. We first found that the scute structure of sterlet sturgeon depends on the sex. The found dependencies with the help of machine learning algorithms open a possibility for creation of sex determination equipment using the artificial intelligence. Our results open a perspective for creation of sex determination methods for other 23 sturgeon species, which can increase the efficiency of caviar aquaculture and restoration of sturgeons in natural waters.