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1.
在脊椎动物系统进化中,鱼类处于承前启后的关键地位.与高等脊椎动物相比,鱼类的性别决定机制具有原始性、多样性和易变性,并具有所有脊椎动物的性别决定方式,存在从雌雄同体到雌雄异体的各种性别类型,性逆转在鱼类也是较为常见的现象.  相似文献   

2.
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   

3.
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。  相似文献   

4.
FTZ-F1基因属于孤核受体超家族成员,最初是在果蝇(Drosophila)中发现的,该基因在果蝇胚胎发生的早期调控体节分化基因ftshi-tarazu(FTZ)表达。目前已经发现了很多它的同源基因。研究证明它在类固醇生成、性别分化过程中都发挥着重要的作用。鱼类在脊椎动物系统进化中处于承前启后的地位,是脊椎动物中分布最广、种类最多的类群,具有多种多样的生物学特征和重大的经济价值,所以对于鱼类性别决定机理的研究具有重大意义。文章就鱼类中发现的性别相关基因FTZ-F1,及该基因在胚胎发育过程中的作用、在性逆转鱼中的作用及与芳香化酶的相互作用关系等进行了综述,旨在为系统研究鱼类性别决定机制提供参考。  相似文献   

5.
鱼类性别决定的遗传基础研究概况   总被引:14,自引:4,他引:10       下载免费PDF全文
童金苟 《水产学报》2003,27(2):169-176
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   

6.
鱼类的性别决定和性染色体   总被引:12,自引:5,他引:7  
全世界现存鱼类约有 2 4 6 18种 ,分属 5 7目 ,4 82科 ,4 2 5 8属 ,是脊椎动物中分布最广 ,种类最多的类群 ,具有多种多样的生物学特性和重大的经济价值。在脊椎动物系统进化中 ,鱼类处于承先启后的地位 ,有着长久的进化历史和繁多演化分枝。鱼类在进化过程中表现出各种趋同性、趋异性和保守性 ,变化纷繁 ,物种进化异常活跃[1] 。鱼类作为较低等的脊椎动物 ,在性别决定中也有多种表现形式 ,例如鱼类中有些物种是雌雄同体的 ,这在其它高等脊椎动物中是没有的。即在同一个体中同时具有两种性腺 ,行自体受精。而另有些物种则是连续性雌雄同体鱼…  相似文献   

7.
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。  相似文献   

8.
鱼类性别决定的研究进展   总被引:3,自引:0,他引:3  
有关鱼类性别决定的研究主要集中在温度、性激素、芳香化酶以及随机重复序列、核受体基因等对性别分化的调控方面。由于鱼类所处分类地位较低 ,生活环境千差万别 ,鱼类性别决定没有一个普遍的模式 ,目前研究的鱼类又各不相同 ,因此象哺乳动物那样的性别决定级联模式还没能阐述。本综述旨在阐述近几年有关鱼类性别决定机制方面的研究动态和进展 ,为系统研究鱼类性别决定机制提供参考  相似文献   

9.
<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。  相似文献   

10.
鱼类性别决定机制的研究进展   总被引:3,自引:0,他引:3  
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。  相似文献   

11.
The Neotropical freshwater fish fauna is very rich—according to the most recent catalogue 71 families and 4,475 species have been described. However, only a small amount of general information is available on the composition of Neotropical marine fishes. In Brazil, 1,298 marine species have been recorded. General analysis of available cytogenetic and population genetic data clearly indicates research has been mainly concentrated on freshwater fishes. Thus, today, cytogenetic information is available for 475 species of Characiformes, 318 species of Siluriformes, 48 species of Gymnotiformes, 199 freshwater species that do not belong to the superorder Ostariophysi, and only 109 species of marine fishes. For the species studied, only about 6% have sex chromosomes and about 5% have supernumerary or B chromosomes. A review of the cytogenetic studies shows that these data have provided valuable information about the relationships between fish groups, the occurrence of cryptic species and species complexes, the mechanism of sex determination and sex chromosome evolution, the distribution of nucleolus organizer regions, the existence supernumerary chromosomes, and the relationship between polyploidy and evolution. In relation to populations in Neotropical marine waters, the studies have shown the presence of cryptic species, which has important implications for fishery management. Different levels of genetic structuring can be found among Neotropical freshwater migratory fish species. This raises important implications for fish population genetic diversity and consequently its sustainable utilization in inland fisheries and aquaculture, specifically for conservation of ichthyo-diversity and survival.  相似文献   

12.
In most vertebrate classes, the hypothalamus and pituitary have well-defined roles in the control of reproduction. Until recently, there was little evidence for neuroendocrine control of reproduction in lampreys, one of the only two living representative groups of the oldest lineage of vertebrates, the Agnathans. The question whether there is hypothalamic control over reproduction has special significance since these fishes, with the hagfishes, are modern descendants of the most primitive vertebrates available for study. This paper summarizes the studies on the structure and function of lamprey GnRH which provide evidence for the regulatory influence of the hypothalamus on the pituitary-gonadal axis. These data imply that evolution of this mechanism most likely antedated the origin of all known vertebrates.  相似文献   

13.
There is growing societal and scientific interest in the welfare status of fish used for commercial enterprise. As animal welfare is primarily concerned with the quality of life of a conscious, sentient organism, the question of whether fishes are even capable of consciousness must first be addressed in order to assess their welfare status. Recently, there has been a resurgence of research investigating the biological basis for human consciousness, and our current understanding of the cognitive mechanisms underlying fish behaviour has likewise improved significantly. Combined, these research perspectives create an opportunity to better comprehend the phylogeny of traits associated with consciousness, as well as the emergence of consciousness itself during vertebrate evolution. Despite the availability of this literature, contemporary reviews or published studies investigating the probability of conscious states occurring in fishes often do so without considering new perspectives or data. In this paper, we review and critique recent publications that report equivocal conclusions favouring the absence or presence of consciousness in various fishes. By introducing other data into these analyses, we demonstrate that there are alternative perspectives which support the existence of consciousness in fishes as a plausible concept. An accurate assessment of the mental capacity of fishes will require enhanced knowledge of their forebrain neuroanatomy, an understanding of how such structures mediate behavioural responses, and an analysis of that information within the context of contemporary theory related to the evolution of consciousness in higher vertebrates.  相似文献   

14.
Genetic and environmental factors may interact to control sex determination in fishes. A common pattern of initial female differentiation and subsequent male transformation before maturation in non‐hermaphroditic fishes and after maturation in sequentially hermaphroditic fishes has suggested that changes in developmental timing may be responsible for the evolution of various expressions of sexual lability. Sequential hermaphroditism is rare in freshwater fishes, but investigators report degrees of sexual lability at four distinct life stages in cichlid fishes. Some cichlids undergo genetic sex determination and are not labile. Lability at the larval stage allows temperature or pH to determine sex. Social interactions apparently determine sex at the juvenile stage in the Midas cichlid (Amphilophus citrinellus). Most reports of post‐maturational sex change in cichlids are anecdotal or unsubstantiated. The common occurrence of same‐sex spawning suggests that many species are incapable of sex change. Sequential hermaphroditism is concluded not to be typical, except for the checkerboard cichlid (Crenicara punctulata), which regularly undergoes functional female‐to‐male transformation. Expression of sexual lability at four life stages in one family of fishes corroborates a role for developmental timing in the evolution of sequential hermaphroditism as well as environmentally controlled sex determination. The broad phylogenetic distribution of sexual lability in cichlids indicates that processes capable of producing sex change are generally present. The rarity of sequential hermaphroditism in cichlids and possibly other freshwater fishes is likely due to unpredictability of food and therefore potential mate distributions compared with coral reef habitats.  相似文献   

15.
Assigning individual fish to populations using microsatellite DNA markers   总被引:11,自引:0,他引:11  
New statistical developments combined with the use of highly polymorphic microsatellite DNA markers enable the determination of the population of origin of single fish, resulting in numerous new research possibilities and applications in practical management of fish populations. We first describe three main categories of methods available, i.e. (i) assignment tests and related methods, (ii) discriminant function analysis and (iii) artificial neural networks. In all these, individuals can be assigned to the population from which their multilocus genotypes are most likely to be derived. Assignment tests are based on calculations of the likelihood of multilocus genotypes in populations, based on allele frequencies. Discriminant function analysis is based on multivariate statistics, whereas artificial neural networks formulate predictions through exposure to correct solutions. Assignment tests are the methods of choice when considering genetic data alone, whereas discriminant function analysis and artificial neural networks may be useful when genetic data are combined with, for instance, morphological and ecological data. Assignment tests can be used to assess the genetic distinctness of populations, for discriminating among closely related species and to directly identify immigrants or individuals of immigrant ancestry, and thereby study patterns of dispersal among populations, including sex‐biased dispersal. In a conservation context, assignment tests can be used to assess the genetic impact of domesticated fish on wild populations and for determining if extant fish populations are in fact indigenous or descendants from stocked fish or strayers, and they can be applied in forensics, for instance to reveal poaching. Assignment tests are at present most useful for studies of freshwater and anadromous fishes owing to stronger genetic differentiation among populations than in marine fishes. However, some genetically divergent populations of marine fishes have been discovered, which could be used as natural laboratories for studying dispersal and gene flow. It is foreseen that ongoing developments in statistical methods, combined with improved techniques for screening large numbers of loci, will permit assignment methods to become standard tools in studies on the biology of fishes.  相似文献   

16.
鲑鳟鱼类是典型的冷水性鱼类,经济价值高,是世界重要经济养殖鱼类之一。然而,随着其养殖产量攀升,养殖密度增大,养殖环境恶化,鲑鳟鱼类寄生虫病的发生和危害也日趋频繁和严重,严重制约了产业的健康发展。鲑鳟鱼常见的、危害较为严重的寄生虫主要包括三代虫(Gyrodactylus)、鱼虱(Caligus rogercresseyi)、阿米巴原虫(Neoparamoeba perurans)、脑碘泡虫(Myxobolus cerebralis)、苔藓鲑四囊虫(Tetracapsuloides bryosalmonae)和库道虫(Kudoa spp.)。这些寄生虫生活史简单,繁殖速度快,大多寄生在鱼体表面及体内的各种组织器官上,导致鱼体生长缓慢、抵抗力下降,引起鱼体损伤并造成死亡。在防治方法上,通过物理控制、化学药物和免疫治疗相结合的方法进行综合防控。本文对鲑鳟鱼常见寄生虫病领域的研究和成果进行简要综述,以期为鲑鳟鱼寄生虫病的研究和防治提供参考。  相似文献   

17.
Nitrogen (N) and phosphorus (P) are important limiting or co‐limiting nutrients in many aquatic ecosystems. Consumers such as fishes can significantly impact the balance and redistribution of these nutrients through consumer‐driven nutrient recycling. Intraspecific variation in nutrient excretion rates can therefore have significant ecosystem impacts. Among individuals of sexually dimorphic consumers, variation in population size structure and sex ratio could potentially have impacts of similar magnitude. We tested for the effects of body size and sex on consumer‐driven nutrient recycling by measuring N and P excretion rates from eight species of poeciliid fishes. We found a strong positive effect of size on N excretion rates, as has been previously described among species. However, we found no effect of size on P excretion rates, nor did we find any difference in N or P excretion rates between sexes. Our work provides a preliminary analysis of how sexual dimorphism can lead to disparate nutrient excretion rates within consumer populations. These results indicate that variation in population sex ratios of sexually dimorphic consumers could have impacts at the ecosystem scale.  相似文献   

18.
In vertebrates, water and osmolyte homeostasis is controlled by at least three hormonal systems: the hypothalamo-neurohypophysial system, the renin-angiotensin-aldosterone system and the atrial natriuretic factor system. The first system implies neuroendocrine reflexes involving an afferent neural limb from osmo- and baroreceptors to hypothalamus and an efferent endocrine limb from secretory neurons to target cell receptors and transduction to intracellular effectors, namely water and sodium channels. Evolution can affect any level of this molecular cascade. Whereas virtually all vertebrate species have two neurohypophysial hormones, an oxytocin-like and a vasopressin-like peptides, the most primitive vertebrates, Cyclostomata (lampreys and hagfishes) possess a single peptide, vasotocin, so that an early gene duplication occurred before the emergence of fishes, about 400 million years ago. The remarkable evolutionary stability of neurohypophysial hormones in bony vertebrates allows us to trace two main lineages: isotocin-mesotocin-oxytocin and vasotocin-vasopressin. In contrast, in cartilaginous fishes, the oxytocin-like peptides display a great evolutionary diversity: we have identified glumitocin in rays, aspargtocin and valitocin in the spiny dogfish, asvatocin and phasvatocin in the spotted dogfish, and oxytocin in the chimaera. Whereas bony vertebrates regulate their blood osmotic pressure (about 250–450 mOsm kg-1 H2O) essentially through salts, cartilaginous fishes use urea as the main osmolyte for adjusting their osmotic pressure above the external medium (about 1050 mOsm kg-1 H2O for marine fishes). The hypothesis is made that the stability of neurohypophysial hormones in bony vertebrates is due to their implication in ion-based osmoregulation (selective evolution), whereas in Chondrichthyes the occurrence of urea-based osmoregulation has relieved the hormones from this function and therefore made them free to vary (neutral evolution).  相似文献   

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