浅析斑马鱼性别决定的调控因素

性别决定是经典而高度保守的生物过程。在许多物种中性别决定是以遗传为基础的,个体所携带的性染色体决定了性别。然而,由于鱼类性腺发育呈现高度可变性、复杂性的特点,其性别决定机制仍未有定论。斑马鱼作为一个研究发育和疾病的重要脊椎模式动物,性别决定和分化的高度可塑性使其成为研究生理和环境因素对性腺发育影响及其作用机制的独特模型。本综述总结近年来对斑马鱼性别决定及分化过程的研究,为探索鱼类性别决定机制提供新的见解。     

调控鱼类性腺分化基因的研究进展

鱼类种类繁多, 其性别决定机制也几乎涵盖了所有的动物类型。近几年来, 随着分子生物学技术的不断更新, 关于鱼类性别决定机制的研究, 尤其是对调控性腺分化基因的克隆、表达及功能验证取得了突破性进展。文章从性腺分化、核受体家族、类固醇合成酶类和卵母细胞结构基因4个方面综述了调控鱼类性腺分化基因的研究进展。       

一个新的泥鳅雄性特异DNA片段（简报）

世界上现存鱼类多达24000余种．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。与高等脊椎动物相比．其性别决定具有多样性和可塑性。大多数鱼类的性别决定机制很原始。性染色体的分化处于萌芽状态。在已进行细胞遗传学研究的1700多种鱼类中．大约有176种（占10．4％）发现有明显的异型性染色体。     

两栖动物的性别决定和分化

性别发育是进化生物学领域备受关注的研究热点之一。性别发育主要包括性别决定和性别分化,脊椎动物的性别决定主要分为基因性别决定和环境性别决定两种模式。两栖动物的性别决定属于基因型性别决定模式,其基因型性别由受精时两性配子的性染色体决定,但性腺分化所产生的表型性别还会受环境温度和性激素的修饰。在两栖动物中性别逆转的现象普遍存在,其相关的生理和分子机制也有一定的研究。本文从性别相关基因对性别决定的影响、温度对两栖动物性别分化的影响、性激素对两栖动物性别分化的影响、温度和性激素对性别相关基因表达的影响等四方面对两栖动物性别决定和性别分化的生理和分子机制进行一定的概述,并提出了未来两栖动物性别发育研究的重点。     

鱼类性别异形和性别决定的遗传基础及其生物技术操控

鱼类养殖对世界食品特别是动物蛋白的持续供给做出了至关重要的贡献.鱼类生殖对策的多样性,特别是单性雌核生殖方式的利用已开创了鱼类遗传育种的典型范例.不少鱼类在生长和个体大小等重要经济性状上表现出显著的性别异形.性别特异分子标记的开发和性别控制生物技术的发展为增加鱼产量及其经济价值提供了重要的技术途径.随着基因组学和分子遗传学技术的迅速发展,鱼类性别异形的遗传基础逐步被揭示,鱼类性别决定机制及其性别决定相关基因的鉴定已经取得了重大进展.本文对此进行了概述,以期为该领域的深入研究提供一些方向性和目标性思考.     

鱼类和两栖类性别决定的研究进展

鱼类和两栖类在脊椎动物的演化过程中是非常关键的两个类群,人们对于这两类动物性别决定的研究已经取得了一些进展.这些进展不仅对动物性别决定演化的研究有基础性贡献,而且对发展养殖业也有理论指导意义.     

低等脊椎动物的性别

低等动物的一些类群是不存在性别的,为单亲遗 传。性别也是进化的产物。低等脊推动物的性决定、 性分化和性比三方面都有不同于其他脊推动物的特殊 之处。近十几年的研究发现,鱼类、两栖类、爬行类等 低等脊椎动物,存在两种性决定机制,即性染色体和孵 化温度决定性别。     

鲟鱼性别分化相关基因研究进展

鲟鱼是目前世界上最古老的鱼类之一,其肉质鲜美,营养丰富,鱼卵加工成的鱼子酱具有极高的经济价值。鲟鱼鱼子酱价格居高不下,因此养殖雌性鲟鱼比养殖雄鱼具有更高的经济前景。由于鲟鱼外形无法辨别雌雄,目前,通常借助超声波、内窥镜等仪器进行早期性别鉴定,但鉴别准确性无法保证。因此采用现代分子生物学技术探究鲟鱼性别决定及性别分化机制有助于早期鲟鱼性别鉴定技术的开发及实现鲟鱼全雌化苗种培育。总结了鱼类性别决定与性别分化相关基因的研究现状,综述了目前在鲟鱼上性别决定与性别分化相关基因的研究进展并预测了未来的研究方向及研究趋势。     

我国水产生物技术的研究进展

水产生物技术是生物技术的重要组成部分,应用于水产养殖的各个学科中。从水产动物功能基因的筛选与克隆、分子标记的筛选与应用、基因工程和细胞工程育种、性别决定机制和性别控制研究、鱼类低温生物工程研究等五个方面阐述我国水产生物技术的研究进展。     

被子植物雌雄异株性别决定与性别连锁标记

雌雄异株是雌雄性别分离的一种性系统,在被子植物中广泛分布。一般认为雌雄异株的性别决定受遗传、环境和激素三者的影响和调控。随着第二代测序技术和分子标记技术的发展,对于被子植物雌雄异株性别决定的研究已深入到基因水平。现从性别决定机制及性别连锁的分子标记对被子植物雌雄异株的研究进行总结,并对未来的研究方向进行了展望,以期为深入研究雌雄异株的遗传机制及系统发生奠定基础。     

黑腹果蝇的性别控制

性别的形成包括两个过程,即性别决定和性别分化。果蝇的性别控制研究包括性别决定、性别分化、性别鉴定、性别诱导和性别控制5个方面。性别决定是在两种不同发育途径之间的选择,它提供了一个研究基因调控的模式系统。果蝇的性别决定问题已经研究得相当详细［1］。性别分化是使胚胎向着雌性或雄性发育的过程,决定了性别表型。果蝇的性别分化也取得了不少研究成果。近年来,许多重要的性别调控基因已被克隆和鉴定。随着果蝇基因组全序列测定的完成,果蝇的性别控制研究将会更为深入而完善。本文对与黑腹果蝇性别决定和性别分化相关的一些问题进行综述。     

部分水产养殖动物性别控制基因的研究进展

动物的性别是受遗传或环境等因素控制的。自从在哺乳动物中发现了性别决定基因SRY后,还发现了许多其他与性别控制和性腺发育相关的基因。由于海水养殖动物的性别控制技术在遗传育种和生产中十分重要,因此利用现代分子生物技术研究性别控制的基因成为热点。本文综述了鱼类、锯缘青蟹、海龟和海胆等水产养殖动物性别控制基因的研究进展。     

Diverse and variable sex determination mechanisms in vertebrates

Sex is prevalent in nature and sex determination is one of the most fundamental biological processes, while the way of initiating female and male development exhibits remarkable diversity and variability across vertebrates. The knowledge on why and how sex determination mechanisms evolve unusual plasticity remains limited. Here, we summarize sex determination systems, master sex-determining genes and gene-regulatory networks among vertebrates. Recent research advancements on sex determination system transition are also introduced and discussed in some non-model animals with multiple sex determination mechanisms. This review will provide insights into the origin, transition and evolutionary adaption of different sex determination strategies in vertebrates, as well as clues for future perspectives in this field.     

From the origin of sex-determining factors to the evolution of sex-determining systems

Sex determination is typically classified as either genotypic or environmental. However, this dichotomy obscures the developmental origin and evolutionary modification of determinants of sex, and therefore hinders an understanding of the processes that generates diversity in sex-determining systems. Recent research on reptiles and fish emphasizes that sex determination is a multifactorial regulatory process that is best understood as a threshold dichotomy rather than as the result of genetically inherited triggers of development. Here we critically assess the relationship between the developmental origin of sex-determining factors and evolutionary transitions in sex-determining systems. Our perspective emphasizes the importance of both genetic and nongenetic causes in evolution of sex determination and may help to generate predictions with respect to the evolutionary patterns of sex-determining systems and the underlying diversity of developmental and genetic regulatory networks.     

脊椎动物性别决定和分化的分子机制研究进展

哺乳类性别决定是多种转录因子和生长因子相继表达和相互调控的结果。SRY的表达启动雄性通路并诱导下游雄性特异基因SOX9、AMH等的表达。FOXL2在雌性未分化性腺表达,WNT-4和DAX1也在雌性性别决定或分化时期表达,表明雌性通路也是受特定基因调控的,而并非“默认通路”。鸟类的性别也是由遗传基因决定的,EFT1(雌性)和DMRT1(雄性)可能是性别决定候选基因。爬行类为温度性别决定的典型,温度可能通过调节雌激素水平和控制性别特异遗传基因表达决定性别。大部分两栖类性别受环境因素影响,但发现DMRT1和DAX1可能与其精巢发育有关。鱼类性别决定和分化方式差异很大,多种因素(遗传基因、环境因素、类固醇激素等)参与了这一过程。从青Q鳉Y染色体定位克隆的DMY,被认为是第一个非哺乳类脊椎动物雄性性别决定基因。所有这些表明脊椎动物性别决定和分化机制是多样化的。     

Sex Determination in Reptiles: An Update

Sex determination and sex differentiation are two separate butrelated phenomena. Sex differentiation is a programmed cascadeof events in which the indifferent gonad develops as a testisor an ovary with the appropriate urogenital and secondary sexcharacters. Sex determination is the event that sets this cascadein motion. In placental mammals, there is good evidence thatsex is determined by a gene on the Y chromosome (SRY) that initiatestestis formation. In the absence of SRY an ovary develops. Thereare, however, examples of placental mammal that develop as normalmales with no detectable SRY. In reptiles, sex differentiationappears to be similar to mammals (i.e., the same genes and hormonesact ina similar manner), but sex determination is clearly verydifferent. Ovarian differentiation in placental mammals canoccur in the absence of estrogen or an estrogen receptor. Ovariandifferentiation in reptiles requires the presence of estrogen.In the absence of estrogen a testis develops. In TSD reptiles,embryos will develop as females when treated with estrogen evenif eggs are incubated at male-inducing temperatures, and conversely,will develop as males when estrogen synthesis is blocked ineggs incubated at female-inducing temperatures. A number ofother genes have also been shown to be important in mammaliansex determination. One of these genes, Sox9, which is expressedin differentiating mouse testis, has recently been found tobe expressed in embryonic reptile testis. Other genes that appearto be common to both mammals and reptiles in the sex determiningcascade are SF- 1, MIH, and possibly DAX-1. Current researchis now focused on how the gene that produces the enzyme necessaryfor estrogen synthesis (aromatase) is regulated in the embryosof reptiles with genetic or environmental sex determination.Controversial issues in reptilian sex determination are 1) therole of the brain in gonadal sex determination, and 2) the roleof steroid hormones in the yolk prior to sex determination     

Effect of rearing temperature on sex ratio in juvenile Atlantic halibut, Hippoglossus hippoglossus

Several flatfish species exhibit temperature-dependent sex determination. This research investigated the effects of rearing temperature on sex ratio in Atlantic halibut, Hippoglossus hippoglossus, a species in which females grow larger and faster than males under culture conditions. Previous research has shown that ovarian differentiation occurs in Atlantic halibut in the size interval of 38–50 mm, and precedes the differentiation of testes. In the current study, triplicate groups of juvenile Atlantic halibut were reared at each of three temperatures (7, 12 and 15°C) from an initial mean size of 21 mm to a final mean size of 80 mm (total length). The sex of each fish was then determined by macroscopic and histological examination of the gonads. Sex ratios were not significantly different from 1:1 in any group, suggesting that sex in this species is not influenced by temperature.     

棕色田鼠性别决定研究进展

哺乳动物性别决定方式属于雄性异配型性别决定, 依赖于Y染色体, SRY基因是性别决定中最重要的基因。文章报道了棕色田鼠指名亚种有Y染色体, 但是Y染色体上没有SRY基因, 性别决定不依赖于SRY基因, 排除了R-spondin 1基因是性别决定基因, 同时讨论了棕色田鼠指名亚种SRY基因缺失后可能的性别决定 机制。     

Sex chromosomes in flowering plants

Sex chromosomes in dioecious and polygamous plants evolved as a mechanism for ensuring outcrossing to increase genetic variation in the offspring. Sex specificity has evolved in 75% of plant families by male sterile or female sterile mutations, but well-defined heteromorphic sex chromosomes are known in only four plant families. A pivotal event in sex chromosome evolution, suppression of recombination at the sex determination locus and its neighboring regions, might be lacking in most dioecious species. However, once recombination is suppressed around the sex determination region, an incipient Y chromosome starts to differentiate by accumulating deleterious mutations, transposable element insertions, chromosomal rearrangements, and selection for male-specific alleles. Some plant species have recently evolved homomorphic sex chromosomes near the inception of this evolutionary process, while a few other species have sufficiently diverged heteromorphic sex chromosomes. Comparative analysis of carefully selected plant species together with some fish species promises new insights into the origins of sex chromosomes and the selective forces driving their evolution.