爬行动物的温度依赖型性别决定

脊椎动物性别决定模式一直是进化生物学领域的热点问题,它对个体发育和自然种群性比组成都具有深刻的影响。性别决定模式根据主要成因可分为基因依赖型性别决定(GSD)和环境依赖型性别决定(ESD)2大类,其中温度依赖型性别决定(TSD)又是ESD中的主要性别决定模式。多数羊膜类脊椎动物具有稳定的GSD模式,而爬行动物的性别决定模式则丰富多样,即使是亲缘关系很近的物种也具有不同的模式。研究者们以爬行动物为模型动物开展了许多关于脊椎动物性别决定方面的工作。本文综述了近年来爬行动物TSD的最新研究进展,回顾了温度和性激素对TSD爬行类动物的影响及其进化适应意义,以及气候变化与TSD爬行类的关系,并提出了今后爬行动物TSD研究的重点。     

温度依赖型性别决定在爬行动物中的研究进展

爬行动物性别决定方式主要有遗传依赖型性别决定(genetic sex determination,GSD)和环境依赖型性别决定(environmental sex determination,ESD),而ESD又以温度依赖型性别决定(temperature sex determination,TSD)为主。研究爬行动物TSD有助于人们弄清楚环境条件对物种表型的影响,从而更好地利用环境条件和遗传基础的共同机制来人为的改善或者诱导具TSD型物种的进化方向,以实现自然和人类的最大利益。该篇综述从母系活动、气候变化(全球气候变暖)、类固醇以及TSD机制四个方面总结了近年来关于爬行动物TSD的最新研究。     

爬行动物温度决定性别的现象与机制

性别决定是生物学的一个核心问题。性别决定模式依据决定因素可以分为基因型性别决定(GSD)和环境型性别决定(ESD)2类。温度依赖型性别决定(TSD)是一种特殊的ESD模式,胚胎性别是由发育过程中所经历的温度决定。简要评述了爬行动物TSD与GSD的关系、TSD的类型、TSD的生理和生态调控以及分子机制,归纳了TSD的各种适应性意义假说,并提出今后TSD研究的重点方向。     

环境决定爬行动物性别研究的进展

爬行动物的性别决定机制有两种,一种是由环境决定性别,另一种是异型性染色体决定性别。前者,在爬行动物中具有普遍性;未发现有异型性染色体的爬行动物,其性别由环境因子决定。剧烈的环境条件,可能压倒基因型性别决定。H-Y抗原,可检测未发现异型性染色体决定性别物种的遗传决定型。     

爬行动物的生殖

爬行动物是最早出现的真正陆栖脊椎动物 ,是完全适应陆地生活的类群。为了适应特殊和复杂的陆上生活环境 ,爬行动物在一些器官系统的组成和机能方面或多或少地发生了一些改变 ,其生殖系统也不例外。1　雄性交接器官　在生殖季节 ,爬行动物全部种类毫无例外地都要在陆地上或由水登陆进行繁殖 ,行体内受精。为了保证体内受精的顺利完成 ,在生殖系统的组成上爬行动物雄性发展了交接器官。但是不同的类群在雄性交接器官的形态和结构上有所不一样。爬行动物现生种类有 4目 :龟鳖目、鳄形目、喙头蜥目和有鳞目 ,除了分布于新西兰的喙头蜥目 (仅含…     

芦笋性别决定与性别分化研究进展

从芦笋性别表现及其决定的遗传基础、性别分化途径,性别决定基因的定位以及性别分化特异表达基因的分离与分析等方面来综述芦笋性别决定与性别分化最新研究进展。目前,已构建了围绕芦笋性别决定基因M比较精细的遗传图谱,将M定位在L5染色体着丝点附近的0.63 cM区域内,并构建了含有8个跨叠克隆群的物理图谱,但由于大量重复序列的存在,跨叠克隆之间的空隙不能闭合;同时先后分离得到11个芦笋花器官发育特异表达基因,并通过序列分析和原位杂交等技术对这些基因的功能进行了分析。最后,对今后进一步研究提出了建议。     

木本植物性别决定基因研究进展

雌雄异株植物是研究性别决定遗传机制及性染色体起源与进化的理想材料,而克隆性别决定基因是解析性别决定遗传机制的关键。木本植物中有丰富的雌雄异株植物,且包括2种相反的性别决定系统：XY型(雌株为同配型的XX,雄株为异配型的XY)和ZW型(雌株为异配型的ZW,雄株为同配型的ZZ)。此外,不同性别植株的经济价值也有所不同。在木...     

性别决定的研究进展

性别决定和性别分化是最基本的发育事件之一,也是生殖生物学研究的重要领域之一。性别决定是一个复杂的发育调控并涉及了进化时空的多基因多因素多层次的级联网络体系共同决定的活动过程。对性别决定的研究涉及遗传、发育与进化等学科的交叉研究领域,是生命科学中遗传一发育一进化主线条研究的极好模式。该领域的研究对生命活动规律等理论问题的认识具有借鉴和指导意义,并有助于认识性别决定机制。同时,性别决定的研究不仅有助于对动物性别的人为控制,而且利于人类性别分化异常的研究,包括分析病因、寻找可行性治疗方案。     

人类性别决定和性别分化研究进展

SRY基因在人类性别分化中起着关键作用,目前研究认为SRY仅是涉及性别决定过程的基因之一,其他基因和SRY相关基因SOX9,抗副中肾激素基因AMH,编码缁类因子的基因SF1,X－连锁的DAX基因,wilm‘s肿瘤抑制基因WT1等基因都参与了人类性腺分化和发育,本文拟就人类性别决定基因的研究进展及其与人类性别分化的关系作一综述。     

动物的性别决定

性别决定是指有性生物体未分化的生殖腺发育为卵巢或精巢的过程,其在生物界中广泛存在,是生物发育为雌、雄个体不可或缺的过程。对动物性别决定的定义及方式进行论述,主要阐述基因型性别决定、环境型性别决定和二者的相互作用,以及动物通过不同性别的转变来解决其生存过程中存在的各种问题。     

Isolation and development of a molecular sex marker for <Emphasis Type="Italic">Bassiana duperreyi</Emphasis>, a lizard with XX/XY sex chromosomes and temperature-induced sex reversal

Sex determination in the endemic Australian lizard Bassiana duperreyi (Scincidae) is influenced by sex chromosomes and incubation temperature, challenging the traditional dichotomy in reptilian sex determination. Analysis of those interactions requires sex chromosome markers to identify temperature-induced sex reversal. Here, we report the isolation of Y chromosome DNA sequence from B. duperreyi using amplified fragment length polymorphism PCR, the conversion of that sequence to a single-locus assay, and its combination with a single-copy nuclear gene (C-mos) to form a duplex PCR test for chromosomal sex. The accuracy of the assay was tested on an independent panel of individuals with known phenotypic sex. When used on offspring from field nests, our test identified the likely occurrence of a low rate of natural sex reversal in this species. This work represents the first report of Y chromosome sequence from a reptile and one of the few reptile sex tests.     

上海大金山岛的两栖爬行动物

大金山岛位于杭州湾东北角,是上海市最高和最大的基岩岛.该岛人为干扰较少,保留着上海地区珍贵的动植物资源原始本底.2017年5月至2018年10月,在两栖爬行动物的繁殖季节对大金山岛进行了6次全面调查.结果显示,大金山岛是上海市爬行动物多样性最丰富的地区.     

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.     

Ultrastructure of epidermal sensory receptors in Amphibolurus barbatus (Lacertilis: Agamidae)

Summary The histological and ultrastructural organisation of the epidermal sensory organs in Amphibolurus barbatus has been described with respect to their position and possible functions. The sensory organs, located at the scale's edge, are most numerous in scales of the dorsal surface of the head. Most other scales of the body surface have two receptors located laterally to the spine or keel of the scale. In the imbricate scales of the ventral body region, the receptors lie just beneath the reinforced scale lip. Scanning electron microscopy has revealed the surface of the organ to be a crater lacking any surface projections. These sensory organs have a dermal papilla consisting of a nerve plexus and loose connective tissue. The nerve fibres arising from the plexus, pass to the epidermal columnar cells, where some form nerve terminals at the base of the cells, while others pass between them to form nerve terminals embedded in a superficial layer of cuboidal cells. The superficial terminals are held against the overlying keratin by masses of tonofilaments. The keratin is thickened to form a collar around the periphery of the organ but is only about 0.5 m thick immediately above it. Mechanical deformation of the scale's spine or reinforced scale lip may initiate stimulation of the nerve terminals described.     

Do lizards and snakes really differ in their ability to take large prey? A study of relative prey mass and feeding tactics in lizards

Adaptations of snakes to overpower and ingest relatively large prey have attracted considerable research, whereas lizards generally are regarded as unable to subdue or ingest such large prey items. Our data challenge this assumption. On morphological grounds, most lizards lack the highly kinetic skulls that facilitate prey ingestion in macrostomate snakes, but (1) are capable of reducing large items into ingestible-sized pieces, and (2) have much larger heads relative to body length than do snakes. Thus, maximum ingestible prey size might be as high in some lizards as in snakes. Also, the willingness of lizards to tackle very large prey items may have been underestimated. Captive hatchling scincid lizards (Bassiana duperreyi) offered crickets of a range of relative prey masses (RPMs) attacked (and sometimes consumed parts of) crickets as large as or larger than their own body mass. RPM affected foraging responses: larger crickets were less likely to be attacked (especially on the abdomen), more likely to be avoided, and less likely to provide significant nutritional benefit to the predator. Nonetheless, lizards successfully attacked and consumed most crickets ≤35% of the predator’s own body mass, representing RPM as high as for most prey taken by snakes. Thus, although lizards lack the impressive cranial kinesis or prey-subduction adaptations of snakes, at least some lizards are capable of overpowering and ingesting prey items as large as those consumed by snakes of similar body sizes.     

湖南省永州都庞岭自然保护区爬行动物群落结构的调查研究

本文报道了湖南永州都庞岭自然保护区的４１ 种爬行动物, 它们隶属２ 目,１２ 科, 其中龟鳖目３ 科（平胸龟科、龟科、鳖科） ３ 种; 有鳞目中的蜥蜴亚目５ 科（鬣蜥科、壁虎科、石龙子科、蜥蜴科、双足蜥科） ８ 种;蛇亚目４ 科（闪鳞蛇科、游蛇科、眼镜蛇科、蝰科） ３０ 种。保护区内的爬行动物有１２－２％ 属广布动物, ８７－８％ 属东洋界种类。     

Invader danger: lizards faced with novel predators exhibit an altered behavioral response to stress

Animals respond to stressors by producing glucocorticoid stress hormones, such as corticosterone (CORT). CORT acts too slowly to trigger immediate behavioral responses to a threat, but can change longer-term behavior, facilitating an individual's survival to subsequent threats. To be adaptive, the nature of an animal's behavior following elevated CORT levels should be matched to the predominant threats that they face. Seeking refuge following a stressful encounter could be beneficial if the predominant predator is a visual hunter, but may prove detrimental when the predominant predator is able to enter these refuge sites. As a result, an individual's behavior when their CORT levels are high may differ among populations of a single species. Invasive species impose novel pressures on native populations, which may select for a shift in their behavior when CORT levels are high. We tested whether the presence of predatory invasive fire ants (Solenopsis invicta) at a site affects the behavioral response of native eastern fence lizards (Sceloporus undulatus) to elevated CORT levels. Lizards from an uninvaded site were more likely to hide when their CORT levels were experimentally elevated; a response that likely provides a survival advantage for lizards faced with native predatory threats (e.g. birds and snakes). Lizards from a fire ant invaded site showed the opposite response; spending more time moving and up on the basking log when their CORT levels were elevated. Use of the basking log likely reflects a refuge-seeking behavior, rather than thermoregulatory activity, as selected body temperatures were not affected by CORT. Fleeing off the ground may prove more effective than hiding for lizards that regularly encounter small, terrestrially-foraging fire ant predators. This study suggests that invasive species may alter the relationship between the physiological and behavioral stress response of native species.     

昆明市宠物市场爬行动物贸易调查

目的了解昆明市宠物市场上销售爬行动物的种类、数量、来源、价格及市场管理情况,为爬行类资源的保护和管理提供基础资料。方法采用观察和访谈相结合方式进行调查。结果昆明市6个宠物市场爬行动物类共有35种,其中蛇类14种,隶属3科12属;蜥蜴类6种,隶属4科5属;龟类15种,隶属6科12属。国外物种15种,占市场种类的42.9%;国内物种20种,占57.1%。依据《中国物种红色名录》(2004),1种为极危,4种为濒危,2种为易危;属于CITES(2013)附录Ⅱ有5种,附录Ⅲ有3种;属于国家重点保护的有2种。结论昆明市宠物市场爬行动物贸易缺乏相应的法制法规进行监督管理,应尽早制定规章制度加强对市场的管理,使市场更加规范有序。