SEX DETERMINATION IN REPTILES--PIT VIPERS AND TORTOISES

爬行动物的性别决定——毒蛇和陆龟

• 批准号: 3734404
• 负责人: DAVID J MORAFKA
• 金额: --
• 依托单位: CALIFORNIA STATE UNIV-DOMINGUEZ HILLS
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3734404
• 关键词: Chelonia; alternatives to animals in research; animal ecology; biochemical evolution; cytogenetics; environmental stressor; field study; in situ hybridization; karyotype; northern blottings; reptile poison; sex chromosomes; sex determination; snakes; southern blotting; systematic biology; telemetry; temperature

This project will attempt to identify, describe, compare, and contrast the sex determination systems of two different groups of reptiles, pit vipers (subfamily Crotalinae) and tortoises (family Testudinidae). Pit vipers have heterogametic females (ZW, males being ZZ) which determine the sex of their offspring by classical sex chromosome segregation (GSD = Genetic Sex Determination). Tortoises lack sex chromosomes. They are believed to resolve sex through Environmental Sex Determination (ESD), though this has only been demonstrated in one of nearly fifty species (Testudo graeca, Pieau, 1975). NORs and C and G-banded karyotypes will be obtained for all genera in both families (of subfamilies). A new pit viper phylogeny, based upon separate sets of karyotypic, allozyme, DNA-DNA hybridization, visceral topography and karyotypes will be constructed for this widespread and extremely dangerous group of poisonous snakes. An accurate phylogeny will guide toxicologists and immunologists in their search for antibodies effective against the venom components of close relatives as well as pharmacologists in their search for related sources of venom fractions valuable to medicine. Continuous monitoring of natural nests of desert tortoise (Gopherus Agassizii) eggs at Ft. Irwin, California, will provide new information about ambient temperatures fluctuation, relative humidities and gas partial pressures. This information will make possible novel experiments subjecting captive tortoise eggs to variations (both degree and duration) in these same parameters which may produce skewed sex ratios in hatchlings. Morphometric techniques for non-invasive sexing of neonates are proposed using three dimensional fractal geometry. Collaborative studies with MBRS PI John Roberts will include Souther blot hybridization and subsequent in situ hybridization of the mammalian male Sry gene on snake and tortoise genomic DNA, and periodic monitoring of RNA and protein synthesis during tortoise embryogenesis. These changes in gross chromosome morphology, and help explain the selective pressures producing the phylogenetic differences within both groups. In this way, both universal and taxon specific elements in the genetics of sex determination might be resolved.

该项目将尝试识别，描述，比较和对比 两种不同的爬行动物组的性别确定系统 （crotalinae亚家族）和乌龟（家庭睾丸科）。 维普斯 具有异质体女性（ZW，男性为ZZ），这些雌性决定的性别 他们的后代是经典性别染色体隔离（GSD =遗传性别 决心）。 乌龟缺乏性染色体。 他们被认为是 通过环境确定（ESD）解决性别，尽管这有 仅在近五十种（testudo graeca）中得到证明 皮奥（Pieau），1975年）。 NORS和C和G带核型将获得所有属的所有属 （亚家族）的家庭。 基于独立的新维普尔系统发育 核型，同酶，DNA-DNA杂交，内脏地形 并将为此广泛且极其构建核型 危险的有毒蛇。 精确的系统发育将引导 毒理学家和免疫学家在寻找有效的抗体时 针对近亲的毒液成分以及药理学家 在寻找相关的毒液分数来源时， 药品。 连续监测沙漠乌龟的自然巢（Gopherus ft的agassizii）鸡蛋。加利福尼亚州欧文将提供新信息 关于环境温度波动，相对湿度和气体部分 压力。 这些信息将使可能的新实验可能 将圈养的乌龟卵变异（程度和持续时间） 在这些相同的参数中，可能会在孵化场中产生偏斜的性别比。 提出了针对新生儿非侵入性性别的形态计量技术 使用三维分形几何形状。 与MBRS PI John Roberts的合作研究将包括Souther Blot 哺乳动物男性的杂交和随后的原位杂交 蛇和乌龟基因组DNA的基因，并定期监测RNA 和乌龟胚胎发生过程中的蛋白质合成。 这些变化 总体染色体形态，并帮助解释选择性压力 两组内产生系统发育差异。 这样， 性别遗传学中的通用和分类单元特定元素 决心可以解决。