MOLECULAR EVOLUTION OF REPTILES WITH EMPHASIS ON MECHANISMS OF SEX DETERMINATION

爬行动物在核型上倾向于非常保守，但却进化出了一种 性别决定的各种机制，包括遗传型性别 XX/XY型决定，ZZ/ZW型决定性别 类型和环境性别决定，其中性别由 环境刺激，如发育期间的孵化温度。 拟议的实验有两个主要目标：比较 爬行动物不同性别决定机制的分子基础；以及 利用DNA序列数据构建不同物种间的系统发育关系 某些群体的毒蛇。 Southern杂交将用于寻找同源序列 与蛇类基因组DNA中哺乳动物性别决定基因Sry的关系 通过基因决定性别，从沙漠乌龟，与 环境性别决定。如果检测到同源序列，则其 将表明性别决定的所有机制在 基因水平；这可能有助于我们对性染色体的理解 人类的非整倍体综合征。 毒蛇咬伤的很大一部分是由毒蛇造成的。 和死亡人数。拟议的系统发育调查可能有助于 合理生产和使用抗蛇毒血清，并在分离 生物医学上有用的产品。 学生将获得分子遗传学的背景知识，以及 直接操作各种重组DNA技术的经验 和一般的核酸操作。经过一段时间的训练后，他们将 有机会进行独立研究，从而为 继续攻读研究生课程以获得博士学位，以及 竞争激烈的生物医学研究科学家。

Reptiles tend to be very conservative in karyotype, and yet have evolved a variety of mechanisms for sex determination, including genotypic sex determination of the XX/XY type, genotypic sex determination of the ZZ/ZW type, and environmental sex determination, where sex is determined by an environmental stimulus, such as incubation temperature during development. The proposed experiments have two main goals: a comparison of the molecular bases of different sex determination mechanisms in reptiles; and the use of DNA sequence data to construct phylogenetic relationships among certain groups of pit vipers. Southern blot hybridization will be used to look for sequences homologous to the mammalian sex determination gene, Sry, in genomic DNA from pit viper with genotypic sex determination, and from the desert tortoise, with environmental sex determination. If homologous sequences are detected, it will suggest that all mechanisms of sex determination are similar at the genetic level; this may contribute to our understanding of sex chromosome aneuploidy syndromes in humans. The pit vipers are responsible for a large fraction of snakebite injuries and fatalities. The proposed phylogenetic investigations might aid in the rational production and use of antivenins, and in the isolation of biomedically useful products. Student participants will gain a background in molecular genetics, and direct experience in performing a variety of techniques of recombinant DNA and general nuclei acid manipulation. After a training period, they will have the opportunity to conduct independent research, and thereby prepare for further graduate studies leading to a Ph.D. degree, and for careers as competitive biomedical research scientists.