MOLECULAR EVOLUTION OF REPTILES WITH EMPHASIS ON MECHANISMS OF SEX DETERMINATION

爬行动物在核型上往往非常保守，但已经进化出了一种 性别决定的各种机制，包括基因型性别 XX/XY型的确定，ZZ/ZW型的基因型性别确定 类型，和环境性别决定，其中性别是由一个 环境刺激，如发育过程中的孵育温度。 所提出的实验有两个主要目标： 爬行动物不同性别决定机制的分子基础;以及 使用DNA序列数据构建系统发育关系， 某些毒蛇群 Southern印迹杂交将用于寻找同源序列 与哺乳动物性别决定基因Sry的同源性 与基因型性别决定，并从沙漠龟，与 环境性别决定 如果检测到同源序列， 这将表明，所有的性别决定机制是相似的， 遗传水平;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 大部分的蛇咬伤都是由蝮蛇引起的 和死亡人数。 拟议的系统发育研究可能有助于 抗蛇毒血清的合理生产和使用， 生物医学上有用的产品。 学生参与者将获得分子遗传学的背景知识， 在执行各种重组DNA技术的直接经验 和一般的核酸操作。 经过一段时间的训练， 有机会进行独立的研究，从而准备 继续攻读博士学位学位，并为职业生涯， 有竞争力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.