Genetic and functional analyses of sperm length evolution in Drosophila

精子是最多样化的细胞类型，在形态上表现出快速和戏剧性的进化变化。然而，人们对精子形态的遗传学和适应性意义知之甚少。研究建议：(1)研究精子长度与女性生殖道内运动/行为的关系；(2)确定对精子长度有重大影响的基因。这些研究将在果蝇种群中进行，这些种群已经被实验进化为拥有异常短或长的精子，以及几个在精子长度上有很大差异的密切相关物种。所有种群都经过基因改造，可以产生头部在荧光灯下发出绿色或红色光芒的精子。这种材料将在第一次研究中明确区分两次交配的雌性中不同雄性的精子，并在体内直接观察精子的实时运动以及精子与精子和精子与雌性的相互作用。第二项研究将使用突破性的基因测序技术(即限制性内切酶相关DNA图谱)来确定与精子长度变异相关的基因。拟议的研究有可能在生殖生理和遗传学、性选择和物种形成等领域产生分水岭进展。在这项工作的过程中，将培养许多本科生和研究生。因此，我们对女性精子行为的了解以及对导致精子形成的候选基因的识别也可能导致我们对人类不孕不育的理解和治疗的进步，以及用于保护受威胁和濒危物种的辅助生殖技术的进一步发展。

Spermatozoa are the most diverse cell type, exhibiting rapid and dramatic evolutionary changes in form. However, the genetics and adaptive significance of sperm form are poorly understood. Investigations are proposed (1) to examine the relationship between sperm length and motility/behavior within the female reproductive tract, and (2) to identify genes of major influence on sperm length. These studies will be conducted with populations of the fruit fly Drosophila melanogaster that have been experimentally evolved to have unusually short or long sperm, and several closely related species differing substantially in sperm length. All populations have been genetically engineered to produce sperm whose heads glow green or red under fluorescent light. This material will enable, in the first investigation, unambiguous discrimination among sperm from different males within twice-mated females, as well as direct observation in vivo of real-time sperm motility and sperm-sperm and sperm-female interactions. The second investigation will use breakthrough gene sequencing technology (i.e., restriction-site associated DNA mapping) to identify genes associated with sperm length variation.The proposed research has the potential to generate watershed advances in the fields of reproductive physiology and genetics, sexual selection and speciation. Many undergraduate and graduate students will be trained in the course of this work. Resulting progress in our understanding of sperm behavior within females and the identification of candidate genes contributing to sperm form are also likely to lead to advances in our understanding and treatment of human infertility and in the further development of assisted reproductive technologies used in the preservation of threatened and endangered species.