Dissertation Research: Molecular Characterization and Population Biology of P Elements in Natural Populations of Drosophila

Kidwell转座因子（TEs）存在于大多数生物体中，包括人类、苍蝇、植物和细菌，它们可以构成高达40%或更多的遗传物质。尽管它们数量众多，但人们对TEs的进化方式知之甚少。本课题旨在研究果蝇（Drosophila） te家族P元素的进化过程。te是可移动的DNA片段，可以自我复制并插入宿主物种的新染色体位点。像病毒一样，它们也可以转移到新的宿主身上。对两种果蝇的P元素DNA进行测序。目标是：1)评估自然种群中P元素结构和序列的变化；2)研究不同元素区域的核苷酸取代率，并评估这些取代率揭示了选择性约束的存在；3)估算P元素在果蝇种间的迁移速率。这项研究将有助于理解基因组中te的进化和维持过程。由于TEs和病毒在宿主入侵能力和DNA结构上有相似之处，这些结果将揭示病毒本身是如何在宿主生物中维持和进化的。

9701252 Kidwell Transposable elements (TEs) are present in most organisms, including humans, flies, plants and bacteria, where they can constitute up to 40% or more of the genetic material. Despite their abundance, very little is known about how TEs evolve. This project is to study the evolution of P elements, a family of TEs found in fruitflies of the genus Drosophila. TEs are mobile DNA segments that can self-replicate and insert into new chromosomal sites of the host species. Like viruses, they can also transfer to new hosts. P element DNA of flies of two Drosophila species will be sequenced. The goals are 1) to assess variation in P element structure and sequence in natural populations; 2) to investigate nucleotide substitution rates in different element regions and to assess what those rates reveal about the presence of selective constraints; and 3) to estimate the rate of transfer of P elements between Drosophila species. This investigation will contribute to understanding the processes that determine the evolution and maintenance of TEs in genomes through time. Because TEs and viruses have similarities in host invasion capabilities and in DNA structure, these results will shed light on how viruses themselves are maintained and evolve in their host organisms.