Population Genetics of Transposable Element Copy Number in Drosophilia

Nuzhdin9815621转座元件(TES)是通过将自身插入新的DNA位置而倍增的DNA序列。在包括人类在内的高等真核生物中，TE转位是突变的主要来源。然而，关于转位活动是如何被调控的，人们知之甚少。努日丁博士将推断自然选择和宿主-TE共同进化在维持宿主基因组中稳定的TE拷贝数量方面的相对贡献。TE活性通常受到宿主的限制；然而，许多基因组有证据表明TE突然爆发。努日丁博士将首先检验TE表达有害这一假设。如果自然选择对表达TES的反应比对缺乏启动子的反应更强烈，这一假说将得到支持。第二个具体目标是推断是什么导致了实验果蝇种群的TE爆炸。为此，将确定负责限制CopiA转座的宿主基因，并将对其允许转座的变体进行分子表征。结果将阐明决定TE活性的因素，以及它们在自然种群中的维持和传播。这一知识将有助于防止未来可能发生的TE爆炸事件，无论是在圈养中逃避自然选择的物种，还是在人类身上都可能发生这种情况。

Nuzhdin9815621Transposable elements (TEs) are DNA sequences that multiply by inserting themselves into new DNA positions. TE transpositions are a major source of mutation in higher eukaryotes including humans. Little is known, however, of how transpositional activity is regulated. Dr. Nuzhdin will infer the relative contribution of natural selection and host-TE co-evolution in maintaining a stable number of TE copies in a host genome. TE activity is normally restricted by the host; however, many genomes have evidence of sudden TE explosions. Dr. Nuzhdin will first test the hypothesis that TE expression is deleterious. This hypothesis will be supported if natural selection acts more strongly against expressing TEs than against those lacking promoters. The second specific aim is to infer what causes TE explosions in model experimental Drosophila populations. For this, the host genes responsible for the restriction of copia transposition will be identified, and their variants permitting transpositions will be molecularly characterized. Results will shed light on the factors determining TE activity, and their maintenance and spread in natural populations. This knowledge will help to prevent possible future instances of TE explosions, which are likely in species escaping natural selection in captivity, as well as in humans.