Evolution of the Retrotransposons R1 and R2

小行星9601198 转座因子是真核生物基因组的重要组成部分，在决定基因组的大小和结构方面发挥着重要作用。R1和R2是在所有昆虫谱系和所有节肢动物纲中发现的插入在28 S核糖体RNA基因中的逆转录转座因子。将从现代和古代昆虫目以及节肢动物的每一类中分离R1和R2元件，并在开放阅读框的区域中进行测序。这些信息将用于构建系统发育树，目的是确定这些元素自节肢动物起源以来是否存在。将研究果蝇属内R1和/或R2的高度发散家族的起源和稳定性。每个家庭是否可以独立地调节自己的水平插入和横向转移的问题将得到解决。将调查这些元素在维持在高和低平均水平的物种中的种群动态。这些研究将通过计算机模拟来补充，以确定重组和反转录转座的简单模型是否可以解释观察到的分布。 %移动的元件或其残余物占大多数真核生物基因组的30%。这些元件可能对真核生物染色体的大小和结构产生了重大影响，值得注意的是，关于它们的进化、调节以及对宿主的成本或效益的许多基本问题仍然没有答案。这项研究将增加我们对宿主基因组中转座因子的遗传影响所知甚少。 ***

9601198 Eickbush Transposable elements, abundant components of eukaryotic genomes, have probably played a significant role in determining the size and structure of these genomes. R1 and R2 are retrotransposable elements found inserted in the 28S ribosomal RNA genes in all insect lineage's and in all classes of Arthropods. R1 and R2 elements from modern and ancient insect orders, as well as from each class of Arthropod will be isolated and sequenced in the region of the open reading frame. That information will be used to construct a phylogenetic tree with the goal of determining if the elements have been present since the origin of arthropods. The origin and stability of highly divergent families of R1 and/or R2 within the genus Drosophila will be studied. The questions of whether each family can independently regulate its own level of insertion and of horizontal transfer will be addressed. The population dynamics of these elements in species where they are maintained at high and low average levels will be investigated. These studies will be complemented by computer simulations to determine whether simple models of recombination and retrotransposition can explain the observed distributions. %%% Mobile elements or their remnants represent as much as 30% of the genomes of most eukaryotes. It is probable that these elements have had a significant impact on size and structure of eukaryotic chromosomes and it is remarkable that many basic questions concerning their evolution, regulation and costs or benefits to their hosts remain unanswered. This study will add to the little we know of the genetic impact of transposable elements in host genomes. ***