REGULTION IN STRONGYLOIDES STERCORALIS

寄生线虫使全世界数百万人患病或衰弱。在这些线虫的绝大多数中，第三幼虫期（L3）构成脊椎动物宿主的感染期。无论这些L3在感染过程中是如何获得的，它们都可以被视为过渡性的，处于发育停滞的状态，只有在暴露于最终宿主中存在的线索时才被重新激活。 这些寄生虫调节L3发育的机制尚不清楚，这方面的研究因缺乏涉及寄生线虫的分子遗传系统而受到阻碍。相比之下，L3的发育生物学，包括在连续和停滞（dauer）发育之间的转换，已经在自由生活的线虫秀丽隐杆线虫中进行了积极的研究，从而产生了关于该生物体的丰富的相关分子遗传信息。这项研究的总体目标是确定是否有类似于C。线虫还调节寄生虫粪类圆线虫的发育。S.选择Stercoralis作为模型是因为，在众多其他功能和形态学相似性中，这种蠕虫具有另一种自由生活周期，使人想起C.，优雅这个建议的具体目的是，首先，确定在S。与控制C. stercoralis发育的daf途径的胰岛素样分支上的四个关键基因同源。秀丽隐杆线虫L3.为此目的的工作将强调PCR方法，包括基于已发表的C. elegans基因序列研究的目标基因是C.秀丽线虫DAF-2、AGE-1、DAF-18和DAF-16。其次，我们将研究假定的S的功能。Stercoralis daf同系物。推定的dauer诱导基因的功能同源性将通过用特异性双链RNA切除转录物来确定。通过在适当的C.秀丽线虫突变体最后，我们将奋进开发S. stercoralis，以评估推定的调控基因的功能。目前广泛采用的DNA转化方法是C.通过显微注射到性腺合胞体中将使秀丽隐杆线虫适应。

Parasitic nematodes sicken or debilitate millions of persons worldwide.. In the vast majority of these nematodes the third larval stage (L3) constitutes the infective stage for the vertebrate host. Regardless of how these L3 are acquired during the infection process, they may be viewed as transitional , in a state of developmental arrest, which are reactivated only then exposed to cues present in the definitive host. The mechanism by which these parasites regulate development in the L3 remain unclear, studies in this area having been hampered by the lack of a molecular genetic system involving a parasitic nematode. By contrast, the developmental biology of L3, including the switch between continuous and arrested (dauer( development, has been under active investigation in the free-living nematode Caenorhabditis elegans, resulting in a wealth of relevant molecular genetic information on that organism. The overall goal of the proposed study is to ascertain whether mechanisms similar to those acting in C. elegans also regulate development in the parasite Strongyloides stercoralis. S. stercoralis was chosen as a model because, among numerous other functional and morphological similarities, this worm has an alternative free-living cycle reminiscent of the continuous development cycle of C., elegans. The specific aims of this proposal are, first, to ascertain the existence in S. stercoralis of homologs to four key genes on the insulin-like branch of the daf pathway which controls development in C. elegans L3. Work toward this aim w3ill stress a PCR approach involving primers based on published C. elegans gene sequences. Genes targeted for study are homologs of C. elegans daf-2, age-1, daf-18 and daf-16. Second, we will investigate the function of the putative S. stercoralis daf homologs. Functional homology of putative dauer inducing genes will be ascertained by ablating transcripts with specific double stranded RNA. Homology of dauer inducers and putative dauer suppressing genes will be investigated by complementation studies in appropriate C. elegans mutants. Finally, we will endeavor to develop methods for germ line transformation of S. stercoralis in order to assess function of putative regulatory genes. Methods widely used for DNA transformation of C. elegans via microinjection into gonadal syncytia will be adapted.