Functional genomics of molluscan schistosome development

描述（由申请人提供）：拟议研究的长期目标是鉴定和功能表征人类血吸虫曼氏血吸虫（Schistosoma mansoni）蚓内幼虫发育调节基因。血吸虫在蜗牛中间宿主内的发育是复杂的，包括蜗牛感染的微小体、母孢子囊、子孢子囊，最后是人类感染的尾蚴。因为据推测，从微小菌到母孢子囊的转变涉及从自由生活到寄生存在的许多生理适应，因此假设这种转变是由基因表达的关键阶段特异性变化调节的。同样，在母孢子囊中开始无性生殖（胚胎发生），产生多个子孢子囊，并在子孢子中形成尾蚴，被认为是通过基因的差异表达以特定阶段的方式精心安排的发育过程。

DESCRIPTION (provided by applicant): The long-term goal of the proposed research is to identify and functionally characterize the genes regulating intramolluscan larval development in the human blood fluke Schistosoma mansoni. Schistosome development within the snail intermediate host is complex, involving several stages including the snail-infective miracidium, mother sporocyst, daughter sporocyst, and finally the human-infective cercaria. Because the miracidium -to-mother sporocyst transition is assumed to involve numerous physiological adaptations going from its free-living to parasitic existence, it is hypothesized that such a transition is regulated by critical, stage-specific changes in gene expression. Similarly, the initiation of asexual reproduction (embryogenesis) in mother sporocysts to give rise to multiple daughter sporocysts and within daughters, the formation of cercariae, is presumed to involve developmental processes orchestrated through the differential expression of genes in a stage-specific fashion. However, to date, very little is known regarding the identity of genes expressed in molluscan larval stages, especially the asexually reproducing sporocysts, and there exists no information on changes in gene expression profiles associated with sequential development from the miracidium to mother sporocyst to daughter sporocyst stages. To address this critical information gap, and to begin investigating the hypothesis that larval development is driven by defined stage-specific changes in gene expression, the following specific aims are proposed: (1) to evaluate gene expression profiles for miracidia and mother sporocysts (early-and late-developing) under in vitro culture conditions by employing S. mansoni oligonucleotide gene microarrays; (2) to confirm and validate in vitro DNA microarray results by measuring expression of specific genes in mother sporocysts developing under in vivo infections conditions; (3) to investigate the effects of snail host factors on larval schistosome gene expression using schistosome gene microarray analyses, followed by identification and characterization of larval expression-modulating snail molecules; and (4) to evaluate whether specific genes found to be upregulated in a larval stage-associated manner are functionally tied to defined developmental phenotypes using double-stranded RNA interference methods. It is anticipated that the proposed microarray profiling approach will fill a critical information gap regarding S. mansoni larval stage-associated gene expression, and will provide important insights into the role of specific genes in regulating the developmental process. Results of this work may lead to novel strategies for controlling infections within the snail host by disrupting specific larval development-dependent genes or their products.