Functional genomics of molluscan schistosome development

描述(由申请人提供)：这项拟议研究的长期目标是识别和功能表征在人类血吸虫曼氏血吸虫中调节软体内幼虫发育的基因。血吸虫在钉螺中间宿主体内的发育是复杂的，包括钉螺感染毛虫、母孢子囊、子孢囊，最后是人感染尾蚴。由于毛虫到母孢子囊的转变被认为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关键的、阶段特异性的基因表达变化来调节的。同样，在母孢子囊中启动无性繁殖(胚胎发生)以产生多个子孢子囊和在子孢子囊内形成尾蚴，被推定涉及通过以阶段特定的方式差异表达基因来协调发育过程。 然而，到目前为止，人们对软体动物幼虫阶段，特别是无性繁殖的孢子囊中表达的基因的同源性知之甚少，也没有关于从毛虫到母孢子囊再到子孢子囊的顺序发育过程中基因表达谱变化的信息。为了解决这一关键信息 GAP，并开始研究幼虫发育是由明确的阶段特异性基因表达变化驱动的假设，提出了以下具体目标：(1)利用曼氏链球菌寡核苷酸基因芯片评估体外培养条件下毛虫和母孢子囊(早期和晚期发育)的基因表达谱；(2)通过测量表达水平来确认和验证体外DNA微阵列结果 目的：(1)研究在体内感染条件下发育的母孢子囊中的特定基因；(3)利用血吸虫基因微阵列分析钉螺宿主因素对幼虫血吸虫基因表达的影响，然后鉴定和鉴定调控幼虫表达的蜗牛分子；以及(4)用双链RNA干扰方法评估已发现在幼虫阶段相关上调的特定基因是否在功能上与特定的发育表型相关。预计拟议的 微阵列方法将填补曼氏血吸虫幼虫阶段相关基因表达的关键信息空白，并将为特定基因在调节发育过程中的作用提供重要的见解。这项工作的结果可能会导致新的战略 用于通过干扰特定的依赖于幼虫发育的基因或其产物来控制蜗牛宿主内的感染。

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.