Metabolic interdependency of tsetse fly symbiosis

描述(由申请人提供)：采采蝇具有很高的公共卫生和农业意义，因为它在非洲锥虫病的传播中具有重要的媒介作用。布氏锥虫(Trypanosoma brucei subspp.)它们依靠采采蝇的发育、重组、繁殖和传播。采采蝇还含有两种肠道细菌共生体，Wigglesworth glossinidia和Sodalis glossinidius。据信，这些微生物共生体提供了代谢能力，使采采人的专门生活方式成为唯一的血液喂养。血液虽然富含氨基酸和脂肪，但缺乏许多B族维生素，尤其是硫胺素。目前提案的总体目标是检查共生代谢整合及其在采采蝇适合性和媒介能力中的作用。这项研究背后的具体假设是，Sodalis和Wigglesworth的能量处理是采采蝇微生物动态平衡的关键因素，干扰改变了宿主的适合性和媒介能力。这一假设基于以下观察结果。首先，在采摘发育的代谢密集期，苏丹花和威格尔斯沃斯的生长动态相似，这支持了能量加工中的重叠作用。其次，Wigglesworth和Sodalis的显著增殖发生在普通成虫(即新成虫)生活期，也就是野生采采蝇媒介能力最高的发育期。第三，比较基因组分析以及它们在采采绒中肠内的物理接近，表明从头合成硫胺素(维生素B1)是由Wigglesworth独家完成的，随后由Sodalis通过硫胺素挽救途径获得。第四，我们的初步数据表明，红豆草的增殖需要外源维生素的供应。第五，我们的初步数据还表明，无论是在培养中还是在采采蝇体内，钠硫胺挽救途径都受到外源硫胺素的反向调节，特别是硫胺素一磷酸(TMP)。为了验证我们的假设，我们将通过表达分析和遗传操作来检验苏丹斯硫胺素挽救途径的功能调节。采采蝇，Glossina morsitans morsitans，将与苏丹斯硫胺素招募突变体重组，并评估宿主健康特征。最后，补充维生素B对降低非一般无采采蝇的高媒介能力的效果将被调查。更多地了解采采蝇共生体的能量处理过程，扩大了我们对采采蝇生物学的现有知识，并可能刺激抗击非洲锥虫病的替代战略。 与公共卫生相关：采采蝇具有很高的公共卫生和农业意义，因为它在非洲锥虫病的传播中发挥了媒介作用。采采蝇还拥有有限的消化道微生物群落，这些微生物群落是其宿主生物学的关键组成部分，也与锥虫感染共存。这项研究扩大了我们对采采蝇生物学的理解，并为媒介控制策略提供了潜在的新途径。

DESCRIPTION (provided by applicant): The tsetse fly is of high public health and agricultural significance due to its obligate vector role in the transmission of African trypanosomiasis. Trypanosomes (Trypanosoma brucei subspp.) rely on the tsetse fly for their development, recombination, multiplication and transmission. Tsetse flies also harbour two enteric bacterial symbionts, Wigglesworthia glossinidia and Sodalis glossinidius. It is believed that these microbial symbionts provide metabolic capabilities that enable tsetse's specialized lifestyle of exclusive blood feeding. Blood although rich in amino acids and lipids is deficient in many B vitamins, particularly thiamine. The overall objective of the current proposal is to examine symbiotic metabolic integration and its role in tsetse fly fitness and vector competence. The specific hypothesis behind the proposed research is that energy processing by Sodalis and Wigglesworthia serves as a critical factor in the microbial homeostasis of the tsetse fly with disruption altering host fitness and vector competence. This hypothesis is based on the following observations. First, the similar growth dynamics of Sodalis and Wigglesworthia during metabolically intensive periods of tsetse development supports overlapping roles in energy processing. Second, significant Wigglesworthia and Sodalis proliferation occurs at the teneral adult (i.e. newly eclosed) life stage, the developmental period of highest vector competence in wild type tsetse flies. Third, comparative genomic analyses as well as their physical proximity within the tsetse midgut, suggests that de novo thiamine (Vitamin B1) synthesis is exclusively performed by Wigglesworthia and subsequently acquired by Sodalis through a thiamine salvage pathway. Fourth, our preliminary data demonstrate that the proliferation of Sodalis density requires vitamins provided by an exogenous source. Fifth, our preliminary data also suggests that the Sodalis thiamine salvage pathway is inversely regulated by exogenous sources of thiamine, specifically thiamine monophosphate (TMP), both in culture and within the tsetse fly. To test our hypothesis, the functional regulation of the Sodalis thiamine salvage pathway will be examined through expression analyses and genetic manipulation. Tsetse flies, Glossina morsitans morsitans, will be reconstituted with Sodalis thiamine recruitment mutants and host fitness traits evaluated. Lastly, the effect of B-vitamin supplementation towards reducing the higher vector competence exhibited by non-teneral Wigglesworthia-free tsetse flies will be investigated. A greater understanding of the energy processing of tsetse fly symbionts expands our existing knowledge of tsetse fly biology and may stimulate alternative strategies towards combating African trypanosomiasis. PUBLIC HEALTH RELEVANCE: The tsetse fly is of high public health and agricultural significance due to its vector role in the transmission of African trypanosomiasis. Tsetse flies also harbour a limited digestive tract microbial community that are critical components of their host's biology and also co-localize with trypanosome infections. The proposed research expands our understanding of tsetse fly biology and offers potential novel avenues for vector control strategies.