Department of Medical and Molecular Genetics, Indiana University School of Medicine, South Bend, Indiana, USA.
PLoS Negl Trop Dis. 2013 May 16;7(5):e2215. doi: 10.1371/journal.pntd.0002215. Print 2013.
Despite the devastating impact of mosquito-borne illnesses on human health, surprisingly little is known about mosquito developmental biology, including development of the olfactory system, a tissue of vector importance. Analysis of mosquito olfactory developmental genetics has been hindered by a lack of means to target specific genes during the development of this sensory system. In this investigation, chitosan/siRNA nanoparticles were used to target semaphorin-1a (sema1a) during olfactory system development in the dengue and yellow fever vector mosquito Aedes aegypti. Immunohistochemical analyses and anterograde tracing of antennal sensory neurons, which were used to track the progression of olfactory development in this species, revealed antennal lobe defects in sema1a knockdown fourth instar larvae. These findings, which correlated with a larval odorant tracking behavioral phenotype, identified previously unreported roles for Sema1a in the developing insect larval olfactory system. Analysis of sema1a knockdown pupae also revealed a number of olfactory phenotypes, including olfactory receptor neuron targeting and projection neuron defects coincident with a collapse in the structure and shape of the antennal lobe and individual glomeruli. This study, which is to our knowledge the first functional genetic analysis of insect olfactory development outside of D. melanogaster, identified critical roles for Sema1a during Ae. aegypti larval and pupal olfactory development and advocates the use of chitosan/siRNA nanoparticles as an effective means of targeting genes during post-embryonic Ae. aegypti development. Use of siRNA nanoparticle methodology to understand sensory developmental genetics in mosquitoes will provide insight into the evolutionary conservation and divergence of key developmental genes which could be exploited in the development of both common and species-specific means for intervention.
尽管蚊媒疾病对人类健康造成了毁灭性的影响，但人们对蚊子的发育生物学，包括嗅觉系统的发育，了解甚少。嗅觉系统是一个载体组织，对蚊子的嗅觉发育遗传分析一直受到缺乏在这个感觉系统发育过程中靶向特定基因的手段的阻碍。在这项研究中，壳聚糖/siRNA 纳米颗粒被用于在登革热和黄热病载体蚊子埃及伊蚊的嗅觉系统发育过程中靶向 semaphorin-1a（sema1a）。免疫组织化学分析和触角感觉神经元的逆行追踪，用于追踪该物种嗅觉发育的进展，揭示了 sema1a 敲低第四龄幼虫触角叶缺陷。这些发现与幼虫气味追踪行为表型相关，表明 Sema1a 在发育中的昆虫幼虫嗅觉系统中具有以前未报道的作用。对 sema1a 敲低蛹的分析也揭示了许多嗅觉表型，包括嗅觉受体神经元靶向和投射神经元缺陷，同时伴随着触角叶和单个神经节的结构和形状崩溃。这项研究是我们所知的在黑腹果蝇之外对昆虫嗅觉发育进行的首次功能遗传分析，确定了 Sema1a 在埃及伊蚊幼虫和蛹嗅觉发育过程中的关键作用，并提倡使用壳聚糖/siRNA 纳米颗粒作为在埃及伊蚊胚胎后发育过程中靶向基因的有效手段。使用 siRNA 纳米颗粒方法学来了解蚊子的感觉发育遗传学将提供对关键发育基因的进化保守性和趋异的深入了解，这些基因可以在共同和特定物种干预手段的开发中得到利用。
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