Construction of a lipid-based barrier against dehydration in Drosophila melanogaster

生物体需要在出生后保护自己免受干燥。一般来说，在脊椎动物和无脊椎动物中，脂肪在胚胎的终末分化过程中被结合到皮肤中，以建立一种屏障，防止失水。自上世纪30年代的S以来，人们推测，一种在组织学上已被鉴定但分子上尚未确定的儿茶酚胺-脂-蛋白复合体--角质蛋白--是昆虫皮肤细胞外部分角质层防水的关键元素。研究还表明，昆虫表面的游离脂有助于抵抗干燥。昆虫角质层中脂质结合和组装的分子机制在很大程度上还没有得到研究。在本项目中，我建议研究在果蝇体内建立基于脂质的防水屏障中Snustorr(Snu)、Torr和Snustorr snarlik(Snsl)蛋白的作用。特别是在幼虫SNU(编码类似TorR的ABC转运蛋白)和SNSL(编码胞外蛋白)的突变体中，角质层假定的防水层受到严重破坏。在这些突变的胚胎中，角质蛋白的组织学检测一直失败。简而言之，我假设SNSL稳定细胞外脂质，这一过程需要SNU和TORR的底物，从而推动角质层防水屏障的形成。在一系列使用标记的角质层蛋白和标记的脂质的活体成像显微镜实验中，结合精密的电子显微镜，我试图解开基于脂质的屏障形成的系统和细胞途径，并整合SNU、TorR和SNSL在这些过程中的功能。借此，这项工作将有助于理解角质蛋白，这是分子生物学中的一个经典和中心问题。这些数据可能有助于开发针对昆虫的特定杀虫剂，用于智能、生态正确的害虫管理。此外，器官分化过程中脂质分布的实时成像是该领域的开创性工作。

Organisms need to protect themselves against desiccation after birth. Generally, in vertebrates and invertebrates, lipids are incorporated into the skin during its terminal differentiation in the embryo in order to establish a barrier preventing uncontrolled water loss. Since the 30's of the last century it is postulated that a histologically identified, but yet molecularly uncharacterised catecholamine-lipid-protein complex named cuticulin is a crucial element of the waterproofness of the cuticle, the extracellular part of the insect skin. It has also been shown that free lipids at the surface of insects contribute to desiccation resistance. The molecular mechanisms of lipid incorporation and assembly in the insect cuticle are largely unstudied.In the present project, I propose to investigate the roles of the genetically identified Snustorr (Snu), Torr and Snustorr snarlik (Snsl) proteins in establishing a lipid-based waterproof barrier in the fruit fly Drosophila melanogaster. Especially in larvae mutant for snu (coding - like torr - for an ABC transporter) and snsl (coding for an extracellular protein) the presumptive waterproof layer of the cuticle is severely damaged. Consistently, histological detection of cuticulin fails in these mutant embryos. In brief, I hypothesise that Snsl stabilises extracellular lipids and that the substrates of Snu and perhaps Torr are needed for this process thereby driving the formation of the cuticular waterproof barrier. In a series of live imaging microscopy experiments using tagged cuticle proteins and marked lipids, combined with elaborate electron microscopy, I seek to unravel the systemic and cellular pathways of lipid-based barrier formation and integrate the function of Snu, Torr and Snsl in these processes. By this, this work would contribute to the understanding of cuticulin, a classical and central problem in molecular biology. The data may serve to develop insect-specific pesticides for intelligent, ecologically correct pest management. Moreover, live imaging of lipid distribution during organ differentiation constitutes a pioneering work in the field.