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

• Applicant: Privatdozent Dr. Bernard Moussian
• Subject Area: Developmental Biology ; Evolutionary Cell and Developmental Biology (Zoology)
• Term: from 2014 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269083421

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.

• DFG Programme: Research Grants