Short distance non-autonomy and intercellular transfer of chitin synthase in Drosophila

Abstract The complex structure of insect exoskeleton has inspired material scientists and engineers. Chitin is a major component of the cuticle and it is synthesized by the enzyme chitin synthase. There is a single chitin synthase gene (kkv) in Drosophila facilitating research on the function of chitin. Previous editing of kkv lead to the recovery of a viable hypomorphic allele. Experiments described in this paper argue that a reduction in chitin synthase leads to the shafts of sensory bristles becoming fragile and frequently breaking off as the animals age. This is likely due to reduced chitin levels and further suggests that chitin plays a role in resilience of insect cuticle. The different layers in cuticle are continuous across the many epidermal cells that secrete the cuticle that covers the body. Little is known about the mechanisms responsible for this continuity. Using genetic mosaics and scanning electron microscopy this paper establishes that kkv shows short range cell non-autonomy. It also provides evidence for 2 possible mechanisms. One is the intercellular transfer of Kkv protein from one cell to its neighbors and the second is the deposition of cuticular material across the boundaries of neighboring cells.