RT Journal Article
SR Electronic
T1 The localization of chitin synthase mediates the patterned deposition of chitin in developing Drosophila bristles
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 718841
DO 10.1101/718841
A1 Paul N. Adler
YR 2019
UL http://biorxiv.org/content/early/2019/07/30/718841.abstract
AB The insect exoskeketon is a morphologically complex structure that is a key for the life style of this very successful group of animals. The cuticular cytoskeleton contains proteins, lipids and the N-acetyl glucosamine polymer chitin. Chitin is a highly patterned and essential component of the insect exoskeleton synthesized by chitin synthase. In most body regions chitin fibrils are found in a stack of parallel arrays that can be detected by transmission electron microscopy. Each array is rotated with respect to the layers above and below. In sensory bristles, chitin primarily accumulates in bands parallel to the proximal/distal axis of the bristle. These bands are visible by confocal microscopy providing experimental advantages. We have used this cell type and an edited chitin synthase gene to establish that the bands of chitin are closely associated with stripes of chitin synthase. This argues that the localization of chitin synthase plays an important role in mediating the patterned deposition of chitin in insect cuticle. However, other data suggest this connection may not be absolute. Several genes are essential for proper chitin deposition. We found one of these, Rab11 is required for the insertion of chitin synthase into the plasma membrane and a second, duskylike is required for plasma membrane chitin synthase to properly localize into stripes. We also established that the actin cytoskeleton is required for the proper localization of chitin synthase and chitin in developing sensory bristles. An unexpected finding is that chitin synthase and other membrane proteins are shed during or after the process of cuticle deposition and this may explain cases where there is a lack of a sharp phenotypic boundary between cells that have or lack chitin synthase activity.