The role of Dynein Heavy Chain in Drosophila bristle growth. Anna Melkov, Uri Abdu. Department of Life Sciences, Ben-Gurion University, Beer-Sheva 84105, Israel.

   The highly elongated Drosophila sensory bristles have proven to be a valuable model system for studying cellular morphogenesis. Recently work in our lab showed that microtubuli (MT's) in the bristle are composed of two different MT's sets. The first MT population comprises stable, minus end-distal unipolarized MTs. The second MT population is dynamic and shows mixed polarity. However, the mechanism by which bristle MT's organize is still unknown. We focused our analysis on Dynein Heavy Chain (DHC) gene, since it was shown that DHC have a crucial role in controlling the orientation of axonal MTs in Drosophila. We further characterized the bristle defects in several viable trans-heterozygous dhc mutants using scanning electron microscopy. We noticed that dhc macrocheata but not microcheata are much shorter than their counterpart wild type ones. Moreover, the first two-third of the bristles length (both in micro-and macrocheta) was wider with abnormally organized surface grooves, with the ridges not being parallel to each other. Then, the bristle becomes much thinner and flattened towards the bristle tip and its surface was smooth. More than 50% of the bristles were split at the base, with a minute extension in opposite direction to the bristle growth. In the next future we will study the mechanism by which dhc affects bristle growth.