Drosophila hemolectin gene is expressed in embryonic and larval hemocytes and its knock down causes bleeding defects.

AbstractWe have previously identified and characterized Drosophila hemolectin (Hml) in the conditioned medium of a Drosophila cell line. Thededuced amino acids sequence contains a number of domains conserved in human von Willebrand factor, coagulation factor V/VIII, andcomplement factors. To characterize Hml localization and function, we have established two transgenic lines (hml-GAL4and UAS-hmlRNAi). By crossing hml-GAL4with UAS-eGFP,we observed that Hml is specifically expressed in embryonic and in larval hemocytes.We determined that Hml is expressed in a subpopulation of plasmatocytes and crystal cells but not in lamellocytes. hml RNAi larvae areviable and do not display obvious developmental defects under normal conditions. However, they show a bleeding defect upon injury. Weconfirmed that the failure to seal a wound is not due to a defect in melanin production or in phenoloxidase activity. The expression ofamtimicrobial peptides was not significantly affected on hml RNAi adults. Altogether, our data strongly suggest that Hml is involved inhemostasis and/or coagulation in Drosophila larvae.© 2003 Elsevier Inc. All rights reserved.