DIFFERENTIAL ACCUMULATION AND TISSUE DISTRIBUTION OF MOSQUITO HEXAMERINS DURING METAMORPHOSIS

The pupal hexamerins were characterized for two mosquitoes representat ive of the culicine and anopheline families, Aedes aegypti and Anophel es gambiae. Like higher Diptera, both mosquito species express two typ es of hexamerins, Hex-1 and Hex-2, whose subunits are distinguished by different levels of methionine and aromatic amino acids. In A. aegypt i there are two heterohexamers, AaHex-1 and AaHex-2. In A. gambiae the re are two homohexamers, AgHex-1.1 and AgHex-1.2, and one heterohexame r, AgHex-2. These hexamerins are rich in aromatic residues, with 18-23 % Phe + Tyr for Hex-1 subunits and 13-17% Phe + Tyr for Hex-2 subunits . In addition, both mosquito species synthesize methionine-rich Hex-1 subunits: Aedes AaHex-1 gamma (8% met) and Anopheles AgHex-1.1 (3.9% m et). Aedes Hex-1 and Hex-2 proteins exhibit different, stage-specific tissue distributions: AaHex-2 is the primary hexamerin of late larval hemolymph whereas AaHex-1 is the most important non-hemolymph protein of early pupae. Although both proteins are stored in the pupal fat bod y, peak AaHex-1 levels are 2-fold higher. Both pupal protein levels de cline rapidly between 25 and 36 h after pupation. Furthermore, AaHex-1 not only reaches peak values in female Aedes pupae later than in male s, but the methionine-rich AaHex-1 gamma subunit level is specifically higher in females. These observations suggest different roles for Hex -1 and Hex-2 during mosquito development. (C) 1997 Elsevier Science Lt d. All rights reserved.