Expression patterns of the larval and adult hexamerin genes of Musca domestica

Hexamerins are proteins found in high abundance in the haemolymph of larval and adult insects. The expression patterns of the genes encoding the house fly, Musca domestica, hexamerins were determined by Northern analyses usin g cDNAs as probes. A cDNA, A1, hybridized to a fat body-specific messenger RNA (mRNA) which is detectable in larvae until pupation. Antibodies raised to the larval-specific hexamerin, Hex-L, bind recombinant protein encoded b y a 5' rapid amplification of cDNA ends (race) product of A1, A2, indicatin g that the A cDNAs likely represent the genes encoding Hex-L. The F1, F2 an d F3 cDNAs, corresponding to genes encoding an adult, female-enriched hexam erin, Hex-F, hybridized with an mRNA isolated from protein-fed females whic h has a temporal expression profile similar to that observed for the accumu lation of Hex-F. Furthermore, expression of the mRNAs hybridizing to the F cDNAs is correlated with the abundance of Hex-F protein during the gonotrop hic cycles. The mRNA transcription profiles indicate that the Hex-L and Hex -F genes are regulated in a sex-, tissue- and developmental phase-dependent manner. This stage-specific expression of hexamerins contrasts with the ex pression patterns of hexamerins seen in other insects. The conceptual trans lation products of larval hexamerin cDNAs showed identity with larval serum protein 1 (LSP1)-type hexamerins while the deduced products of the female hexamerin cDNAs showed the highest identity with LSP2-type hexamerins. Geno mic analyses showed that the larval hexamerin and female hexamerin genes fr om M. domestica belong to two distinct multigenic families.