CLONING OF CDNAS FOR CECROPIN-A AND CECROPIN-B, AND EXPRESSION OF THEGENES IN THE SILKWORM, BOMBYX-MORI

cDNA clones coding cecropins A and B were isolated from a cDNA library constructed from the fat body of immunized Bombyx mori larvae. The cl oned cDNAs had an open reading frame of 63 amino acids, indicating the primary translated peptides were processed to form mature cecropins o f 35 amino acid residues. The homology in the coding regions of cecrop ins A and B was 73%. In immunized fat body, the expression of both cec ropin A and B genes reached the maximal level 5h after the injection o f soluble peptidoglycan, and the high level was maintained until 9 h a fter immunization. The cecropin A and B genes were expressed at high l evels in fat body and hemocytes, at lower but significant levels in ma lpighian tube, slightly in midgut, and none in silk gland.