CLONING OF 2 CDNAS ENCODING 3 SMALL SERINE-PROTEASE INHIBITING PEPTIDES FROM THE DESERT LOCUST SCHISTOCERCA-GREGARIA AND ANALYSIS OF TISSUE-DEPENDENT AND STAGE-DEPENDENT EXPRESSION

This study describes the cloning of two cDNAs encoding three serine-pr otease-inhibiting peptides, SGPI I, II and III, which were recently id entified from ovarian extracts of the desert locust, Schistocerca greg aria. The first cDNA codes for the precursor polypeptides of SGPI I an d SGPI II; the second encodes only a single inhibitor, SGPI III. North ern-blot analysis revealed an approximate length of 0.8 kb for SGPI-I/ II mRNA and 0.6 kb for SGPI-III mRNA. The transcripts are present in s everal locust tissues, but they could not be detected in the midgut. T he gene for SGPI-I/II is abundantly transcribed during all larval and adult stages, whereas SGPI-III mRNA is mainly present in adults. North ern-blot hybridization also revealed important changes in the SGPI-mRN A content during the molting cycle and during the adult reproductive c ycle. Moreover, a differential hormonal control was observed in adult females which had been treated with precocene, juvenile hormone or ecd ysone.