Cloning of two cDNAs encoding three small serine protease inhibiting peptides from the desert locust Schistocerca gregaria and analysis of tissue‐dependent and stage‐dependent expression

Abstract

This study describes the cloning of two cDNAs encoding three serine-protease-inhibiting peptides, SGPI I, II and III, which were recently identified from ovarian extracts of the desert locust, Schistocerca gregaria. The first cDNA codes for the precursor polypeptides of SGPI I and SGPI II; the second encodes only a single inhibitor, SGPI III. Northern-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 several locust tissues, but they could not be detected in the midgut. The gene for SGPI-I/II is abundantly transcribed during all larval and adult stages, whereas SGPI-III mRNA is mainly present in adults. Northern-blot hybridization also revealed important changes in the SGPI-mRNA content during the molting cycle and during the adult reproductive cycle. Moreover, a differential hormonal control was observed in adult females which had been treated with precocene, juvenile hormone or ecdysone.

A Review of the Most Important Classes of Serine Protease Inhibitors in Insects and Leeches

“…Important changes in transcript levels occur during development. Vanden Broeck et al also provided evidence indicating that the expression of the inhibitors is hormonally regulated [55]. cDNA cloning revealed two isoforms of a novel pacifastin-related precursor in Schistocerca gregaria, SGPP-3, which codes for three putative inhibitor peptides, two novel peptides (SGPI-4A en C) and a peptide (SGPI-4B), which most likely corresponds to the earlier purified SGPI-4.…”

“…Similarly, SGPI-1 and SGPI-2 are derived from a single polypeptide precursor in Schistocerca gregaria [55], called Schistocerca gregaria pacifastin-related precursor-1 or SGPP-1, whereas SGPI-3 is encoded by an additional precursor, SGPP-2 [55]. The transcripts are present in several locust tissues, but not in the midgut.…”

Purification and characterization of an insulin-related peptide in the desert locust, Schistocerca gregaria: immunolocalization, cDNA cloning, transcript profiling and interaction with neuroparsin

“…Gregarious desert locusts, S. gregaria (Forskål), were reared under crowded conditions according to the method previously described by Vanden Broeck et al (1998). Breeding of solitarious desert locusts was performed under isolated conditions as described by Hoste et al (2002).…”

“…In order to compensate for possible variations due to pipetting errors and differences in reverse transcriptase efficiency, a S. gregaria b-actin transcript was analyzed as an endogenous control. Our previous studies indicated that the levels of this mRNA remain quite constant in locust tissues, regardless of developmental or physiological conditions (Vanden Broeck et al 1998, Janssen et al 2001, Claeys et al 2003. Primers for the endogenous control were described previously (Claeys et al 2005).…”

Early events in crustacean innate immunity

“…The most e$cient inhibitor of crayfish ppA is pacifastin which contains a light chain with nine proteinase inhibitor subunits and a heavy chain containing three transferrin lobes [70]. The molecule is held together by a peptide bond and forms a new class of proteinase inhibitors named pacifastin-like serine proteinase inhibitors and which are present in, and can inhibit the proPO system in many insects [71,72].…”