CHARACTERIZATION OF THE GENE FOR LEUCOMYOSUPPRESSIN AND ITS EXPRESSION IN THE BRAIN OF THE COCKROACH DIPLOPTERA-PUNCTATA

Using HPLC separation, radioimmunoassay, and subsequent bioassay, we h ave detected the presence of an active peptide, which co-elutes with t he insect myoinhibitory peptide leucomyosuppressin, in the brain of th e cockroach Diploptera punctata, We have isolated a cDNA encoding the precursor for this peptide from cDNA libraries representing D. punctat a brain RNA, The cDNA sequence contains an open reading frame that upo n translation would result in a prepropolypeptide of 96 amino acids. P roteolytic cleavage of the predicted precursor could result in several peptides, including a 10 amino acid C-terminal peptide that would, up on modification of the NH2 and COOH-terminal amino acids, be identical to the insect FLRFamide, leucomyosuppressin, No other RFamide product s are predicted to be processed from the precursor, Southern blot anal ysis indicates that the gene is present in the D. punctata genome in a single copy, Northern blot analysis shows that the gene is predominan tly expressed as a 3.8 kb mRNA in cockroach brain. Study of the expres sion of the leucomyosuppressin gene in D. punctata brain, using in sit u hybridization, indicates that expression occurs primarily in the par s intercerebralis of the protocerebrum, a region showing abundant FMRF amide-like immunoreactive neurosecretory cells, Immunohistochemistry a nd HPLC coupled to radioimmunoassay indicates that leucomyosuppressin represents a significant proportion of FMRFamide-related peptide produ ction in the brain, However, HPLC analysis also indicates the presence of significant levels of other related peptides, demonstrating the pr esence of more than one FMRFamide-related gene in this insect. Crown c opyright (C) 1996 Published by Elsevier Science Ltd.