A brain peptide stimulates release of amylase from the midgut tissue of larvae of Opisina arenosella Walk. (Lepidoptera: Cryptophasidae)

Abstract

Brain extracts from 3 to 4 day old final (eighth) instar larvae of Opisina arenosella (Lepidoptera) stimulate amylase release from midgut preparations maintained in vitro. This effect of the brain extract was both time and dose dependent. The brain factor stimulating enzyme release may be a peptide as it is heat stable and susceptible to treatment with proteolytic enzymes. For purification of the brain factor, a head extract prepared in 2% NaCl was first precipitated in 80% aqueous acetone and then fractionated by DEAE cellulose ion exchange chromatography. The fraction OCF 2, from ion exchange chromatography was further purified on a Sephadex G25 column. The fraction designated as OCF 2.3 obtained by gel filtration showed maximum activity and it was selected for HPLC analysis. HPLC elution profiles of OCF 2.3 showed two major peaks separated by a time interval of 0.107 min. The two overlapping peaks of OCF 2.3 may represent either different forms of a peptide or different peptides of a family. The molecular weight OCF 2.3 was estimated to be 1070 Da.