Identification of proteases from leaf beetle (Oulema spp.) by selective protease inhibitorsIdentyfikacja proteaz skrzypionek (Oulema spp.) za pomocą selektywnych inhibitorów proteaz

Abstract

Summary The aim of the study was the identification of gut proteases of leaf beetle Oulema spp. Leaf beetles like aphids or saddle gall midge belong to main cereal pests in Poland. Two species of leaf beetles are common in Poland: cereal leaf beetle (Oulema melanopus, Linnaeus 1758) and grey leaf beetle (Oulema gallaeciana, Heydel 1870). The larvae of both species damage the assimilation surface of plant leaves. Leaf beetles were collected from the fields. The larvae of leaf beetles were immobilized on ice and then homogenized. For identification of different gut proteases polyacrylamide gel separation (in-gel protease assay condition) and selective inhibitors E-64 (trans-epoxysuccinyl-L-leucylamido(4-guanidino)butane) for cysteine protease and PMSF (Phenylmethylsulfonyl fluoride) for serine protease were used. Two kind of proteases: serine and cysteine were identified in guts of leaf beetles. This aspect is very important because insects utilize proteases to digest plant material and to gain exogenous amino acids.