Exogenous and endogenous protease inhibitors in the gut of the fall armyworm larvae, Spodoptera frugiperda

Abstract

A dose-dependent inhibition of endogenous trypsin and aminopeptidase occurs in the lumen of Spodoptera frugiperda after feeding L6 larvae exogenous inhibitors soybean trypsin inhibitor (SBTI), tosyl-L-lysine chloromethyl ketone-HCl (TLCK), or bestatin, respectively, for 3 days. TLCK inhibits trypsin in tissue extracts and in secretions more strongly than SBTI. The aminopeptidase released into the lumen (containing the peritrophic membrane) is strongly inhibited by bestatin, but the membrane-bound enzyme is not. A bound enzyme may be more resistant to an inhibitor than unbound. A cross-class elevation of aminopeptidase activity occurs in response to ingested trypsin inhibitor, but there was no cross-class effect of aminopeptidase inhibitor (bestatin) on trypsin activity. An endogenous trypsin and aminopeptidase inhibitor is present in the lumen and ventricular cells. The strength of the endogenous trypsin inhibition seems to be in the same range as that resulting from ingestion of the exogenous inhibitor SBTI. In some insect species, considerable trypsin secretion occurs in unfed as well as in fed animals, and endogenous protease inhibitors might function to protect the ventricular epithelium by inactivation of trypsin when less food is available.

Role of Proteases in Extra-Oral Digestion of a Predatory Bug,Andrallus spinidens

“…Endogenous trypsin inhibitors from larvae of possible prey of A. spinidens were determined by a method described by Lwalaba et al (2010) with slight modifications. The larvae used in this experiment consisted of C. suppressalis, N. aenescens, P. brassicae, H. cunea , and E. kuhniella .…”

First Microsatellites fromSpodoptera frugiperda(Lepidoptera: Noctuidae) and Their Potential use for Population Genetics

“…in Samia cynthia (Druri) (Hashimoto et al 2008), whereas Serpin-1 is a serine-protease inhibitor (Potempa et al 1994), known to be involved in insect-immune response and to present exon expansion in Lepidoptera (Hegedus et al 2008). Other sequences with non intuitive function would be those of ␣-amylases, but these enzymes can be activated up to Þve times in S. frugiperda during larva feeding (Lwalaba et al 2010).…”

Dietary and phylogenetic correlates of digestive trypsin activity in insect pests

“…Paracrine regulation may be coupled to the presence of endogenous inhibitors. Their level is increased during starvation (Lwalaba et al, 2010b;Soares et al, 2011;Van Hoef et al, 2011) and protect gut tissue and digestive enzymes from proteolytic degradation by prematurely activated trypsin (Elpidina et al, 2001b).…”