title: The impact of ingested potato type II inhibitors on the production of the major serine proteases in the gut of Helicoverpa armigera.
abstract: The flowers of the ornamental tobacco produce high levels of a series of 6 kDa serine protease inhibitors (NaPIs) that are effective inhibitors of trypsins and chymotrypsins from lepidopteran species. These inhibitors have a negative impact on the growth and development of lepidopteran larvae and have a potential role in plant protection. Here we investigate the effect of NaPIs on the activity and levels of serine proteases in the gut of Helicoverpa armigera larvae and explore the adaptive mechanisms larvae employ to overcome the negative effects of NaPIs in the diet. Polyclonal antibodies were raised against a Helicoverpa punctigera trypsin that is a target for NaPIs and two H. punctigera chymotrypsins; one that is resistant and one that is susceptible to inhibition by NaPIs. The antibodies were used to optimize procedures for extraction of proteases for immunoblot analysis and to assess the effect of NaPIs on the relative levels of the proteases in the gut and frass. We discovered that consumption of NaPIs did not lead to over-production of trypsins or chymotrypsins but did result in excessive loss of proteases to the frass.
authors.affiliation: La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Melbourne, Victoria 3086, Australia.
authors.forename: J A
authors.initials: JA
authors.lastname: Stevens
authors.forename: K M
authors.initials: KM
authors.lastname: Dunse
authors.forename: R F
authors.initials: RF
authors.lastname: Guarino
authors.forename: B L
authors.initials: BL
authors.lastname: Barbeta
authors.forename: S C
authors.initials: SC
authors.lastname: Evans
authors.forename: J A
authors.initials: JA
authors.lastname: West
authors.forename: M A
authors.initials: MA
authors.lastname: Anderson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D041981:Gastrointestinal Tract / Q000201:enzymology; D007300:Insect Control; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009036:Moths / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D011198:Solanum tuberosum / Q000737:chemistry*; D014357:Trypsin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D010936:Plant Extracts; D014361:Trypsin Inhibitors; D002918:Chymotrypsin; D014357:Trypsin