Midgut proteinases of Sitotroga cerealella (Oliver) (Lepidoptera:Gelechiidae): Characterization and relationship to resistance in cereals
Midgut proteinases are vital to the insects which digest ingested food in the midgut. Insect midgut proteinases, therefore, have been considered as possible targets for the control of insect pests. Proteinaceous proteinase inhibitors are very attractive for their potential use in developing insect resistant plant varieties via genetic engineering. Sitotroga cerealella is one of the major storage pests of cereals, and no antibiotic resistance in wheat against this insect has been identified to date. A series of diagnostic inhibitors, thiol-reducing agents and a metal-ion chelator were used in the identification of proteinases in crude extracts from S. cerealella larval midguts with both protein and ester substrates. The partial inhibition of proteolytic activity in crude midgut extract toward ({sup 3}H)-methemoglobin by pepstatin A suggested the presence of another proteinase which was sensitive to pepstatin A. The optimum pH range for the proteolytic activity, however, indicated that the major midgut proteinases were not carboxyl proteinases. Two proteinases were successfully purified by a combination of fractionation with ammonium sulfate, gel permeation and anion exchange chromatography. Characterization of the enzymes with the purified enzyme preparations confirmed that the two major proteinases were serine endoproteinases with trypsin-like and chymotrypsin-like specificities respectively. Bioassays were conducted using the artificial seeds to test naturally occurring proteinaceous proteinase inhibitors of potential value. Soybean trypsin inhibitor and the Bowman-Birk proteinase inhibitor had adverse effects on the development of the insect. A predictive model was constructed to evaluate effects of seed resistance in conjunction with other control methods on S. cerealella population dynamics.
- Research Organization:
- Purdue Univ., Indianapolis, IN (United States)
- OSTI ID:
- 5604987
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Tigutcystatin, a cysteine protease inhibitor from Triatoma infestans midgut expressed in response to Trypanosoma cruzi
Molt cycle-associated changes in calcium-dependent proteinase activity that degrades actin and myosin in crustacean muscle
Related Subjects
CEREALS
DISEASE RESISTANCE
LEPIDOPTERA
INFECTIVITY
PEPTIDE HYDROLASES
CHEMICAL COMPOSITION
CHELATING AGENTS
ENZYME ACTIVITY
ENZYME INHIBITORS
FRACTIONATION
GENETIC ENGINEERING
ION EXCHANGE CHROMATOGRAPHY
LARVAE
MATHEMATICAL MODELS
REAGENTS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
ARTHROPODS
CHROMATOGRAPHY
ENZYMES
GRAMINEAE
HYDROGEN COMPOUNDS
HYDROLASES
INSECTS
INVERTEBRATES
ISOTOPE APPLICATIONS
LILIOPSIDA
MAGNOLIOPHYTA
PLANTS
SEPARATION PROCESSES
550201* - Biochemistry- Tracer Techniques