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J Insect Physiol

Title:		Degradation of the S. frugiperda peritrophic matrix by an inducible maize cysteine protease
Author(s):		Mohan S; Ma PW; Pechan T; Bassford ER; Williams WP; Luthe DS;
Address:		"Department of Biochemistry and Molecular Biology, Box 9659, Mississippi State, MS 39762, USA"
Journal Title:		J Insect Physiol
Year:		2006
Volume:		20051021
Issue:		1
Page Number:		21 - 28
DOI:		10.1016/j.jinsphys.2005.08.011
ISSN/ISBN:		0022-1910 (Print) 0022-1910 (Linking)
Abstract:		"A unique 33-kDa cysteine protease (Mir1-CP) rapidly accumulates at the feeding site in the whorls of maize (Zea mays L.) lines that are resistant to herbivory by Spodoptera frugiperda and other lepidopteran species. When larvae were reared on resistant plants, larval growth was reduced due to impaired nutrient utilization. Scanning electron microscopy (SEM) indicated that the peritrophic matrix (PM) was damaged when larvae fed on resistant plants or transgenic maize callus expressing Mir1-CP. To directly determine the effects of Mir1-CP on the PM in vitro, dissected PMs were treated with purified, recombinant Mir1-CP and the movement of Blue Dextran 2000 across the PM was measured. Mir1-CP completely permeabilized the PM and the time required to reach full permeability was inversely proportional to the concentration of Mir1-CP. Inclusion of E64, a specific cysteine protease inhibitor prevented the damage. The lumen side of the PM was more vulnerable to Mir1-CP attack than the epithelial side. Mir1-CP damaged the PM at pH values as high as 8.5 and more actively permeabilized the PM than equivalent concentrations of the cysteine proteases papain, bromelain and ficin. The effect of Mir1-CP on the PMs of Helicoverpa zea, Danaus plexippus, Ostrinia nubilalis, Periplaneta americana and Tenebrio molitor also was tested, but the greatest effect was on the S. frugiperda PM. These results demonstrate that the insect-inducible Mir1-CP directly damages the PM in vitro and is critical to insect defense in maize"
Keywords:		Animals Cysteine Endopeptidases/isolation & purification/metabolism/*pharmacology Digestive System/drug effects Hemolymph/chemistry Hydrogen-Ion Concentration Insecta/drug effects Permeability/drug effects Spodoptera/*drug effects Temperature Zea mays/*en;
Notes:		"MedlineMohan, S Ma, P W K Pechan, T Bassford, E R Williams, W P Luthe, D S eng Research Support, U.S. Gov't, Non-P.H.S. England 2005/10/26 J Insect Physiol. 2006 Jan; 52(1):21-8. doi: 10.1016/j.jinsphys.2005.08.011. Epub 2005 Oct 21"