Multiple mechanisms for enhancement of glutathione S-transferase activities in Spodoptera frugiperda (Lepidoptera: Noctuidae)

Document Type

Article

Publication Date

1-1-1995

Abstract

Glutathione S-transferase activities toward 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-dichloro-4-nitrobenzene (DCNB) were measured from fat body homogenates of chemically-treated and untreated Spodoptera frugiperda larvae. In assays with untreated insects, four GST activities were separable on the basis of substrate preference and pH optima: two active in DCNB metabolism and two with activity toward CDNB. Both GST activities toward DCNB increased following injection of 8-methoxypsoralen (8-MOP) but were unaffected by pentamethylbenzene (PMB). Induction by 8-MOP was inhibited in a dose-dependent manner by co-administration of PMB, suggesting that PMB acts as an antagonist of 8-MOP-mediated induction. In contrast, activities toward CDNB increased following PMB, but not 8-MOP injection, and co-administration of 8-MOP blocked PMB-mediated enhancement of one GST/CDNB activity, but had no effect on the other. These results confirm previous reports of multiple forms of GSTs in insects and suggest that expression of GST activities in this insect is controlled by multiple mechanisms. © 1995.

Publication Source (Journal or Book title)

Insect Biochemistry and Molecular Biology

First Page

347

Last Page

353

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