Multiple forms of esterase in the larvae of Pectinophora gossypiella treated with three volatile oils.

Heba Hassan,Sondos Mohamed

doi:10.21608/eajbsa.2008.15746

Heba Hassan, Sondos Mohamed

Open Access

https://doi.org/10.21608/eajbsa.2008.15746

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Abstract

In the present work, polyacrylamide gel electrophoresis were used for detection the forms of esterase in the last larval instar of Pectinophora gossypiella. The larvae were treated as newly hatched larvae with sublethal concentration(LC50) of three volatile oils (Petroselinum sativum, Coriandrum sativum and Cymbapoyon citratus). The larval tissues showed response towards α - naphthyl acetate and βnaphthyl acetate substrates. The esterase bands have been classified according to their reaction with three specific inhibitors (Eserine, Chlorphrifos and Fenitrothion). The results were showed great differences in number of zones of esterase activity and in substrate specificity between treated and untreated samples. Five, four, seven and six esterase bands in untreated and (P. sativum, C. sativum and C. citrates) treated samples respectively, show activity towards α- naphthyl acetate. Six, five, seven and seven esterases were able to hydrolyze β- naphthyl acetate in previous samples arrangement. In the case of α - naphthyl acetate, volatile oils caused the increasing of arylestrases and carboxylestrases activities, while cholinesterase activity was inhibited.

Highlights

Esterases exhibit a greater degree of polymorphism than other enzymes because they act on a class of molecules many of which come directly from external environment (Kojima et al, 1970)
Untreated and treated larvae were homogenized, centrifuged and kept frozen. *Esterases analysis: Esterase bands were separated by Polyacrylamide gel electrophoresis (PAGE) according to the method of (Salama et al, 1992)
Esterases can often be separated into isozymes with different substrate specificities

Summary

Introduction

Esterases exhibit a greater degree of polymorphism than other enzymes because they act on a class of molecules many of which come directly from external environment (Kojima et al, 1970). The esterases can break an ester bond with the help of a water molecule. Most enzymes of this class hydrolyze endogenous substances and are important in intermediary metabolism (Sivakumarm and Maya, 1991), but can play a role in detoxification of xenobiotics (Shen and Dowd, 1991). Because most insecticides are ester of substituted phosphoric, carbamic, or cyclopropanecarboxylic acids, they are subjected to degradation by esterases (Devonshire, 1991). These esterases can often be separated into isozymes with different substrate specificities. Estreases can be divided as follows; Carboxylestrases inhibited by organophosphorus compounds but not by carbamate (eserine); Cholinesterases inhibited by organophosphorus and carbamate compounds and Arylesterases not inhibited by organophosphorus and carbamate compounds (Augustinsson, 1961)

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