E. Cohen et al., EPOXIDE HYDROLASE IN THE BULB MITE RHIZOGLYPHUS-ROBINI - PROPERTIES AND INDUCTION, Experimental & applied acarology, 17(5), 1993, pp. 381-392
Using styrene oxide as substrate, most of the epoxide hydrolase (EH) a
ctivity monitored in the bulb mite Rhizoglyphus robini was associated
with the microsomal compartment. The microsomal and cytosolic EHs did
not display any significant preference in hydrating trans stilbene oxi
de (TSO) and cis stilbene oxide (CSO). The microsomal EH, which has a
Km value of 5x10(-5) M and pH optimum of 7.8, was sensitive to ethanol
and its activity was inhibited to a moderate extent by 4-fluorochalco
ne oxide, TSO, CSO and trans-chalcone oxide at a level of 10(-4) M. Mi
crosomal EH was considerably induced (4-5-fold) in mites feeding garli
c and onion, or ingesting TSO-impregnated filter papers. Other epoxide
s like CSO, 2,4-dichlorostilbene oxide, methyl chalcone oxide and hept
achlor epoxide displayed moderate induction levels (1.4-2.6-fold). Of
the toxicants assayed only sodium phenobarbital was a potent inducer.
Lindane, malathion and DDT did not stimulate EH activity and 3-methyl-
cholanthrene was even inhibitory. A decrease in EH activity was observ
ed with a number of phytochemicals tested such as sinigrin, flavone, m
enthol, trans-beta-carotene, chalcone, allyl sulphide and trans-cinnam
ic acid.