Characterisation of Dermanyssus gallinae glutathione S-transferases and their potential as acaricide detoxification proteins

Table 1 The effect of selected acaricides on the ability of rDeg-GSTs to catalyse the conjugation of glutathione to the colorimetric substrate CDNB

Treatment	Concentration	% reduction in Deg-GST activity ± SEM
		rDeg-GST-1 (0.3 μg GST/well)	rDeg-GST-2 (1.5 μg GST/well)	rDeg-GST-3 (1.5 μg GST/well)
NBC	1.0 mM	50.84 ± 1.4^b	18.1 ± 1.7^b	33.3 ± 2.1^b
Spinosad	0.1 mM	−17.46 ± 3.6	1.7 ± 5.5	−18.8 ± 5.7
Permethrin	0.1 mM	35.39 ± 0.9^b	0.5 ± 3.0	−0.30 ± 0.3
Phoxim	0.1 mM	56.38 ± 3.0^b	14.8 ± 1.5^a	20.56 ± 2.5^a
Abamectin	0.1 mM	17.31 ± 2.1^a	4.3 ± 4.2	−0.57 ± 9.6
No treatment	NA	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0

rDeg-GSTs were incubated together with appropriate defined concentrations of acaricides, 4-nitrobenzyl chloride (NBC) or ethanol diluent (as a no-treatment control) for 10 mins at RT prior to the addition of 1.0 mM CDNB substrate. The final concentrations of acaricides and NBT used in these assay were selected on the basis of their solubility and inhibitory effect in several similar GST inhibition assays [68–70, 85]. The absorbance at 340 nm (A_340nm) was measured immediately (background absorbance of the treatments) and again at 20 mins. The assay was repeated 3 times. The A_340nm values at 20 mins were adjusted for background absorbance and the percentage reduction in Deg-GST activity, compared to the no treatment control, calculated and is presented along with ± SEM. Differences in the activities of each rDeg-GST in the presence or absence of each acaricide were assessed using a one-way ANOVA followed by pairwise comparison using Tukey’s post-hoc analysis
^aSignificant 90 % simultaneous confidence intervals using Tukey post-hoc test of ANOVA data
^bSignificant 95 % simultaneous confidence intervals using Tukey post-hoc test of ANOVA data

ISSN: 1756-3305