| In order to clarify the detoxification mechanisms of physiological response to heat stress on Tetrarcychus urticae (Koch) in greenhouse, the females adult of T. urticae were treated in 2 h, 4 h, 6 h under three different high temperatures (36℃, 39℃ and 42℃) , respectively. The specific activity, enzyme kinetics (michaelis constants, Km and maximal velocities, Vmax) of multifunctional oxidase (MFO), carboxylesterase (CarE) and glutathione S-transferase (GST) of T. urticae were measured. The interaction between heat stress and treatment time showed a significant difference tested by two-way ANOVA (P<0.05). The results showed that, the specific activity and enzyme kinetics of CarE, MFO, GST were differently affected. Specific activity: the specific activity of CarE was higher than the control except the 6 h treatment at 39℃, the specific activity of MFO was higher than the control except the 6 h treatment at 42℃, the specific activity of GST was higher than the control except the 2 h treatment at 42℃. Enzyme kinetics: the Km value of CarE was higher than the control except the 2 h, 4 h treatment at 36℃ and 6 h treatment at 39℃, the Km value of MFO was lower than the control except the 6 h treatment at 39℃ and 4 h treatment at 42℃, the Km value of GST was higher than the control except the 2 h treatment at 36℃. The Vmax value of CarE was higher than the control except the 2 h, 4 h treatment at 36℃, the Vmax value of MFO was higher than the control except the 4 h treatment at 42℃, the Vmax value of GST was higher than the control in all treatments. The results indicated that Tetrarcychus urticae can change the specific activity of detoxification enzymes to resist high temperature. MFO had the highest affinity with substrate and the fastest catalytic rate, it was likely to play a dominant role in the response of resisting high temperature, compared with CarE and GST. |
About Journal