棉蚜抗氧化乐果品系及敏感品系羧酸酯酶性质的比较

在室内用氧化乐果逐代筛选的棉蚜抗性品系，相对于敏感品系的抗性倍数是17。用α-乙酸萘酯（α-NA）、α-丁酸萘酯（α-NB）、α-磷酸萘酯（α-NP）和β-磷酸萘酯（β-NP）作底物比较研究了氧化乐果抗性和敏感品系棉蚜Aphis gossypii羧酸酯酶的比活力、米氏常数（K_m）和最大反应速度V_max）等有关的动力学常数。以α-NA和α-NB作底物时，抗性品系棉蚜的比活力显著低于敏感品系的；以α-NP和β-NP作底物时，两个品系棉蚜的比活力、K_m和V_max没有明显差异。用α-NA、β-NA作底物染色做酯酶同工酶电泳，抗性品系棉蚜的酯酶同工酶染色比敏感品系棉蚜的浅。

Characteristics of carboxylesterase in omethoate-resistant and susceptible strains of cotton aphid, Aphis gossypii

A strain of organophosphate (OP) resistant cotton aphid, Aphis gossypii was selected by exposure to omethoate insecticide in the laboratory. The resistance factor of this strain was 17 times that of an OP-susceptible strain of cotton aphid. Four substrates, α-naphthyl acetate (α-NA), α-naphthyl butyrate (α-NB), α-naphthyl phosphate (α-NP) and β-naphthyl phosphate (β-NP), were used to determine carboxylesterase activity, Michaelis constants (K_m) and maximum velocities (V_max) in OP-susceptible and resistant strains of cotton aphids. Carboxylesterase activity was significantly lower in the OP-resistant strain than the OP-susceptible strain when α-NA and β-NB were used as substrates and the same trends were obtained by native polyacrylamide gel electrophoresis (PAGE) analysis. However, no significant difference was found between OP-susceptible and resistant strains when α-NP and β-NP were used as substrates.