论文部分内容阅读
霍乱毒素(CTX)可激活兴奋性异三聚体G蛋白(Gαs)的α_亚基和刺激电压门控L_型钙通道,而昆虫的L_型钙通道可能是拟除虫菊酯类杀虫剂的作用靶点。为进一步探讨农业害虫对拟除虫菊酯类杀虫剂产生抗药性的作用机理,我们检测了CTX对三氟氯氰菊酯抗性及敏感棉铃虫Helicoverpaarmigera中枢神经细胞电压门控L_型钙通道的调节作用。分别急性分离三氟氯氰菊酯抗性及敏感的3～4龄棉铃虫幼虫胸腹神经节细胞,并在改良的L15培养基(加入或未加入700ngmL的CTX)中培养12～16h。钡离子为载流子,应用全细胞膜片钳技术记录电压门控L_型钙通道电流。结果显示,CTX可使敏感组棉铃虫神经细胞L_型钙通道的峰值电流密度增大36%、峰值电压左移5mV,但对抗性组棉铃虫神经细胞L_型钙通道无上述作用。并且,CTX对敏感组及抗性组棉铃虫神经细胞L_型钙通道的激活电位、翻转电位、激活曲线和失活曲线等其他一些参数的影响也不明显。在无CTX作用时,所检测到的抗性组与敏感组棉铃虫神经细胞L_型钙通道的上述参数值间差异不显著。结果提示,棉铃虫神经细胞内存在Gs腺苷酸环化酶(AC)cAMP蛋白激酶A(PKA)L_型钙通道信号调节系统;与敏感棉铃虫神经细胞L_型钙通道相比,三氟氯氰菊酯抗性棉铃虫神经细胞L_型钙通道的活性相对不易受到CTX调节,这可能与昆虫对拟除虫菊酯产生抗药性的机理有关。
Cholera toxin (CTX) activates the α_ subunit of excitatory heterotrimeric G protein (Gαs) and stimulates the voltage-gated L-type calcium channel, whereas the insect L-type calcium channel may be pyrethroid insecticide The role of agents target. In order to further investigate the mechanism of pesticide resistance to pyrethroid insecticides, we examined the regulatory effect of CTX on cyhalothrin-sensitive and voltage-gated L-type calcium channels in Helicoverpa armigera central nervous cells. Thoracic and abdominal ganglion cells of cyhalothrin-resistant and sensitive 3 to 4-day-old larvae were acutely isolated and cultured in modified L15 medium (with or without addition of 700 ng mL of CTX) for 12-16 h. Barium ions as carriers, the use of whole-cell patch clamp technology to record voltage-gated L-type calcium channel current. The results showed that CTX could increase the peak current density of L - type calcium channel in sensitive group by 36% and shift the peak voltage to left by 5mV, but did not do so in the antagonistic group. Moreover, CTX had no significant effect on the activation potential, turnover potential, activation curve and inactivation curve of L-type calcium channels in the sensitive and resistant groups of H. armigera neurons. In the absence of CTX, there was no significant difference between the above-mentioned parameters of the L-type calcium channel of the tested resistant group and the sensitive group of the Helicoverpa armigera neuronal cells. The results suggest that there is Gs-adenylyl cyclase (AC) cAMP protein kinase A (PKA) L-type calcium channel signal regulating system in the neurons of H. armigera. Compared with the L-type calcium channels of the sensitive bollworm neurons, The activity of L-type calcium channel in cypermethrin-resistant cotton bollworm neurons is relatively less susceptible to CTX regulation, which may be related to the mechanism of insecticide resistance to pyrethroid.