Eufemia NA, Epel D
Hopkins Marine Station, Stanford University, Oceanview Blvd., Pacific Grove, USA
Aquat Toxicol. 2000 May 1;49(1-2):89-100. doi: 10.1016/s0166-445x(99)00068-5.
A multixenobiotic resistance mechanism (MXR) related to the P-glycoprotein multidrug transporter protein (p-gp) has been identified and characterized in several marine invertebrates. p-gp activity and protein titer is induced by exposure to toxins, supporting the suggestion that the role for this transporter is protection from xenobiotics by reducing accumulation of toxins in cells. In this study, we report on the specificity of the induction of the transporter by various chemical and physical stressors. p-gp substrates (including the pesticides pentachlorophenol and chlorthal) as well as non-substrates (including DDE and sodium arsenite) induced p-gp activity and protein titer in the gill tissues of the mussel Mytilus californianus. Similarly, mussels exposed to heat shock of 20 degrees C or 25 degrees C exhibited increased p-gp titer and activity compared to mussels held at ambient (12 degrees C) temperature seawater. Some of the same treatments that induced an increase in p-gp caused a concomitant increase in hsp70, but hsp induction was not always associated with induction of the p-gp protein. These findings suggest that p-gp induction in mussels may be part of a general cellular stress response. This response, however, does not appear to be always coupled with the hsp70 response in mussels.
一种与P-糖蛋白多药转运蛋白（p-gp）相关的多异种生物抗性机制（MXR）已在几种海洋无脊椎动物中得到鉴定和表征。暴露于毒素会诱导p-gp活性和蛋白滴度，这支持了该转运蛋白的作用是通过减少细胞中毒素的积累来保护机体免受异种生物侵害的观点。在本研究中，我们报告了各种化学和物理应激源对该转运蛋白诱导的特异性。p-gp底物（包括农药五氯苯酚和毒草胺）以及非底物（包括滴滴涕和亚砷酸钠）均可诱导加州贻贝鳃组织中的p-gp活性和蛋白滴度。同样，与处于环境温度（12摄氏度）海水中的贻贝相比，暴露于20摄氏度或25摄氏度热休克的贻贝p-gp滴度和活性有所增加。一些诱导p-gp增加的相同处理会同时导致hsp70增加，但hsp诱导并不总是与p-gp蛋白的诱导相关。这些发现表明，贻贝中p-gp的诱导可能是一般细胞应激反应的一部分。然而，这种反应在贻贝中似乎并不总是与hsp70反应相关联。
