Achard M, Baudrimont M, Boudou A, Bourdineaud J P
Laboratoire d'Ecophysiologie et Ecotoxicologie des Systèmes Aquatiques, Université Bordeaux 1/UMR CNRS 5805, Place du Dr Peyneau, 33120 Arcachon, France.
Aquat Toxicol. 2004 May 12;67(4):347-57. doi: 10.1016/j.aquatox.2004.01.014.
Multixenobiotic resistance mechanisms (MXR) related to the mammalian P-glycoprotein multidrug transporter protein (P-gp) are known to occur in several marine invertebrates. In the present work, we report on the induction of an MXR protein by various heavy metals in the gills of the freshwater clam Corbicula fluminea. The evaluation of the MXR protein level was assessed by Western blot using a specific monoclonal antibody raised against the human P-gp (C219). A field transplantation experiment, where clams were caged in a gradient relative to an industrial site, demonstrated a positive relationship between MXR levels and (a) metal pollution (Cd and Zn) in the environment and (b) metal bioaccumulation in the gills. To establish this correlative relationship, clams were exposed to different levels of cadmium (15-60 microg l(-1)) for up to 15 days in a controlled laboratory experiment. MXR protein levels increased in time for all treatments (including the control). However, the highest levels of MXR protein titer were expressed in clams that had been exposed to the lowest dose of cadmium. The causes for this observed inverse relationship between the exposure dose and the MXR induction is discussed. MXR protein titer was also shown to be induced by other heavy metals (zinc, inorganic mercury, and copper).
已知与哺乳动物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）存在于多种海洋无脊椎动物中。在本研究中，我们报告了各种重金属在淡水蛤类河蚬鳃中诱导MXR蛋白的情况。使用针对人P-gp（C219）产生的特异性单克隆抗体，通过蛋白质印迹法评估MXR蛋白水平。在一个现场移植实验中，将蛤类放置在相对于一个工业场所的梯度环境中，结果表明MXR水平与（a）环境中的金属污染（镉和锌）以及（b）鳃中的金属生物积累之间存在正相关关系。为了确定这种相关关系，在一个受控的实验室实验中，将蛤类暴露于不同水平的镉（15 - 60微克/升）长达15天。所有处理组（包括对照组）的MXR蛋白水平均随时间增加。然而，暴露于最低剂量镉的蛤类中MXR蛋白滴度最高。本文讨论了观察到的暴露剂量与MXR诱导之间这种反比关系的原因。MXR蛋白滴度也被证明可由其他重金属（锌、无机汞和铜）诱导。
