Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Av. Itália km 8, 96.203-900, Rio Grande, Rio Grande do Sul, Brazil.
Comp Biochem Physiol C Toxicol Pharmacol. 2012 Nov;156(3-4):140-7. doi: 10.1016/j.cbpc.2012.08.001. Epub 2012 Aug 7.
The estuarine crab Neohelice granulata was exposed (96 h) to a sublethal copper concentration under two different physiological conditions (hyperosmoregulating crabs: 2 ppt salinity, 1 mg Cu/L; isosmotic crabs: 30 ppt salinity, 5 mg Cu/L). After exposure, gills (anterior and posterior) were dissected and activities of enzymes involved in glycolysis (hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase), Krebs cycle (citrate synthase), and mitochondrial electron transport chain (cytochrome c oxidase) were analyzed. Membrane potential of mitochondria isolated from anterior and posterior gill cells was also evaluated. In anterior gills of crabs acclimated to 2 ppt salinity, copper exposure inhibited hexokinase, phosphofructokinase, pyruvate kinase, and citrate synthase activity, increased lactate dehydrogenase activity, and reduced the mitochondrial membrane potential. In posterior gills, copper inhibited hexokinase and pyruvate kinase activity, and increased citrate synthase activity. In anterior gills of crabs acclimated to 30 ppt salinity, copper exposure inhibited phosphofructokinase and citrate synthase activity, and increased hexokinase activity. In posterior gills, copper inhibited phosphofructokinase and pyruvate kinase activity, and increased hexokinase and lactate dehydrogenase activity. Copper did not affect cytochrome c oxidase activity in either anterior or posterior gills of crabs acclimated to 2 and 30 ppt salinity. These findings indicate that exposure to a sublethal copper concentration affects the activity of enzymes involved in glycolysis and Krebs cycle, especially in anterior (respiratory) gills of hyperosmoregulating crabs. Changes observed indicate a switch from aerobic to anaerobic metabolism, characterizing a situation of functional hypoxia. In this case, reduced mitochondrial membrane potential would suggest a decrease in ATP production. Although gills of isosmotic crabs were also affected by copper exposure, changes observed suggest no impact in the overall tissue ATP production. Also, findings suggest that copper exposure would stimulate the pentose phosphate pathway to support the antioxidant system requirements. Although N. granulata is very tolerant to copper, acute exposure to this metal can disrupt the energy balance by affecting biochemical systems involved in carbohydrate metabolism.
河口蟹 Neohelice granulata 在两种不同生理条件下（高渗透压调节蟹：2 ppt 盐度，1 mg Cu/L；等渗蟹：30 ppt 盐度，5 mg Cu/L）下暴露（96 h）于亚致死铜浓度下。暴露后，解剖前鳃和后鳃，分析糖酵解（己糖激酶、磷酸果糖激酶、丙酮酸激酶、乳酸脱氢酶）、三羧酸循环（柠檬酸合酶）和线粒体电子传递链（细胞色素 c 氧化酶）相关酶的活性。还评估了从前鳃和后鳃细胞分离的线粒体的膜电位。在适应 2 ppt 盐度的螃蟹的前鳃中，铜暴露抑制己糖激酶、磷酸果糖激酶、丙酮酸激酶和柠檬酸合酶的活性，增加乳酸脱氢酶的活性，并降低线粒体膜电位。在后鳃中，铜抑制己糖激酶和丙酮酸激酶的活性，并增加柠檬酸合酶的活性。在适应 30 ppt 盐度的螃蟹的前鳃中，铜暴露抑制磷酸果糖激酶和柠檬酸合酶的活性，并增加己糖激酶的活性。在后鳃中，铜抑制磷酸果糖激酶和丙酮酸激酶的活性，并增加己糖激酶和乳酸脱氢酶的活性。铜不影响适应 2 和 30 ppt 盐度的螃蟹的前鳃和后鳃中的细胞色素 c 氧化酶的活性。这些发现表明，亚致死铜浓度的暴露会影响糖酵解和三羧酸循环中相关酶的活性，特别是在高渗透压调节蟹的前鳃（呼吸鳃）中。观察到的变化表明从有氧代谢到无氧代谢的转变，表明功能缺氧的情况。在这种情况下，减少的线粒体膜电位会导致 ATP 产生减少。尽管等渗蟹的鳃也受到铜暴露的影响，但观察到的变化表明对组织整体 ATP 产生没有影响。此外，研究结果表明，铜暴露会刺激戊糖磷酸途径以支持抗氧化系统的需求。尽管 N. granulata 对铜非常耐受，但急性暴露于这种金属会通过影响参与碳水化合物代谢的生化系统来破坏能量平衡。
