Barreira Luísa A, Mudge Stephen M, Bebianno Maria J
CIMA, FCMA - Faculty of Marine and Environmental Sciences, Campus de Gambelas, University of Algarve, 8000-810 Faro, Portugal.
Environ Toxicol. 2007 Apr;22(2):203-21. doi: 10.1002/tox.20257.
Seasonal variation of antioxidant enzymes activities (superoxide dismutase, catalase, and glutathione peroxidases) and lipid peroxidation (LPO) were studied in the clam Ruditapes decussatus in relation to body burdens of polycyclic aromatic hydrocarbons (PAHs). Clams were sampled in eight sites from the Ria Formosa lagoon. PAH concentrations were seasonally rather than spatially dependent, being higher in summer (August). Antioxidant enzymes activities and LPO levels in the clam digestive gland were also seasonally dependent. Antioxidant enzymes presented distinct seasonal variations: Mit SOD (superoxide dismutase activity measured in the mitochondrial fraction) was induced in the summer and down-regulated in winter and spring, while Cyt SOD activity (measured in the cytosolic fraction) was highest in autumn and lower in the summer. Neither Mit nor Cyt SOD were related to the clam PAH body burden, suggesting that cells are using other antioxidant systems to eliminate oxyradicals. Catalase (CAT), however, was induced in spring and down-regulated in summer, the inverse of the PAH concentrations in clam tissues. CAT induction in spring appears to be related to the excess of oxyradicals arising from the metabolic activity associated with the reproductive cycle. Conversely, the decrease in CAT activity in the summer may be related to the high water temperatures reached in the Ria Formosa (up to 30 degrees C). Glutathione peroxidases (total fraction - T-GPx and dependent on selenium - Se-GPx) presented a similar seasonal pattern, and were negatively related to PAH concentrations, which may indicate a precarious state of the clams, associated with PAH toxicity. Similarly, LPO was also inversely correlated to the PAH concentrations indicating that increases in PAH concentrations were not causing membrane oxidative damage in R. decussatus digestive gland. The results suggest that antioxidant enzymes in R. decussatus digestive gland are strongly affected by seasonal factors stressing the need of other experiments to clarify the PAHs effect on this clam species.
研究了斑纹蚬（Ruditapes decussatus）体内抗氧化酶活性（超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶）和脂质过氧化（LPO）的季节性变化及其与多环芳烃（PAHs）体内负荷的关系。在福尔摩沙河口泻湖的八个地点采集了蛤蜊样本。PAH浓度具有季节性而非空间依赖性，夏季（8月）浓度较高。蛤蜊消化腺中的抗氧化酶活性和LPO水平也具有季节性依赖性。抗氧化酶呈现出明显的季节性变化：线粒体超氧化物歧化酶（Mit SOD，在线粒体部分测得的超氧化物歧化酶活性）在夏季被诱导，在冬季和春季下调，而胞质超氧化物歧化酶（Cyt SOD）活性（在胞质部分测得）在秋季最高，在夏季较低。Mit SOD和Cyt SOD均与蛤蜊PAH体内负荷无关，这表明细胞正在使用其他抗氧化系统来清除氧自由基。然而，过氧化氢酶（CAT）在春季被诱导，在夏季下调，与蛤蜊组织中PAH浓度的变化相反。春季CAT的诱导似乎与生殖周期相关的代谢活动产生的过量氧自由基有关。相反，夏季CAT活性的降低可能与福尔摩沙河口达到的高水温（高达30摄氏度）有关。谷胱甘肽过氧化物酶（总部分 - T-GPx和依赖硒的部分 - Se-GPx）呈现出类似的季节性模式，并且与PAH浓度呈负相关，这可能表明蛤蜊处于不稳定状态，与PAH毒性有关。同样，LPO也与PAH浓度呈负相关，表明PAH浓度的增加并未导致斑纹蚬消化腺中的膜氧化损伤。结果表明，斑纹蚬消化腺中的抗氧化酶受到季节性因素的强烈影响，强调需要进行其他实验来阐明PAHs对这种蛤蜊物种的影响。
