Gagné F, Blaise C, Pellerin J, Pelletier E, Strand J
Environment Canada, St. Lawrence Centre, 105 McGill Street, 7th Floor, Montreal, Que., Canada H2Y 2E7.
Ecotoxicol Environ Saf. 2006 Jul;64(3):348-61. doi: 10.1016/j.ecoenv.2005.04.007. Epub 2005 Jun 6.
The purpose of this study was to examine the health status and gametogenetic activity in Mya arenaria clams collected at various sites in the St. Lawrence Estuary (Quebec, Canada) and in the Odense Fjord (Denmark). Clam soft tissues were analyzed for metals/metalloids and organotin compounds to confirm their exposure to these contaminants. Their health status was assessed by a test battery of biomarkers designed to measure the early biological effects of contaminants, which include expression of defence mechanisms such as xenobiotic conjugation (glutathione S-transferase), expression of stress proteins (i.e., heme oxygenase and metallothioneins), changes in gametogenetic activity, and individual morphometric characteristics. Clam tissues were also examined for the presence of oxidative damage to lipids, formation of DNA strand breaks, and alterations in heme metabolism. The results showed that clams sampled from sites with either ferry activity or intensive boat traffic in marinas were contaminated by metals/metalloids such as Ag, Al, As, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sn, V, and Zn. The clams also contained relatively high amounts of tributyltin (TBT) in their tissues (in the ng TBT/g range for both areas), with digestive glands containing more organotins than did gonadal tissues. Moreover, clams collected from TBT-contaminated sites had higher amounts of tin-heme adducts and lower total heme in their digestive glands. Condition factor, age distribution, and sex ratio were significantly altered in clams from impacted sites in the Saguenay Fjord and accompanied by an increased male/female sex ratio. Gametogenetic activity was also negatively affected, as revealed by reductions in gonadosomatic index, maturation index, aspartate transcarbamylase activity, and vitellogenin-like proteins. The Saguenay Fjord clams displayed a complex pattern of stress responses and damage such as increased heme oxygenase activity, phase 2 conjugation enzyme activity, lipid peroxidation, and altered DNA strand breaks. The integration of biomarker response data into a biomarker index at the whole-individual level (morphometric characteristics) and for various organs (gill, digestive gland, and gonad) revealed that, relative to the control site, morphological characteristics and gonadal activity were most affected at the most contaminated site, while the effects were more pronounced in the digestive gland and gill at moderately impacted sites. We conclude that the health status of M. arenaria clams at these contaminated sites is compromised, with obvious disruption of reproductive activity.
本研究的目的是检测在圣劳伦斯河口（加拿大魁北克）和欧登塞峡湾（丹麦）不同地点采集的砂海螂蛤的健康状况和配子发生活性。分析蛤软组织中的金属/类金属和有机锡化合物，以确认它们接触这些污染物的情况。通过一组旨在测量污染物早期生物学效应的生物标志物来评估它们的健康状况，这些生物标志物包括防御机制的表达，如异生物质结合（谷胱甘肽S-转移酶）、应激蛋白的表达（即血红素加氧酶和金属硫蛋白）、配子发生活性的变化以及个体形态特征。还检查蛤组织中脂质氧化损伤、DNA链断裂的形成以及血红素代谢的改变情况。结果表明，从有渡轮活动或码头船只交通密集的地点采集的蛤受到银、铝、砷、钴、铬、铜、铁、汞、锰、钼、镍、铅、锡、钒和锌等金属/类金属的污染。蛤组织中还含有相对较高含量的三丁基锡（TBT）（两个区域均在纳克TBT/克范围内），消化腺中的有机锡含量高于性腺组织。此外，从受TBT污染地点采集的蛤的消化腺中锡-血红素加合物含量较高，总血红素含量较低。在萨格奈峡湾受影响地点的蛤中，条件因子、年龄分布和性别比例发生了显著变化，同时雄/雌性别比例增加。配子发生活性也受到负面影响，表现为性腺指数、成熟指数、天冬氨酸转氨甲酰酶活性和类卵黄蛋白原减少。萨格奈峡湾的蛤表现出复杂的应激反应和损伤模式，如血红素加氧酶活性增加、Ⅱ相结合酶活性增加、脂质过氧化和DNA链断裂改变。将生物标志物反应数据整合到个体整体水平（形态特征）和各个器官（鳃、消化腺和性腺）的生物标志物指数中发现，相对于对照地点，在污染最严重的地点，形态特征和性腺活动受影响最大，而在中等受影响的地点，消化腺和鳃的影响更为明显。我们得出结论，这些受污染地点的砂海螂蛤的健康状况受到损害，生殖活动明显受到干扰。
