College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang, 325035, People's Republic of China.
College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang, 325035, People's Republic of China.
Chemosphere. 2020 Jun;248:125974. doi: 10.1016/j.chemosphere.2020.125974. Epub 2020 Jan 22.
Clam farming comprises an important part of China's economy. However, increasing pollution in the ocean caused by toxic metals has led to the bioaccumulation of toxic metals in marine animals, especially the bivalves such as clams, and the consequence of heavy metal-associated toxicity in these animals. Such toxicity can enhance the production of reactive oxygen species (ROS) within the tissues of the animals. In aquatic species, oxidative stress mechanisms have been studied by measuring the antioxidant and oxidative damage index in the tissues. The objectives of this study were to investigate the levels of different toxic metals and the extent of oxidative stress responses in the clam Sinonovacula constricta at different growth periods (from May to October) in an aquaculture farm in Wengyang, an important economic shellfish culture zone in Zhejiang Province, China. Water and sediment samples taken from the farm were subjected to Pb, Hg, Cd, Cr assays. Overall, the levels of these metals in the water and sediment could be considered as light pollution, though the levels of Hg in the water (0.266) and Cd in the sediment (0.813) could be considered as reaching moderate pollution. In addition, the levels of these metals, HO, MDA and GSH content, antioxidant enzyme (CAT, SOD, GPx) activities as well as the level of metallothioneins (MT) mRNA in the tissues of S. constricta were also analyzed. The levels of Pb, Hg, Cd, Cr increased with increasing culturing time, and a higher level of these metals was accumulated in the visceral mass than in the foot. The levels of MDA and GSH, as well as the level of SOD activity in the viscera and foot of S. constricta increased with increasing metal accumulation. However, CAT and GPX activities, HO level and the expression of MT initially increased and then decreased. This suggested that S. constricta might have the ability to control oxidative damage by triggering antioxidant defense in coordination with the metal sequestering response. The results also implied that toxic metal pollution should be taken into account when selecting the site to be used as an aquaculture farm. In addition, the visceral mass should be considered to be a good tissue for measuring the level of metal pollutants.
养蛤业是中国经济的重要组成部分。然而，海洋中有毒金属造成的污染不断增加，导致海洋动物，特别是蛤类等双壳类动物体内有毒金属的生物蓄积，以及这些动物与重金属相关的毒性。这种毒性会增加动物组织内活性氧物质 (ROS) 的产生。在水生动物中，通过测量组织中的抗氧化剂和氧化损伤指标来研究氧化应激机制。本研究的目的是调查中国浙江省重要经济贝类养殖区翁阳养殖农场不同生长时期（5 月至 10 月）的缢蛏体内不同有毒金属的水平和氧化应激反应的程度。对养殖场的水样和底泥样进行 Pb、Hg、Cd、Cr 检测。总的来说，养殖场水和沉积物中这些金属的含量可以认为是轻度污染，尽管水中的 Hg（0.266）和沉积物中的 Cd（0.813）含量可以认为达到中度污染。此外，还分析了这些金属、HO、MDA 和 GSH 含量、抗氧化酶（CAT、SOD、GPx）活性以及组织中金属硫蛋白（MT）mRNA 的水平。随着养殖时间的增加，Pb、Hg、Cd、Cr 的含量增加，并且内脏团中这些金属的含量高于足部。S. constricta 内脏和足部的 MDA 和 GSH 水平以及 SOD 活性水平随着金属积累的增加而增加。然而，CAT 和 GPX 活性、HO 水平和 MT 的表达最初增加，然后减少。这表明，S. constricta 可能具有通过触发抗氧化防御与金属螯合反应相协调来控制氧化损伤的能力。研究结果还表明，在选择用作养殖场的地点时，应考虑有毒金属污染问题。此外，应考虑将内脏团作为测量金属污染物水平的良好组织。
