Department of Zoology, Vidyasagar University, Midnapore, West Bengal, India; PG Department of Biological sciences, Midnapore City College, Midnapore, West Bengal, India.
Department of Research and Development, Burst Biologics, 3501 W Elder Street, Boise, Idaho, USA.
Ecotoxicol Environ Saf. 2018 Aug 15;157:482-490. doi: 10.1016/j.ecoenv.2018.04.001.
Owing to increasing concern of global climate-change, temperature rise is of great interest which can be primarily evaluated from the seasonal variations in some organisms. Aquatic environment can be extremely stressful to its inhabitants because most of them are poikilothermous. In the present study, attempt was made to evaluate the biological effects of oxidative-stress and adaptive/antioxidant capacities during temperature variations (36-40 °C for 24hrs to 72hrs) in Bellamya bengalensis both in environmental and laboratory conditions by testing some biomarkers like HSP70, catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH) and glutathione reductase (GR). The biomarker potency of the molecules and the anti-oxidative metabolic-network was postulated and extrapolated to find its resemblance to the climate-change associated organismal variations. In a natural and eco-restored environment in the Eastern part of India, 10-20 fold increases in CAT, SOD and HSP70 protein expressions (Western blot results) were noticed in Bellamya paralleling to their increased enzymatic activities (gel zymogram studies) due to the seasonal (summer versus winter) temperature variation. It is evident from the consecutive three years' study that this variation resulted in the unfavorable physico-chemical changes of water quality parameters like dissolved oxygen, biochemical oxygen demand, alkalinity and consequently decreased the animal density in summer. And that was revived due to their higher reproduction-rate in post rainy/winter season when temperature normalizes resulting in a restoration of favorable environment. In laboratory condition, the reduced GR and increased GPx indicated the oxidative damage as evident by higher tissue MDA level following to higher mortality. Changes in SOD and CAT activities suggest activation of physiological mechanism to scavenge the ROS produced during heat stress. However, when mortality increased at different time points (36 °C - 72 h and 38 °C - 72 h), these enzyme activities also decreased as they failed to save the tissues from ROS. The results suggest that temperature variation does alter the active oxygen metabolism by modulating antioxidant enzyme activities, which can be used as biomarker to detect sub-lethal effects of climate change-associated pollution. The parity in environmental and laboratory experimental results may justify this laboratory experiment as model heat-stress experiment and indicate temperature as a universal stressor which alone or in combination with other water parameters initiates a consistent adapting behavior. The Bellamya bengalensis being the highest faunal representative in its habitat may serve as a good bioindicator species.
由于对全球气候变化的日益关注，温度升高引起了极大的关注，这可以主要通过一些生物体的季节性变化来评估。水生环境对其居民来说可能极其紧张，因为它们中的大多数都是变温动物。在本研究中，通过测试 HSP70、过氧化氢酶 (CAT)、超氧化物歧化酶 (SOD)、还原型谷胱甘肽 (GSH) 和谷胱甘肽还原酶 (GR) 等生物标志物，尝试评估了温度变化（36-40°C 24 小时至 72 小时）对孟加拉沼螺在环境和实验室条件下的氧化应激和适应/抗氧化能力的生物学影响。假设分子的生物标志物效力和抗氧化代谢网络，并将其推断为与气候变化相关的机体变化的相似性。在印度东部的自然和生态恢复环境中，由于季节性（夏季与冬季）温度变化，在孟加拉沼螺中观察到 CAT、SOD 和 HSP70 蛋白表达（Western blot 结果）增加了 10-20 倍，与其增加的酶活性（凝胶酶谱研究）相平行。连续三年的研究表明，这种变化导致了水质参数（如溶解氧、生化需氧量、碱度）的不利理化变化，从而导致夏季动物密度降低。而在雨季/冬季后，由于繁殖率较高，温度恢复正常，环境得到恢复，动物密度又有所增加。在实验室条件下，GR 减少和 GPx 增加表明氧化损伤，因为较高的组织 MDA 水平表明在高温应激下产生了更高的组织 MDA 水平。SOD 和 CAT 活性的变化表明，生理机制被激活以清除热应激产生的 ROS。然而，当死亡率在不同时间点（36°C-72 小时和 38°C-72 小时）增加时，这些酶活性也降低，因为它们无法使组织免受 ROS 的伤害。结果表明，温度变化确实通过调节抗氧化酶活性改变了活性氧代谢，可以作为检测与气候变化相关污染的亚致死效应的生物标志物。环境和实验室实验结果的一致性可以证明这种实验室实验是一种模型热应激实验，并表明温度是一种普遍的应激源，它单独或与其他水参数结合，会引发一致的适应行为。孟加拉沼螺是其栖息地中最高的动物代表，可能是一种很好的生物指标物种。
