低剂量重金属对两栖动物运动生物力学的毒理效应及作用机理

运动对两栖动物的捕食、逃生和繁殖具有重要意义，决定着种群动态。运动生物力学是反映运动能力的关键指标，易受水体中重金属类环境激素的影响。为研究低剂量重金属对两栖动物运动生物力学的毒理效应及神经激素调节机理，用常见的重金属（镉、汞和铅）对三种不同发育阶段的两栖动物进行长期处理，从运动力学、运动器官和运动效果等三个方面探讨了重金属对运动生物力学的毒理效应。.重金属主要通过干扰两栖动物体内神经和激素的调节而影响其运动生物力学。利用电生理学、免疫组织化学、原位杂交、实时荧光定量PCR和蛋白免疫印迹等方法探讨重金属干扰下体内神经（神经元特征及传导速度、神经递质含量、神经递质及受体基因与蛋白表达水平）和激素（激素和激素受体的表达位点及表达量）的作用机理，构建“重金属-体内神经激素调节-运动生物力学”影响机制。该研究有利于阐明环境激素造成两栖动物种群下降机制，为受胁动物的保护与恢复提供理论依据。

Environmental pollution has increased substantially in the last decades due to a great number of industrial, agricultural, commercial and domestic waste, effluents and emissions as well as hazardous substances. Among them, heavy metals play as endocrine-disrupting chemicals to cause a variety of health problems, which are considered as the toxicity of environmentally significant elements. Anuran amphibians are particularly vulnerable and easily absorb environmental pollutants at the stage of the eggs and larvae. The influence of low exposure doses of these metals such as cadmium, mercury and lead, on the endocrine system, possible mechanisms of action, and consequent health effects are strongly correlated with amphibians. Movement is one of the crucial aspects in anuran amphibians, which defines as the spatial and temporal scale of an organism’s interactions with other organisms, resources and reproduction. Movement can lead to individual gene flow, population persistence, adaptation, fitness and natural selection during the fundamental process of anuran amphibians. A lack of understanding about the influences of low doses of heavy metals on the movement of anurans may prevent the full understandings of species declines even extinction or the population dynamics. So it is necessary to focus on the toxicological problems involvement in heavy metals on the movement in amphibians. .The objective of our aim is to elucidate the regulation mechanism relating to heavy metals, the jumping movement and internal regulation mechanism which provide the theoretical support for the protection and restoration in amphibians. We use low doses of the heavy metals (cadmium, mercury and lead) to treat the widely distributed amphibians (Pelophylax nigromaculata and Bufo gargarizans) for a long period of time. The treatment includes three different developmental stages of the treated amphibians. Movement is mainly determined by the structural and functional properties of limb kinematic patterns, muscle structure and skeleton. We research the influences of heavy metals on the biomechanics of amphibian movement combining with the motion mechanics (three-dimensional dynamics, jumping force and muscle contraction force), motion organs (skeleton and skeletal muscle) and motion effects (predation rate, escape rate and mating rate). The neurons, neurotransmitter (acetylcholine, 5-hydroxytryptamine and γ-amino butyric acid) and hormones (thyrotropin releasing hormone, gonadotropin releasing hormone, growth hormone, thyroid stimulating hormone, gonadotropin, thyroid hormone and testosterone) have significant modulatory effects on the movement in amphibians respectively. The interactions of movement and the regulations in the body (the nerves and hormones) suggest that extending mechanistic movement studies or field investigations that take the neural endocrinology into account could engender a deeper mechanisms between the heavy metals and amphibian movement. Therefore, we use electrophysiology, radioimmunity, immunohistochemistry, in situ hybridization, quantitative real-time PCR assay and western blot hybridization methods to determine nerve variables (neuronal characteristics and conduction velocity, neurotransmitter content, and the gene and protein expression levels of the neurotransmitters or its receptors), and the locations or levels of hormone genes and protein expressions respectively. In this perspective, we research the influences of heavy metals on amphibian movement ecology, identify critical movement mechanism, and provide a theoretical support for how understanding the heavy metal influences of amphibian movement. This study is helpful to elucidate the mechanism relationship among the low doses of heavy metals, regulations of neurons and hormones, and movement biomechanics in amphibians, which provide theoretical supports and help develop solutions for more effective amphibian conservation.