低剂量重金属类环境激素长时期暴露对两栖动物声学通讯的影响及激素调控机制

Acoustic communication is the major component of social behavior in anuran amphibians, and plays a key role in mate choice decisions and reproductive success. Amphibian acoustic communication is vulnerable to environmental hormones influence,and the effect of acoustic communication influence amphibian populaton dynamics.Heavy metals are the main component of environmental hormones in water. They enter the natural environment through multiple sources, and amphibians are exposed to them via several modes. Although environmental hormones compounds are assumed to contribute to the worldwide decline of amphibian populations by adverse effects on sexual differentiation, evidence for heavy metals affecting amphibian mating behavior is lacking. In order to study the mechanism of the impact of heavy metals on amphibian acoustic communication, we use the heavy metals at low, environmentally relevant concentrations. We consider the ecological implications of development stage difference disruption by heavy metals. We use the low doses of heavy metals (including mercury, cadmium and lead), to treat on African clawed frogs (Xenopus laevis) in three different development periods for the long-term treatment, the first treatment is from the zygote to adult, the second one is from juvenileto adult and the third is adult. Male amphibian mating signals convey important mate quality information to females. We address effects of heavy metals on amphibian acoustic communication and discuss how amphibians may respond to altered signals from three aspects, including its vocal organs, mating calling behavior and mating effect. The vocal organ mainly is the larynx. Mating calling behavior is the signals of male and female amphibians. The mating effect includes mating success rate, spawning rate and offspring hatch rates. These mating signals are dependent on hormones for their production and maintenance. Affecting various aspects of the amphibian hormones, can impair hormonal functioning by binding to or blocking hormone receptors, or by altering production and function of hormones or hormone receptors. Disrupting these hormones pathways jeopardizes signal resulting in changed mating behavior. Hormones mainly include androgen, estrogen and arginine vasopressin. The hormone content can be detected through the micro dialysis technology and radioimmunoassay. The hormone receptors distribution is in the brain nerve nuclei and throat, which can be dectected through immunohistochemistry, in situ hybridization and real-time fluorescence quantitative RT-PCR method.The findings will indicate the mechanism that heavy metals inflence the level and local of hormone in vivo, and further influence the acoustic communication.The study might contribute to the decline mechanism of amphibian populations via interferences with the mating success of amphibians exposed by the environment hormones, and provide theoretical basis for the preservation and restoration of ecological environment.

声学通讯对无尾两栖动物的配偶选择和成功繁殖起关键作用，而两栖动物的声学通讯易遭受环境激素的影响，其声学通讯效果直接决定着两栖动物的种群动态。重金属是水体中常见的一类环境激素，为研究其对两栖动物声学通讯的影响机制，用自然生境中主要的重金属（低剂量的汞、镉和铅）对三种不同发育时期（受精卵、幼蛙和成体）的非洲爪蟾进行了长期处理，从声学通讯器官、通讯行为和通讯效果三个方面系统地探讨了重金属对两栖动物声学通讯的影响效应。通过微透析技术及放射免疫方法测定非洲爪蟾体内调控声学通讯的激素（雄激素、雌激素和精氨酸加压素）含量，采用原位杂交、免疫组织化学和实时荧光定量RT-PCR方法测定调控声学通讯的激素受体（脑区核团和喉门）表达位点和表达量，构建"重金属类环境激素-体内激素（水平和位点）-声学通讯"机制。该研究有利于了解两栖动物种群数量下降机制，为两栖动物生殖生态环境的保护和恢复提供理论支撑。

声学通讯对无尾两栖动物的配偶选择和成功繁殖起关键作用，而两栖动物的声学通讯易遭受环境激素的影响，其声学通讯效果直接决定着两栖动物的种群动态。重金属是水体中常见的一类环境激素，为研究其对两栖动物声学通讯的影响机制，用自然生境中主要的重金属对三种不同发育时期的两栖动物进行了长期处理，从其生长发育、声学通讯器官变化、通讯行为和通讯效果等系统地探讨了重金属对两栖动物声学通讯的影响效应，测定动物体内调控声学通讯的激素含量和分析调控声学通讯的激素受体表达位点和表达量，结果表明，低剂量的重金属对两栖动物的声学通讯具有影响，可以导致其幼体的生长发育延缓，声学通讯器官喉门发育延缓，声学通讯行为和能力下降，导致其体内的雄激素、雌激素和精氨酸加压素的含量下降，在喉门和大脑内的表达量减少等。该研究有利于了解两栖动物种群数量下降机制，为两栖动物生殖生态环境的保护和恢复提供理论支撑。