Evolution of resistance to scorpion neurotoxins

亚利桑那树皮蝎（Centruroides exilicauda）和条纹树皮蝎（C。vittatus）生产 选择性结合神经和肌肉的可兴奋膜中的电压门控离子通道的神经毒素， 产生神经和神经肌肉系统的过度兴奋。南方蚱蜢鼠 （Onychomys torridus）和Mearns' grasshopper小鼠（O. arenicola）是蝎子的贪婪捕食者， 美国沙漠Southern和Mearns的蚱蜢小鼠表现出对树皮的生理抵抗力 蝎子毒液蚱蜢鼠种群之间毒液抗性的变异性与 树皮蝎同域分布和异地分布的地理格局。电生理分析表明， 蚱蜢鼠神经和肌肉中的通道对蝎子神经毒素不敏感。目的 该项目的目的是确定耐药细胞离子通道不敏感性的分子遗传基础。 小鼠，以表征耐药水平表型差异的分子变异， 他们的人口，并评估模式的选择基因参与毒素抗性。离子通道 将检查编码基因的结构和功能变化，这些变化赋予对毒素的不敏感性。

The Arizona bark scorpion (Centruroides exilicauda) and the striped bark scorpion (C. vittatus) produce neurotoxins that selectively bind voltage-gated ion channels in excitable membranes of nerve and muscle, producing hyper-excitability of the nervous and neuromuscular systems. Southern grasshopper mice (Onychomys torridus) and Mearns' grasshopper mice (O. arenicola) are voracious predators of scorpions in U.S. deserts. Southern and Mearns' grasshopper mice demonstrate physiological resistance to bark scorpion venom. Variability in venom resistance among grasshopper mice populations co-varies with geographic patterns of bark scorpion sympatry and allopatry. Electrophysiological assays show that ion channels in the nerve and muscle of grasshopper mice are insensitive to scorpion neurotoxins. The purpose of the proposed project is to determine the molecular genetic basis of ion channel insensitivity in resistant mice, to characterize the molecular variation underlying phenotypic differences in resistance levels among their populations, and to assess patterns of selection on genes involved in toxin resistance. Ion channel encoding genes will be examined for structural and functional changes that impart insensitivity to toxins.