喜马拉雅旱獭作为药物线粒体毒性替代模型的可行性分析

Feasibility Analysis of Himalayana Marmot as an Alternative Model of Drug Mitochondrial Toxicity Evaluation

目的为了探讨我国青藏高原喜马拉雅旱獭是否可以作为核苷类药物线粒体毒性评价替代模型，本研究从旱獭的系统进化关系对喜马拉雅旱獭在旱獭属中的系统分类地位进行了比较分析。方法以线粒体细胞色素b（Cytb）基因作为遗传进化分析的分子标记，对我国青藏高原喜马拉雅旱獭的Cytb进行了序列测定，并结合已有的旱獭Cytb基因序列对所有旱獭属的种群进行了系统进化分析。结果喜马拉雅旱獭Cytb基因长1140bp，碱基A、T、C、G的平均含量分别为33．2％、25．4％、28．8％、12．6％。Cy咖基因表现出很强的碱基组成偏向性，即在A、T、G、C四种碱基中，G的含量明显低于其他三种碱基的含量。旱獭的@加基因的氨基酸使用频率具有一定的偏向性，亮氨酸（Leu）和异亮氨酸（Ile）的使用频率最高，分别为15．69％和11．87％，而半胱氨酸（Cys）使用频率最低为1．08％。与其它旱獭相比，喜马拉雅异亮氨酸（Ile）和半胱氨酸（cys）的使用频率分别为1．32％和11．87％。系统进化分析结果表明我国喜马拉雅旱獭（M.himalyana）、蒙古旱獭（M.sibirica）、灰旱獭（M.caudata）和红旱獭（M.bobak）与北美旱獭（Woodchuck）属于同一进化组群（置信度为100）。结论喜马拉雅旱獭与美洲旱獭具有较近的亲缘进化关系，属同一组群进化而来，这为寻找新型的核苷类药物线粒体毒性评价替代实验动物模型提供了理论依据。

Objective To explore whether Marmots himalayana could replace woodchuck as an alternative model for evaluating the toxicity of nucleotide analogue drugs, the phylogenetic relation of Marmots himalayana with other Marmots were analyzed based on a molecular marker, mitochondrial cytochrome b （Cytb） gene. Methods Cytb genes from Marmots himalayana were sequenced and phylogenetic analysis were performed combined with existing Marmots Cyth gene sequences. Results The Cytb gene of Marmots himalayana was composed of 1140bp nucleotides, in which the average content of A, T, C and G was 33.2%, 25.4%, 28.8%, 12.6% respectively. Significant nucleotides and amino acids bias in Marmots Cytb genes were found： the content of G was significantly lower than that of A, T and C, the usage frequencies of leucine （Leu） and isoleucine （Ile） （11.87% and 15.69% respectively） were significantly higher than that of cysteine （Cys） （1.08%） in all marmots. However, the usage frequencies of isoleucine （Ile, 11.87%） and cysteine （Cys, 1.32%） in Cytb gene of Marmots himalayana from Qinghai-Tibet Plateau were significantly higher than that of other Marmotas. Phylogenetic analysis showed that Chinese M.himalayana, M.sibirica, M.caudata and M.bobak has a close genetic relation- ship with North America Marmots （Woodchuck）, suggesting they were originated from the same species group.Conclusion A close genetic relationship was found between Marmots Himalayana and woodchuck, which provide new evidence for establishing an alternative model for evaluating nucleotide analogue drugs using Marmots Himalayana.