中文摘要：

α-银环蛇毒素（α-bungarotoxin）是一种突触后神经毒素，广泛存在于眼镜蛇科蛇类的毒腺中，对于该基因cDNA多态性是否真实一直存有争议。本研究从银环蛇基因组DNA中克隆到α-银环蛇毒素基因序列，并对其中5个克隆进行测序和序列比对分析。作为参照，从同一次反转录得到的cDNA混合物中，克隆了蛇毒神经生长因子cDNA，并对其进行测序、比对和突变情况分析。综合各研究组报道的α-银环蛇毒素cDNA序列、α-银环蛇毒素基因序列和神经生长因子cDNA序列的突变情况，发现α-银环蛇毒素cDNA的多态性在基因组模板上不存在对应的变化，因此推测这种多态性不是从不同的转录本而来，同时考虑到不同研究小组报道的序列突变位点并没有出现相同的情况，因此其多样性也不是RNA编辑的结果。可见这种cDNA序列上的多样性很可能是由反转录过程以及基因克隆过程中人为引入的错误造成的。

英文摘要：

Alphaobungarotoxin is one of the post-synaptic neurotoxins, which widely exists in the Elapidae venom. The polymorphism of α-bungarotoxin＇s cDNA sequences has been controversial in previous reports. In the present study, cloning of α-bungarotoxin gene from the genomic DNA, sequencing of five clones and analysis of their polymorphism were reported. Furthermore, we cloned and sequenced the nerve growth factor （NGF） gene from the same cDNA pool as a standard, and compared the mutation rates among different sources of α-bungarotoxin cDNAs, α-bungarotoxin genes and NGF cDNA. The results indicated that there was no diversification in the genome or comparability in the mutative points between different sequences. Therefore, we speculate that the polymorphism of α-bungarotoxin cDNA resulted neither from different transcripts, nor from RNA editing, but possibly from reverse transcript processes and gene-cloning processes.