新生隐球菌ITS与IGS2基因的分类比较研究

Phylogenetic studies of Cryptococcus neoformans based on IGS2 and ITS gene analyses

目的探讨ITS及IGS2基因片段对新生隐球菌各变种及基因型分类与鉴定的应用价值。方法根据本课题前期研究结果及GenBank发表的基因序列资料,研究新生隐球菌3个变种的ITS和IGS2基因片段信息,用CLUSTERW软件构建以上两种基因的系统发育进化树并进行分析,了解其亲缘关系。结果对新生隐球菌各菌株ITS基因型的IGS2区域片段分析结果显示,IGS2基因片断具有丰富的变异和信息位点。同ITS基因序列比较显示,IGS2基因在亚种内也具有同步进化和变异的特征。结论IGS2基因序列分析可作为新生隐球菌种间及种内基因分类鉴定有效的分子生物学方法;多种基因分类鉴定方法的联合应用,可更有效和准确地鉴定新生隐球菌并揭示其种内不同基因亚型间的遗传进化关系。

Objective To study the classification and identification capabilities of IGS2 and ITS genes on the varieties and genotypes of Cryptococcus neoformans. Methods According to the previous study and the published gene data from Genbank, the phylogenetic trees （Neghbor-joining method） of C. neoformans strains were constructed based on IGS2 and ITS genes by using CLUSTER w software. Results Sequence analyses of the intergenic spacer 2 （IGS2） associated with rDNA revealed significant differences in nucleotide composition within three varieties of C. neoformans. The phylogenetic positions of C. neoformans strains can be agreed with each other based on the IGS2 and ITS gene information. Conclusion Compared with ITS gene analysis, IGS2 nucleotide sequences are more suitable for strain level differentiation of C. neoformans. Therefore, the combination of different molecular methods is recommended for the accurate taxonomic analyses of the intra-species relationship.