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目的:探讨rnc基因缺失后变形链球菌蔗糖依赖性黏附能力的改变,并分析其在细菌生物膜早期黏附中的作用机制.方法:采用PCR连接诱变法构建变形链球菌rnc基因缺失突变株,通过蔗糖依赖性黏附实验对比变形链球菌rnc基因缺失突变菌株和标准株UA159的黏附能力;RT-qPCR验证rnc缺失后变形链球菌蔗糖依赖性黏附相关基因的表达水平差异.结果:rnc缺失突变株蔗糖依赖性黏附能力及生物膜成膜能力较变形链球菌UA159降低;rnc缺失后蔗糖依赖性黏附相关调控基因gbpB,gtfB,gtfD,dexA显著上调,而gbpC、gbpD显著下调.结论:rnc缺失影响蔗糖依赖性黏附相关基因的表达,降低了变形链球菌蔗糖依赖性黏附能力,影响其致龋性.“,”Objective:The aim of the current study was to verify the involvement of rnc gene in the sucrose-depend-ent cell adherence of Streptococcus mutans(S.mutans),and to analyze its functional roles.Methods:An rnc knockout mutant (Smurnc)was constructed by PCR ligation mutagenesis in S.mutans UA159.Sucrose-dependent cell adherence assay was performed to compare the adhesion ability of Streptococcus mutans UA159 and Smurnc.RT-qPCR was used to analyze the effects of rnc knockout on the expression of the sucrose-dependent cell adherence related genes at the transcriptional level. Results:The sucrose-dependent adhesion and the biofilm formation decreased in Smurnc.Expression of the sucrose-depend-ent cell adherence related genes gbpB,gtfB,gtfD and dexA had been significantly upregulated,gbpC and gbpD of the rnc knockout mutant had been significantly downregulated.Conclusion:Based on these findings,it was established that rnc deple-tion impaired sucrose-dependent adherence of S.mutans UA159.rnc gene may regulate the expression of sucrose-dependent adherence related genes and involve in the cariogenecity of Strptococcus mutans.