中文摘要：

目的检测白念珠菌体外抗氧化及调节转录的基因表达情况,进一步了解白念珠菌抗氧化机制在体外生长状态下的作用。方法选取白念珠菌标准株sc5314、3株临床分离保存株及7例临床念珠菌性阴道炎分泌物分离株（白念珠菌）,接种培养鉴定为白念珠菌后,分别将体外SDB振荡培养2 h、6 h、24 h、72 h、120 d的菌液（含未培养0h）,用Trizol法提取总RNA,反转录为cDNA后进行实时荧光定量PCR,检测体外各时间点抗氧化基因及抗氧化转录因子的基因表达情况,运用Ct值比较法进行表达量的相对定量分析。结果与0 h相比,体外6 hSOD2表达增加7.47倍,经Wilcoxon配对符号秩和检验显示P值小于0.01,差异具有统计学意义。其他各基因2 h及6 h分别与0 h相比P值均〉0.01,其表达差异不具有统计学意义。体外培养1 d后各基因表达明显增加,CaHog1、CAP1、CAT及SOD5在第3天达最高,分别为24.23、3.34、33.64及14.72倍;SOD2在第1天达最高为68.95倍;CaSkn7在第5天达最高为7.21倍。经Wilcoxon配对符号秩和检验显示SOD5第1天P值为0.013,其余基因表达P均〈0.01,表达差异具有统计学意义。结论当外界营养逐渐耗竭时,白念珠菌会动态加强抗氧化基因的表达,以抵抗机体内、外产生的氧化压力,其中SOD2可能是最早增加表达的抗氧化基因,3条抗氧化感受通路的转录调节基因均有增加表达,提示3条抗氧化感受通路在适应体外营养限制过程中起了重要作用。

英文摘要：

Objective To evaluate anti-oxidative gene expression in clinical isolates, so as to explore the anti-oxidative stress response in in vitro culture. Methods C. albicans standard strain SC5314 , three clinical isolates and seven samples from vaginal candidiasis were cultured in SDB at various time point （2 h,6 h, 24 h, 72 h, 120 h）. The total RNA of C. albicans in in vitro cultures were isolated by Trizol method, and were anylized by reverse transcription real-time PCR. The comparative Ct method were applied to detect relative gene expression of antioxidant enzyme （ CAT,SOD2 ,SOD5 ） and anti-oxidative related transcription factors （ CaHogl, CaSkn7, CAPI ） of C. albicans in ivtro. Results SOD2 gene expression at 6 h up-regulated 7.47-fold of that before culture （0 h） （wilcoxon signed-rank matched-pair test P 〈0.01 ）. All genes showed obvious up-regulation after one-day in vitro cul- ture. CaHog1, CAP1, CAT, SOD5 reached the highest level on day 3 that 24.23, 3.34, 33.64, or 14.72-fold of those precuhure （0 h）. The most highest level of CaSkn7 and SOD＇2 appeared on day 5 and day 1, with 7.21 and 68.95-fold compared to those preculture （0 h）. The up-regulation of all genes over 1 day had statistically significant （ wilcoxon signed-rank matched-pair test P 〈 0.01 ） except SOD5 on day 1 （ P =0. 013）. Conclusions When the nutrient is exhausted from the growth medium, anti-oxidative related gene ofC. albicans will up regulate dynamically to resist both endogenous and exogenous oxidative stress. In this study, SOD2 was the most early up-regulated antioxidant gene. The three transcription factors of oxidative stress response signal pathways were significantly up-regulated throughout the time-course, which suggestded the three oxidative stress response signal pathways play an important role in adaption of limited nutrient in vitro.