长期高盐刺激诱导白假丝酵母菌耐受氧化应激

Long-term exposure to high concentration of salt stress induces antioxidative response in Candida albicans

目的观察长期高浓度氯化钠刺激对白假丝酵母菌耐受氧化应激能力的影响。方法选用2株白假丝酵母菌国际标准株SC5314和ATCC76615,用含有1mol/L氯化钠的YEPD培养液连续培养24d,考察子代与亲本菌对氧化应激的耐受能力。采用real-time RT-PCR考察白假丝酵母菌抗氧化酶的转录水平,并测定其抗氧化酶的活性,利用丙二醛(MDA)测定试剂盒衡量白假丝酵母菌脂质过氧化损伤,并测量白假丝酵母菌菌体细胞内活性氧水平。结果长期用高浓度氯化钠刺激能增加白假丝酵母菌对过氧化氢(12mmol/L)和咪康唑(4μg/ml)的耐受性,促进其抗氧化酶的转录,使抗氧化酶SOD1、CAT1、谷胱甘肽还原酶(GR,转录基因为TTR1)的转录水平升高2～5倍,增强抗氧化酶的活性(P<0.05),降低脂质过氧化损伤(P<0.01),减少菌体细胞内活性氧水平(P<0.001)。结论长期高浓度氯化钠刺激能够增强白假丝酵母菌耐受氧化应激的能力。

Objective To investigate the effect of long-term exposure to high concentration of sodium chloride on resistance to oxidative stress in Candida albicans （C. albicans）. Methods Two C. albicans strains, SC5314 and ATCC76615, were challenged with 1 mol/L NaC1 for 24 consecutive days. Spot assay was performed to compare the resistance to hydrogen peroxide and miconazole between the wild-type and derivative strains. The transcription levels of antioxidant enzymes, including superoxide dismutase （SOD1）, catalase （CAT1）, and glutathione reductase （GR）, were determined by real-time RT-PCR, and their activities were also examined. Peroxidation of lipid was examined by determining the contents of malondialdehyde （MDA） ; the cellular level of reactive oxygen species （ROS） was also determined. Results Long-term exposure to high concentration of sodium chloride enhanced the resistance of C. albicans to oxidative stress （hydrogen peroxide [12 mmol/L] and miconazole [4μg/ml]）; the exposure increased the transcription of antioxidant enzymes, SOD1, CAT1, and GR by 2-5 folds; and it also significantly increased the activities of the antioxidant enzymes （P 〈 0. 05）. Meanwhile, it significantly alleviated the peroxidation of lipid （P〈0.01） and decreased the intracellular ROS contents （P〈0.01）. Conclusion Long-term exposure to salt stress can increase the resistance to oxidative stress in C. albicans.