Global transcriptomic changes elicited by sodB deletion and menadione exposure in Aspergillus nidulans

Manganese superoxide dismutases (MnSODs) play a pivotal role in the preservation of mitochondrial integrity and function in fungi under various endogenous and exogenous stresses. Deletion of Aspergillus nidulans mnSOD/sodB increased oxidative stress sensitivity and apoptotic cell death rates as well as affected antioxidant enzyme and sterigmatocystin productions, respiration, conidiation and the stress tolerance of conidiospores. The physiological consequences of the lack of sodB were more pronounced during carbon-starvation than in the presence of glucose. Lack of SodB also affected the changes in the transcriptome, recorded by high-throughput RNA sequencing, in menadione sodium bisulfite (MSB)-exposed, submerged cultures supplemented with glucose. Surprisingly, the difference between the global transcriptional changes of the ?sodB mutant and the control strain was relatively small indicating that the SodB-dependent maintenance of mitochondrial integrity was not essential under these experimental conditions. Owing to the outstanding physiological flexibility of the Aspergilli, certain antioxidant enzymes and endogenous antioxidants together with the reduction in mitochondrial functions well compensated for the lack of SodB. The lack of sodB reduced the growth of surface cultures more than submerged culture, which should be considered in future development of fungal disinfection methods. Overall design: Comparative gene expression profiling analysis of RNA-seq data for mycelia of Aspergillus nidulans reference strain, and DsodB mutant under menadione (MSB) treated and untreated conditions with three biological replicates.

锰超氧化物歧化酶（MnSODs）在真菌应对各类内源性与外源性胁迫时，对维持线粒体完整性与功能发挥关键作用。构巢曲霉（Aspergillus nidulans）mnSOD/sodB基因的敲除，会提升菌株对氧化胁迫的敏感性与细胞凋亡率，同时影响抗氧化酶、柄曲霉素的合成，以及呼吸作用、产孢过程与分生孢子的胁迫耐受性。sodB缺失所引发的生理效应，在碳源饥饿条件下比葡萄糖存在时更为显著。在添加葡萄糖的浸没式培养体系中，经甲萘醌亚硫酸氢钠（MSB）处理的样本里，SodB的缺失同样会通过高通量RNA测序检测到转录组的变化。令人意外的是，ΔsodB突变体与对照菌株的全局转录组变化差异相对较小，这表明在该实验条件下，依赖SodB的线粒体完整性维持并非必需。鉴于曲霉属具备卓越的生理灵活性，部分抗氧化酶与内源性抗氧化物质，辅以线粒体功能的下调，可有效弥补SodB的缺失。sodB的缺失对表面培养菌丝生长的抑制效果强于浸没式培养，这一结论在未来真菌消毒方法的开发中值得纳入考量。
实验设计概要：针对构巢曲霉参考菌株与ΔsodB突变体的菌丝体RNA测序数据开展对比基因表达谱分析，分别在甲萘醌亚硫酸氢钠（MSB）处理与未处理的条件下进行，每组设置3次生物学重复。