National Research Council Postdoctoral Research Associate, National Research Laboratory, Washington, DC, USA.
Center for Biomolecular Science and Engineering, Naval Research Laboratory, Washington, DC, USA.
Environ Microbiol. 2020 Apr;22(4):1310-1326. doi: 10.1111/1462-2920.14936. Epub 2020 Feb 18.
The melanized yeast Exophiala dermatitidis is resistant to many environmental stresses and is used as a model for understanding the diverse roles of melanin in fungi. Here, we describe the extent of resistance of E. dermatitidis to acute γ-radiation exposure and the major mechanisms it uses to recover from this stress. We find that melanin does not protect E. dermatitidis from γ-radiation. Instead, environmental factors such as nutrient availability, culture age and culture density are much greater determinants of cell survival after exposure. We also observe a dramatic transcriptomic response to γ-radiation that mobilizes pathways involved in morphological development, protein degradation and DNA repair, and is unaffected by the presence of melanin. Together, these results suggest that the ability of E. dermatitidis to survive γ-radiation exposure is determined by the prior and the current metabolic state of the cells as well as DNA repair mechanisms, and that small changes in these conditions can lead to large effects in radiation resistance, which should be taken into account when understanding how diverse fungi recover from this unique stress.
黑酵母 Exophiala dermatitidis 能够抵抗多种环境压力，被用作研究黑色素在真菌中的多种作用的模型。在这里，我们描述了 E. dermatitidis 对急性γ射线照射的抗性程度，以及它从这种应激中恢复所使用的主要机制。我们发现黑色素并不能保护 E. dermatitidis 免受γ射线的伤害。相反，环境因素，如营养物质的可用性、培养年龄和培养密度，是暴露后细胞存活的更大决定因素。我们还观察到对γ射线的剧烈转录组反应，它动员了参与形态发育、蛋白质降解和 DNA 修复的途径，并且不受黑色素的影响。总之，这些结果表明，E. dermatitidis 能够在γ射线照射下存活，这取决于细胞的先前和当前代谢状态以及 DNA 修复机制，而这些条件的微小变化可能会导致辐射抗性的巨大变化，在理解不同真菌如何从这种独特的应激中恢复时，应该考虑到这一点。
