Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan Carlos, ESCET, C/Tulipán s/n, 28933, Móstoles, Madrid, Spain.
Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC), Plaza de Murillo 2, 28014, Madrid, Spain.
Microb Ecol. 2020 Apr;79(3):604-616. doi: 10.1007/s00248-019-01427-2. Epub 2019 Sep 6.
Lichens undergo desiccation/rehydration cycles and are permeable to heavy metals, which induce free radicals. Nitrogen monoxide (NO) regulates important cellular functions, but the research on lichen NO is still very scarce. In Ramalina farinacea thalli, NO seems to be involved in the peroxidative damage caused by air pollution, antioxidant defence and regulation of lipid peroxidation and photosynthesis. Our hypothesis is that NO also has a critical role during the rehydration and in the responses to lead of its isolated phycobionts (Trebouxia sp. TR9 and Trebouxia jamesii). Therefore, we studied the intracellular reactive oxygen species (ROS) production, lipid peroxidation and chlorophyll autofluorescence during rehydration of thalli and isolated microalgae in the presence of a NO scavenger and Pb(NO). During rehydration, NO scavenging modulates free radical release and chlorophyll autofluorescence but not lipid peroxidation in both thalli and phycobionts. Pb(NO) reduced free radical release (hormetic effect) both in the whole thallus and in microalgae. However, only in TR9, the ROS production, chlorophyll autofluorescence and lipid peroxidation were dependent on NO. In conclusion, Pb hormetic effect seems to depend on NO solely in TR9, while is doubtful for T. jamesii and the whole thalli.
地衣经历干燥/复水循环，且对重金属具有通透性，这会诱导自由基的产生。一氧化氮（NO）调节着重要的细胞功能，但关于地衣 NO 的研究仍然非常匮乏。在长松萝藻（Ramalina farinacea）藻体中，NO 似乎参与了由空气污染引起的过氧化损伤、抗氧化防御以及脂质过氧化和光合作用的调节。我们的假设是，NO 在藻体的复水过程中和对铅的反应中也起着关键作用，其藻体的共生藻（Trebouxia sp. TR9 和 Trebouxia jamesii）也是如此。因此，我们研究了藻体和分离的微藻在 NO 清除剂和 Pb(NO)存在下复水过程中细胞内活性氧（ROS）的产生、脂质过氧化和叶绿素自发荧光。在复水过程中，NO 清除剂调节自由基的释放和叶绿素自发荧光，但不调节藻体和共生藻的脂质过氧化。Pb(NO) 降低了整个藻体和微藻中的自由基释放（毒物兴奋效应）。然而，只有在 TR9 中，ROS 的产生、叶绿素自发荧光和脂质过氧化才依赖于 NO。总之，Pb 的毒物兴奋效应似乎仅在 TR9 中依赖于 NO，而在 T. jamesii 和整个藻体中则不确定。
