Department of Bioscience and Biotechnology and Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, 20224, Taiwan, ROC.
Department of Bioscience and Biotechnology and Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, 20224, Taiwan, ROC.
Chemosphere. 2020 Jan;238:124653. doi: 10.1016/j.chemosphere.2019.124653. Epub 2019 Aug 23.
Discharge of heated effluent at 8-12 °C above ambient into water areas is known to retard the growth of aquatic organisms due to heat stress. Nucleotide excision repair (NER) maintains genome integrity by removing helix-distorting adducts such as UV-induced DNA lesions. This study explored how NER in zebrafish (Danio rerio) embryos at different hours post fertilization (hpf) responded to + 8.5 °C heat shock for 30 min. Our transcription-based repair assay monitoring the ability of zebrafish extracts to upregulate a UV-suppressed gene expression detected a 2-fold increase of NER capacity in 10 hpf early embryos after heat stress. In contrast, heat stress caused a mild inhibition of NER capacity in 24 hpf mid-early embryos. Heat-treated and untreated 10 hpf zebrafish extracts displayed similar levels of UV-damaged-DNA binding activities, while an apparently weaker (6-4) photoproduct (6-4 PP) binding activity was present in heat-stressed 24 hpf zebrafish extracts. Heat stress enhanced UV-induced NER in 10 hpf embryos by increasing the efficiency of damage incision/excision based on both genomic DNA electrophoresis and terminal deoxytransferase (TdT)-mediated end labeling assay. UV-irradiated embryos preexposed to heat stress produced a significantly larger amount of NER-associated DNA fragments about 20-30 nucleotides in length than embryos only heat-treated or irradiated. Correlated with its inhibitory effect on 6-4 PP damage recognition, heat stress downregulated damage incision/excision activities in 24 hpf embryos. Hence, thermal stress may positively or negatively modulate NER capacity in zebrafish embryos at different stages by targeting at the step of DNA incision/excision or damage recognition.
将温度高于环境 8-12°C 的热水排放到水域中已知会由于热应激而减缓水生生物的生长。核苷酸切除修复 (NER) 通过去除螺旋扭曲加合物（如紫外线诱导的 DNA 损伤）来维持基因组完整性。本研究探讨了在受精后不同小时 (hpf) 的斑马鱼 (Danio rerio) 胚胎中的 NER 如何对 30 分钟的+8.5°C 热休克做出反应。我们的转录修复测定监测了斑马鱼提取物上调被紫外线抑制的基因表达的能力，发现热应激后，10 hpf 早期胚胎的 NER 能力增加了 2 倍。相比之下，热应激导致 24 hpf 中早期胚胎的 NER 能力受到轻度抑制。热处理和未处理的 10 hpf 斑马鱼提取物显示出相似水平的紫外线损伤-DNA 结合活性，而在热应激的 24 hpf 斑马鱼提取物中存在明显较弱的（6-4）光产物（6-4 PP）结合活性。热应激通过提高基于基因组 DNA 电泳和末端转移酶 (TdT)-介导的末端标记测定的损伤切割/切除效率，增强了 10 hpf 胚胎中的紫外线诱导的 NER。与热应激对 6-4 PP 损伤识别的抑制作用相关，热应激下调了 24 hpf 胚胎中的损伤切割/切除活性。因此，热应激可能通过靶向 DNA 切割/切除或损伤识别步骤，对不同阶段的斑马鱼胚胎中的 NER 能力产生正向或负向调节作用。
