Datkhile Kailas D, Gaikwad Pallavi S, Ghaskadbi Saroj S, Mukhopadhyaya Rita, Nath Bimalendu B
a Department of Zoology , Savitribai Phule Pune University , Pune , India.
b Molecular Biology Division, Bhabha Atomic Research Centre , Trombay, Mumbai , India.
Int J Radiat Biol. 2015;91(9):742-8. doi: 10.3109/09553002.2015.1062572. Epub 2015 Sep 16.
Chironomus ramosus is one of the recently reported radiotolerant insects. Salivary gland cells of fourth instar larvae respond to ionizing radiations with increases in the levels of antioxidant enzymes and chaperone proteins. Here we made an attempt to study the state of nuclear DNA after exposure of larvae to a lethal dose for 20% of the population (LD(20)) of gamma radiation (2200 Gy, at a dose rate 5.5 Gy/min).
Genomic DNA preparations were subjected to competitive ELISA (Enzyme linked immunosorbent assay) for detection of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and dynamic light scattering (DLS) to monitor any radiation-induced damage. Single salivary gland cells were subjected to alkaline single cell gel electrophoresis (ASCGE), comet assay and pulsed field gel electrophoresis (PFGE) to check for DNA double-strand breaks.
Results from all four experimental procedures confirmed damage of nucleobases and fragmentation of nuclear DNA immediately after radiation. Some 48 h after radiation exposure, modified 8-oxodG residues returned to basal level, homodispersity of genomic DNA reappeared, the length of comet tail regressed significantly (ASCGE) and PFGE pattern matched with that of high molecular weight unirradiated DNA.
Chironomus ramosus larvae showed control of DNA damage as observed over 48 h in post irradiation recovery which could be attributed to their ability to tolerate gamma radiation stress.
多突摇蚊是最近报道的耐辐射昆虫之一。四龄幼虫的唾液腺细胞对电离辐射的反应是抗氧化酶和伴侣蛋白水平升高。在此，我们试图研究幼虫暴露于γ射线（2200 Gy，剂量率5.5 Gy/分钟）的致死剂量（导致20%的群体死亡，即LD(20)）后核DNA的状态。
基因组DNA制剂用于竞争性酶联免疫吸附测定（ELISA）以检测8-氧代-7,8-二氢-2'-脱氧鸟苷（8-氧代dG），并采用动态光散射（DLS）监测任何辐射诱导的损伤。单个唾液腺细胞进行碱性单细胞凝胶电泳（ASCGE）、彗星试验和脉冲场凝胶电泳（PFGE）以检查DNA双链断裂情况。
所有四个实验程序的结果均证实辐射后立即出现核碱基损伤和核DNA片段化。辐射暴露约48小时后，修饰的8-氧代dG残基恢复到基础水平，基因组DNA的均一性重新出现，彗星尾长度显著缩短（ASCGE），且PFGE图谱与未辐照的高分子量DNA图谱匹配。
多突摇蚊幼虫在辐射后48小时的恢复过程中显示出对DNA损伤的控制，这可能归因于它们耐受γ射线辐射应激的能力。
