Abstract
Since radiation protection has been intended for humans, most studies on radiation biology have been made in mammals including humans. Recently, however, international organizations such as ICRP, UNSCEAR and IAEA began to make an effort for construction of a framework for radiation protection of non-human biota and environments. We have therefore started to study radiation effects on phytoplankton, which is important as a producer in aquatic ecosystems.
Transcriptome was analyzed in acutely gamma-irradiated green alga Pseudokirchneriella subcapitata, which is one of the species most commonly used in ecotoxicity tests of chemicals, but for which genomic sequence information is lacking. This transcriptome analysis was therefore carried out by HiCEP, which is based on AFLP and thus requires no sequence information1).
Approximately 7,000 expressed genes were detected. Expression levels of approximately 800-900 genes were affected at 100 to 300 Gy. Nucleotide sequences of 41 up-regulated genes were determined. The quantitative RT-PCR validated the up-regulation. Two genes had homology to genes involved in DNA repair. One resembled DEAD/DEAH box helicase genes, and the other resembled SNF2/RAD54 family and RAD26 genes2). Further characterization of the affected genes will contribute to finding biomarkers for detection of radiation effects and elucidating molecular mechanisms of responses to radiation, which are expected to have some differences from those in mammals.
1) Fukumura et al., Nucleic Acids Research 31: e94, 2003.
2) Fuma et al., Bulletin of Environmental Contamination and Toxicology 83, 301-306, 2009.
