Co-expression of antioxidant enzymes with expression of p53, DNA repair, and heat shock protein genes in the gamma ray-irradiated hermaphroditic fish Kryptolebias marmoratus larvae

- Novel identification of DNA repair-related genes in fish.
- Investigation of whole expression profiling of DNA repair genes upon gamma radiation.
- Analysis of effects of gamma radiation on antioxidant system and cell stress proteins.
- Usefulness of verification of pathway-based profiling for mechanistic understanding.

To investigate effects of gamma ray irradiation in the hermaphroditic fish, Kryptolebias marmoratus larvae, we checked expression of p53, DNA repair, and heat shock protein genes with several antioxidant enzyme activities by quantitative real-time RT-PCR and biochemical methods in response to different doses of gamma radiation. As a result, the level of gamma radiation-induced DNA damage was initiated after 4 Gy of radiation, and biochemical and molecular damage became substantial from 8 Gy. In particular, several DNA repair mechanism-related genes were significantly modulated in the 6 Gy gamma radiation-exposed fish larvae, suggesting that upregulation of such DNA repair genes was closely associated with cell survival after gamma irradiation. The mRNA expression of p53 and most hsps was also significantly upregulated at high doses of gamma radiation related to cellular damage. This finding indicates that gamma radiation can induce oxidative stress with associated antioxidant enzyme activities, and linked to modulation of the expression of DNA repair-related genes as one of the defense mechanisms against radiation damage. This study provides a better understanding of the molecular mode of action of defense mechanisms upon gamma radiation in fish larvae.