Oryzias javanicus에서 카드뮴에 의해 유도된 스트레스 관련 유전자들의 발현

Abstract

Environmental stress dramatically induces stress responsiveness in an organism and it affects its related genes expressions. We obtained several stress-responsive genes (metallothionein, catalase, superoxide dismutase, glutathion S-transferase, cytochrome P-450, uniquitin) from cadmium exposed Oryzias javanicus and investigated their expression changes in fishes exposed to a variety of concentrations of cadmium. Metallothioneins (MTs) play a key role in the detoxification of heavy metals and its gene expression changes are useful to monitor heavy metal exposure as a biomarker. We designed targeted primers for the stress responsive genes including MT from highly conserved region in various organisms and have cloned by reverse transcription polymerase chain reaction (RT-PCR) with RNA extracted from Oryzias javanicus liver. The six groups of medaka fish (n=5, respectively) were exposed to various concentrations of cadmium (0.1, 1, 10, 100, 1000, 10000 ppb) for 24 hr then total RNAs were extracted from livers. The gene expression changes in six groups were investigated by northern blot analysis, comparing with non-exposed control group. Northern blot results indicated that MT gene expression was significantly induced by cadmium stress and the level of each transcript was elevated in Cd-exposed Oryzias javanicus comparing the non-exposed control in a dose-dependent manner. Expression changes of other genes were also investigated using real-time PCR method and we obtained the similar results to MT expression result.