자바송사리의 metallothionein 유전자: cDNA 클로닝 및 유전자 발현 연구

Abstract

Metallothioneins (MTs) are a family of low molecular weight, heavy metal-bindingproteins characterized by a high cysteine content and lack of aromatic amino acids. MTs bind 7 to 12 heavy metal atoms per molecule of protein. They are ubiquitous in the animal and plant kingdoms and are found in prokaryotes. This protein plays 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 MT targeted primers from highly conserved region of metallothionein gene in various organisms and have cloned by reverse transcription polymerase chain reaction (RT-PCR) with RNA extracted from Oryzias javanicus liver. To investigate MT gene expression change in heavy metal-exposed Oryzias javanicus, 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 liver, gill and intestine. The gene expression changes of MT in eight 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 (Cd) stress and the level of each transcript was elevated in Cd-exposed Oryzias javanicus comparing the non-exposed control in a dose-dependent manner.