Main content area

Heavy Metal-Induced Differential Gene Expression of Metallothionein in Javanese Medaka, Oryzias javanicus

Woo, Seonock, Yum, Seungshic, Jung, Jee Hyun, Shim, Won Joon, Lee, Chang-Hoon, Lee, Taek-Kyun
Marine biotechnology 2006 v.8 no.6 pp. 654-662
Oryzias javanicus, biomarkers, cadmium, chromium, complementary DNA, copper, cysteine, dose response, fish, freshwater, gene expression regulation, genes, heavy metals, intestines, liver, messenger RNA, metallothionein, monitoring, muscles, nickel, quantitative polymerase chain reaction, seawater, silver, zinc
A metallothionein (MT) gene was isolated for the first time from Javanese medaka, Oryzias javanicus, which shows high adaptability from freshwater to seawater. The full-length cDNA of MT from O. javanicus (OjaMT) comprises 349 bp, excluding the poly(A)⁺ stretch, and codes for a total of 60 amino acids. The positions of cysteine residues are highly conserved. The pattern of OjaMT expression induced by six heavy metals was analyzed via real-time quantitative polymerase chain reaction (PCR). The level of hepatic OjaMT mRNA was increased in a dose-dependent manner by Ag, Cd, Cu, and Zn after 24 h of exposure. However, after Cr and Ni exposure, a significant decrease in OjaMT levels was observed. Cadmium-induced OjaMT expression was detectable in fishes as young as 3 months. After Cd exposure, OjaMT induction was prominent in intestine and liver and moderate in muscle and gill. OjaMT mRNA levels could represent a good biomarker for monitoring heavy metals in seawater.