Metallothionein induction in the RTH-149 cell line as an indicator for heavy metal bioavailability in a brackish environment: Assessment by RT-competitive PCR

Estuarine and marine near-shore environments are often subjected to heavy metal pollution. We establish a bioassay using the quantitative evaluation of metallothionein (MT) transcript in the fish hepatoma cell line, RTH-149, as a tool for detecting heavy metal pollution in brackish-marine water containing other pollutants in addition to heavy metals. RT-competitive polymerase chain reaction was used for the quantitative evaluation of the transcript in absolute units. Cadmium was used as a model pollutant to optimize two parameters of the assay: exposure periods (24, 96, 144 h) and salinity (0%, 25%, 50%, 75%, 100% sea water). Results revealed that salinity at or below 25% sea water at an exposure period of 144 h are the preferable conditions for detecting MT mRNA levels for in vitro assays employed on water samples from highly polluted brackish habitats.