Mutagenesis, Vol. 18, No. 1, 73-76,
January 2003
© 2003 UK Environmental Mutagen Society/Oxford University Press
Application of a sea urchin micronucleus assay to monitoring aquatic pollution: influence of sample osmolality
1 Yokohama City Institute of Health, 1-2-17 Takigashira, Isogo-ku, Yokohama 235-0012, Japan and 2 Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
We have improved our sea urchin micronucleus assay for aquatic samples and used it to evaluate marine pollution. We found that the water samples we had collected for 2 years from the Tokyo bay coast near Tokyo, an industrial megalopolis, were positive due to the water samples being hypo-osmotic rather than to chemical pollutants. The evidence was as follows: (i) the osmolality and salinity of the samples were about half that of sea water; (ii) the micronucleus frequency induced in the water sample decreased to the control level when the osmolality was increased to that of sea water; (iii) artificial sea water diluted with distilled water induced micronuclei dilution-dependently. Since micronucleus induction in the sea urchin assay is influenced by sample osmolality, the osmolality must be adjusted to that of sea water for the assay and osmotic pressure must be considered when evaluating water pollution.
3 To whom correspondence should be addressed at present address: Division of Environmental Policy, Environmental Protection Bureau, Yokohama City, Minato-cho 1-1, Naka-ku, Yokohama 231-0017, Japan. Tel: +81 45 671 4103; Fax: +81 45 641 3580; Email: ki00-saotome{at}city.yokohama.jp