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Title: The detection of mutagenic chemicals in the marine environment
Author: Kadhim, M. A.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1983
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Chemical mutagens dispersed in the marine environment are usually in low concentration and episodic in occurrence. The possibility of detecting such dispersed mutagens by utilizing bioconcentrator organisms coupled with a microbial mutagen assay may offer a useful screening protocol. There is a problem inherent with testing a complex biological extract. If a reversion assay is used, the nutrient necessary for growth may be present. Methods for minimizing this difficulty are discussed. Alcoholic extracts from a variety of marine organisms, collected from many areas of the United States of America of known exposure to chemical effluent and a "clean" area at different times of the year, have been assayed for the presence of mutagenic chemicals using a short term assay, the bacterial fluctuation test. The genetic activity of extracts of these organisms was dependent on the organisms sampled, the sites, and the time of collection. The edible mussel Mytilus edulis, was the main biological concentrator employed in this study. Extracts of mussels collected from a number of sites in the U.K. both adjacent to industrial areas and those exposed to oil pollution, were assayed for mutagenicity using the Salmonella typhimurium strains TA98 and TAIOO. Nitric acid and chloroform-methanol extracts of the edible mussel Mytilus edulis and the common limpet Patella vulgate collected from the Pembrokshire area of S. Wales before, during, and after an oil spill, were tested for mutagenic activity with a microbial mutagen assay. The acidic anachloroform-methanol extracts corresponding to the period of the presence of the oil spill were shown to contain chemicals capable of inducing direct and indirect mutation in bacteria. In the case of the visually most severely polluted site, the presence of direct mutagene was still detectable more than one year after the original oil spill. Nitric acid and alcoholic extracts of three types of tissues from the mussel Mytilus edulis collected over 2 years at monthly intervals, from the Gower Peninsula in the U.K., were tested for mutagenicity with Salmonella typhimurium TA98 and TAIOO in fluctuation tests. Both alcohol and acid extracts showed considerable variation in activity levels, reaching maximal levels during the summer months. Greater activity was observed with strain TA98. However, in the case of digestive gland extracts, the period of mutagenic activity was detectable earlier in the year with a peak during mid-summer. Studies upon the effects of both mammalian and mussel microsome preparation indicated that at least a fraction of the variation in mutagenic activity was dependent upon seasonal variation in the activation capacity of mussel tissues. The same population of mussel tissues extracted in different solvents and extraction methods exhibited a different quality and quantity of mutagenic activity in bacteria. This suggests the presence of a variety of chemicals with different characteristics in mussel tissue which can be extracted in different treatment methods and cause mutation in bacterial cu 1 tunes. The results of the present study indicate that the major activity detected in the mutagenicity assays does not derive from the presence of heavy metals or nitrosamines. Reconstruction experiments indicate that polychlorinated biphenyls may be converted into mutagenic chemicals species during extraction in the presence of mussel tissue and may represent candidate compounds for detection in our assays.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available