engleski

Field investigations of MFO-induction in freshwater and marine fishes: Beginnings of MFO-measurements and evaluation of acquired data

The initial attempts to explain the interrelationships of Mixed Function Oxygenase (MFO) induction of gentoxic loads of aquatic bodies are redressed. The interesting problem whether avertebrates possess obligatory end/or inducible MFOs was attacked by investigations on 16 marine organisms belonging to 6 different families. In some of the enzyme activities have been found. Applications of methods for MFO assessment are discussed in context with DNA damage. In native animals within 20 minutes after injection of a gentoxin, as benzo(a)pyrene, a "Fast Effect" is seen, which consists in an ephemeral DNA damage. It is not until many hours later that a rise in MFO activity is observed which is paralleled by renewed DNA damage. The conditions for MFO induction have been investigated more thoroughly with the see spider Maja as the example. Organ distribution of MFO activities, their inhibition, as well as the problem of superinduction by inhibitors of macromolecular synthesis are demonstrated. Dynamic equilibrium of MFO activities in territorially attached fish of the genus Blennius have been found in accordance with territorial loads, the data of which have been already known otherwise. When some time later an oil spill accident occurred, is resulting highly significant rise in MFO activities in these fish populations that had been measured formerly could be demonstrated with high sensitivity and its cause clearly stated for the first time. Also in shoal fish, depending on the region of catch, specific MFO activities of different extents are found, which could be sorted according to definite groups. During year-long investigations with 14 day exposures of fish ti river water, MFO fluctuations have been found that may mirror fluctuations of genotoxic loads. In other measurments however, when short-time exposures were compared to parallel and overlapping long-time exposures, results are seen that are hard to interprete. They may stem from superpositions of phase-shifted increases and fadings of MFO activities. At times a pronounced relation between water temperature and MFO activity could be observed. Interpretation of the results of MFO measurements with respect to genotoxic loads may be influenced further considerably, especially when it comes to mixed pollution by modulation compounds that by themselves are not genotoxic

mixed function oxygenases ; fish ; oil spill ; benzo(a)pyrenemonooxygenase

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