| Abstract: | Our experience in DNA alteration assessment tells us that aquatic vertebrates, in general, and also some of the invertebrates, by living in polluted areas acquire altered DNA; DNA alterations being defined either as single-strand breaks, and/or alkali sensitive or single-strand specific nuclease-cleavable sites (sse). This can be shown by several methods: (i) Alkaline filter elution;1 (ii) fluorescence analysis of DNA unwinding;2 (iii) alkaline sucrose density gradient centrifugation;3 (iv) alkaline unwinding analysis with hydroxyapatite differentiation;4 (v) nucleoid sedimentation analysis;5 (vi) supercoiled DNA relaxation detection by electrophoresis;6 and (vii) measurement of DNA molecular weight distributions with the electron microscope.7 The amount of sse per DNA mass can be a function of either an increased activity of DNA damaging agents or agents that inhibit DNA repair. Among DNA damaging agents are polycyclic aromatic hydrocarbons (PAH), that can cause sse by the ‘fast effect’8 or after induction upon uptake, through the action of mixed function oxygenase (MFO). Since MFO induction within certain limits is a function of PAH concentration measurement of this enzyme activity enables at least partial interpretation of the DNA alteration status, which can be a two-phase process. |
