Abstract:
Nucleic acid estimates in tissues of marine macrophytes with the fluorochromes
Hoechst 33258 and ethidium homodimer were severely impaired by high concentrations
of interfering compounds. The isolation and extraction techniques used pointed
towards compounds of low molecular weight and of polar characteristics that were
insensitive to organic solvent extraction and enzymatic degradation. Interference was
therefore thought to primarily arise from high concentrations of phenols commonly
found in many seaweeds, which might prevent successful fluorochrome binding by
complex formation with nucleic acids. None of the investigated isolation methods was
sufficiently effective to allow accurate estimates of total nucleic acid content or to
reliably establish the metabolic status of seaweeds by RNA/DNA ratios. Despite the
uncertainties involved in nucleic acid estimations, DNA isolated by size exclusion
chromatography was successfully used to show preliminary evidence for photo-activated
DNA repair in marine macrophytes.
