COMPARISON OF SEVERAL SPECTROFLUOROMETRIC METHODS FOR MEASURING RNA AND DNA CONCENTRATIONS IN THE DEPOSIT-FEEDING BIVALVE ABRA-OVATA

DNA concentrations, RNA concentrations, and corresponding RNA/DNA ratios of the deposit-feeding bivalve Abra ovata were measured using seven spectrofluorimetric methods. Highly significant differences in DNA concentrations, RNA concentrations, and RNA/DNA ratios were found. The analysis of the effects of the main steps involved in these protocols showed that: (i) the presence of detergent in the extracting buffer is absolutely necessary; (ii) the centrifugation step is essential; and (iii) there are several problems associated with the purification of nucleic acids with phenol-chloroform-isoamylalcohol (this procedure affected the linearity of the response of the DNA-specific fluorochrome, and modified the responses of the two non-specific fluorochromes; moreover, this effect was dependent on BSA concentration). Based on these results, a protocol for the quantification of nucleic acids is recommended.