Species-specific phytoplankton growth rates via diel DNA synthesis cycles. II DNA quantification and model verification in the dino-flagellate Heterocapsa triquetra

Abstract

ABSTRACT: The DNA content of individual cells, after being stained by a DNA-specific fluorescent dye, was quantified by a TV camera-based microfluorometry system. Under proper dye concentrations, fluorescence intensity of a stained nucleus was in proportion to the amount of nuclear DNA. Durations of die1 cell cycle phases were estimated with DNA histograms from 2 partially synchronized cultures of the dinoflagellate Heterocapsa tn'quetra. Estimates of growth rate were calculated from phase durations and compared to the growth rates estimated by cell counts. Growth rates calculated by various mathemahcal procedures and sampling intervals were simllar, and the calculated growth rate via DNA synthesis gave a reasonably good estimate of the rate calculated by increase in cell density. This technique is promising in its application to species-specific growth rates in the field