The effect of light intensity and light-dark cycle (12 : 12) on the percentage of cells with diploid DNA in monospecific cultures of microalgae Phaeodactylum tricornutum Bohlin, Nitzschia sp. 3, Prorocentrum pusillum Shiller, P. cordatum (Ostf.) Dodge, Isochrysis galbana Parke was studied by flow cytometry. It was shown that the proportion of cells in G2 phase was significantly higher in high-intensity lighting. In all species strong correlation (r2 > 0.98) was revealed between the potential growth rate of algae determining by the mitotic index, and their specific production as measured by the increase in number. The possibility of flow cytometry use for cell cycle analysis and evaluation of potential growth rates of picophytoplankton and nanophytoplankton of the Black Sea. At three stations in Sevastopol and Quarantine bays potential growth rate of pico- and nanophytoplankton in the surface layer was 0.2–1.0 d-1 (year-round sampling in 2010 at 3 stations, totally 120 samples). Maximum values of this parameter corresponded to the number of annual peaks of phytoplankton number.
Keywords: flow cytometry, microalgae, phytoplankton, mitotic index, growth rate, SYBR Green I
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