Regulation of alkaline phosphatase synthesis in Phaeocystis sp

WHM van Boekel, MJW Veldhuis

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In short-term experiments, cells of Phaeocystis sp. grown under phosphate-sufficient conditions were harvested and transferred to phosphate-depleted medium. In these cultures alkaline phosphatase activity (APA) developed after a lag-phase of 8 h; addition of cycloheximide (10 pm01 I-') partly inhibited APA development. Addition of organic phosphate (AMP, 0.5 pm01 l-l) did not have an
inducing effect on alkaline phosphatase synthesis. These results indicate that in Phaeocystis sp, alkaline phosphatase synthesis is controlled by the external phosphate concentration. Synthesis is derepressed at low inorganic phosphate concentration in the medium; the threshold concentration for derepression
was ca 0.5 pm01 1-' phosphate. The dark synthesis rate of alkaline phosphatase in Phaeocystis sp. was not correlated with the length of the preceding light period for both colony cells and single cells, although at least a 2 h light period was needed by colony cells to give an enhanced dark synthesis rate
compared with a dark control. In a batch culture growth experiment APA developed during the exponential growth phase of Phaeocystis sp. APA development was found to be independent of the initial N/P ratio of the medium. The results imply that APA is not a good indicator of phosphorus limitation in Phaeocystis sp.
Original languageEnglish
Pages (from-to)281-289
Number of pages9
JournalMarine Ecology Progress Series
Issue number3
Publication statusPublished - 22-Mar-1990
Externally publishedYes

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