Chlorophyll Turnover in Skeletonema costatum, a Marine Plankton Diatom |
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Authors: | Riper D M Owens T G Falkowski P G |
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Affiliation: | Oceanographic Sciences Division; Department of Energy and Environment, Brookhaven National Laboratory, Upton, New York 11973. |
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Abstract: | [3H]- and δ-[14C]Aminolevulinic acids were incorporated into the chlorophylls of Skeletonema costatum, a marine plankton diatom. In the stationary phase of growth, the tetrapyrrole-based pigments reached steady-state labeling after 10 hours. Under conditions of exponential cell division and chlorophyll accumulation, 3H was rapidly lost from the labeled chlorophylls and was replaced with 14C derived from δ-[4−14C]aminolevulinic acid. The kinetics of isotope dilution suggests recycling of tetrapyrrole precursors and/or two pigment pools, containing both chlorophyll a and chlorophyllide c, one which turns over rapidly (10 hours) and another which turns over more slowly (100 hours). Calculation of turnover times varied from 3 to 10 hours for chlorophyll a and from 7 to 26 hours for chlorophyllide c. The data suggest the dynamics of chlorophyll metabolism in S. costatum and explain the diatom's ability to undergo light-shade adaptation within a generation time. |
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