RRC ID 33938
Author Tsuji Y, Yamazaki M, Suzuki I, Shiraiwa Y.
Title Quantitative Analysis of Carbon Flow into Photosynthetic Products Functioning as Carbon Storage in the Marine Coccolithophore, Emiliania huxleyi.
Journal Mar. Biotechnol.
Abstract The bloom-forming coccolithophore Emiliania huxleyi (Haptophyta) is a dominant marine phytoplankton, cells of which are covered with calcareous plates (coccoliths). E. huxleyi produces unique lipids of C37-C40 long-chain ketones (alkenones) with two to four trans-unsaturated bonds, β-glucan (but not α-glucan) and acid polysaccharide (AP) associated with the morphogenesis of CaCO3 crystals in coccoliths. Despite such unique features, there is no detailed information on the patterns of carbon allocation into these compounds. Therefore, we performed quantitative estimation of carbon flow into various macromolecular products by conducting (14)C-radiotracer experiments using NaH(14)CO3 as a substrate. Photosynthetic (14)C incorporation into low molecular-mass compounds (LMC), extracellular AP, alkenones, and total lipids except alkenones was estimated to be 35, 13, 17, and 25 % of total (14)C fixation in logarithmic growth phase cells and 33, 19, 18, and 18 % in stationary growth phase cells, respectively. However, less than 1 % of (14)C was incorporated into β-glucan in both cells. (14)C-mannitol occupied ca. 5 % of total fixed (14)C as the most dominant LMC product. Levels of all (14)C compounds decreased in the dark. Therefore, alkenones and LMC (including mannitol), but not β-glucan, function in carbon/energy storage in E. huxleyi, irrespective of the growth phase. Compared with other algae, the low carbon flux into β-glucan is a unique feature of carbon metabolism in E. huxelyi.
Volume 17(4)
Pages 428-40
Published 2015-8
DOI 10.1007/s10126-015-9632-1
PMID 25874681
PMC PMC4486895
MeSH Calcium Carbonate / metabolism* Carbon / metabolism* Carbon Radioisotopes / metabolism Chemical Fractionation Chromatography, Gas Chromatography, Thin Layer Haptophyta / chemistry* Haptophyta / growth & development Haptophyta / physiology* Ketones / metabolism Kinetics Lipids / biosynthesis* Lipids / chemistry Pacific Ocean Photosynthesis / physiology* Polysaccharides / metabolism Queensland Sodium Bicarbonate / metabolism beta-Glucans / metabolism
IF 2.798
Times Cited 3
Algae NIES-837