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INORGANIC CARBON ACQUISITION BY CHRYSOPHYTES 1
Author(s) -
Maberly Stephen C.,
Ball Lucy A.,
Raven John A.,
Sültemeyer Dieter
Publication year - 2009
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2009.00734.x
Subject(s) - alkalinity , bicarbonate , total inorganic carbon , oxygen , carbonic anhydrase , carbon dioxide , biology , carbon fibers , partial pressure , acetazolamide , anoxic waters , environmental chemistry , analytical chemistry (journal) , biochemistry , chemistry , ecology , materials science , physiology , organic chemistry , composite number , composite material , enzyme , endocrinology
Twelve species, representing 12 families of the chrysophytes sensu lato, were tested for their ability to take up inorganic carbon. Using the pH‐drift technique, CO 2 compensation points generally varied between 1 and 20 μmol · L −1 with a mean concentration of 5 μmol · L −1 . Neither pH nor alkalinity affected the CO 2 compensation point. The concentration of oxygen had a relatively minor effect on CO 2 ‐uptake kinetics, and the mean CO 2 compensation point calculated from the kinetic curves was 3.6 μmol · L −1 at 10–15 kPa starting oxygen partial pressure and 3.8 μmol · L −1 at atmospheric starting oxygen partial pressure (21 kPa). Similarly, uptake kinetics were not affected by alkalinity, and hence concentration of bicarbonate. Membrane inlet mass spectrometry (MIMS) in the presence and absence of acetazolamide suggested that external carbonic anhydrase in Dinobryon sertularia Ehrenb. and Synura petersenii Korschikov was either very low or absent. Rates of net HCO 3 − uptake were very low (∼5% of oxygen evolution) using MIMS and decreased rather than increased with increasing HCO 3 − concentration, suggesting that it was not a real uptake. The CO 2 compensation points determined by MIMS for CO 2 uptake and oxygen evolution were similar to those determined in pH‐drift and were >1 μmol · L −1 . Overall, the results suggest that chrysophytes as a group lack a carbon‐concentrating mechanism (CCM), or an ability to make use of bicarbonate as an alternative source of inorganic carbon. The possible evolutionary and ecological consequences of this are briefly discussed.