Contrasting modes of inorganic carbon acquisition amongst Symbiodinium (Dinophyceae) phylotypes
Growing concerns over ocean acidification have highlighted the need to critically understand inorganic carbon acquisition and utilization in marine microalgae. Here, we contrast these characteristics for the first time between two genetically distinct dinoflagellate species of the genus Symbiodinium...
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Veröffentlicht in: | The New phytologist 2013-10, Vol.200 (2), p.432-443 |
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Zusammenfassung: | Growing concerns over ocean acidification have highlighted the need to critically
understand inorganic carbon acquisition and utilization in marine microalgae.
Here, we contrast these characteristics for the first time between two
genetically distinct dinoflagellate species of the genus
Symbiodinium (phylotypes A13 and A20) that live in
symbiosis with reef-forming corals.
Both phylotypes were grown in continuous cultures under identical environmental
conditions. Rubisco was measured using quantitative Western blots, and
radioisotopic 14C uptake was used to characterize light- and total
carbon dioxide (TCO2)-dependent carbon fixation, as well as inorganic
carbon species preference and external carbonic anhydrase activity.
A13 and A20 exhibited similar rates of carbon fixation despite cellular
concentrations of Rubisco being approximately four-fold greater in A13. The
uptake of CO2 over
was found to support the majority of carbon fixation in
both phylotypes. However, A20 was also able to indirectly utilize
by first converting it to
CO2 via external carbonic anhydrase.
These results show that adaptive differences in inorganic carbon acquisition have
evolved within the Symbiodinium genus, which thus carries
fundamental implications as to how this functionally key genus will respond to
ocean acidification, but could also represent a key trait factor that influences
their productivity when in hospite of their coral hosts. |
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ISSN: | 0028-646X 1469-8137 |
DOI: | 10.1111/nph.12379 |