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The response of Thalassiosira pseudonana to long-term exposure to increased CO2 and decreased pH.

ABSTRACT: The effect of ocean acidification conditions has been investigated in cultures of the diatom Thalassiosira pseudonana CCMP1335. Expected end-of-the-century pCO(2) (aq) concentrations of 760 µatm (equivalent to pH 7.8) were compared with present-day condition (380 µatm CO(2), pH 8.1). Batch culture pH changed rapidly because of CO(2) (aq) assimilation and pH targets of 7.8 and 8.1 could not be sustained. Long-term (?100 generation) pH-auxostat, continuous cultures could be maintained at target pH when cell density was kept low (<2×10(5) cells mL(-1)). After 3 months continuous culture, the C:N ratio was slightly decreased under high CO(2) conditions and red fluorescence per cell was slightly increased. However, no change was detected in photosynthetic efficiency (F(v)/F(m)) or functional cross section of PS II (?(PSII)). Elevated pCO(2) has been predicted to be beneficial to diatoms due to reduced cost of carbon concentration mechanisms. There was reduced transcription of one putative ?-carbonic anhydrase (CA-4) after 3 months growth at increased CO(2) but 3 other ?-CAs and the small subunit of RUBISCO showed no change. There was no evidence of adaptation or clade selection of T. pseudonana after ?100 generations at elevated CO(2). On the basis of this long-term culture, pH change of this magnitude in the future ocean may have little effect on T. pseudonana in the absence of genetic adaption.

SUBMITTER: Crawfurd KJ

PROVIDER: S-EPMC3203894 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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The response of Thalassiosira pseudonana to long-term exposure to increased CO2 and decreased pH.

Crawfurd Katharine J KJ Raven John A JA Wheeler Glen L GL Baxter Emily J EJ Joint Ian I

PloS one 20111028 10

The effect of ocean acidification conditions has been investigated in cultures of the diatom Thalassiosira pseudonana CCMP1335. Expected end-of-the-century pCO(2) (aq) concentrations of 760 µatm (equivalent to pH 7.8) were compared with present-day condition (380 µatm CO(2), pH 8.1). Batch culture pH changed rapidly because of CO(2) (aq) assimilation and pH targets of 7.8 and 8.1 could not be sustained. Long-term (∼100 generation) pH-auxostat, continuous cultures could be maintained at target pH ...[more]

PMID: 22053201

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Project description:BackgroundSilicon plays important biological roles, but the mechanisms of cellular responses to silicon are poorly understood. We report the first analysis of cell cycle arrest and recovery from silicon starvation in the diatom Thalassiosira pseudonana using whole genome microarrays.ResultsThree known responses to silicon were examined, 1) silicified cell wall synthesis, 2) recovery from silicon starvation, and 3) co-regulation with silicon transporter (SIT) genes. In terms of diatom cell wall formation, thus far only cell surface proteins and proteins tightly associated with silica have been characterized. Our analysis has identified new genes potentially involved in silica formation, and other genes potentially involved in signaling, trafficking, protein degradation, glycosylation and transport, which provides a larger-scale picture of the processes involved. During silicon starvation, an overrepresentation of transcription and translation related genes were up-regulated, indicating that T. pseudonana is poised to rapidly recover from silicon starvation and resume cell cycle progression upon silicon replenishment. This is in contrast to other types of limitation, and provides the first molecular data explaining the well-established environmental response of diatoms to grow as blooms and to out-compete other classes of microalgae for growth. Comparison of our data with a previous diatom cell cycle analysis indicates that assignment of the cell cycle specific stage of particular cyclins and cyclin dependent kinases should be re-evaluated. Finally, genes co-varying in expression with the SITs enabled identification of a new class of diatom-specific proteins containing a unique domain, and a putative silicon efflux protein.ConclusionsAnalysis of the T. pseudonana microarray data has provided a wealth of new genes to investigate previously uncharacterized cellular phenomenon related to silicon metabolism, silicon's interaction with cellular components, and environmental responses to silicon.

Dataset Information

The response of Thalassiosira pseudonana to long-term exposure to increased CO2 and decreased pH.

Publications

The response of Thalassiosira pseudonana to long-term exposure to increased CO2 and decreased pH.

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