The CO2 switch in diatoms

Young, Jodi N.; Morel, François M. M.

doi:10.1038/nclimate2691

Cited by 15 publications

(7 citation statements)

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“…Marine diatoms are dominant marine primary producers [1] and have adapted to modern-day levels of CO 2 by operating a carbon concentrating mechanism (CCM), which allows them to elevate the concentration of CO 2 at the site of fixation by RubisCO [6]. When levels of seawater CO 2 increase, this can stimulate diatom growth through increased photosynthesis and lower energy use though downregulation of their CCMs [52,53]. In our study, enriched CO 2 resulted in significant increases in photosynthetic efficiency, in terms of the maximum quantum yield (Fv/Fm: F 3,8 = 4.17, p < 0.05; Figure 2A), maximum light utilisation efficiency (α: F 3,8 = 4.18, p < 0.05; Figure 2B) as well as maximum absolute electron transport rate (ETRmax: F 3,8 = 7.34, p < 0.05; Figure 2C).…”

Section: Resultsmentioning

confidence: 99%

Diatoms Dominate and Alter Marine Food-Webs When CO2 Rises

et al. 2019

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Diatoms are so important in ocean food-webs that any human induced changes in their abundance could have major effects on the ecology of our seas. The large chain-forming diatom Biddulphia biddulphiana greatly increases in abundance as pCO2 increases along natural seawater CO2 gradients in the north Pacific Ocean. In areas with reference levels of pCO2, it was hard to find, but as seawater carbon dioxide levels rose, it replaced seaweeds and became the main habitat-forming species on the seabed. This diatom algal turf supported a marine invertebrate community that was much less diverse and completely differed from the benthic communities found at present-day levels of pCO2. Seawater CO2 enrichment stimulated the growth and photosynthetic efficiency of benthic diatoms, but reduced the abundance of calcified grazers such as gastropods and sea urchins. These observations suggest that ocean acidification will shift photic zone community composition so that coastal food-web structure and ecosystem function are homogenised, simplified, and more strongly affected by seasonal algal blooms.

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Section: Resultsmentioning

confidence: 99%

Diatoms Dominate and Alter Marine Food-Webs When CO2 Rises

et al. 2019

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“…(Wei et al, 2019) and T. pseudonana (Clement et al, 2017b;Jensen et al, 2019b). Cyclic AMP (cAMP) is a general [CO 2 ] signalling molecule that regulates gene expression (Ohno et al, 2012;Hennon et al, 2015;Young and Morel, 2015). High CO 2 corresponds to 20,000 to 50,000 ppm but in Hennon et al (2015) it is 800 ppm and low CO 2 is 50 to 400 ppm.…”

Section: Discussionmentioning

confidence: 99%

“…These elements, CCRE1 to 3, are critical for the transcriptional response to ambient CO 2 via the level of the second messenger cAMP (Ohno et al, 2012;Tanaka et al, 2016). The sensing of CO 2 mediated by cAMP has been reported in cyanobacteria, fungi and mammals (Matsuda et al, 2011) and also in T. pseudonana (Hennon et al, 2015;Young and Morel, 2015). The transcriptional activation of PtCA2 in response to the decrease in CO 2 concentration was strongly light-dependent, such that either CO 2 or the absence of light can down-regulate the promoter.…”

Section: Biophysical Ccmmentioning

confidence: 99%

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Regulation of Carbon Metabolism by Environmental Conditions: A Perspective From Diatoms and Other Chromalveolates

et al. 2020

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Diatoms belong to a major, diverse and species-rich eukaryotic clade, the Heterokonta, within the polyphyletic chromalveolates. They evolved as a result of secondary endosymbiosis with one or more Plantae ancestors, but their precise evolutionary history is enigmatic. Nevertheless, this has conferred them with unique structural and biochemical properties that have allowed them to flourish in a wide range of different environments and cope with highly variable conditions. We review the effect of pH, light and dark, and CO 2 concentration on the regulation of carbon uptake and assimilation. We discuss the regulation of the Calvin-Benson-Bassham cycle, glycolysis, lipid synthesis, and carbohydrate synthesis at the level of gene transcripts (transcriptomics), proteins (proteomics) and enzyme activity. In contrast to Viridiplantae where redox regulation of metabolic enzymes is important, it appears to be less common in diatoms, based on the current evidence, but regulation at the transcriptional level seems to be widespread. The role of post-translational modifications such as phosphorylation, glutathionylation, etc., and of protein-protein interactions, has been overlooked and should be investigated further. Diatoms and other chromalveolates are understudied compared to the Viridiplantae, especially given their ecological importance, but we believe that the ever-growing number of sequenced genomes combined with proteomics, metabolomics, enzyme measurements, and the application of novel techniques will provide a better understanding of how this important group of algae maintain their productivity under changing conditions.

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“…However, no homolog proteins of CCM1 and LCR1 have been described in stramenopiles, alveolates, or haptophytes. In diatoms, it is believed that a transcriptional regulation of the response to CO 2 might exist, which is mediated by the second messenger cAMP [107]. In fact, a bZIP transcription factor in P. tricornutum (ptbZIP11) is shown to bind specifically to a CO 2 -cAMP responsive element in the regulatory region of the ptca1 gene, encoding for the pyrenoidal β-CA [108].…”

Section: Regulation Of Ca Expressionmentioning

confidence: 99%

Insights on the Functions and Ecophysiological Relevance of the Diverse Carbonic Anhydrases in Microalgae

Jensen

Maberly

Gontero

2020

IJMS

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Carbonic anhydrases (CAs) exist in all kingdoms of life. They are metalloenzymes, often containing zinc, that catalyze the interconversion of bicarbonate and carbon dioxide—a ubiquitous reaction involved in a variety of cellular processes. So far, eight classes of apparently evolutionary unrelated CAs that are present in a large diversity of living organisms have been described. In this review, we focus on the diversity of CAs and their roles in photosynthetic microalgae. We describe their essential role in carbon dioxide-concentrating mechanisms and photosynthesis, their regulation, as well as their less studied roles in non-photosynthetic processes. We also discuss the presence in some microalgae, especially diatoms, of cambialistic CAs (i.e., CAs that can replace Zn by Co, Cd, or Fe) and, more recently, a CA that uses Mn as a metal cofactor, with potential ecological relevance in aquatic environments where trace metal concentrations are low. There has been a recent explosion of knowledge about this well-known enzyme with exciting future opportunities to answer outstanding questions using a range of different approaches.

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The CO2 switch in diatoms

Cited by 15 publications

References 10 publications

Diatoms Dominate and Alter Marine Food-Webs When CO2 Rises

Diatoms Dominate and Alter Marine Food-Webs When CO2 Rises

Regulation of Carbon Metabolism by Environmental Conditions: A Perspective From Diatoms and Other Chromalveolates

Insights on the Functions and Ecophysiological Relevance of the Diverse Carbonic Anhydrases in Microalgae

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