@article {phelps_carbon_2021,
	title = {Carbon Isotope Fractionation in Noelaerhabdaceae Algae in Culture and a Critical Evaluation of the Alkenone Paleobarometer},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {22},
	number = {7},
	year = {2021},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021GC009657},
	pages = {e2021GC009657},
	abstract = {The carbon isotope fractionation in algal organic matter ($\varepsilon$p), including the long-chain alkenones produced by the coccolithophorid family Noelaerhabdaceae, is used to reconstruct past atmospheric CO2 levels. The conventional proxy linearly relates $\varepsilon$p to changes in cellular carbon demand relative to diffusive CO2 supply, with larger $\varepsilon$p values occurring at lower carbon demand relative to supply (i.e., abundant CO2). However, the response of Gephyrocapsa oceanica, one of the dominant alkenone producers of the last few million years, has not been studied closely. Here, we subject G. oceanica to various CO2 levels by increasing pCO2 in the culture headspace, as opposed to increasing dissolved inorganic carbon (DIC) and alkalinity concentrations at constant pH. We note no substantial change in physiology, but observe an increase in $\varepsilon$p as carbon demand relative to supply decreases, consistent with DIC manipulations. We compile existing Noelaerhabdaceae $\varepsilon$p data and show that the diffusive model poorly describes the data. A meta-analysis of individual treatments (unique combinations of lab, strain, and light conditions) shows that the slope of the $\varepsilon$p response depends on the light conditions and range of carbon demand relative to CO2 supply in the treatment, which is incompatible with the diffusive model. We model $\varepsilon$p as a multilinear function of key physiological and environmental variables and find that both photoperiod duration and light intensity are critical parameters, in addition to CO2 and cell size. While alkenone carbon isotope ratios indeed record CO2 information, irradiance and other factors are also necessary to properly describe alkenone $\varepsilon$p.},
	keywords = {alkenone, carbon dioxide, carbon isotope, coccolithophore, irradiance, paleobarometry, rcc, RCC1303},
	issn = {1525-2027},
	doi = {10.1029/2021GC009657},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021GC009657},
	author = {Phelps, Samuel R. and Hennon, Gwenn M. M. and Dyhrman, Sonya T. and Hern{\'a}ndez Lim{\'o}n, Mar{\'\i}a D. and Williamson, Olivia M. and Polissar, Pratigya J.}
}
@article {Hennon2017,
	title = {Diverse CO2-Induced responses in physiology and gene expression among eukaryotic phytoplankton},
	journal = {Frontiers in Microbiology},
	volume = {8},
	number = {December},
	year = {2017},
	note = {tex.mendeley-tags: RCC1303},
	month = {dec},
	pages = {1{\textendash}14},
	abstract = {With rising atmospheric CO2, phytoplankton face shifts in ocean chemistry including increased dissolved CO2 and acidification that will likely influence the relative competitive fitness of different phytoplankton taxa. Here we compared the physiological and gene expression responses of six species of phytoplankton including a diatom, a raphidophyte, two haptophytes, and two dinoflagellates to ambient (\~400 ppm) and elevated (\~800 ppm) CO2. Dinoflagellates had significantly slower growth rates and higher, yet variable, chlorophyll a per cell under elevated CO2. The other phytoplankton tended to have increased growth rates and/or decreased chlorophyll a per cell. Carbon and nitrogen partitioning of cells shifted under elevated CO2 in some species, indicating potential changes in energy fluxes due to changes in carbon concentrating mechanisms (CCM) or photorespiration. Consistent with these phenotypic changes, gene set enrichment analyses revealed shifts in energy, carbon and nitrogen metabolic pathways, though with limited overlap between species in the genes and pathways involved. Similarly, gene expression responses across species revealed few conserved CO2-responsive genes within CCM and photorespiration categories, and a survey of available transcriptomes found high diversity in biophysical CCM and photorespiration expressed gene complements between and within the four phyla represented by these species. The few genes that displayed similar responses to CO2 across phyla were from understudied gene families, making them targets for further research to uncover the mechanisms of phytoplankton acclimation to elevated CO2. These results underscore that eukaryotic phytoplankton have diverse gene complements and gene expression responses to CO2 perturbations and highlight the value of cross-phyla comparisons for identifying gene families that respond to environmental change.},
	keywords = {algae, biophysical CCM, C4 CCM, carbon concentrating mechanism, carbon concentrating mechanism (CCM), ccm, photorespiration, RCC1303, transcriptomics},
	issn = {1664-302X},
	doi = {10.3389/fmicb.2017.02547},
	url = {http://journal.frontiersin.org/article/10.3389/fmicb.2017.02547/full},
	author = {Hennon, Gwenn M. M. and Hern{\'a}ndez Lim{\'o}n, Mar{\'\i}a D. and Haley, Sheean T. and Juhl, Andrew R. and Dyhrman, Sonya T.}
}
