Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2

• Published in: Philosophical transactions of the Royal Society of London. Series B. Biological sciences 2013-10, Vol.368 (1627), p.20130049-20130049
• Main Authors: Benner, Ina, Diner, Rachel E., Lefebvre, Stephane C., Li, Dian, Komada, Tomoko, Carpenter, Edward J., Stillman, Jonathon H.
• Format: Article
• Language: English
• Subjects: Acclimatization - physiology; Acidification; Analysis of Variance; Base Sequence; Calcification, Physiologic - genetics; Calcification, Physiologic - physiology; Carbon Dioxide - adverse effects; Climate Change; Coccolithophore; Coccolithus huxleyi; DNA Primers - genetics; Emiliania huxleyi; Gene Expression Profiling; Gene Expression Regulation - physiology; Haptophyta - genetics; Haptophyta - metabolism; Haptophyta - physiology; Hydrogen-Ion Concentration; Molecular Sequence Data; Oceans and Seas; Real-Time Polymerase Chain Reaction; RNA-seq; Sequence Analysis, RNA; Temperature; Transcriptome
• ISSN: 0962-8436; 1471-2970
• DOI: 10.1098/rstb.2013.0049

Increased atmospheric pCO2 is expected to render future oceans warmer and more acidic than they are at present. Calcifying organisms such as coccolithophores that fix and export carbon into the deep sea provide feedbacks to increasing atmospheric pCO2. Acclimation experiments suggest negative effects of warming and acidification on coccolithophore calcification, but the ability of these organisms to adapt to future environmental conditions is not well understood. Here, we tested the combined effect of pCO2 and temperature on the coccolithophore Emiliania huxleyi over more than 700 generations. Cells increased inorganic carbon content and calcification rate under warm and acidified conditions compared with ambient conditions, whereas organic carbon content and primary production did not show any change. In contrast to findings from short-term experiments, our results suggest that long-term acclimation or adaptation could change, or even reverse, negative calcification responses in E. huxleyi and its feedback to the global carbon cycle. Genome-wide profiles of gene expression using RNA-seq revealed that genes thought to be essential for calcification are not those that are most strongly differentially expressed under long-term exposure to future ocean conditions. Rather, differentially expressed genes observed here represent new targets to study responses to ocean acidification and warming.