title: Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2.
abstract: 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.
authors: Romberg Tiburon Center for Environmental Studies, San Francisco State University, Tiburon, CA 94920, USA. ibenner@sfsu.edu
authors: Ina
authors: I
authors: Benner
authors: Rachel E
authors: RE
authors: Diner
authors: Stephane C
authors: SC
authors: Lefebvre
authors: Dian
authors: D
authors: Li
authors: Tomoko
authors: T
authors: Komada
authors: Edward J
authors: EJ
authors: Carpenter
authors: Jonathon H
authors: JH
authors: Stillman
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000704:Analysis of Variance; D001483:Base Sequence; D002113:Calcification, Physiologic / Q000235:genetics / Q000502:physiology*; D002245:Carbon Dioxide / Q000009:adverse effects*; D017931:DNA Primers / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D058087:Haptophyta / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D060888:Real-Time Polymerase Chain Reaction; D017423:Sequence Analysis, RNA; D013696:Temperature
chemical_list: D017931:DNA Primers; D002245:Carbon Dioxide
keywords: RNA-seq; acidification; climate change; coccolithophore; transcriptome
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