Browsing by Author "Richier, Sophie"

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    Pan genome of the phytoplankton Emiliania underpins its global distribution
    (2013) Read, Betsy A.; Kegel, Jessica; Klute, Mary J.; Kuo, Alan; Lefebvre, Stephane C.; Maumus, Florian; Mayer, Christoph; Miller, John; Monier, Adam; Salamov, Asaf; Young, Jeremy; Aguilar, Maria; Claverie, Jean-Michel; Frickenhaus, Stephan; Gonzalez, Karina; Herman, Emily K.; Lin, Yao-Cheng; Napier, Johnathan; Ogata, Hiroyuki; Sarno, Analissa F.; Shmutz, Jeremy; Schroeder, Declan; de Vargas, Colomban; Verret, Frederic; von Dassow, Peter; Valentin, Klaus; Van de Peer, Yves; Wheeler, Glen; Dacks, Joel B.; Delwiche, Charles F.; Dyhrman, Sonya T.; Gloeckner, Gernot; John, Uwe; Richards, Thomas; Worden, Alexandra Z.; Zhang, Xiaoyu; Grigoriev, Igor V.; Allen, Andrew E.; Bidle, Kay; Borodovsky, M.; Bowler, C.; Brownlee, Colin; Cock, J. Mark; Elias, Marek; Gladyshev, Vadim N.; Groth, Marco; Guda, Chittibabu; Hadaegh, Ahmad; Iglesias-Rodriguez, Maria Debora; Jenkins, J.; Jones, Bethan M.; Lawson, Tracy; Leese, Florian; Lindquist, Erika; Lobanov, Alexei; Lomsadze, Alexandre; Malik, Shehre-Banoo; Marsh, Mary E.; Mackinder, Luke; Mock, Thomas; Mueller-Roeber, Bernd; Pagarete, Antonio; Parker, Micaela; Probert, Ian; Quesneville, Hadi; Raines, Christine; Rensing, Stefan A.; Riano-Pachon, Diego Mauricio; Richier, Sophie; Rokitta, Sebastian; Shiraiwa, Yoshihiro; Soanes, Darren M.; van der Giezen, Mark; Wahlund, Thomas M.; Williams, Bryony; Wilson, Willie; Wolfe, Gordon; Wurch, Louie L.
    Coccolithophores have influenced the global climate for over 200 million years(1). These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems(2). They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering them visible from space(3). Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO2 production or uptake, sequestration and export to the deep ocean(4). Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate that E. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions.
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    Response of the calcifying coccolithophore Emiliania huxleyi to low pH/high pCO2: from physiology to molecular level
    (2011) Richier, Sophie; Fiorini, Sarah; Kerros, Marie-Emmanuelle; von Dassow, Peter; Gattuso, Jean-Pierre
    The emergence of ocean acidification as a significant threat to calcifying organisms in marine ecosystems creates a pressing need to understand the physiological and molecular mechanisms by which calcification is affected by environmental parameters. We report here, for the first time, changes in gene expression induced by variations in pH/pCO(2) in the widespread and abundant coccolithophore Emiliania huxleyi. Batch cultures were subjected to increased partial pressure of CO2 (pCO(2); i.e. decreased pH), and the changes in expression of four functional gene classes directly or indirectly related to calcification were investigated. Increased pCO(2) did not affect the calcification rate and only carbonic anhydrase transcripts exhibited a significant down-regulation. Our observation that elevated pCO(2) induces only limited changes in the transcription of several transporters of calcium and bicarbonate gives new significant elements to understand cellular mechanisms underlying the early response of E. huxleyi to CO2-driven ocean acidification.