title: TRANSCRIPTOME ANALYSES REVEAL DIFFERENTIAL GENE EXPRESSION PATTERNS BETWEEN THE LIFE-CYCLE STAGES OF EMILIANIA HUXLEYI (HAPTOPHYTA) AND REFLECT SPECIALIZATION TO DIFFERENT ECOLOGICAL NICHES(1).
abstract: Coccolithophores, especially the abundant, cosmopolitan species Emiliania huxleyi (Lohmann) W. W. Hay et H. P. Mohler, are one of the main driving forces of the oceanic carbonate pump and contribute significantly to global carbon cycling, due to their ability to calcify. A recent study indicates that termination of diploid blooms by viral infection induces life-cycle transition, and speculation has arisen about the role of the haploid, noncalcifying stage in coccolithophore ecology. To explore gene expression patterns in both life-cycle stages, haploid and diploid cells of E. huxleyi (RCC 1217 and RCC 1216) were acclimated to limiting and saturating photon flux densities. Transcriptome analyses were performed to assess differential genomic expression related to different ploidy levels and acclimation light intensities. Analyses indicated that life-cycle stages exhibit different properties of regulating genome expression (e.g., pronounced gene activation and gene silencing in the diploid stage), proteome maintenance (e.g., increased turnover of proteins in the haploid stage), as well as metabolic processing (e.g., pronounced primary metabolism and motility in the haploid stage and calcification in the diploid stage). Furthermore, higher abundances of transcripts related to endocytotic and digestive machinery were observed in the diploid stage. A qualitative feeding experiment indicated that both life-cycle stages are capable of particle uptake (0.5 μm diameter) in late-stationary growth phase. Results showed that the two life-cycle stages represent functionally distinct entities that are evolutionarily shaped to thrive in the environment they typically inhabit.
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyDepartment of Geosciences at Utrecht University, P.O. Box 80021, 3508 Utrecht, the NetherlandsAlfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyCNRS, UMR7144 & Université Pierre et Marie Curie, Station Biologique de Roscoff, Équipe EPPO, Place George Teissier, 29680 Roscoff, FranceAlfred Wegener Institute for polar and marine research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Sebastian D
authors.initials: SD
authors.lastname: Rokitta
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyDepartment of Geosciences at Utrecht University, P.O. Box 80021, 3508 Utrecht, the NetherlandsAlfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyCNRS, UMR7144 & Université Pierre et Marie Curie, Station Biologique de Roscoff, Équipe EPPO, Place George Teissier, 29680 Roscoff, FranceAlfred Wegener Institute for polar and marine research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Lennart J
authors.initials: LJ
authors.lastname: de Nooijer
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyDepartment of Geosciences at Utrecht University, P.O. Box 80021, 3508 Utrecht, the NetherlandsAlfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyCNRS, UMR7144 & Université Pierre et Marie Curie, Station Biologique de Roscoff, Équipe EPPO, Place George Teissier, 29680 Roscoff, FranceAlfred Wegener Institute for polar and marine research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Scarlett
authors.initials: S
authors.lastname: Trimborn
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyDepartment of Geosciences at Utrecht University, P.O. Box 80021, 3508 Utrecht, the NetherlandsAlfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyCNRS, UMR7144 & Université Pierre et Marie Curie, Station Biologique de Roscoff, Équipe EPPO, Place George Teissier, 29680 Roscoff, FranceAlfred Wegener Institute for polar and marine research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Colomban
authors.initials: C
authors.lastname: de Vargas
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyDepartment of Geosciences at Utrecht University, P.O. Box 80021, 3508 Utrecht, the NetherlandsAlfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyCNRS, UMR7144 & Université Pierre et Marie Curie, Station Biologique de Roscoff, Équipe EPPO, Place George Teissier, 29680 Roscoff, FranceAlfred Wegener Institute for polar and marine research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Rost
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyDepartment of Geosciences at Utrecht University, P.O. Box 80021, 3508 Utrecht, the NetherlandsAlfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, GermanyCNRS, UMR7144 & Université Pierre et Marie Curie, Station Biologique de Roscoff, Équipe EPPO, Place George Teissier, 29680 Roscoff, FranceAlfred Wegener Institute for polar and marine research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: John
keywords: endocytosis; life-cycle stages; microarray; quantitative RT-PCR; transcriptome profiling