Transcriptome analysis of functional differentiation between haploid and diploid cells of Emiliania huxleyi, a globally significant photosynthetic calcifying cellReportar como inadecuado

Transcriptome analysis of functional differentiation between haploid and diploid cells of Emiliania huxleyi, a globally significant photosynthetic calcifying cell - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Genome Biology

, 10:R114

First Online: 15 October 2009Received: 14 April 2009Revised: 19 August 2009Accepted: 15 October 2009


BackgroundEukaryotes are classified as either haplontic, diplontic, or haplo-diplontic, depending on which ploidy levels undergo mitotic cell division in the life cycle. Emiliania huxleyi is one of the most abundant phytoplankton species in the ocean, playing an important role in global carbon fluxes, and represents haptophytes, an enigmatic group of unicellular organisms that diverged early in eukaryotic evolution. This species is haplo-diplontic. Little is known about the haploid cells, but they have been hypothesized to allow persistence of the species between the yearly blooms of diploid cells. We sequenced over 38,000 expressed sequence tags from haploid and diploid E. huxleyi normalized cDNA libraries to identify genes involved in important processes specific to each life phase 2N calcification or 1N motility, and to better understand the haploid phase of this prominent haplo-diplontic organism.

ResultsThe haploid and diploid transcriptomes showed a dramatic differentiation, with approximately 20% greater transcriptome richness in diploid cells than in haploid cells and only ≤ 50% of transcripts estimated to be common between the two phases. The major functional category of transcripts differentiating haploids included signal transduction and motility genes. Diploid-specific transcripts included Ca, H, and HCO3 pumps. Potential factors differentiating the transcriptomes included haploid-specific Myb transcription factor homologs and an unusual diploid-specific histone H4 homolog.

ConclusionsThis study permitted the identification of genes likely involved in diploid-specific biomineralization, haploid-specific motility, and transcriptional control. Greater transcriptome richness in diploid cells suggests they may be more versatile for exploiting a diversity of rich environments whereas haploid cells are intrinsically more streamlined.

AbbreviationsBBSBardet-Biedl syndrome

CDDConserved Domains Database

DHCflagellar dynein heavy chain

ESTexpressed sequence tag

Fv-Fmmaximum quantum yield of photosytem II

GPA-glutamic acid-proline-alanine- coccolith-associated glycoprotein

KEGGKyoto Encyclopedia of Genes and Genomes

KOGNCBI eukarote orthologous group

MLmaximum likelihood

NCKXK-dependent Na-Ca exchanger

RTreverse transcription

RT-PCRreverse transcription PCR

SLC4Cl-bicarbonate exchanger solute carrier family 4

UTRuntranslated region

VCX1vacuolar-type Ca-H antiporter


Electronic supplementary materialThe online version of this article doi:10.1186-gb-2009-10-10-r114 contains supplementary material, which is available to authorized users.

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Autor: Peter von Dassow - Hiroyuki Ogata - Ian Probert - Patrick Wincker - Corinne Da Silva - Stéphane Audic - Jean-Michel Claver


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