title: Clade-Specific Quantitative Analysis of Photosynthetic Gene Expression in Prochlorococcus.
abstract: Newly designed primers targeting rbcL (CO2 fixation), psbA (photosystem II) and rnpB (reference) genes were used in qRT-PCR assays to assess the photosynthetic capability of natural communities of Prochlorococcus, the most abundant photosynthetic organism on Earth and a major contributor to primary production in oligotrophic oceans. After optimizing sample collection methodology, we analyzed a total of 62 stations from the Malaspina 2010 circumnavigation (including Atlantic, Pacific and Indian Oceans) at three different depths. Sequence and quantitative analyses of the corresponding amplicons showed the presence of high-light (HL) and low-light (LL) Prochlorococcus clades in essentially all 182 samples, with a largely uniform stratification of LL and HL sequences. Synechococcus cross-amplifications were detected by the taxon-specific melting temperatures of the amplicons. Laboratory exposure of Prochlorococcus MED4 (HL) and MIT9313 (LL) strains to organic pollutants (PAHs and organochlorine compounds) showed a decrease of rbcL transcript abundances, and of the rbcL to psbA ratios for both strains. We propose this technique as a convenient assay to evaluate effects of environmental stressors, including pollution, on the oceanic Prochlorococcus photosynthetic function.
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Catalonia, Spain.
authors.forename: María-Carmen
authors.initials: MC
authors.lastname: Fernández-Pinos
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Catalonia, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Casado
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Catalonia, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: Caballero
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, Tennessee, United States of America.
authors.forename: Erik R
authors.initials: ER
authors.lastname: Zinser
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Catalonia, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Dachs
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Catalonia, Spain.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Piña
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D002734:Chlorophyll / Q000378:metabolism; D017753:Ecosystem; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D005843:Geography; D008027:Light; D009792:Oceans and Seas; D010788:Photosynthesis / Q000235:genetics*; D045332:Photosystem II Protein Complex / Q000235:genetics; D010802:Phylogeny; D048929:Prochlorococcus / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics; D012623:Seawater / Q000737:chemistry / Q000382:microbiology; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D014874:Water Pollutants, Chemical; C422369:photosystem II, psbA subunit; D002734:Chlorophyll; C101625:RbcL protein, plastid; D012273:Ribulose-Bisphosphate Carboxylase