title: Metatranscriptomes reveal functional variation in diatom communities from the Antarctic Peninsula.
abstract: Functional genomics of diatom-dominated communities from the Antarctic Peninsula was studied using comparative metatranscriptomics. Samples obtained from diatom-rich communities in the Bransfield Strait, the western Weddell Sea and sea ice in the Bellingshausen Sea/Wilkins Ice Shelf yielded more than 500K pyrosequencing reads that were combined to produce a global metatranscriptome assembly. Multi-gene phylogenies recovered three distinct communities, and diatom-assigned contigs further indicated little read-sharing between communities, validating an assembly-based annotation and analysis approach. Although functional analysis recovered a core of abundant shared annotations that were expressed across the three diatom communities, over 40% of annotations (but accounting for <10% of sequences) were community-specific. The two pelagic communities differed in their expression of N-metabolism and acquisition genes, which was almost absent in post-bloom conditions in the Weddell Sea community, while enrichment of transporters for ammonia and urea in Bransfield Strait diatoms suggests a physiological stance towards acquisition of reduced N-sources. The depletion of carbohydrate and energy metabolism pathways in sea ice relative to pelagic communities, together with increased light energy dissipation (via LHCSR proteins), photorespiration, and NO3(-) uptake and utilization all pointed to irradiance stress and/or inorganic carbon limitation within sea ice. Ice-binding proteins and cold-shock transcription factors were also enriched in sea ice diatoms. Surprisingly, the abundance of gene transcripts for the translational machinery tracked decreasing environmental temperature across only a 4 °C range, possibly reflecting constraints on translational efficiency and protein production in cold environments.
authors: Centre of Marine Sciences, University of the Algarve, Faro, Portugal.
authors: Gareth A
authors: http://orcid.org/0000-0002-0768-464X
authors: GA
authors: Pearson
authors: Centre of Marine Sciences, University of the Algarve, Faro, Portugal.
authors: Asuncion
authors: A
authors: Lago-Leston
authors: Centre of Marine Sciences, University of the Algarve, Faro, Portugal.
authors: Fernando
authors: F
authors: Cánovas
authors: Centre of Marine Sciences, University of the Algarve, Faro, Portugal.
authors: Cymon J
authors: CJ
authors: Cox
authors: Centre of Marine Sciences, University of the Algarve, Faro, Portugal.|Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Crete, Greece.
authors: Frederic
authors: F
authors: Verret
authors: Global Change Department, IMEDEA (CSIC-UIB), Instituto Mediterráneo de Estudios Avanzados, Esporles, Mallorca, Spain.
authors: Sebastian
authors: S
authors: Lasternas
authors: Global Change Department, IMEDEA (CSIC-UIB), Instituto Mediterráneo de Estudios Avanzados, Esporles, Mallorca, Spain.|Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia.
authors: Carlos M
authors: CM
authors: Duarte
authors: Global Change Department, IMEDEA (CSIC-UIB), Instituto Mediterráneo de Estudios Avanzados, Esporles, Mallorca, Spain.|Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia.
authors: Susana
authors: S
authors: Agusti
authors: Centre of Marine Sciences, University of the Algarve, Faro, Portugal.
authors: Ester A
authors: EA
authors: Serrão
mesh_terms: D000864:Antarctic Regions; D044822:Biodiversity; D002244:Carbon / Q000378:metabolism; D003080:Cold Temperature; D017377:Diatoms / Q000145:classification / Q000302:isolation & purification / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D020869:Gene Expression Profiling; D046448:Ice Cover; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010802:Phylogeny
chemical_list: D009566:Nitrates; D002244:Carbon; D009584:Nitrogen