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dc.coverage.spatialSAN FRANCISCO
dc.creatorVásquez-Perez, Luz
dc.creatorCembella, Allan
dc.creatorFriedel, Maik
dc.creatorFuentes-Valdés, Juan
dc.creatorGlockner, Gernot
dc.creatorMurillo, Alejandro
dc.creatorPlominsky, Álvaro
dc.creatorSoto-Liebe, Katia
dc.creatorStucken, Karina
dc.description.abstractCyanobacterial morphology is diverse, ranging from unicellular spheres or rods to multicellular structures such as colonies and filaments. Multicellular species represent an evolutionary strategy to differentiate and compartmentalize certain metabolic functions for reproduction and nitrogen (N(2)) fixation into specialized cell types (e.g. akinetes, heterocysts and diazocytes). Only a few filamentous, differentiated cyanobacterial species, with genome sizes over 5 Mb, have been sequenced. We sequenced the genomes of two strains of closely related filamentous cyanobacterial species to yield further insights into the molecular basis of the traits of N(2) fixation, filament formation and cell differentiation. Cylindrospermopsis raciborskii CS-505 is a cylindrospermopsin-producing strain from Australia, whereas Raphidiopsis brookii D9 from Brazil synthesizes neurotoxins associated with paralytic shellfish poisoning (PSP). Despite their different morphology, toxin composition and disjunct geographical distribution, these strains form a monophyletic group. With genome sizes of approximately 3.9 (CS-505) and 3.2 (D9) Mb, these are the smallest genomes described for free-living filamentous cyanobacteria. We observed remarkable gene order conservation (synteny) between these genomes despite the difference in repetitive element content, which accounts for most of the genome size difference between them. We show here that the strains share a specific set of 2539 genes with >90% average nucleotide identity. The fact that the CS-505 and D9 genomes are small and streamlined compared to those of other filamentous cyanobacterial species and the lack of the ability for heterocyst formation in strain D9 allowed us to define a core set of genes responsible for each trait in filamentous species. We presume that in strain D9 the ability to form proper heterocysts was secondarily lost together with N2 fixation capacity. Further comparisons to all available cyanobacterial genomes covering almost the entire evolutionary branch revealed a common minimal gene set for each of these cyanobacterial traits.
dc.relationinstname: Conicyt
dc.relationreponame: Repositorio Digital RI2.0
dc.relationinstname: Conicyt
dc.relationreponame: Repositorio Digital RI2.0
dc.titleThe smallest known genomes of multicellular and toxic cyanobacteria: comparison, minimal gene sets for linked traits and the evolutionary implications
dc.description.investmentarticleFondecyt, Chile [1050433, 1080075]; Fondef, Chile [MR07I1005]; Millennium Nucleus [EMBA P04/007]; Programa de Cooperacion Cientifica Internacional (PCCI) CONICYT/DFG; EU [GOCE CT-2004-511154]; Alfred Wegener Institute (Helmholtz Society)
dc.title.journalPLOS ONE
dc.title.journalabbreviationPLoS One
dc.description.agradFinancial support for this work was provided by Grants from Chile (to M. V.): Fondecyt 1050433 and 1080075; Fondef MR07I1005; Millennium Nucleus EMBA P04/007; and Programa de Cooperacion Cientifica Internacional (PCCI) CONICYT/DFG between the P. Universidad Catolica de Chile and the Alfred Wegener Institute for Polar and Marine Research (Helmholtz Foundation). Additional operational support was obtained from the EU-project ESTTAL (GOCE CT-2004-511154) (to A. C.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The first author (K. S.) received a scholarship from the Alfred Wegener Institute (Helmholtz Society) under the MARCOPOLI program in Earth and Environment and is a member of the MarMic program administered from the MPI for Marine Microbiology.

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