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Co-occurring Synechococcus ecotypes occupy four major oceanic regimes defined by temperature, macronutrients and iron.

ABSTRACT: Marine picocyanobacteria, comprised of the genera Synechococcus and Prochlorococcus, are the most abundant and widespread primary producers in the ocean. More than 20 genetically distinct clades of marine Synechococcus have been identified, but their physiology and biogeography are not as thoroughly characterized as those of Prochlorococcus. Using clade-specific qPCR primers, we measured the abundance of 10 Synechococcus clades at 92 locations in surface waters of the Atlantic and Pacific Oceans. We found that Synechococcus partition the ocean into four distinct regimes distinguished by temperature, macronutrients and iron availability. Clades I and IV were prevalent in colder, mesotrophic waters; clades II, III and X dominated in the warm, oligotrophic open ocean; clades CRD1 and CRD2 were restricted to sites with low iron availability; and clades XV and XVI were only found in transitional waters at the edges of the other biomes. Overall, clade II was the most ubiquitous clade investigated and was the dominant clade in the largest biome, the oligotrophic open ocean. Co-occurring clades that occupy the same regime belong to distinct evolutionary lineages within Synechococcus, indicating that multiple ecotypes have evolved independently to occupy similar niches and represent examples of parallel evolution. We speculate that parallel evolution of ecotypes may be a common feature of diverse marine microbial communities that contributes to functional redundancy and the potential for resiliency.

SUBMITTER: Sohm JA

PROVIDER: S-EPMC4737926 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

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Co-occurring Synechococcus ecotypes occupy four major oceanic regimes defined by temperature, macronutrients and iron.

Sohm Jill A JA Ahlgren Nathan A NA Thomson Zachary J ZJ Williams Cheryl C Moffett James W JW Saito Mak A MA Webb Eric A EA Rocap Gabrielle G

The ISME journal 20150724 2

Marine picocyanobacteria, comprised of the genera Synechococcus and Prochlorococcus, are the most abundant and widespread primary producers in the ocean. More than 20 genetically distinct clades of marine Synechococcus have been identified, but their physiology and biogeography are not as thoroughly characterized as those of Prochlorococcus. Using clade-specific qPCR primers, we measured the abundance of 10 Synechococcus clades at 92 locations in surface waters of the Atlantic and Pacific Oceans ...[more]

PMID: 26208139

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Project description:BACKGROUND: Anaplasma phagocytophilum is the etiological agent of granulocytic anaplasmosis in humans and animals. Wild animals and ticks play key roles in the enzootic cycles of the pathogen. Potential ecotypes of A. phagocytophilum have been characterized genetically, but their host range, zoonotic potential and transmission dynamics has only incompletely been resolved. METHODS: The presence of A. phagocytophilum DNA was determined in more than 6000 ixodid ticks collected from the vegetation and wildlife, in 289 tissue samples from wild and domestic animals, and 69 keds collected from deer, originating from various geographic locations in The Netherlands and Belgium. From the qPCR-positive lysates, a fragment of the groEL-gene was amplified and sequenced. Additional groEL sequences from ticks and animals from Europe were obtained from GenBank, and sequences from human cases were obtained through literature searches. Statistical analyses were performed to identify A. phagocytophilum ecotypes, to assess their host range and their zoonotic potential. The population dynamics of A. phagocytophilum ecotypes was investigated using population genetic analyses. RESULTS: DNA of A. phagocytophilum was present in all stages of questing and feeding Ixodes ricinus, feeding I. hexagonus, I. frontalis, I. trianguliceps, and deer keds, but was absent in questing I. arboricola and Dermacentor reticulatus. DNA of A. phagocytophilum was present in feeding ticks and tissues from many vertebrates, including roe deer, mouflon, red foxes, wild boar, sheep and hedgehogs but was rarely found in rodents and birds and was absent in badgers and lizards. Four geographically dispersed A. phagocytophilum ecotypes were identified, that had significantly different host ranges. All sequences from human cases belonged to only one of these ecotypes. Based on population genetic parameters, the potentially zoonotic ecotype showed significant expansion. CONCLUSION: Four ecotypes of A. phagocytophilum with differential enzootic cycles were identified. So far, all human cases clustered in only one of these ecotypes. The zoonotic ecotype has the broadest range of wildlife hosts. The expansion of the zoonotic A. phagocytophilum ecotype indicates a recent increase of the acarological risk of exposure of humans and animals.

Project description:Synechococcus sp. WH 8102 is a motile marine cyanobacterium isolated originally from the Sargasso Sea. To test the response of this organism to cadmium (Cd), generally considered a toxin, cultures were grown in a matrix of high and low zinc (Zn) and phosphate (PO4 (3-)) and were then exposed to an addition of 4.4 pM free Cd(2+) at mid-log phase and harvested after 24 h. Whereas Zn and PO4 (3-) had little effect on overall growth rates, in the final 24 h of the experiment three growth effects were noticed: (i) low PO4 (3-) treatments showed increased growth rates relative to high PO4 (3-) treatments, (ii) the Zn/high PO4 (3-) treatment appeared to enter stationary phase, and (iii) Cd increased growth rates further in both the low PO4 (3-) and Zn treatments. Global proteomic analysis revealed that: (i) Zn appeared to be critical to the PO4 (3-) response in this organism, (ii) bacterial metallothionein (SmtA) appears correlated with PO4 (3-) stress-associated proteins, (iii) Cd has the greatest influence on the proteome at low PO4 (3-) and Zn, (iv) Zn buffered the effects of Cd, and (v) in the presence of both replete PO4 (3-) and added Cd the proteome showed little response to the presence of Zn. Similar trends in alkaline phosphate (ALP) and SmtA suggest the possibility of a Zn supply system to provide Zn to ALP that involves SmtA. In addition, proteome results were consistent with a previous transcriptome study of PO4 (3-) stress (with replete Zn) in this organism, including the greater relative abundance of ALP (PhoA), ABC phosphate binding protein (PstS) and other proteins. Yet with no Zn in this proteome experiment the PO4 (3-) response was quite different including the greater relative abundance of five hypothetical proteins with no increase in PhoA or PstS, suggesting that Zn nutritional levels are connected to the PO4 (3-) response in this cyanobacterium. Alternate ALP PhoX (Ca) was found to be a low abundance protein, suggesting that PhoA (Zn, Mg) may be more environmentally relevant than PhoX.

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Co-occurring Synechococcus ecotypes occupy four major oceanic regimes defined by temperature, macronutrients and iron.

Publications

Co-occurring Synechococcus ecotypes occupy four major oceanic regimes defined by temperature, macronutrients and iron.

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