Annual variability of phytoplankton and bacteria in the subtropical North Pacific Ocean at Station ALOHA during the 1991–1994 ENSO event

Campbell, Lisa; Liu, Hongbin; Nolla, Hector; Vaulot, Daniel

doi:10.1016/s0967-0637(96)00102-1

Cited by 266 publications

(243 citation statements)

References 40 publications

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“…Crocosphaera-like cell abundances at station KM0703.025 reached 3.84-4.70 Â 10 3 cells per ml between 37 and 45 m depth (the C. watsoniienriched horizon), but were much less abundant at the surface, at 75 m, and were not detected by microscopy at the depth of the deep chlorophyll maximum (106 m, see Figure 1). This was the highest abundance of C. watsonii observed anywhere to date (Campbell et al, 1997(Campbell et al, , 2005Charpy, 2005;Church et al, 2005;Foster et al, 2007;Zehr et al, 2007b). The C. watsonii-enriched horizon corresponded to distinct peaks of chlorophyll a fluorescence and total particle concentration.…”

Section: Resultsmentioning

confidence: 84%

In situ transcriptomic analysis of the globally important keystone N2-fixing taxon Crocosphaera watsonii

et al. 2009

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The diazotrophic cyanobacterium Crocosphaera watsonii supplies fixed nitrogen (N) to N-depleted surface waters of the tropical oceans, but the factors that determine its distribution and contribution to global N 2 fixation are not well constrained for natural populations. Despite the heterogeneity of the marine environment, the genome of C. watsonii is highly conserved in nucleotide sequence in contrast to sympatric planktonic cyanobacteria. We applied a whole assemblage shotgun transcript sequencing approach to samples collected from a bloom of C. watsonii observed in the South Pacific to understand the genomic mechanisms that may lead to high population densities. We obtained 999 C. watsonii transcript reads from two metatranscriptomes prepared from mixed assemblage RNA collected in the day and at night. The C. watsonii population had unexpectedly high transcription of hypothetical protein genes (31% of protein-encoding genes) and transposases (12%). Furthermore, genes were expressed that are necessary for living in the oligotrophic ocean, including the nitrogenase cluster and the iron-stress-induced protein A (isiA) that functions to protect photosystem I from high-light-induced damage. C. watsonii transcripts retrieved from metatranscriptomes at other locations in the southwest Pacific Ocean, station ALOHA and the equatorial Atlantic Ocean were similar in composition to those recovered in the enriched population. Quantitative PCR and quantitative reverse transcriptase PCR were used to confirm the high expression of these genes within the bloom, but transcription patterns varied at shallower and deeper horizons. These data represent the first transcript study of a rare individual microorganism in situ and provide insight into the mechanisms of genome diversification and the ecophysiology of natural populations of keystone organisms that are important in global nitrogen cycling.

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Section: Resultsmentioning

confidence: 84%

In situ transcriptomic analysis of the globally important keystone N2-fixing taxon Crocosphaera watsonii

et al. 2009

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“…Prochlorococcus is typically the most abundant photoautotroph in tropical and subtropical waters (Campbell et al, 1994;Partensky et al, 1999), and its abundance varies seasonally at some locations (Campbell et al, 1997;DuRand et al, 2001). Studies of cultured isolates have revealed the optimal light and temperature levels differ among the strains (Moore et al, 1998(Moore et al, , 2002Moore and Chisholm, 1999;Zinser et al, 2007), as do the nutrient pools available to them (Moore et al, 2002(Moore et al, , 2005.…”

Section: Introductionmentioning

confidence: 99%

Temporal dynamics of Prochlorococcus ecotypes in the Atlantic and Pacific oceans

et al. 2010

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To better understand the temporal and spatial dynamics of Prochlorococcus populations, and how these populations co-vary with the physical environment, we followed monthly changes in the abundance of five ecotypes-two high-light adapted and three low-light adapted-over a 5-year period in coordination with the Bermuda Atlantic Time Series (BATS) and Hawaii Ocean Time-series (HOT) programs. Ecotype abundance displayed weak seasonal fluctuations at HOT and strong seasonal fluctuations at BATS. Furthermore, stable 'layered' depth distributions, where different Prochlorococcus ecotypes reached maximum abundance at different depths, were maintained consistently for 5 years at HOT. Layered distributions were also observed at BATS, although winter deep mixing events disrupted these patterns each year and produced large variations in ecotype abundance. Interestingly, the layered ecotype distributions were regularly reestablished each year after deep mixing subsided at BATS. In addition, Prochlorococcus ecotypes each responded differently to the strong seasonal changes in light, temperature and mixing at BATS, resulting in a reproducible annual succession of ecotype blooms. Patterns of ecotype abundance, in combination with physiological assays of cultured isolates, confirmed that the low-light adapted eNATL could be distinguished from other low-light adapted ecotypes based on its ability to withstand temporary exposure to high-intensity light, a characteristic stress of the surface mixed layer. Finally, total Prochlorococcus and Synechococcus dynamics were compared with similar time series data collected a decade earlier at each location. The two data sets were remarkably similar-testimony to the resilience of these complex dynamic systems on decadal time scales.

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“…Moreover, their endosymbiotic engulfment by eukaryotic cells gave rise to algae and plants, the dominating photoautrophic organisms today (Knoll, 2008). However, cyanobacteria remain responsible for a high percentage of the annual primary production of organic biomass and represent a major sink for the greenhouse gas CO 2 in open oceans (Campbell et al, 1997).…”

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confidence: 99%

Metabolic and Transcriptomic Phenotyping of Inorganic Carbon Acclimation in the Cyanobacterium Synechococcus elongatus PCC 7942

et al. 2011

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The amount of inorganic carbon is one of the main limiting environmental factors for photosynthetic organisms such as cyanobacteria. Using Synechococcus elongatus PCC 7942, we characterized metabolic and transcriptomic changes in cells that had been shifted from high to low CO 2 levels. Metabolic phenotyping indicated an activation of glycolysis, the oxidative pentose phosphate cycle, and glycolate metabolism at lowered CO 2 levels. The metabolic changes coincided with a general reprogramming of gene expression, which included not only increased transcription of inorganic carbon transporter genes but also genes for enzymes involved in glycolytic and photorespiratory metabolism. In contrast, the mRNA content for genes from nitrogen assimilatory pathways decreased. These observations indicated that cyanobacteria control the homeostasis of the carbon-nitrogen ratio. Therefore, results obtained from the wild type were compared with the MP2 mutant of Synechococcus 7942, which is defective for the carbon-nitrogen ratio-regulating PII protein. Metabolites and genes linked to nitrogen assimilation were differentially regulated, whereas the changes in metabolite concentrations and gene expression for processes related to central carbon metabolism were mostly similar in mutant and wild-type cells after shifts to low-CO 2 conditions. The PII signaling appears to down-regulate the nitrogen metabolism at lowered CO 2 , whereas the specific shortage of inorganic carbon is recognized by different mechanisms.

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Annual variability of phytoplankton and bacteria in the subtropical North Pacific Ocean at Station ALOHA during the 1991–1994 ENSO event

Cited by 266 publications

References 40 publications

In situ transcriptomic analysis of the globally important keystone N2-fixing taxon Crocosphaera watsonii

In situ transcriptomic analysis of the globally important keystone N2-fixing taxon Crocosphaera watsonii

Temporal dynamics of Prochlorococcus ecotypes in the Atlantic and Pacific oceans

Metabolic and Transcriptomic Phenotyping of Inorganic Carbon Acclimation in the Cyanobacterium Synechococcus elongatus PCC 7942

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