The Cycle of Organic Phosphorus in the Gulf of Maine

Redfield, Alfred C.; Smith, Homer P.; Ketchum, Bostwick H.

doi:10.2307/1537605

Cited by 77 publications

(39 citation statements)

References 3 publications

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“…Interestingly, the "low Pi" concentrations utilized in this work appear to be much higher than levels found in the Hawaiian coastal waters inhabited by E. scolopes. Assays completed to determine the [P i ] (14) of seawater showed phosphate levels of Ͻ100 nM (data not shown), which is consistent with previous studies (3,65,68). However, this does not account for organic phosphate sources, which along with phosphate availability in the host light organ should be considered in future work.…”

Section: Discussionsupporting

confidence: 85%

Bright Mutants ofVibrio fischeriES114 Reveal Conditions and Regulators That Control Bioluminescence and Expression of theluxOperon

et al. 2010

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Vibrio fischeri ES114, an isolate from the Euprymna scolopes light organ, produces little bioluminescence in culture but is ϳ1,000-fold brighter when colonizing the host. Cell-density-dependent regulation alone cannot explain this phenomenon, because cells within colonies on solid medium are much dimmer than symbiotic cells despite their similar cell densities. To better understand this low luminescence in culture, we screened ϳ20,000 mini-Tn5 mutants of ES114 for increased luminescence and identified 28 independent "luminescence-up" mutants with insertions in 14 loci. Mutations affecting the Pst phosphate uptake system led to the discovery that luminescence is upregulated under low-phosphate conditions by PhoB, and we also found that ainS, which encodes an autoinducer synthase, mediates repression of luminescence during growth on plates. Other novel luminescence-up mutants had insertions in acnB, topA, tfoY, phoQ, guaB, and two specific tRNA genes. Two loci, hns and lonA, were previously described as repressors of bioluminescence in transgenic Escherichia coli carrying the light-generating lux genes, and mutations in arcA and arcB were consistent with our report that Arc represses lux. Our results reveal a complex regulatory web governing luminescence and show how certain environmental conditions are integrated into regulation of the pheromone-dependent lux system.Vibrio fischeri is a valuable model for examining bioluminescence, pheromone signaling, and symbiotic bacteria-animal interactions. Studies of V. fischeri's mutualistic interactions have gained momentum since the discovery that this bacterium's light organ symbiosis with the Hawaiian bobtail squid, Euprymna scolopes, can be reconstituted in the laboratory (54,70,83). Moreover, the bioluminescence induced by V. fischeri in the host light organ is a pheromone-mediated behavior, making this an attractive system for examining environmental influences on bacterial pheromone signaling in a natural infection. Largely because of interest in this symbiosis, strain ES114, which was isolated from the E. scolopes light organ, has become the experimental strain of choice for many studies of V. fischeri.The genetic basis of bioluminescence in V. fischeri ES114 is fundamentally similar to that of other characterized V. fischeri strains (31, 32). The lux genes responsible for bioluminescence, luxABCDE and -G, are found together with the regulatory genes luxR and luxI and are arranged with luxR divergently transcribed from the luxICDABEG operon, as shown in Fig. 1 (24, 25, 56). Light is generated when luciferase, comprised of LuxA and LuxB, binds to FMNH 2 , O 2 , and an aliphatic aldehyde, and then converts these substrates to FMN, water, and an aliphatic acid (35, 76). LuxC, LuxD, LuxE, and LuxG (re)generate luciferase's aldehyde and FMNH 2 substrates (12, 64).The remaining genes in this cluster, luxI and luxR, underlie a pheromone-mediated regulatory mechanism often referred to as quorum sensing. LuxI generates the membrane-permeable autoinducer pheromone N-3-oxoh...

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Section: Discussionsupporting

confidence: 85%

Bright Mutants ofVibrio fischeriES114 Reveal Conditions and Regulators That Control Bioluminescence and Expression of theluxOperon

et al. 2010

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“…There is evidence that organic phosphorus may become available fairly quickly (Cooper, 1935;Redfield, Smith & Ketchum, 1937;Seiwell & Seiwell, 1938). Since organic phosphorus is formed by the breakdown of living matter, at midwinter it is likely to be proportional to the inorganic phosphate available in a given area for plant growth.…”

Section: The Winter Maximum Of Phosphatementioning

confidence: 99%

Phosphate in the English Channel, 1933–8, with A Comparison with Earlier Years, 1916 and 1923–32

Cooper

1938

J. Mar. Biol. Ass.

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“…Despite early studies indicating the potential importance of DOP as a nutrient source to primary producers in marine systems (Redfield et al 1937;Butler et al 1979;Jackson and Williams 1985;Rivkin and Swift 1985;Orrett and Karl 1987), many past assessments of nutrient inventories and nutrient limitation have ignored dissolved organic nutrient reservoirs. DOP can be a significant fraction of the TDP pool in surface waters-in some cases, seasonally surpassing levels of DIP (Butler et al 1979;Orrett and Karl 1987;Cotner et al 1997;Karl and Tien 1997).…”

mentioning

confidence: 99%

Dissolved organic phosphorus in the coastal ocean: Reassessment of available methods and seasonal phosphorus profiles from the Eel River Shelf

Monaghan

Ruttenberg

1999

Limnology & Oceanography

128

131

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Methods for quantifying total dissolved phosphorus (TDP) were reevaluated. High-temperature ashing/hydrolysis (Ash/Hydrol.) and Acid Persulfate methods were examined for their ability to quantitatively convert a range of organic-P compounds to orthophosphate. The Ash/Hydrol. method recovered on average 99% of organic-P compounds tested, including phosphonates (compounds with C-P bonds). Contrary to concerns voiced in prior studies, we found no P loss due to volatilization in seawater samples. Poor recovery by the Acid Persulfate method was observed for two compound classes: phosphonates and phospholipids. The Ash/Hydrol. method is recommended for routine TDP analyses.The hydrolysis of dissolved organic phosphorus (DOP) during the phosphomolybdate-blue reaction and the subsequent overestimation of dissolved inorganic phosphorus (DIP) have long been a concern. Extent of hydrolysis of standard DOP compounds was evaluated both during this reaction and over long-term acidified (pH 1.0)/refrigerated and unacidified/frozen storage. Eleven of 12 compounds tested hydrolyzed Ͻ2% during the phosphomolybdate-blue reaction. Phospholipid, phosphosugar, and nucleotide mono-and diphosphate standards stored acidified/refrigerated over 2.5 months were Ͻ5% hydrolyzed; compounds with higher energy phosphate bonds (e.g., phosphocreatine) hydrolyzed to a greater extent. A natural seawater sample showed no hydrolysis over 80 d, however, suggesting that refrigerated storage of acidified samples is a viable option.Seasonal DOP profiles from the Eel River Shelf quantified by the Ash/Hydrol. and Acid Persulfate methods yielded comparable results, indicating that the DOP pool at this site did not contain significant phospholipids or phosphonates, which are underrecovered by the Persulfate method. Recoveries using a third method, Nitrate Oxidation, were on average 7% lower. Surface-water DOP exceeded DIP in summer and was apparently related to biological productivity, underscoring the need to include organic species when evaluating nutrient limitation and creating nutrient budgets.

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The Cycle of Organic Phosphorus in the Gulf of Maine

Cited by 77 publications

References 3 publications

Bright Mutants ofVibrio fischeriES114 Reveal Conditions and Regulators That Control Bioluminescence and Expression of theluxOperon

Bright Mutants ofVibrio fischeriES114 Reveal Conditions and Regulators That Control Bioluminescence and Expression of theluxOperon

Phosphate in the English Channel, 1933–8, with A Comparison with Earlier Years, 1916 and 1923–32

Dissolved organic phosphorus in the coastal ocean: Reassessment of available methods and seasonal phosphorus profiles from the Eel River Shelf

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