Molecular and physiological responses of diatoms to variable levels of irradiance and nitrogen availability: Growth of Skeletonema costatum in simulated upwelling conditions

Smith, G. Jason; Zimmerman, Richard C.; Alberte, Randall S.

doi:10.4319/lo.1992.37.5.0989

Cited by 67 publications

(74 citation statements)

References 58 publications

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“…3,6a) ). We recognize that these estimates are based upon cultured reference species, and rRNA content may vary according to age or nutritional status (e.g., Anderson et al 1999;Miller et al 2004;Smith et al 1992). Nevertheless, we believe that our estimates are reasonable representations of population changes that were captured by a series of discrete samples.…”

Section: Greenfield Et Al Field Applications Of the Espmentioning

confidence: 87%

Field applications of the second‐generation Environmental Sample Processor (ESP) for remote detection of harmful algae: 2006‐2007

Greenfield

Marin

Doucette

et al. 2008

Limnology & Ocean Methods

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We assess the application of the second-generation Environmental Sample Processor (ESP) for the detection of harmful algal bloom (HAB) species in field and laboratory settings using two molecular probe techniques: a sandwich hybridization assay (SHA) and fluorescent in situ hybridization (FISH). During spring 2006, the first time this new instrument was deployed, the ESP successfully automated application of DNA probe arrays for various HAB species and other planktonic taxa, but non-specific background binding on the SHA probe array support made results interpretation problematic. Following 2006, the DNA array support membrane that we were using was replaced with a different membrane, and the SHA chemistry was adjusted. The sensitivity and dynamic range of these modifications were assessed using 96-well plate and ESP array SHA formats for several HAB species found commonly in Monterey Bay over a range of concentrations; responses were significantly correlated (p < 0.01). Modified arrays were deployed in 2007. Compared to 2006, probe arrays showed improved signal:noise, and remote detection of various HAB species was demonstrated. We confirmed that the ESP and affiliated assays can detect HAB populations at levels below those posing human health concerns, and results can be related to prevailing environmental conditions in near real-time.*Corresponding author: E-mail: dgreenfield@belle.baruch.sc.edu AcknowledgmentsWe thank the engineering technicians and machinists at MBARI for their invaluable help and dedication toward instrument development. We also greatly appreciate the hard work and dedication from the crew of the R/V Zephyr and Moss Landing Marine Laboratory, Small Boat Operations, and help from Drs. W. Jones and C. Preston. The authors gratefully acknowledge Drs. Z. Wang and T. Roth for the extraction and analysis of domoic acid in discrete water samples. This project was funded in part by the Monterey Bay Aquarium Research Institute from funds allocated by the David and Lucille Packard Foundation, the National Science Foundation, and the National Aeronautics and Space Administration (OCE-0314222, CCF424599, and NNG06GB34G to CAS, and OCE-0314089 to GJD).Disclaimers: Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. This publication does not constitute an endorsement of any commercial product or intend to be an opinion beyond scientific or other results obtained by the National Oceanic and Atmospheric Administration (NOAA). No reference shall be made to NOAA, or this publication furnished by NOAA, to any advertising or sales promotion which would indicate or imply that NOAA recommends or endorses any proprietary product mentioned herein, or which has as its purpose an interest to cause the advertised product to be used or purchased because of this publication. Limnol. Oceanogr.: Methods 6, 2008, 667-679 © 2008, by the American Society of Limnology and Oceanogra...

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Section: Greenfield Et Al Field Applications Of the Espmentioning

confidence: 87%

Field applications of the second‐generation Environmental Sample Processor (ESP) for remote detection of harmful algae: 2006‐2007

Greenfield

Marin

Doucette

et al. 2008

Limnology & Ocean Methods

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“…In reality this will include some degree of assimilation and perhaps uptake into internal pools, but under steady state conditions, the rates calculated should be equivalent to true incorporation. Such a correlation between NR activity and incorporation has never been consistently achieved before; for example, in studies with diatoms, Smith et al (1992) found only -50% of incorporation was accounted for and Eppley et al (1969) obtained <25%. Morris and Syrett (1965) found that NR activity in Chlorella vulgaris accounted for 100% of incorporation and reasoned that they were not extracting all of the NR; excess activity was expected.…”

Section: Discussionmentioning

confidence: 99%

“…The quantity of enzyme protein can be estimated by immunoassay (e.g. Smith et al 1992), but this then requires conversion from an enzyme quantity to an cnzyme activity. Direct activity measurements, on the other hand, require the assumptions that the enzyme is extracted without damage and that it is saturated with all substrates and cofactors.…”

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confidence: 99%

Nitrate reductase activity quantitatively predicts the rate of nitrate incorporation under steady state light limitation: A revised assay and characterization of the enzyme in three species of marine phytoplankton

Berges

Harrison

1995

Limnology & Oceanography

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The enzyme nitrate reductase (NR) has been proposed as an index of nitrate incorporation rates in marine phytoplankton, but it has proven difficult to interpret NR measurements in field settings because many previous NR assays have been poorly optimized and NR activity in phytoplankton has been poorly characterized under steady state conditions. An NR assay was developed for the diatom Thalassiosira pseudonana using an extraction in phosphate buffer with Triton X-100, EDTA, dithiothreitol, polyvinyl pyrrolidone, and bovine serum albumin. NR activity in homogenates was stable for up to 1 h, but filtered samples could be stored for 96 h in liquid nitrogen without significant loss of activity. Addition of FAD to crude extracts of T. pseudonana had no effect, whereas the effect on desalted extracts or crude extracts from other species, varied from decreases in NR activity to over 250% increases. Half-saturation constants (K,) varied between species; high levels of NADH or nitrate were found to be inhibitory in some cases. These results indicate a wide diversity of forms of NR in marine phytoplankton.Under continuous, light-limited growth, NR activity was quantitatively related to calculated rates of nitrate incorporation (pN) in T. pseudonana, Skeletonema costatum, and three other diatom species examined. The relationship differed for 10 other species; NR activity was equal to bN in some cases, but higher or lower in others. In dinoflagellates, in particular, NR activity was highly correlated with pN, but accounted for ~20% of hN in Amphidinium carterae.The importance of nitrogen metabolism in general, and nitrate metabolism in particular, in the marine environment is based not only on the frequent identification of nitrogen as a nutrient limiting primary production, but also because of the important differences between the fate of production depending on whether newly available nitrogen (e.g. nitrate) or regenerated forms (e.g. ammonium) are used (Dugdale and Goering 1967;Platt et al. 1992). Thus, measurements of rates of nitrate incorporation (sensu Wheeler 1983, i.e. the combination of inorganic nitrogen into large macromolecules such as proteins and nucleic acids) by marine phytoplankton are critical to understanding rates of primary production and biogeochemical cycling in many areas of the oceans.Current methods of estimating rates of nitrate incorporation are based largely on incubation techniques with the stable isotope 15N as a tracer (Dugdale and Wilkerson 1986). It is appreciated that there are problems with this

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“…nitrate (Smith et al 1992;Lomas 2004;Allen et al 2006) in response to increasing concentrations of nitrate (Dugdale et al 1981;MacIsaac et al 1985;Wilkerson and Dugdale 1987). No such shift up has been demonstrated for ammonium (Glibert et al 2016).…”

Section: The Ammonium Paradoxmentioning

confidence: 99%

Nutrient Dynamics of the Delta: Effects on Primary Producers

Dahm¹,

Parker²,

Adelson³

et al. 2016

SFEWS

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Increasing clarity of Delta waters, the emergence of harmful algal blooms, the proliferation of aquatic water weeds, and the altered food web of the Delta have brought nutrient dynamics to the forefront. This paper focuses on the sources of nutrients, the transformation and uptake of nutrients, and the links of nutrients to primary producers. The largest loads of nutrients to the Delta come from the Sacramento River with the San Joaquin River seasonally important, especially in the summer. Nutrient concentrations reflect riverine inputs in winter and internal biological processes during periods of lower flow with internal nitrogen losses within the Delta estimated at approximately 30% annually. Light regime, grazing pressure, and nutrient availability influence rates of primary production at different times and locations within the Delta. The roles of the chemical form of dissolved inorganic nitrogen in growth rates of primary producers in the Delta and the structure of the open-water algal community are currently topics of much interest and considerable debate. Harmful algal blooms have been noted since the late 1990s, and the extent of invasive aquatic macrophytes (both submerged and free-floating forms) has increased especially during years of drought. Elevated nutrient loads must be considered in terms of their ability to support this excess biomass. Modern sensor technology and networks are now deployed that make high-frequency measurements of nitrate, ammonium, and phosphate. Data from such instruments allow a much more detailed assessment of the spatial and temporal dynamics of nutrients. Four fruitful directions for future research include utilizing continuous sensor data to estimate rates of primary production and ecosystem respiration, linking hydrodynamic models of the Delta with the transport and fate of dissolved nutrients, studying nutrient dynamics in various habitat types, and exploring the use of stable isotopes to trace the movement and fate of effluent-derived nutrients.

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Molecular and physiological responses of diatoms to variable levels of irradiance and nitrogen availability: Growth of Skeletonema costatum in simulated upwelling conditions

Cited by 67 publications

References 58 publications

Field applications of the second‐generation Environmental Sample Processor (ESP) for remote detection of harmful algae: 2006‐2007

Field applications of the second‐generation Environmental Sample Processor (ESP) for remote detection of harmful algae: 2006‐2007

Nitrate reductase activity quantitatively predicts the rate of nitrate incorporation under steady state light limitation: A revised assay and characterization of the enzyme in three species of marine phytoplankton

Nutrient Dynamics of the Delta: Effects on Primary Producers

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