Effect of Nitrogen Supply on the Kinetics and Regulation of Nitrate Assimilation in Chlamydomonas reinhardtii Dangeard

Watt, D. A.; Amory, Alan; Cresswell, C. F.

doi:10.1093/jxb/43.5.605

Cited by 21 publications

(31 citation statements)

References 31 publications

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“…(Kessler & Osterheld 1970), Chlamydomonas reinhardtil (Watt et al 1992), and in a survey of 6 species of marine phytoplankton (Hipkin et al 1983); this increase even occurred in cultures that had previously been grown on ammonium and had shown no previous NR activity. It is unclear why this should occur, but suggestions range from a simple derepression of NR synthesis once ammonium is removed, to the presence of oxidative pathways within the cell that provide nitrate in the absence of a nitrogen supply (Watt et al 1992). It is worth noting, however, that Oaks et al (1990) showed that trace nitrate contamination of soil was responsible for a 'no nitrate' induction of NR in higher plants.…”

Section: Effects Of Nitrate Depletionmentioning

confidence: 93%

See 1 more Smart Citation

Laboratory and field responses of algal nitrate reductase to diel periodicity in irradiance, nitrate exhaustion, and the presence of ammonium

Ja¹,

Cochlan²,

Pj³

1995

Mar. Ecol. Prog. Ser.

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Use of nitrate reductase (NR) activlty as an index of rates of nltrate Incorporation in m a n n e phytoplankton has been complicated by inadequate assays, and the high degree of regulation of the enzyme under different non-steady-state conditions The relationship between NR activity and rates of nitrate incorporation was examined uslng a modified NR assay (which Included bovine serum albumln) under diel p e r~o d~c i t y in irrad~ance, following exhaustion of nitrate, and in the presence of ammonium Laboratory experiments using the diatom Thalassiosira pseudonana showed that on a 14 10 h hght dark cycle, NR activity had 2 d~stinct peaks within 1 cycle, one in the m~d d l e of the light period, and the other towards the end of the dark penod Each of these peaks has been noted In previous work, both in culture and in natural populations, but this is the first descnpt~on of both in 1 cycle Throughout the d~e l cycle, NR activ~ty closely matched rates of nitrate incorporation calculated from increases in part~culate nitrogen In the cultures As n~t r a t e was exhausted in the cultures, NR actlvity declined in step w~t h nitrate incorporation rates (estimated from nitrate depletion, increases in part~culate nltrogen or the product of cell growth rate and cell nitrogen content) In cultures where n~t r a t e was substituted by ammonium, no NR activity was detected, but when ammonium was exhausted, background contamination of the medium with nitrate (approximately 1 PM) was suffic~ent to cause the appearance of NR activity and the uptake of nitrate Dally additions of 2 pM ammonium to cultures growing on nitrate had no effect on the r e l a t~o n s h~p between NR activity and nitrate incorporat~on rate The NR assay was used in a preliminary study of natural assemblages of phytoplankton in Monterey Bay, California, USA, during a post-upwelling diatom bloom Die1 periodicity in NR activity was observed that was virtually identical to that found in laboratory cultures Ammonium inhibition on a time scale simllar to that seen in culture was also recorded These preliminary results are promlslng for the use of NR activity to estimate rates of nltrate incorporat~on In field populat~on of phytoplankton KEY WORDS: N~t r a t e reductase . Enzyme activity . Nitrate incorporatlon . Marine phytoplankton .

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Section: Effects Of Nitrate Depletionmentioning

confidence: 93%

“…There are even reports of transient increases in NR activity when nitrogen is depleted, or when algal cells grown on ammonium are transferred to N-free media (e.g. Kessler & Osterheld 1970, Slawyk & Rodier 1986, Watt et al 1992.…”

Section: Introductionmentioning

confidence: 99%

Laboratory and field responses of algal nitrate reductase to diel periodicity in irradiance, nitrate exhaustion, and the presence of ammonium

Ja¹,

Cochlan²,

Pj³

1995

Mar. Ecol. Prog. Ser.

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“…In this study we observed classical MichaeliseMenten kinetics for NH 4 but were unable to determine N uptake kinetics for NO 3 , although comparing rates obtained with saturating level of the two DIN species, there was higher V MAx for NO 3 compared to NH 4 . Deviation (to linear or biphasic) from the hyperbolic relationship for NO 3 uptake at saturating to supersaturating concentrations have been described in many algal species including diatoms (Serra et al, 1978;Watt et al, 1992;Collos et al, 1992Collos et al, , 1997Collos et al, , 2005Lomas and Glibert, 1999b) and upwelled phytoplankton . Two studies (Huntsman and Barber, 1977;Lancelot and Billen, 1985) showed that C and N uptake were coupled during linear NO 3 uptake at high concentrations.…”

Section: Maximal No 3 Uptake Exceeds Maximal Nh 4 Uptakementioning

confidence: 99%

The effect of inorganic nitrogen speciation on primary production in the San Francisco Estuary

Parker

Hogue

Wilkerson

et al. 2012

Estuarine, Coastal and Shelf Science

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Keywords:San Francisco Estuary primary production phytoplankton carbon ammonium nitrate a b s t r a c tWe describe the results of a series of 96-h enclosure experiments conducted using water from stations in the northern San Francisco Estuary (SFE) along a gradient in ammonium (NH 4 ) and nitrate (NO 3 ) concentrations. Using dual-labeled 13 C/ 15 N tracers, we followed the timing and sequence of primary (carbon, C) production and phytoplankton nitrogen (N) use during experimental phytoplankton blooms. Our results show that diatoms consistently drive the phytoplankton blooms in the enclosures. By tracing both C and N uptake we provide clear evidence that high rates of C uptake are linked to phytoplankton NO 3 , and not NH 4 , use. Results from kinetics experiments demonstrated higher specific uptake rates (V MAx ) for NO 3 compared to NH 4 in the SFE. Finally, dissolved inorganic carbon and nutrient drawdown ratios in the enclosures from the chronically high NH 4 regions of the SFE were substantially lower than predicted from the Redfield ratio, suggesting suppressed C uptake, in relation to other elemental uptake. Our conceptual model of the DIN interactions that lead to higher primary production and phytoplankton blooms in the SFE suggests that higher rates of primary production that accompany phytoplankton NO 3 uptake are sufficient to outpace phytoplankton losses, leading to blooms, compared to the lower rates associated with NH 4 uptake (only 20% of that based upon NO 3 ). Historical changes in wastewater practices have increased the proportion of NH 4 to the DIN pool in the SFE leading to reduced access to NO 3 by phytoplankton. This may help to explain some of the reduced primary production and phytoplankton biomass observed there since the 1970s.

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“…Recent studies of nitrate uptake in laboratory cultures of unicellular algae (Ower & Cresswell, 1986;Collos et al, 1992;Watt et al, 1992) have revealed biphasic kinetics, with a first transition near 60 M for Skeletonema costatum and Thalassiosira weissflogii, 150 M for Ankistrodesmus falcatus, and 1100 M in Chlamydomonas reinhardtii. These kinetics are similar to findings in higher plants (Pace & McClure, 1986;Siddiqi et al, 1990), but differ from previous work on unicellular algae.…”

Section: Introductionmentioning

confidence: 99%

Variability in Nitrate Uptake Kinetics of Phytoplankton Communities in a Mediterranean Coastal Lagoon

Collos

Vaquer

Bibent

et al. 1997

Estuarine, Coastal and Shelf Science

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Nitrate uptake kinetics of different phytoplankton communities exhibit great variability over a 1-year period. Classical saturation kinetics accompanied by an induction phase are shown by blooms of Chaetoceros sp. in low nitrate waters. Biphasic kinetics, with transition points between 10 and 50 M, are shown by blooms of Skeletonema costatum and flagellates, while unsaturated kinetics (up to 100 M) are shown by Thalassiosira blooms and flagellate blooms. The latter also exhibit surge uptake of nitrate in situations of negative growth rates and rather high ammonium levels. The uptake patterns of the three diatom genera are similar to those observed in cultures or consistent with known internal nitrate accumulation characteristics. Based on the kinetic patterns presented, it is apparent that, for nitrate concentrations near 50 M such as in upwelling areas, nitrate uptake will be underestimated in present models of nitrate assimilation by a factor of almost 2 for S. costatum and a factor of about 3 for Thalassiosira sp. Academic Press Limited

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Effect of Nitrogen Supply on the Kinetics and Regulation of Nitrate Assimilation in Chlamydomonas reinhardtii Dangeard

Cited by 21 publications

References 31 publications

Laboratory and field responses of algal nitrate reductase to diel periodicity in irradiance, nitrate exhaustion, and the presence of ammonium

Laboratory and field responses of algal nitrate reductase to diel periodicity in irradiance, nitrate exhaustion, and the presence of ammonium

The effect of inorganic nitrogen speciation on primary production in the San Francisco Estuary

Variability in Nitrate Uptake Kinetics of Phytoplankton Communities in a Mediterranean Coastal Lagoon

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