The simultaneous assimilation of ammonium and l-arginine by the marine diatom Phaeodactylum tricornutum Bohlin

Flynn, Kevin J.; Wright, Carrie

doi:10.1016/0022-0981(86)90258-3

Cited by 22 publications

(18 citation statements)

References 32 publications

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“…Since diatoms are thought to be capable of supporting their growth using ammonium, it is possible that the high rates of ammonium uptake and primary productivity we observed were at least in part due to the presence of a diverse group of these organisms. Phaeodactylum tricornutum, for example, has been shown to assimilate both L-arginine and ammonium simultaneously and individually at a rate sufficient for growth (Flynn & Wright 1986). Alternatively, a diverse group of green algae was also present in the plume and was actively transcribing their carbon fixation genes.…”

Section: Discussionmentioning

confidence: 99%

High rates of ammonium recycling drive phytoplankton productivity in the offshore Mississippi River plume

Wawrik¹,

Paul²,

Bronk³

et al. 2004

Aquat. Microb. Ecol.

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As part of an integrated study of the regulation of carbon fixation in the offshore Mississippi River plume, we measured the rates of 15 N-labeled ammonium and nitrate uptake in the surface plume waters from offshore to nearshore along the plume axis towards the Mississippi Delta. Concentrations of nitrate in the plume ranged from 0.19 to 2.5 µM with the highest concentrations primarily in the shoreward stations, while ammonium ranged from 0.17 to 0.44 µM, showing little spatial variability. Rates of ammonium uptake ranged from 16.5 to 260 nM h -1 , and showed a strong trend of increasing values from offshore towards the Mississippi Delta. In contrast, nitrate uptake rates ranged from 3.2 to 25 nM h -1 . The high rates of ammonium uptake in the presence of low ammonium concentrations and elevated nitrate was made possible by elevated rates of ammonium regeneration that exceeded ammonium uptake by 1.7 to 5.7-fold in the plume. The plume exhibited relatively low f-ratios and also contained elevated levels of Synechococcus as determined by flow cytometry and high levels of form IA (α-cyanobacterial) rbcL transcripts. These data suggest that a major portion of the carbon fixation observed in the offshore Mississippi River plume represents recycled production supported by high rates of ammonium regeneration.KEY WORDS: Gulf of Mexico · Mississippi River plume · Nitrate uptake · Ammonium uptake · Nutrient cycling Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 35: [175][176][177][178][179][180][181][182][183][184] 2004 No targeted survey of the plume in this environment has thus far been conducted to study the plume's effect on oligotrophic ocean ecology, phytoplankton composition and nutrient cycling. Previous studies of the plume have primarily been concerned with the plume's impact on coastal ecosystems in the northern GOM shelf region. The plume has, however, been shown to greatly enhance oligotrophic surface productivity and phytoplankton species composition in the oligotrophic GOM (Wawrik et al. 2003).On the shelf, nutrients, irradiance and primary production of the Mississippi River plume have been studied extensively (Lohrenz et al. 1990, Dortch & Whitledge 1992, Pakulski et al. 1995, 2000. Productivity in the most coastal region of the plume is initially limited by turbidity, and highest productivity occurs at intermediate salinities as the plume matures. Nutrients display distinct non-conservative mixing behavior along the salinity gradient of the plume, and both silicate as well as nitrogen have been reported to limit productivity in the higher salinity portions of the plume. High productivity in the plume has been implicated in the formation of extensive regions of hypoxia in bottom waters along the Louisiana and Texas shelf during summer stratification (Dortch et al. 1994, Eadie et al. 1994, Justic et al. 1996.Nitrogen mineralization rates in the Mississippi River plume area have been measured using High Performance Liquid Chromatography (HPLC...

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Section: Discussionmentioning

confidence: 99%

High rates of ammonium recycling drive phytoplankton productivity in the offshore Mississippi River plume

Wawrik¹,

Paul²,

Bronk³

et al. 2004

Aquat. Microb. Ecol.

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“…What is of importance is the extent of arnino-N incorporation which occurs simultaneously with that of other N-sources. Thus during growth of Phaeodactylum tricornutum in a light/dark cycle, ammonium and arginine are simultaneously assimilated, with the incorporation of amino-N contributing 30 % of cell-N (Flynn & Wright 1986). …”

Section: Growth Experimentsmentioning

confidence: 99%

“…The resultant high turbidity may also limit light penetration to less than l m. Thus the phytoplankton of estuaries are subjected to periods of enforced darkness, superimposed on the normal diurnal cycle of day and night, in an environment potentially rich in amino acids. However, because such environments are also rich in other nutrients, amino acids may be used only if, as in Phaeodactylum tricornutum (Flynn & Syrett 1986a, Flynn & Wright 1986, the uptake of amino acids is not inhibited by the presence of a large excess of ammonium or nitrate.…”

Section: Effect Of Darknessmentioning

confidence: 99%

“…A decreased ability to take up an amino acid relative to other N-sources (especially ammonium) which may be taken up more rapidly than required for growth , may indicate either that the amino acid is not taken up at a great rate (perhaps because the products of ammonium assimilation and photosynthesis are already satisfying the requirement), or that it has already been taken up and that, because of transinhibition, further transport is at a low rate (see Flynn & Wright 1986). One possible reason for the low uptake rates of glycine and glutamate measured by Schell(1974) is that these amino acids are some of the first to be derived from photosynthetic incorporation of ammonium or nitrate (Beardall et al 1976).…”

Section: Transinhibitionmentioning

confidence: 99%

“…In contrast with the development of uptake systems for other nitrogenous compounds, amino acid uptake systems also develop in response to carbon-deprivation (Lewin & Hellebust 1975, Kirk & Kirk 1978, Richards & Thurston 1980, Flynn & Syrett 1985, Flynn & Wright 1986). Schell (1974) reported that the uptake of amino acids by natural diatom populations off Alaska is twice as high in darkness as in light.…”

Section: Effect Of Darknessmentioning

confidence: 99%

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Nitrogen sources for the growth of marine microalgae: role of dissolved free amino acids

Flynn¹,

Butler²

1986

Mar. Ecol. Prog. Ser.

170

108

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Dissolved free amino acids (DFAA) form a significant proportion of dissolved fixed nitrogen in marine waters and could provide an additional source of nitrogen for the growth of marine microalgae. With the advent of DFAA analysis by HPLC, recent studies of algal physiology, and an increased awareness of potential experimental errors, doubts are cast over the conclusion that marine microalgae are not net users of DFAA. Results obtained by testing the use of a few amino acids cannot be extrapolated; the full range of amino acids should be used in field experiments. A high rate of uptake of any one amino acid is not to be expected. It is more probable that a simultaneous uptake of several amino acids will occur at a lower rate. It is essential that environmental conditions be taken into account in interpretation of results from field experiments. Results from laboratory and field studies suggest that maximum rates of DFAA uptake would occur in dark conditions in waters depleted of dissolved inorganic nitrogen. Turbid estuaries and coastal waters would also be environments likely to induce a significant uptake of amino acids, because levels of nFA.4 i.n. sl~ch WB!P~S S~C :~!st;l.~.~!y high and the periods of enforced darkness due to turbidity are likely to induce the development of microalgal amino acid uptake systems.

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Kinetics of urea uptake by Melosira italica (Ehr.) Kütz at different luminosity conditions

Cimbleris¹,

Caceres

1991

Hydrobiologia

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The kinetic parameters K, and V,,, for urea uptake by Melosira italica were determined at 160 peinsteins m -2 S -1 and in the dark. The transport systems showed an affinity for the substrate and a storing capacity in the dark (K, = 65.07 pM; V,,, = 2.18 nmoles lo5 cells-' h -') greater than under 160 pE m -2 s -' (K, = 1 11.2 p M ; V,,, = 1.11 nmoles 10' cells -' h -'). Similarly, a reduction in consumption rate of urea under increasing photon flux densities was observed. The use of an inhibitor (potassium cyanide) indicated that the uptake process requires metabolic energy. That urea transport is more important in darkness, may constitute a survival strategy in which this compound is utilized by cells mainly during heterotrophic growth.

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The simultaneous assimilation of ammonium and l-arginine by the marine diatom Phaeodactylum tricornutum Bohlin

Cited by 22 publications

References 32 publications

High rates of ammonium recycling drive phytoplankton productivity in the offshore Mississippi River plume

High rates of ammonium recycling drive phytoplankton productivity in the offshore Mississippi River plume

Nitrogen sources for the growth of marine microalgae: role of dissolved free amino acids

Kinetics of urea uptake by Melosira italica (Ehr.) Kütz at different luminosity conditions

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