Influence of low light and a light

Dark cycle on NO3 - uptake, intracellular NO3 -, and nitrogen isotope fractionation by marine phytoplankton

Joseph Needoba, Paul J. Harrison

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88 Citations (Scopus)

Abstract

The nitrogen isotope enrichment factor (ε) of four species of marine phytoplankton grown in batch cultures was determined during growth in continuous saturating light, continuous low light, and a 12:12-h light:dark cycle, with nitrate as a nitrogen source. The low growth rate that resulted from low irradiance caused an increased accumulation of the intracellular nitrate pool and/or a reduction in cell volume and was correlated to a species-specific increase in the measured ε value, compared with the saturating light conditions. The largest response was in the diatom Thalassiosira weissflogii (Grun.) Fryxell et Hasle, which showed a nearly 3-fold increase between high and low light conditions (6.2-15.2‰). The smallest response was in T. pseudonana (Hustedt) Hasle et Heimdal, which showed no change in the ε value of approximately 5‰ in both high and low light conditions. There was significant but smaller increases in the ε value for the diatom T. rotula Meunier (2.7-5.6‰) and the prymnesiophyte Emiliania huxleyi (Lohm.) Hay et Mohler (4.5-9.4‰) between high and low light levels. In the light:dark experiments, all three diatoms but not the prymnesiophyte exhibited an increase in ε. This increase was linked to the ability of diatoms to assimilate nitrate at night. The results of the these experiments suggest that the light regime influences the relative uptake, assimilation, and efflux rates of nitrate and results in differences in the expression of the isotope effect by the enzyme nitrate reductase. Therefore, variations in nitrate isotope fractionation in nature can be more accurately interpreted when the light regime and species composition are taken into consideration.

Original languageEnglish (US)
Pages (from-to)505-516
Number of pages12
JournalJournal of Phycology
Volume40
Issue number3
StatePublished - Jun 2004
Externally publishedYes

Fingerprint

isotope fractionation
nitrogen isotope
fractionation
photoperiod
phytoplankton
Bacillariophyceae
uptake mechanisms
nitrogen
nitrates
nitrate
diatom
isotopes
Emiliania huxleyi
Thalassiosira
nitrate reductase
isotope
hay
assimilation (physiology)
species diversity
irradiance

Keywords

  • Diatoms
  • Efflux
  • Enrichment factor
  • Intracellular
  • Irradiance
  • Isotope fractionation
  • Light
  • Light:dark cycle
  • Nitrate
  • Prymnesiophyte

ASJC Scopus subject areas

  • Aquatic Science
  • Plant Science

Cite this

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title = "Influence of low light and a light: Dark cycle on NO3 - uptake, intracellular NO3 -, and nitrogen isotope fractionation by marine phytoplankton",
abstract = "The nitrogen isotope enrichment factor (ε) of four species of marine phytoplankton grown in batch cultures was determined during growth in continuous saturating light, continuous low light, and a 12:12-h light:dark cycle, with nitrate as a nitrogen source. The low growth rate that resulted from low irradiance caused an increased accumulation of the intracellular nitrate pool and/or a reduction in cell volume and was correlated to a species-specific increase in the measured ε value, compared with the saturating light conditions. The largest response was in the diatom Thalassiosira weissflogii (Grun.) Fryxell et Hasle, which showed a nearly 3-fold increase between high and low light conditions (6.2-15.2‰). The smallest response was in T. pseudonana (Hustedt) Hasle et Heimdal, which showed no change in the ε value of approximately 5‰ in both high and low light conditions. There was significant but smaller increases in the ε value for the diatom T. rotula Meunier (2.7-5.6‰) and the prymnesiophyte Emiliania huxleyi (Lohm.) Hay et Mohler (4.5-9.4‰) between high and low light levels. In the light:dark experiments, all three diatoms but not the prymnesiophyte exhibited an increase in ε. This increase was linked to the ability of diatoms to assimilate nitrate at night. The results of the these experiments suggest that the light regime influences the relative uptake, assimilation, and efflux rates of nitrate and results in differences in the expression of the isotope effect by the enzyme nitrate reductase. Therefore, variations in nitrate isotope fractionation in nature can be more accurately interpreted when the light regime and species composition are taken into consideration.",
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T1 - Influence of low light and a light

T2 - Dark cycle on NO3 - uptake, intracellular NO3 -, and nitrogen isotope fractionation by marine phytoplankton

AU - Needoba, Joseph

AU - Harrison, Paul J.

PY - 2004/6

Y1 - 2004/6

N2 - The nitrogen isotope enrichment factor (ε) of four species of marine phytoplankton grown in batch cultures was determined during growth in continuous saturating light, continuous low light, and a 12:12-h light:dark cycle, with nitrate as a nitrogen source. The low growth rate that resulted from low irradiance caused an increased accumulation of the intracellular nitrate pool and/or a reduction in cell volume and was correlated to a species-specific increase in the measured ε value, compared with the saturating light conditions. The largest response was in the diatom Thalassiosira weissflogii (Grun.) Fryxell et Hasle, which showed a nearly 3-fold increase between high and low light conditions (6.2-15.2‰). The smallest response was in T. pseudonana (Hustedt) Hasle et Heimdal, which showed no change in the ε value of approximately 5‰ in both high and low light conditions. There was significant but smaller increases in the ε value for the diatom T. rotula Meunier (2.7-5.6‰) and the prymnesiophyte Emiliania huxleyi (Lohm.) Hay et Mohler (4.5-9.4‰) between high and low light levels. In the light:dark experiments, all three diatoms but not the prymnesiophyte exhibited an increase in ε. This increase was linked to the ability of diatoms to assimilate nitrate at night. The results of the these experiments suggest that the light regime influences the relative uptake, assimilation, and efflux rates of nitrate and results in differences in the expression of the isotope effect by the enzyme nitrate reductase. Therefore, variations in nitrate isotope fractionation in nature can be more accurately interpreted when the light regime and species composition are taken into consideration.

AB - The nitrogen isotope enrichment factor (ε) of four species of marine phytoplankton grown in batch cultures was determined during growth in continuous saturating light, continuous low light, and a 12:12-h light:dark cycle, with nitrate as a nitrogen source. The low growth rate that resulted from low irradiance caused an increased accumulation of the intracellular nitrate pool and/or a reduction in cell volume and was correlated to a species-specific increase in the measured ε value, compared with the saturating light conditions. The largest response was in the diatom Thalassiosira weissflogii (Grun.) Fryxell et Hasle, which showed a nearly 3-fold increase between high and low light conditions (6.2-15.2‰). The smallest response was in T. pseudonana (Hustedt) Hasle et Heimdal, which showed no change in the ε value of approximately 5‰ in both high and low light conditions. There was significant but smaller increases in the ε value for the diatom T. rotula Meunier (2.7-5.6‰) and the prymnesiophyte Emiliania huxleyi (Lohm.) Hay et Mohler (4.5-9.4‰) between high and low light levels. In the light:dark experiments, all three diatoms but not the prymnesiophyte exhibited an increase in ε. This increase was linked to the ability of diatoms to assimilate nitrate at night. The results of the these experiments suggest that the light regime influences the relative uptake, assimilation, and efflux rates of nitrate and results in differences in the expression of the isotope effect by the enzyme nitrate reductase. Therefore, variations in nitrate isotope fractionation in nature can be more accurately interpreted when the light regime and species composition are taken into consideration.

KW - Diatoms

KW - Efflux

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KW - Intracellular

KW - Irradiance

KW - Isotope fractionation

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KW - Light:dark cycle

KW - Nitrate

KW - Prymnesiophyte

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M3 - Article

VL - 40

SP - 505

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JF - Journal of Phycology

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