Journal ArticleDOI
Nitrate reductase in Peru current phytoplankton
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Nitrate reductase (NR) activity was assayed by measuring the NADH-dependent formation of nitrite in phytoplankton extracts, and showed diel periodicity, with maximum activity about noon and minimum activity near midnight local time.Abstract:
Nitrate reductase (NR) activity was assayed by measuring the NADH-dependent formation of nitrite in phytoplankton extracts. NR specific activity increased with the nitrate concentration of the water in upwelling areas of the Peru Current. The temperature optimum for NR for natural phytoplankton was 15° to 20°C. NR activity showed diel periodicity, with maximum activity about noon and minimum activity near midnight local time. Rate of nitrate reduction in the extracts averaged only about 15% of the rate of nitrate assimilation in the whole cells.read more
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Comparisons of nitrate uptake, storage, and reduction in marine diatoms and flagellates
TL;DR: Enhanced capacity for NO3− uptake and reduction along with the lower optimum temperature for enzyme activity could explain differences in nitrogen release patterns between diatoms and flagellates after an increase in irradiance.
Journal ArticleDOI
Nitrogen isotope effects in the assimilation of inorganic nitrogenous compounds by marine diatoms
Wada Eitaro,Hattori Akihiko +1 more
TL;DR: In this paper, the isotope fractionation in the assimilation of inorganic nitrogenous compounds was studied using marine diatoms (Phaeodactylum tricornutum and Chaetoceros sp.).
Journal ArticleDOI
Interactions of light and inorganic nitrogen in controlling nitrogen uptake in the sea
J.J. MacIsaac,Richard C. Dugdale +1 more
TL;DR: In this paper, the half-saturation constant for light intensity in nitrate and ammonium uptake is found to be from 1 to 14% of surface light intensity, an intensity range occurring near the bottom of the euphotic zone.
Journal ArticleDOI
Inorganic nutrient uptake and deficiency in algae.
TL;DR: An attempt is made to borrow information from the physiology of bacteria, fungi, and higher plants where they augment observations on algae in an attempt to find new insights into the metabolic roles of nutrients and the mechanisms of their assimilation.
Journal ArticleDOI
A budget of nitrogen recycling in North Sea sediments off the Belgian coast
TL;DR: In this article, a diagenetic model simulating the concentration profile of ammonium and nitrate in the interstitial water of the North Sea sediments of the Belgian coast is presented.
References
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Journal ArticleDOI
Determination of chlorophyll and pheo‐pigments: spectrophotometric equations1
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Half‐saturation constants for uptake of nitrate and ammonium by marine phytoplankton1
TL;DR: In this article, the half-saturation constant (Ks) was computed as a measure of the ability of a species to use low levels of nitrate and ammonium, and the success of Gonyaulax polyedra, often the dominant dinoflagellate in local red water blooms, appears to be due to its vertical migration from the sea surface in daylight to nitrate-rich water at 10-15m depth at night.
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The kinetics of nitrate and ammonia uptake by natural populations of marine phytoplankton
J.J. MacIsaac,Richard C. Dugdale +1 more
TL;DR: In this article, the response of phytoplankton to nitrate and ammonia concentrations has been investigated using nitrogen-15 tracer techniques in the Bering Sea, the waters of southeastern Alaska, and the northeastern tropical Pacific.
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Studies of nitrate reductase in marine phytoplankton1
TL;DR: In this article, the enzyme nitrate reductase was found to be active in marine phytoplankton when growing on ammonium or when the nitrogen source was depleted.