Studies of nitrate transport by marine phytoplankton using TWCl-ClO3 as a transport analogue. I. Physiological findings. [Skeletonema costatum; Nitzschia closterium]
Transport of a nitrate analogue, TWCl-ClO3 , was examined in two diatoms, Skeletonema costatum (Greve.) Cleve and Nitzschia closterium (Ehrenb) W. Sm. A dinoflagellate, Gonyaulax polyedra did not transport ClO3 . Transport of TWCl-ClO3 by diatoms appeared to be active and showed saturation kinetics. The data were fitted by Michaelis-Menten equation at all but the lowest chlorate concentrations (where plots of S vs. v showed a slight concave bend). Affinity of cells for nitrate was considerably higher than for chlorate. The K/sub i/ for nitrate inhibition of chlorate transport was calculated assuming competitive inhibition. Light had little or no effect on chlorate transport. Pulse-chase experiments demonstrated that (1) ClO3 (hence NO3 ) was stored in two intracellular compartments of equal size, (2) internal ClO3 was exchangeable with external ClO3 (rates of efflux and influx were measured), and (3) efflux of intracellular ClO3 showed transient states following a chase of ClO3 or NO3 which stabilized after 10-20 min. Transport of chlorate was a function of growth phase.
- Research Organization:
- Scripps Institution of Oceanography, La Jolla, CA
- OSTI ID:
- 6284388
- Journal Information:
- J. Phycol.; (United States), Journal Name: J. Phycol.; (United States) Vol. 23:1; ISSN JPYLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALGAE
BIOLOGICAL MODELS
CHLORINE 35
CHLORINE ISOTOPES
DIATOMS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
NITRATES
NITROGEN COMPOUNDS
NUCLEI
NUTRIENTS
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
PHYSIOLOGY
PLANTS
STABLE ISOTOPES
TRACER TECHNIQUES
TRANSLOCATION