Importance of passive diffusion in the uptake of polychlorinated biphenyls by phagotrophic protozoa
Kujawinski, Elizabeth B.
Farrington, John W.
Moffett, James W.
MetadataShow full item record
Unicellular protozoan grazers represent a size class of organisms where a transition in the mechanism of chlorobiphenyl (CB) introduction, from diffusion through surface membranes to ingestion of contaminated prey, could occur. This study compares the relative importance of these two processes in the overall uptake of polychlorinated biphenyls by protists. Uptake rates and steady-state concentrations were compared in laboratory cultures of grazing and nongrazing protozoa. These experiments were conducted with a 10-µm marine scuticociliate (Uronema sp.), bacterial prey (Halomonas halodurans), and a suite of 21 CB congeners spanning a range of aqueous solubilities. The dominant pathway of CB uptake by both grazing and nongrazing protozoa was diffusion. Organic-carbon-normalized CB concentrations (in the protozoan cell) were equivalent in grazing and nongrazing protozoa for all congeners studied. Rate constants for uptake into and loss from the protozoan cell were independently determined by using [3,3',4,4'-14C]tetrachlorobiphenyl (IUPAC no. 77), 0.38 ± 0.03 min-1 and (1.1 ± 0.1) × 10-5 (g of organic carbon)-1 min-1, respectively. Magnitudes of the uptake and loss processes were calculated and compared by using a numerical model. The model result was consistent with data from the bioaccumulation experiment and supported the hypothesis that diffusive uptake is faster than ingestive uptake in phagotrophic unicellular protozoa.
Author Posting. © American Society for Microbiology, 2000. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Applied and Environmental Microbiology 66 (2000): 1987-1993, doi:10.1128/AEM.66.5.1987-1993.2000.
Showing items related by title, author, creator and subject.
Involvement of Cytochrome P450 1A in the toxicity of aryl hydrocarbon receptor agonists : alteration arachidonic acid metabolism and production of reactive oxygen species Schlezinger, Jennifer J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1998-08)Two cytochrome P4501A-dependent mechanisms of aryl hydrocarbon receptor (AhR) agonist toxicity were examined in the marine teleost scup (Stenotomus chrysops), alteration of arachidonic acid (AA) metabolism and production ...
The effect of protozoan grazers on the cycling of polychlorinated biphenyls (PCBs) in marine systems Kujawinski, Elizabeth B. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2000-02)Processes affecting organic carbon distribution and composition can control the speciation of organic contaminants such as polychlorinated biphenyls (PCBs) and ultimately determine their residence time in a particular ...
Brownawell, Bruce J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1986-04)Polychlorinated biphenyls (PCBs) were used as model hydrophobic organic compounds (HOC) to study physical~chemical processes which affect the speciation and fate of HOC in coastal environments. The focus of this study ...