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.
Malins, Donald C.; Stegeman, John J.; Anderson, Jack W.; Johnson, Paul M.; Gold, Jordan; Anderson, Katie M. (National Institute of Environmental Health Sciences, 2003-12-18)Structural differences were identified in gill DNA from two groups of English sole collected from Puget Sound, Washington, in October 2000. One group was from the industrialized Duwamish River (DR) in Seattle and the ...
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 ...
Tetrachlorobiphenyl metabolism, toxicity, and regulation of cytochrome P50 expression in a marine teleost fish White, Renee D. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1994-11)The effects of 3,3',4,4'-tetrachlorobiphenyl (TCB) were examined in the marine fish scup (Stenotomus chrysops), focusing on the interactions between TCB and the CYP 1 A 1 enzyme system. A low TCB dose (0.1 mg/kg) elicited ...