Contaminant biotransport by Pacific salmon to Lake Michigan tributaries

The Great Lakes are ideal systems for evaluating the synergistic components of environmental change, such as exotic species introductions and legacy pollutants. Introduced Pacific Salmon (Oncorhynchus spp.) represent an intersection of these drivers because they are non-native species of economic importance that bioaccumulate contaminants during the open water phase of their life cycle. Furthermore, Pacific salmon can deliver a significant pulse of contaminated tissue to tributaries during spawning and subsequent death. Thus, salmon represent a key pathway by which contaminants accumulated in Lake Michigan are transported inland to tributaries that otherwise lack point source pollution. Our research has revealed that salmon exhibit basin-specific persistent organic pollutant (POP) and mercury (Hg) concentrations reflecting pollutant inputs from both current and historic sources. Overall, Lake Michigan salmon were more contaminated with POPs and Hg than conspecifics from Lakes Huron or Superior. Consequently, Lake Michigan salmon pose a higher risk and magnitude of contaminant biotransport and transfer. Resident stream fish (e.g., brook trout) sampled from salmon spawning reaches had higher pollutant concentrations than fish sampled from upstream reaches lacking salmon, but the extent of fish contamination varied among lake basins and streams. In general, Lake Michigan tributaries were the most impacted, suggesting a direct relationship between the extent of salmon-derived contaminant inputs and resident fish contaminant levels. Within and among lake basins, contaminant biotransport by salmon is context dependent and likely reflects a suite of ecological characteristics such as species identity and trophic position, dynamics of the salmon run, watershed land-use, and instream geomorphology such as sediment size. We suggest that future management of salmon-mediated contaminant biotransport to stream communities in the Great Lakes basin should consider biological, chemical, and physical factors that constitute the environmental context

Contaminant biotransport by Pacific Salmon in Lake Michigan: analysis of salmon and stream-resident fish in Great Lakes tributaries

Pacific salmon (Oncorhynchus spp.) can deliver a significant pulse of biomass, including its bioaccumulated contaminants, to tributaries during spawning runs. Thus, salmon transport contaminants accumulated in the Great Lakes (e.g., persistent organic pollutants [POPs], total mercury [THg]) to tributaries that otherwise lack point source pollution. We used a combination of observational surveys, experimental manipulations, and modeling, to (1) assess the extent of salmon-mediated biotransport across the upper Great Lakes; (2) determine pathways by which stream fish become contaminated by salmon; and (3) forecast areas at significant risk from salmon biotransport. Resident stream fish (e.g., brook trout Salvelinus fontinalis) in salmon spawning reaches had higher POP concentrations than fish in upstream reaches lacking salmon, but the extent of contamination varied among lake basins and streams. In contrast, THg concentrations in the same fish did not differ between reaches with and without salmon spawners but exhibited considerable among-site variability. In general, resident fish in Lake Michigan tributaries were the most contaminated by POPs, suggesting a direct relationship between salmon-derived contaminant inputs and resident fish contaminant levels. Experimental exposure to salmon carcasses and eggs for 50 days increased brook trout POP concentrations by 50 times. Eggs are elevated in POPs but depleted in THg compared to whole salmon, suggesting that resident fish contaminant levels reflect direct consumption of eggs rather than indirect food web pathways. Our model suggests that salmon-mediated bioaccumulation is primarily influenced by the size and duration of salmon runs, and secondarily by factors including individual consumption rates, temperature regime, and background pollutant levels. Overall, our research provides increased understanding on the physical, chemical, and biological controls of salmon contaminant biotransport in the Great Lakes region. This research will help inform management decisions in this region with respect to legacy pollution, dam removal, stream connectivity, fish stocking, and non-native species in stream ecosystems

Environmental context and contaminant biotransport by Pacific salmon interact to mediate the bioaccumulation of contaminants by stream-resident fish

1. The extent to which environmental context mediates the uptake of biotransported contaminants by stream-resident organisms is not understood. For example, there is no clear understanding of the extent to which contaminant type, instream characteristics, or resident fish identity interact to influence the uptake of contaminants deposited by Pacific salmon (Oncorhynchus spp.) during their spawning runs. 2. To address this uncertainty, we sampled four stream-resident fish species from 13 watersheds of the Laurentian Great Lakes in locations with and without salmon across a gradient of instream and watershed characteristics. We determined the polychlorinated biphenyl (PCB) and mercury (Hg) concentration along with the stable isotope ratio of C and N for each stream-resident fish. 3. We found that stream-resident fish PCB concentrations were 24-fold higher in reaches with salmon and were positively related to δ15N. In contrast, stream-resident fish Hg concentrations were similar or lower in reaches with salmon and either exhibited a negative or no relationship with δ15N. 4. Based upon AICc, stream-resident fish exhibited species-specific PCB concentrations that were positively related to salmon PCB flux. Hg burdens exhibited an interaction between fish length and salmon Hg flux – as salmon Hg inputs increased, Hg levels decreased with increasing resident fish length. We found no support for models that included the mediating influence of instream or watershed factors. Salmon eggs are enriched in PCBs but have very low Hg concentrations, so our results may be driven by the consumption of salmon eggs by stream-resident fish. 5. Synthesis and applications. Our results highlight that contaminants bioaccumulate differently depending on contaminant type, species identity, and the trophic pathway to contamination. Consequently, consideration of the recipient food web and route of exposure is critical to understanding the fate of biotransported contaminants in ecosystems. The transfer of contaminants by migratory organisms represents an understudied stressor in ecology. Effective management of biotransported contaminants will require the delineation of “hot-spots” of biotransport and implementation of best management practices in those watersheds that receive contaminants from spawning salmon

Effect of nitric oxide on mitochondrial activity of human synovial cells

<p>Abstract</p> <p>Background</p> <p>Nitric oxide (NO) is a messenger implicated in the destruction and inflammation of joint tissues. Cartilage and synovial membrane from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) have high levels of NO. NO is known to modulate various cellular pathways and, thus, inhibit the activity of the mitochondrial respiratory chain (MRC) of chondrocytes and induce the generation of reactive oxygen species (ROS) and cell death in multiple cell types. For these reasons, and because of the importance of the synovial membrane in development of OA pathology, we investigated the effects of NO on survival, mitochondrial function, and activity of fibroblastic human OA synovial cells.</p> <p>Methods</p> <p>Human OA synovia were obtained from eight patients undergoing hip joint replacement. Sodium nitroprusside (SNP) was used as a NO donor compound and cell viability was evaluated by MTT assays. Mitochondrial function was evaluated by analyzing the mitochondrial membrane potential (Δψm) with flow cytometry using the fluorofore DePsipher. ATP levels were measured by luminescence assays, and the activities of the respiratory chain complexes (complex I: NADH CoQ₁reductase, complex II: succinate dehydrogenase, complex III: ubiquinol-cytochrome c reductase, complex IV: cytochrome c oxidase) and citrate synthase (CS) were measured by enzymatic assay. Protein expression analyses were performed by western blot.</p> <p>Results</p> <p>SNP at a concentration of 0.5 mM induced cell death, shown by the MTT method at different time points. The percentages of viable cells at 24, 48 and 72 hours were 86.11 ± 4.9%, 74.31 ± 3.35%, and 43.88 ± 1.43%, respectively, compared to the basal level of 100% (*<it>p </it>< 0.05). SNP at 0.5 mM induced depolarization of the mitochondrial membrane at 12 hours with a decrease in the ratio of polarized cells (basal = 2.48 ± 0.28; SNP 0.5 mM = 1.57 ± 0.11; *<it>p </it>< 0.01). The time course analyses of treatment with SNP at 0.5 mM demonstrated that treatment reliably and significantly reduced intracellular ATP production (68.34 ± 14.3% vs. basal = 100% at 6 hours; *<it>p </it>< 0.05). The analysis of the MRC at 48 hours showed that SNP at 0.5 mM increased the activity of complexes I (basal = 36.47 ± 3.92 mol/min/mg protein, SNP 0.5 mM = 58.08 ± 6.46 mol/min/mg protein; *<it>p </it>< 0.05) and III (basal = 63.87 ± 6.93 mol/min/mg protein, SNP 0.5 mM = 109.15 ± 30.37 mol/min/mg protein; *<it>p </it>< 0.05) but reduced CS activity (basal = 105.06 ± 10.72 mol/min/mg protein, SNP at 0.5 mM = 66.88 ± 6.08 mol/min/mg protein.; *<it>p </it>< 0.05), indicating a decrease in mitochondrial mass. Finally, SNP regulated the expression of proteins related to the cellular cycle; the NO donor decreased bcl-2, mcl-1 and procaspase-3 protein expression.</p> <p>Conclusions</p> <p>This study suggests that NO reduces the survival of OA synoviocytes by regulating mitochondrial functionality, as well as the proteins controlling the cell cycle.</p

Hanford Works Report HW-36734

The absorption of the important fission products by plants is quantitatively presented as a concentration factor which is defined as the ratio of the fission product concentration found in the leaves to the fission product concentration found in the nutrient substrate. Of the fission products, the isotopes of strontium were found to be the most important by virtue of their high concentration factor, long half-life, and low maximum permissible amounts for animals. Iodine and barium follow in importance, with cesium moderately important in some soils. All other fission products have concentration factors less than strontium by 100 or more. The effect on the concentration factor of different agricultural plants, as well as different organs of the same plant, causes variations of about a factor of ten or less for each isotope. The concentration factor tends to increase as the pH of the nutrient substrate is decreased. Addition of stable carrier to the substrate does not decrease the amount of the radioactive isotope that is absorbed into the plant. The presence of iodine and yttrium carrier actually causes a significant increase in the concentration of the respective radioactive isotopes in the plant tissue