What are the toxicological effects of mercury in Arctic biota?

This review critically evaluates the available mercury (Hg) data in Arctic marine biota and the Inuit population against toxicity threshold values. In particular marine top predators exhibit concentrations of mercury in their tissues and organs that are believed to exceed thresholds for biological effects. Species whose concentrations exceed threshold values include the polar bears (Ursus maritimus), beluga whale (Delphinapterus leucas), pilot whale (Globicephala melas), hooded seal (Cystophora cristata), a few seabird species, and landlocked Arctic char (Salvelinus alpinus). Toothed whales appear to be one of the most vulnerable groups, with high concentrations of mercury recorded in brain tissue with associated signs of neurochemical effects. Evidence of increasing concentrations in mercury in some biota in Arctic Canada and Greenland is therefore a concern with respect to ecosystem health

Effects of Chainring Type (Circular vs. Rotor Q-Ring) on 1km Time Trial Performance Over Six Weeks in Competitive Cyclists and Triathletes

The purpose of this study was to examine the effects of chainring type (circular vs. the non- circular Rotor Q-Ring) on performance during a 1km time trial and physiological responses over a six week period. Eight competitive male cyclists and triathletes were pre-tested using the original circular chainring. Graded submaximal exercise tests were followed by the 1km time trial with subjects using their own racing bicycle. The circular chainrings were then removed and replaced with Rotor Q-Rings during the intervention period. Subjects trained and raced with this alteration to their bicycles and repeated the submaximal and 1km performance tests for the next four weeks. Post-testing occurred with the original circular chainrings for the final week of testing. Oxygen consumption, carbon dioxide output, heart rate, ventilation, respiratory exchange ratio, and perceived exertion were continuously measured during the submaximal tests. Blood lactate concentration was measured during the last 30 s of each three minute stage. The main findings were: 1) Significant increases in performance in the 1km time trial with Rotor Q-Rings compared to circular chainrings. Subjects completed the time trial on average 1.6 seconds faster (p \u3c 0.05), increased average speed approximately 0.7 kph (p \u3c 0.05), and increased average power approximately 26 watts (p \u3c 0.05). 2) During submaximal testing, oxygen consumption during weeks 2-4 and heart rate during weeks 1-3 were significantly lower (p \u3c 0.05) with Rotor Q-Rings compared to circular chainrings. Furthermore, 1km time trial improvements occurred after just one week employing the Rotor Q-Rings and results were consistent over subsequent 1km time trials with the Rotor Q-Rings. Performance levels returned to initial values during final testing with the circular chainrings. The maximal oxygen consumption results from the Pre-test and week 5 Post-test further demonstrated that positive performance effects were only evident with the Rotor Q- Rings. While it appears from this study that there may also be positive long term effects as noted by the significant reduction in submaximal oxygen consumption and heart rate during the intervention period (i.e., cycling with Rotor Q-Rings), the majority of the physiological measures we examined do not equivocally support the notion that an adaptation period is necessary for this increased 1km time trial performance

Use of western immunoblot analysis for testing moose serum for Brucella suis biovar 4 specific antibodies

To determine if 12 moose (Alces alces) from northern Alaska with agglutinating antibodies specific for Brucella spp. had been exposed to either B. suis biovar 4 or B. abortus biovar 1, western immunoblot serologic analysis was performed. Differential serologic responses to strain specific A and M antigenic variances of the lipopolysaccharide O-polysaccharide sugar allowed strain identification. Prior to examination, test sera were absorbed with killed whole cells from either B. abortus biovar 1, containing predominately A antigen (A+ M-); B. melitensis biovar 1, containing essentially M antigen (A-M+); or B. suis biovar 4, containing both antigenic types (A+ M+). The resulting sera were then examined by western immunoblot for recognition of either B. abortus biovar 1, B. melitensis biovar 1, or B. suis biovar 4 cell lysates. The results of this study indicate that these moose were exposed to B. suis biovar 4, a known pathogen of caribou (Rangifer taranHIIS) from arctic Alaska

\u3ci\u3eBrucella\u3c/i\u3e Species Survey in Polar Bears (\u3ci\u3eUrsus maritimus\u3c/i\u3e) of Northern Alaska

We report on the presence of specific antibodies to Brucella spp. and Yersinia enterocolitica in polar bears (Ursus maritimus) from northern Alaska (southern Beaufort Sea) during 2003–2006. Based on numerous known stressors (e.g., climate change and loss of sea ice habitat, contaminants), there is increased concern regarding the status of polar bears. Considering these changes, it is important to assess exposure to potentially pathogenic organisms and to improve understanding of transmission pathways. Brucella or specific antibodies to Brucella spp. has been reported in marine mammals. Various assays were used to elucidate the pathway or source of exposure (e.g., “marine” vs. “terrestrial” Brucella spp.) of northern Alaska polar bears to Brucella spp. The standard plate test (SPT) and the buffered Brucella antigen card test (BBA) were used for initial screening for antibodies specific to Brucella. We then evaluated positive reactors (presence of serum antibody specific for Brucella spp.) using immunoblots and competitive enzyme-linked immunosorbent assay (cELISA; based on pinniped-derived Brucella spp. antigen). Annual prevalence of antibody (BBA and SPT) for Brucella spp. ranged from 6.8% to 18.5% over 2003–2006, with an overall prevalence of 10.2%. Prevalence of Brucella spp. antibody did vary by age class. Western blot analyses indicated 17 samples were positive for Brucella spp. antibody; of these, 13 were negative by marine (pinniped) derived Brucella antigen cELISA and four were positive by marine cELISA. Of the four samples positive for Brucella antibody by marine cELISA, three cross-reacted with Y. enterocolitica and Brucella spp. (one sample was Brucella negative and Y. enterocolitica positive). It appears the polar bear antibody does not react with the antigens used on the marine cELISA assay, potentially indicating a terrestrial (nonpinniped) source of Brucella spp

Brucella species survey in polar bears (ursus maritimus) of northern Alaska

We report on the presence of specific antibodies to Brucella spp. and Yersinia enterocolitica in polar bears (Ursus maritimus) from northern Alaska (southern Beaufort Sea) during 2003-2006. Based on numerous known stressors (e.g., climate change and loss of sea ice habitat, contaminants), there is increased concern regarding the status of polar bears. Considering these changes, it is important to assess exposure to potentially pathogenic organisms and to improve understanding of transmission pathways. Brucella or specific antibodies to Brucella spp. has been reported in marine mammals. Various assays were used to elucidate the pathway or source of exposure (e.g., marine vs. terrestrial Brucella spp.) of northern Alaska polar bears to Brucella spp. The standard plate test (SPT) and the buffered Brucella antigen card test (BBA) were used for initial screening for antibodies specific to Brucella. We then evaluated positive reactors (presence of serum antibody specific for Brucella spp.) using immunoblots and competitive enzyme-linked immunosorbent assay (cELISA; based on pinniped-derived Brucella spp. antigen). Annual prevalence of antibody (BBA and SPT) for Brucella spp. ranged from 6.8% to 18.5% over 2003-2006, with an overall prevalence of 10.2%. Prevalence of Brucella spp. antibody did vary by age class. Western blot analyses indicated 17 samples were positive for Brucella- spp. antibody; of these, 13 were negative by marine (pinniped) derived Brucella antigen cELISA and four were positive by marine cELISA. Of the four samples positive for Brucella antibody by marine cELISA, three cross-reacted with Y. enterocolitica and Brucella spp. (one sample was Brucella, negative and Y. enterocolitica positive). It appears the polar bear antibody does not react with the antigens used on the marine cELISA assay, potentially indicating a terrestrial (nonpinniped) source of Brucella spp. © Wildlife Disease Association 2010

Spatial trends and bioaccumulation of organochlorine pollutants in marine zooplankton from the Alaskan and Canadian Arctic

Planktonic copepods (Calanus glacialis and C. hyperboreus; n = 37) and water (n = 19) were collected to examine the spatial distribution and bioaccumulation of organochlorine contaminants (OCs) in the Alaskan and Canadian Arctic. The rank order of total OC (∑ OC) group concentrations in Calanus samples was toxaphene ≥ ∑ polychlorinated biphenyls (PCBs) \u3e ∑ hexachlorcyclohexane (HCH) \u3e ∑ DDT \u3e ∑ chlordane-related compounds (CHLOR) \u3e ∑ chlorobenzenes (ClBz). The dominant analyte was α-HCH in all water and zooplankton samples. The most abundant toxaphene congener in water and zooplankton samples was the hexachlorobornane B6-923. Organochlorine contaminant group concentrations in Alaskan zooplankton and water samples were lower than those in samples collected from sites in the eastern Canadian Arctic. Comparison of PCB and toxaphene congener profiles in zooplankton and water samples suggests that biotransformation by cytochrome P-4502B isozymes is low in Calanus, and limited phase I metabolism may occur. The log relationship of bioaccumulation factor (log BAF) versus octanol-water partition coefficient (log KOW) relationship was near 1:1 for OCs within the log KOW range of 3 to 6. A curvilinear model provided a better relationship between these two variables when OC compounds with log KOW \u3e 6 were included. These results suggest that hydrophobic OCs (log KOW 3-6) in Calanus species are at equilibrium with the water concentrations and that physical partitioning, rather than biotransformation, is the major factor governing OC profiles in marine zooplankton