SUMMARY To study the mechanisms of branchial acid-base regulation, Pacific spiny dogfish were infused intravenously for 24 h with either HCl (495± 79μmol kg-1 h-1) or NaHCO3 (981±235μmol kg-1 h-1). Infusion of HCl produced a transient reduction in blood pH. Despite continued infusion of acid, pH returned to normal by 12 h. Infusion of NaHCO3 resulted in a new steady-state acid-base status at ∼0.3 pH units higher than the controls. Immunostained serial sections of gill revealed the presence of separate vacuolar proton ATPase (V-H+-ATPase)-rich or sodium-potassium ATPase(Na+/K+-ATPase)-rich cells in all fish examined. A minority of the cells also labeled positive for both transporters. Gill cell membranes prepared from NaHCO3-infused fish showed significant increases in both V-H+-ATPase abundance (300±81%) and activity. In addition, we found that V-H+-ATPase subcellular localization was mainly cytoplasmic in control and HCl-infused fish, while NaHCO3-infused fish demonstrated a distinctly basolateral staining pattern. Western analysis in gill membranes from HCl-infused fish also revealed increased abundance of Na+/H+ exchanger 2(213±5%) and Na+/K+-ATPase (315±88%)compared to the control.

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Several viruses can infect wild carnivores but their impact on wildlife health is poorly understood. We investigated the presence, diversity and distribution of various DNA viruses in 303 wolves inhabiting a vast area of the Northwest Territories, Canada, over a period of 13 years. We found evidence for the presence of canine bufavirus (CBuV, 42.6%), canine parvovirus 2 (CPV‐2, 34.0%), canine bocavirus 2 (CBoV‐2, 5.0%), cachavirus (CachaV‐1, 2.6%), canine adenovirus 1 (CAdV‐1, 1%) and minute virus of canines (MVC, 0.3%). To our knowledge, this is the first detection of CBoV‐2, MVC and CachV‐1 in wild animals. We also demonstrate that CBuV and CachaV‐1 were already circulating among wild animals at least 11 and 10 years, respectively, before their discoveries. Although CBuV prevalence was higher, CPV‐2 was the most prevalent virus among juveniles, while CBuV infection was associated with poor nutrition conditions. Even if its prevalence was low, CachaV‐1 had the highest multiple infection rate (87.5%). CadV‐1 and MVC sequences were highly identical to reference strains, but we observed a high diversity among the other viruses and detected three new variants. One CPV‐2 variant and one CBuV variant were endemic since the beginning of the 2000s in the entire investigated region, whereas one CBuV variant and two CBoV‐2 variants were found in a more restricted area over multiple years and CachaV‐1 was found only in one region. Two CPV‐2 variants and one CachaV‐1 variant were observed only once, indicating sporadic introductions or limited circulation. Different patterns of endemicity might indicate that viruses were introduced in the wolf population at different timepoints and that mixing between wolf packs may not be constant. Different epidemiological behaviors depend on viral factors like infectivity, transmission routes, pathogenicity and tissue‐tropism, and on host factors like proximity to densely populated areas, carnivory and pack density and mixing.