Isotopic signature of N(2)O produced by marine ammonia-oxidizing archaea

The ocean is an important global source of nitrous oxide (N(2)O), a greenhouse gas that contributes to stratospheric ozone destruction. Bacterial nitrification and denitrification are thought to be the primary sources of marine N(2)O, but the isotopic signatures of N(2)O produced by these processes are not consistent with the marine contribution to the global N(2)O budget. Based on enrichment cultures, we report that archaeal ammonia oxidation also produces N(2)O. Natural-abundance stable isotope measurements indicate that the produced N(2)O had bulk δ(15)N and δ(18)O values higher than observed for ammonia-oxidizing bacteria but similar to the δ(15)N and δ(18)O values attributed to the oceanic N(2)O source to the atmosphere. Our results suggest that ammonia-oxidizing archaea may be largely responsible for the oceanic N(2)O source.     

Presence of anti-platelet IgM and IgG antibodies in dogs naturally infected by Leishmania infantum

Thirty-three dogs, naturally infected by Leishmania infantum, were enrolled in the study and were classified as oligo-symptomatic (n. 15) and symptomatic or markedly symptomatic (n. 18). A control group was 10 healthy dogs. A haematological profile was obtained and the dogs serum was employed to assess the presence of platelet binding IgM and IgG antibodies (PBIgM, PBIgG) using flow cytometry. FITC labelled goat anti-dog IgM or IgG were used to detect PBIgM and PBIgG. Samples with a mean fluorescence intensity (MFI) that was 100 channels higher on a log scale for more than 30% of the platelets than seen in negative control platelets from a healthy dog were considered positive for the presence of anti-platelet antibodies (PBIg). Twenty-one (63.3%) dogs revealed the presence of PBIg. Six of them were oligo-symptomatic while 15 showed moderate or severe clinical signs of illness. All the dogs with PBIg showed the presence of PBIgM, with nine animals showing both PBIgM and PBIgG. Nine of 18 symptomatic or markedly symptomatic dogs showed thrombocytopenia, while normal platelet counts were observed in all oligo-symptomatic animals. Eight of 9 thrombocytopenic animals showed the presence of PBIgM, while six of them showed PBIgG. One thrombocytopenic dog was negative for PBIg. This study is the first report documenting the presence of PBIg in natural canine leishmaniasis implying a pathogenic association between thrombocytopenia and the presence of antibody against platelet membrane.     

Early exposure to probiotics in a canine model of atopic dermatitis has long-term clinical and immunological effects

Probiotics modulate the immune response and may have protective effects against atopic dermatitis (AD). Clinical trials using dogs with spontaneous disease are limited by confounding factors such as different diets, environments and sensitizations while a more controlled evaluation is possible using experimental models. A validated model of canine AD showed that early exposure to Lactobacillus rhamnosus GG (LGG) significantly decreases allergen-specific IgE and partially prevents AD in the first 6 months of life. This study is a follow-up three years after discontinuation of LGG. Clinical signs were evaluated after allergen challenge with ragweed, timothy, Dermatophagoides farinae. Allergen-specific IgE, IL-10 and TGF-β were measured on the 1st day of challenge, before allergen exposure. Normal dogs were included as controls. Analyses included seven dogs in the non-probiotic and nine in the probiotic litter. For clinical scores, a 2-Group × 9-Time Analysis of Variance showed significant effects of group (p=0.0003, probiotic相似文献