Nitrite, an electron donor for anoxygenic photosynthesis

We report a previously unknown process in which anoxygenic phototrophic bacteria use nitrite as an electron donor for photosynthesis. We isolated a purple sulfur bacterium 98% identical to Thiocapsa species that stoichiometrically oxidizes nitrite to nitrate in the light. Growth and nitrate production strictly depended on both light and nitrite. This is the first known microbial mechanism for the stoichiometric oxidation of nitrite to nitrate in the absence of oxygen and the only known photosynthetic oxidation in the nitrogen cycle. This work demonstrates nitrite as the highest-potential electron donor for anoxygenic photosynthesis known so far.     

Quantitative autoradiography of [3H]muscimol binding in rat brain

A simple quantitative autoradiographic technique for the study of neurotransmitter receptors that includes the use of a tritium-sensitive film permits saturation, kinetic, and competition studies of brain samples as small as 0.01 cubic millimeter. This technique was used to study [3H]muscimol binding in rat brain. Unilateral gamma-aminobutyric acid receptor supersensitivity was observed in the substantia nigra pars reticulata after production of localized lesions of the ipsilateral corpus striatum.     

Tracing the origin and fate of NOx in the Arctic atmosphere using stable isotopes in nitrate

Atmospheric nitrogen oxides (NOx =NO+ NO2) play a pivotal role in the cycling of reactive nitrogen (ultimately deposited as nitrate) and the oxidative capacity of the atmosphere. Combined measurements of nitrogen and oxygen stable isotope ratios of nitrate collected in the Arctic atmosphere were used to infer the origin and fate of NOx and nitrate on a seasonal basis. In spring, photochemically driven emissions of reactive nitrogen from the snowpack into the atmosphere make local oxidation of NOx by bromine oxide the major contributor to the nitrate budget. The comprehensive isotopic composition of nitrate provides strong constraints on the relative importance of the key atmospheric oxidants in the present atmosphere, with the potential for extension into the past using ice cores.     

Toxoplasma gondii in Switzerland: a serosurvey based on meat juice analysis of slaughtered pigs, wild boar, sheep and cattle

Toxoplasmosis is one of the most important zoonotic diseases worldwide and is caused by the protozoan Toxoplasma gondii. Besides vertical infection during pregnancy, humans can get infected post-natally either by peroral uptake of sporulated Toxoplasma oocysts or by ingestion of tissue cysts upon consumption of raw or undercooked meat. The aim of this study was to approximate the risk of human infection via meat consumption by estimating the seroprevalence of T. gondii in slaughtered animals in Switzerland and to compare data with prevalences assessed 10 years ago. The study included pigs, cattle, sheep and wild boar of different age groups and housing conditions whenever possible and applicable. A P-30-ELISA was used to detect T. gondii-specific antibodies and to determine seroprevalences in meat juice of slaughtered animals. A total of 270 domestic pigs (120 adults, 50 finishing, 100 free-ranging animals), 150 wild boars, 250 sheep (150 adults, 100 lambs) and 406 cattle (47 calves, 129 heifers, 100 bulls, 130 adult cows) were tested. Seropositivity increased with the age of the assessed animals. Independent of the age-group, the overall seroprevalence was lowest in wild boars (6.7%), followed by pigs (23.3%), cattle (45.6%) and sheep (61.6%), respectively. Conventional fattening pigs and free-ranging pigs surprisingly had comparable seroprevalences (14.0% and 13.0%, respectively). Unlike in other European countries, where generally a decrease in the number of seropositive animals had been observed, we found that the prevalence of seropositive animals, when compared with that of 10 years ago, had increased for most species/age groups. Conclusively, the results demonstrated a high seroprevalence of T. gondii in animals slaughtered for meat production and revealed that increasing age of the animals is a more important risk factor than housing conditions in Switzerland.