Comprehensive and quantitative assessment of nitrate dynamics in two contrasting forested basins along the Sea of Japan using dual isotopes of nitrate.

The recent deposition rates of atmospheric nitrate derived from east Asia to the Japanese forested watershed facing the Sea of Japan are of serious concern. However, export ratios and the seasonality of atmospheric nitrate versus microbial nitrate from forest soils to upstreams have not yet been quantified. Furthermore, the influence of local nitrogen sources and internal biogeochemical processes are still unclear. To determine the influence of watershed properties and atmospheric nitrogen deposition on nitrate dynamics in two adjacent basins (the Kita and Minami Rivers) located in central Japan, we conducted seasonal synoptic surveys using the dual isotopes of nitrate. It was found that nitrate regenerated through nitrification in the forest soil was likely the dominant nitrogen source in both basins from the upstream to downstream waters. However, nitrate concentrations and the direct leaching ratio of atmospheric nitrate were considerably higher in the Kita River Basin than in the Minami River Basin, possibly due to the difference in forest environments. In the Kita River Basin, geographic trait such as altitude may be one factor regulating the sensitivity of forest ecosystem to nitrogen deposition. Quantitative assessments of nitrate outflows from the sub-basins revealed that nitrogen leached from the forest soil was a major source (61-81%) of nitrate loading to the coastal sea.

Zoonotic sporotrichosis. Transmission to humans by infected domestic cat scratching: report of four cases in São Paulo, Brazil.

BACKGROUND: Sporotrichosis is a chronic, granulomatous, deep mycosis caused by the dimorphic fungus Sporothrix schenckii that usually results in indolent cutaneous lesions. OBJECTIVE: To describe four cases of human sporotrichosis transmitted by domestic cats in south-eastern Brazil. METHODS: Confirmation of the diagnosis was performed by histopathology, culture, and/or inoculation of hamsters. RESULTS: In all cases, the clinical findings in both cat and human groups were highly distinctive of the disease. In all human cases, there was a previous history of cat scratching before the development of lymphocutaneous lesions. Histopathology of the human lesions demonstrated the classical granulomatous and exudative pattern with scarce or absent fungal elements. Conversely, in cats, the cutaneous lesions were multiple, extensive, necrotic, exudative, and ulcerated. Histopathology revealed a widespread histiocytic reaction with a large number of fungal organisms. Disseminated lymphatic and visceral mycotic infection was observed in two necropsied cats. CONCLUSIONS: Domestic cats may be an important carrier of agents of sporotrichosis to humans.