Nasopharyngeal cryptococcosis

Naturally occurring cryptococcosis in five cats, a dog and a koala is described. Involvement of the nasopharynx was documented in all patients, and nasopharyngeal mass lesions accounted for the major presenting complaints in four. Signs referable to nasopharyngeal disease included snoring, stertor, inspiratory dyspnoea and aerophagia. Diagnoses were made by caudal rhinoscopy using a retroverted flexible endoscope, vigorous orthograde flushing with saline, or at necropsy. Concurrent cryptococcal rhinitis was present in all cases, although involvement appeared limited to the caudal nasal cavity in most cases. Typical signs of nasal cavity disease, such as sneezing and nasal discharge, were often absent. Treatment of nasopharyngeal cryptococcosis should include physical dislodgement or debulking of lesion(s) to provide immediate alleviation of upper airway obstruction, followed by systemic antifungal therapy to eliminate residual infection from the nasal cavity. Infections caused by Cryptococcus neoformans var gattii accounted for a disproportionately large number of these cases.     

The genomic sequence of the bovine T cell receptor gamma TRG loci and localization of the TRGC5 cassette

The bovine and ovine TRG genes have previously been shown to be located in two loci, TRG1 and TRG2, in contrast to human and mouse TRG genes that are located in a single locus. The bovine TRG1 and TRG2 loci are located on chromosome 4 at 4q3.1 and 4q1.5-2.2, respectively. The complete genomic organization of the two bovine loci is described: each locus comprises three cassettes, each one includes one or several variable genes (TRGV) and one or several joining genes (TRGJ) preceding a constant (TRGC) gene. The location of the TRGC5 cassette is conclusively described in 5' of the TRG1 locus. Analysis of 17 TRGV belonging to 10 different subgroups, 8 TRGJ and 6 TRGC genes is conducted which comprises the most comprehensive list to date.     

Spatial Assessment of Land Degradation Risk for the Okavango River Catchment,Southern Africa

The Okavango catchment in southern Africa is subject to environmental as well as socio‐economic transformation processes such as population growth and climate change. The degradation of soil and vegetation by deforestation and overgrazing is one of the downsides of this development, reducing the capacity of the land to provide ecosystem functions and services. In this study, climate simulations are brought together with secondary socioeconomic, pedologic and remote‐sensing data in a GIS‐based assessment of the factors commonly associated with land degradation risk. A high resolution overview is provided for decision‐makers and stakeholders in the region by identifying priority intervention areas where a long‐term decline in ecosystem function and land productivity is most likely to occur. The approach combines 19 risk factors into seven individual ratings for topography, landcover, soil, demography, infrastructure, livestock pressure and climate. These ratings are then weighted and combined into an integrated degradation risk index (DRI). The results show that the land degradation risk is quite heterogeneously distributed in the study area and caused by different factors. Three hot‐spots are identified and compared, one of which is in the far northwestern part of the catchment, one around the local center Rundu and one on the outskirts of the Okavango Delta. We conclude that the approach is suitable to give an overview on degradation risk in the study area, although the classification process is a crucial procedure that should be standardized for further research. Copyright © 2015 John Wiley & Sons, Ltd.     

水稻土中铁氧化物的厌氧还原及其对微生物过程的影响

采用厌氧泥浆恒温培养实验 ,测定了添加 6种外源氧化铁后土壤中Fe(Ⅱ )和Fe(Ⅲ )浓度的变化 ,探讨了不同氧化铁的还原能力及其对土壤产H2 、产CO2 、产乙酸和产CH4 过程的影响。结果表明 :无定形氧化铁和纤铁矿易于被还原 ,两者的最终还原程度大体相同 ,但无定形氧化铁存在还原滞后现象 ;针铁矿、赤铁矿、Al取代针铁矿和Al取代赤铁矿难以被还原 ,表现出与对照相同的还原特征 ;铁还原能导致土壤中H2 和乙酸稳态浓度的降低 ,有效抑制了甲烷产生 ;添加Fe(OH) 3和纤铁矿后 ,Fe(Ⅲ )还原占总电子传递的贡献率由对照的 1 8.3 0 %增至 63 .3 2 %和 46.90 % ,而形成甲烷的电子传递贡献率由对照的 80 .92 %降至 3 5 .85 %和 5 2 .3 2 % ,Fe(Ⅲ )还原对电子的竞争消耗 ,使土壤产甲烷过程被强烈抑制     

Decomposition of atmospheric hydrogen by soil microorganisms and soil enzymes

The decomposition of atmospheric hydrogen in different types of soil was measured. The decomposition of H₂ was apparently a first-order reaction. H₂ decomposition activity was proportional to the amount of soil with maximum activities at soil water contents of approx. 6–11% (w/w). The activity was lower under anaerobic conditions, but was constant between 1–20% O₂. It was destroyed by autoclaving and was partially inactivated by fumigation with NH₃, CHC1₃ or acetone, by u.v. irradiation and by treatment with NaCN or NaN₃, indicating that biological processes in the soil were responsible for the observed H₂ decomposition. Treatment of soil with toluene or CHCl₃ caused only a partial inactivation. Incubation of soil in the presence of streptomycin or actidione reduced H₂ decomposition by less than 50%, whereas CO consumption was abolished. The H₂ decomposition rates showed H₂ saturation curves with apparent Michaelis-Menten kinetics. Cooperative effects were not observed. V_max was reached at approx. 200 μl1^?1. The K_m values for H₂ were in the range of 30μl 1^?1, but increased to higher values, when the soil had been pretreated with high H₂ mixing ratios. Apparently, the observed H₂ decomposition by soil is not only due to the activity of viable microorganisms, but soil enzymes as well.     

Influence of thiosulfate on nitrification,denitrification, and production of nitric oxide and nitrous oxide in soil

Thiosulfate and CS₂ inhibit nitrification. The effect of the addition of thiosulfate on the turnover of inorganic N compounds was tested in an Egyptian and a German arable soil under nitrifying and denitrifying conditions. For nitrification, the soils were amended with NH _inf4 ^sup+ and incubated under aerobic conditions. For denitrification, the soils were amended with NO _inf3 ^sup- and incubated under anaerobic conditions. In both cases, the thiosulfate decreased with time while tetrathionate accumulated to an intermediate extent. Both compounds disappeared completely after <25 days. Production of CS₂ was not observed. Carbonyl sulfide was produced only in the Egyptian soil, but production decreased with increasing amounts of added thiosulfate. Under nitrifying conditions, the addition of increasing amounts of thiosulfate (25, 50, and 100 g S g^-1 dry weight) resulted in decreasing rates of NH _inf4 ^sup+ oxidation to NO _inf3 ^sup- ; it also resulted in an increasing intermediate accumulation of NO _inf2 ^sup- and NO, and in an increasing production of N₂O. Under denitrifying conditions, the addition of increasing amounts of thiosulfate did not significantly affect the rate of NO _inf3 ^sup- reduction, and resulted in an increasing intermediate accumulation of NO _inf2 ^sup- and of NO only in the German soil in which the production of N₂O was slightly inhibited by thiosulfate. These results demonstrate that the nitrification of NH _inf4 ^sup+ and NO _inf2 ^sup- was inhibited by increasing concentrations of thiosulfate and/or tetrathionate without involving the formation of volatile S compounds as potential nitrification inhibitors. Denitrification was not affected by the addition of thiosulfate.     

Competition for electron donors among nitrate reducers,ferric iron reducers,sulfate reducers,and methanogens in anoxic paddy soil

Slurries of anoxic paddy soil were either freshly prepared or were partially depleted in endogenous electron donors by prolonged incubation under anaerobic conditions. Endogenous NO ₃ ^– was reduced within 4 h, followed by reduction of Fe³⁺ and SO ₄ ^2– , and later by production of CH₄. Addition of NO ₃ ^– slightly inhibited the production of Fe²⁺ in the depleted but not in the fresh paddy soil. Inhibition was overcome by the addition of H₂, acetate, or a mixture of fatty acids (and other compounds), indicating that these compounds served as electron donors for the bacteria reducing NO ₃ ^– and/or ferric iron. Addition on NO ₃ ^– also inhibited the reduction of SO ₄ ^2– in the depleted paddy soil. This inhibition was only overcome by H₂, but not by acetate or a mixture of compounds, indicating that H₂ was the predominant electron donor for the bacteria involved in NO ₃ ^– and/or SO ₄ ^2– reduction. SO ₄ ^2– reduction was also inhibited by exogenous Fe³⁺, but only in the depleted paddy soil. This inhibition was overcome by either H₂, acetate, or a mixture of compounds, suggesting that they served as electron donors for reduction of Fe³⁺ and/or SO ₄ ²⁺ . CH₄ production was inhibited by NO ₃ ^– both in depleted and in fresh paddy soil. Fe³⁺ and SO ₄ ^2– also inhibited methanogenesis, but the inhibition was stronger in the depleted than in the fresh paddy soil. Inhibition of CH₄ production was paralleled by a decrease in the steady state concentration of H₂ to a level which provided a free enthalpy of less than G=–17 kJ mol^-1 CH₄ compared to more than G=–32 kJ mol^-1 CH₄ in the control. The results indicate that in the presence of exogenous fe³⁺ or SO ₄ ²⁺ , methanogenic bacteria were outcompeted for H₂ by bacteria reducing Fe³⁺ or SO ₄ ²⁺ .Deceased on 27 December 1992