308 research outputs found

    Long-term P weathering and recent N deposition control contemporary plant-soil C, N, and P

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    Models are needed to understand how plant-soil nutrient stores and fluxes have responded to the last two centuries of widespread anthropogenic nutrient pollution and predict future change. These models need to integrate across carbon, nitrogen, and phosphorus (C, N, and P) cycles and simulate changes over suitable timescales using available driving data. It is also vital that they are constrainable against observed data to provide confidence in their outputs. To date, no models address all of these requirements. To meet this need, a new model, N14CP, is introduced, which is initially applied to Northern Hemisphere temperate and boreal ecosystems over the Holocene. N14CP is parameterized and tested using 88 northern Europe plot-scale studies, providing the most robust test of such a model to date. The model simulates long-term P weathering, based on the assumption of a starting pool of weatherable P (Pweath0, g m−2), which is gradually transformed into organic and sorbed pools. Nitrogen fixation (and consequently primary production) is made dependent on available P. In the absence of knowledge about the spatial variability of Pweath0, N14CP produces good average soil and plant variables but cannot simulate variations among sites. Allowing Pweath0 to vary between sites improves soil C, N, and P results greatly, suggesting that contemporary soil C, N, and P are sensitive to long-term P weathering. Most sites were found to be N limited. Anthropogenic N deposition since 1800 was calculated to have increased plant biomass substantially, in agreement with observations and consequently increased soil carbon pools

    Soil organic carbon and associated soil properties in Enset (Ensete ventricosum Welw. Cheesman)-based homegardens in Ethiopia

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    Enset (Ensete ventricosum Welw. Cheesman)-based homegardens have long been practiced as central elements of agricultural land management and food security in south and southwest Ethiopia. In contrast to the homegardens’ biodiversity and role in food security, soil quality has received little attention. Objective of this study was to assess soil quality parameters in typical homegardens in comparison with adjacent croplands, both under continuous management for >30 years. The study was undertaken at high (2200–2330 masl), mid (1799–1849 masl), and low (1349–1381 masl) elevation in the central Omo-Gibe basin, southwest Ethiopia. Through interviews of 49 randomly selected farm households, and soil sampling at six paired sites at high and mid elevations, and five paired sites of low elevation, we found that homegardens received the majority of household waste and manure and were less frequently tilled. By contrast, some, but not all, croplands occasionally received inorganic fertilizer. Homegarden soil had significantly greater (P < 0.05) soil organic carbon (SOC) concentrations than croplands. At 0–20 cm depth, SOC concentrations in homegardens (22.4–26.4 mg

    Malaria parasites (Plasmodium spp.) infecting introduced, native and endemic New Zealand birds

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    Avian malaria is caused by intracellular mosquito-transmitted protist parasites in the order Haemosporida, genus Plasmodium. Although Plasmodium species have been diagnosed as causing death in several threatened species in New Zealand, little is known about their ecology and epidemiology. In this study, we examined the presence, microscopic characterization and sequence homology of Plasmodium spp. isolates collected from a small number of New Zealand introduced, native and endemic bird species. We identified 14 Plasmodium spp. isolates from 90 blood or tissue samples. The host range included four species of passerines (two endemic, one native, one introduced), one species of endemic pigeon and two species of endemic kiwi. The isolates were associated into at least four distinct clusters including Plasmodium (Huffia) elongatum, a subgroup of Plasmodium elongatum, Plasmodium relictum and Plasmodium (Noyvella) spp. The infected birds presented a low level of peripheral parasitemia consistent with chronic infection (11/15 blood smears examined). In addition, we report death due to overwhelming parasitemia in a blackbird, a great spotted kiwi and a hihi. These deaths were attributed to infections with either Plasmodium spp. lineage LINN1 or P. relictum lineage GRW4. To the authors’ knowledge, this is the first published report of Plasmodium spp. infection in great spotted and brown kiwi, kereru and kokako. Currently, we are only able to speculate on the origin of these 14 isolates but consideration must be made as to the impact they may have on threatened endemic species, particularly due to the examples of mortality

    Der Konflikt in Afghanistan : Historischer und gesellschaftlicher Hintergrund, Evolution und Lageentwicklung – ein Positionspapier

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    This study is part of a larger project, the aim of which is to elucidate “mental health nurses” attitudes towards their patients'. In this study, nurses' and patients' attitudes are described from the perspective of both parties using a qualitative approach. The informants were selected from a rehabilitation unit for young adults, below 40, suffering from psychosis at a psychiatric clinic that provides acute psychiatric care. The informant group consisted of three dyads: three patients with various diagnoses and three nurses with primary responsibility for the patients' daily care. The aim of this particular study was to extend our preliminary understanding of nurses' attitudes towards psychiatric patients in the context of psychiatric in-patient care, by elucidating the patient's “inner” picture of her/his past, present and future and the nurse's picture of the same patient's past, present and future. Data were collected and analysed using a phenomenological-hermeneutic approach and the narrative picturing technique. For each picture and group, 15 related sub-themes emerged, on the basis of which six themes were formulated. The findings show that the nurses overrate their own importance when it comes to the patient's well-being on the ward. All the nurses emphasize confirmation and safety as the basis of their nursing care, while in the patient's picture the nurses represent a replication of childhood demands, which probably means that nursing care risks becoming a continuation of the patient's childhood estrangement

    Biochemical Properties of a Novel Cysteine Protease of Plasmodium vivax, Vivapain-4

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    Plasmodium vivax affects hundreds of millions each year and results in severe morbidity and mortality. Plasmodial cysteine proteases (CPs) play crucial roles during the progression of malaria since inhibition of these molecules impairs parasite growth. These CPs might be targeted for new antimalarial drugs. We characterized a novel P. vivax CP, vivapain-4 (VX-4), which appeared to evolve differentially among primate Plasmodium species. VX-4 showed highly unique substrate preference depending on surrounding micro-environmental pH. It effectively hydrolyzed benzyloxycarbonyl-Leu-Arg-4-methyl-coumaryl-7-amide (Z-Leu-Arg-MCA) and Z-Phe-Arg-MCA at acidic pH and Z-Arg-Arg-MCA at neutral pH. Three amino acids (Ala90, Gly157 and Glu180) that delineate the S2 pocket were found to be substituted in VX-4. Alteration of Glu180 abolished hydrolytic activity against Z-Arg-Arg-MCA at neutral pH, indicating Glu180 is intimately involved in the pH-dependent substrate preference. VX-4 hydrolyzed actin at neutral pH and hemoglobin at acidic pH, and participated in plasmepsin 4 activation at neutral/acidic pH. VX-4 was localized in the food vacuoles and cytoplasm of the erythrocytic stage of P. vivax. The differential substrate preferences depending on pH suggested a highly efficient mechanism to enlarge biological implications of VX-4, including hemoglobin degradation, maturation of plasmepsin, and remodeling of the parasite architecture during growth and development of P. vivax

    A strategy to discover new organizers identifies a putative heart organizer

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    Organizers are regions of the embryo that can both induce new fates and impart pattern on other regions. So far, surprisingly few organizers have been discovered, considering the number of patterned tissue types generated during development. This may be because their discovery has relied on transplantation and ablation experiments. Here we describe a new approach, using chick embryos, to discover organizers based on a common gene expression signature, and use it to uncover the anterior intestinal portal (AIP) endoderm as a putative heart organizer. We show that the AIP can induce cardiac identity from non-cardiac mesoderm and that it can pattern this by specifying ventricular and suppressing atrial regional identity. We also uncover some of the signals responsible. The method holds promise as a tool to discover other novel organizers acting during development

    The role of nutrition in integrated programs to control neglected tropical diseases

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    There are strong and direct relationships between undernutrition and the disease caused by infectious organisms, including the diverse pathogens labeled as neglected tropical diseases (NTDs). Undernutrition increases the risk of infection, the severity of disease and the risk that children will die, while the physical damage, loss of appetite, and host responses during chronic infection can contribute substantially to undernutrition. These relationships are often synergistic. This opinion article examines the role of nutrition in controlling NTDs and makes the point that mass drug treatment - the major strategy currently proposed to control several diseases - is crucial to controlling disease and transmission, but is only the start of the process of physical recovery. Without adequate energy and nutrients to repair damaged tissues or recover lost growth and development, the benefits of treatment may not be evident quickly; the effects of control programs may be not appreciated by beneficiaries; while vulnerability to reinfection and disease may not be reduced. There is substantial potential for nutritional interventions to be added to large-scale programs to deliver drug treatments and thereby contribute, within a broad strategy of public health interventions and behavior change activities, to controlling and preventing NTDs in populations, and to restoring their health
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