Nitrous Oxide Loss from Poultry Manure-Amended Soil after Rain

Land application of poultry wastes in Kentucky will increase as the broiler industry grows. If poultry manure stimulates N2O loss from soil it will reduce the fertilizer N value of this waste. In contrast, stimulated N2O loss in grass filter strips receiving the runoff from manured fields could help reduce contamination of surface water by NO−3. Our objectives were to determine (i) if poultry manure stimulated N2O loss in soil after rainfall and (ii) if there was an edge-of-field effect on N2O loss in grass filters intercepting runoff from amended soil. Soil covers were used to measure N2O loss from a well-drained, poultry manure-amended, silt loam soil immediately after simulated rainfall and were also used to measure N2O loss from grass filters intercepting their surface runoff. Nitrous oxide loss from manure-amended soil was greater than from unamended controls and ranged from 5 to 13 mg N2O-N m−2 h−1. The maximum N2O loss was equivalent to 3.2 kg N2O-N ha−1d−1. Nitrous oxide loss from grass filters intercepting runoff ranged from 0.1 to 1.4 mg N2O-N m−2 h−1 and was significantly greater than portions of the grass filters that did not intercept runoff. Nitrous oxide loss from poultry manure-amended soils was greater than N2O loss typically measured from waste-amended agricultural soils. However, it only represented up to 0.7% of the total N in the applied manure

Filter Strip Length and Fecal Bacteria Trapping from Poultry Waste - An Update

Cheap, efficient, and environmentally sound waste disposal will be needed as Kentucky\u27s broiler industry expands. The filter strip length needed to protect water resources from contaminants in surface runoff is a pressing issue in waste management and water quality. In a previous Soil Science News and Views (Vol. 15, No. 8) we reported that grass filter strips as short as 15 feet can trap over 90% of the fecal bacteria eroding from land-applied and incorporated poultry waste during runoff following rainstorms. In this update, we provide some additional information and conclusions from that study on filter strip length, based on comparisons of filter strips receiving equal amounts of surface runoff

Nitrous Oxide Flux from Poultry-Manured Erosion Plots and Grass Filters after Simulated Rain

Adding carbon-rich materials to fields, like manure, may enhance denitrification. Grass filters, which are used to trap surface runoff from these fields, may also provide a carbon-rich environment that favors water infiltration and denitrification. Nitrous oxide (N2O) may be evolved these settings. It is a radiatively important trace gas and intermediate in the denitrification pathway and several other microbial processes. We measured N2O flux, after simulated rain, using a soil cover technique in poultry-manured plots and grass filters receiving their runoff. Intact soil cores were used to relate the N2O flux to the denitrification potential of the plots. Nitrous oxide fluxes were smaller in grass filters than in manured plots, even though more denitrifying bacteria were present. The average N2O flux in the three most dynamic erosion plots was 755 µg N2O-N m−2h−1, which was 39% of the maximal denitrification rate measured in acetylene-blocked, NO−3-amended soil cores. Nitrous oxide flux immediately after rainfall was greater than N2O flux measurements reported for similar agricultural settings

Trapping Fecal Bacteria and Sediment in Surface Runoff From Cropland Treated With Poultry Litter

Between 1991 and 1994 the broiler population exploded in Kentucky as the poultry industry began to expand. The Kentucky Department of Agriculture predicts that within four years annual broiler production could exceed 275 million birds. This may be good for Kentucky\u27s economy but it carries some important environmental consequences. If expansion continues as anticipated, the estimated waste production from broilers for processing could reach 300,000 tons per year (assuming each broiler house produces 150,000 birds per year and the yearly manure and litter production per house is approximately 160 tons)

Use of Riparian Vegetated Filter Strips to Reduce Nitrate and Fecal Contamination in Surface Water

This research assessed fecal bacteria trapping in surface runoff by grass filters and their potential to enhance NO3- removal via denitrification. Grass filter strips 9.0 m long trapped over 99% of the soil in surface runoff in 1992. Fecal coliform removal was less than 75%. In 1993, 9.0 and 4.5 m grass filter strips trapped 99 and 95% of the sediment, respectively. Fecal coliform trapping efficiency was 90% in 9.0 m grass filters and 75% in 4.5 m filters. Fecal streptococci trapping efficiency was 77% in 9.0 m grass filters and only 56% in 4.5 m filters. Fecal coliform concentration in grass filter strip runoff consistently exceeded 200 fecal coliforms per 100 mL. Grass filter strips which minimized sediment loss did not reduce fecal contamination of water to acceptable levels when runoff occurred. Nitrous oxide fluxes were smaller in grass filters than in manured plots. In 1993, N2O loss ranged from 2050 to 11120 mg N2O-N m-2 h-1 in amended soil and 160 to 1060 mg N2O-N m-2 h-1 in grass filter strips. Denitrification was not apparently enhanced in the grass filters relative to the manured soil

An Electrophysiological and Pharmacological Study of the Properties of Human iPSC-Derived Neurons for Drug Discovery

Human stem cell-derived neurons are increasingly considered powerful models in drug discovery and disease modeling, despite limited characterization of their molecular properties. Here, we have conducted a detailed study of the properties of a commercial human induced Pluripotent Stem Cell (iPSC)-derived neuron line, iCell [GABA] neurons, maintained for up to 3 months in vitro. We confirmed that iCell neurons display neurite outgrowth within 24 h of plating and label for the pan-neuronal marker, βIII tubulin within the first week. Our multi-electrode array (MEA) recordings clearly showed neurons generated spontaneous, spike-like activity within 2 days of plating, which peaked at one week, and rapidly decreased over the second week to remain at low levels up to one month. Extracellularly recorded spikes were reversibly inhibited by tetrodotoxin. Patch-clamp experiments showed that iCell neurons generated spontaneous action potentials and expressed voltage-gated Na and K channels with membrane capacitances, resistances and membrane potentials that are consistent with native neurons. Our single neuron recordings revealed that reduced spiking observed in the MEA after the first week results from development of a dominant inhibitory tone from GABAergic neuron circuit maturation. GABA evoked concentration-dependent currents that were inhibited by the convulsants, bicuculline and picrotoxin, and potentiated by the positive allosteric modulators, diazepam, chlordiazepoxide, phenobarbital, allopregnanolone and mefenamic acid, consistent with native neuronal GABAA receptors. We also show that glycine evoked robust concentration-dependent currents that were inhibited by the neurotoxin, strychnine. Glutamate, AMPA, Kainate and NMDA each evoked concentration-dependent currents in iCell neurons that were blocked by their selective antagonists, consistent with the expression of ionotropic glutamate receptors. The NMDA currents required the presence of the co-agonist glycine and were blocked in a highly voltage-dependent manner by Mg2+ consistent with the properties of native neuronal NMDA receptors. Together, our data suggest that such human iPSC-derived neurons may have significant value in drug discovery and development and may eventually largely replace the need for animal tissues in human biomedical research

Comparative genomics of the pathogenic ciliate Ichthyophthirius multifiliis, its free-living relatives and a host species provide insights into adoption of a parasitic lifestyle and prospects for disease control

Background: Ichthyophthirius multifiliis, commonly known as Ich, is a highly pathogenic ciliate responsible for ‘white spot’, a disease causing significant economic losses to the global aquaculture industry. Options for disease control are extremely limited, and Ich’s obligate parasitic lifestyle makes experimental studies challenging. Unlike most well-studied protozoan parasites, Ich belongs to a phylum composed primarily of free-living members. Indeed, it is closely related to the model organism Tetrahymena thermophila. Genomic studies represent a promising strategy to reduce the impact of this disease and to understand the evolutionary transition to parasitism. Results: We report the sequencing, assembly and annotation of the Ich macronuclear genome. Compared with its free-living relative T. thermophila, the Ich genome is reduced approximately two-fold in length and gene density and three-fold in gene content. We analyzed in detail several gene classes with diverse functions in behavior, cellular function and host immunogenicity, including protein kinases, membrane transporters, proteases, surface antigens and cytoskeletal components and regulators. We also mapped by orthology Ich’s metabolic pathways in comparison with other ciliates and a potential host organism, the zebrafish Danio rerio. Conclusions: Knowledge of the complete protein-coding and metabolic potential of Ich opens avenues for rational testing of therapeutic drugs that target functions essential to this parasite but not to its fish hosts. Also, a catalog of surface protein-encoding genes will facilitate development of more effective vaccines. The potential to use T. thermophila as a surrogate model offers promise toward controlling ‘white spot’ disease and understanding the adaptation to a parasitic lifestyle

Post-peak fracture behavior during direct shear tests of rock joints

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