Soil amidase activity in polyacrylamide-treated soils and potential activity toward common amide-containing pesticides

 Polyacrylamide (PAM) is currently used as an irrigation water additive to significantly reduce the amount of soil erosion that occurs during furrow irrigation of crops. Elevated soil amidase activity specific toward the large PAM polymer has been reported in PAM-treated field soils; the substrate specificity of the induced amidase is uncertain. PAM-treated and untreated soils were assayed for their capacity to hydrolyze the amide bond in carbaryl (Sevin), diphenamid (Dymid), and naphthalene acetamide. Based on results obtained with a soil amidase assay, there was no difference between PAM-treated and untreated soils with respect to the rate of amide bond hydrolysis of any of the agrochemicals tested. It appears that under these assay conditions the PAM-induced soil amidase is not active toward the amide bonds within these molecules. However, carbaryl was hydrolyzed by a different soil amidase. To our knowledge, this is the first soil enzyme assay-based demonstration of the hydrolysis of carbaryl by a soil amidase. Received: 23 June 1999     

Direct measurement of the current-phase relation of a superfluid 3He-B weak link

Direct measurements of the current-phase relation, I versus Deltaphi, for a weak link coupling two reservoirs of B-phase superfluid helium-3 (3He-B) were made over a wide range of temperatures. The weak link consists of a square array of 100-nanometer-diameter apertures. For temperatures T such that T/Tc >/= 0.6 (where Tc is the superfluid transition temperature), I approximately sin(Deltaphi). At lower temperatures, I(Deltaphi) approaches a straight line. Several remarkable phenomena heretofore inaccessible to superconducting Josephson junctions, including direct observation of quantum oscillations and continuous knowledge of Deltaphi, were also observed.     

Effect of breed of cattle on innate resistance to infection with <i>Babesia bovis, B bigemina and Anaplasma marginale

Objective To assess the innate resistance of naive Bos taurus, Bos taurus cross Bos indicus and Bos indicus cattle to virulent Babesia bovis, B bigemina and Anaplasma marginale parasites. Design Groups of 10, pure B indicus, fi B indicus cross,/B indicus cross and pure B taurus steers were infected with virulent B bovis, B bigemina and A marginale parasites. Procedure Sequential infections were carried out by intravenous inoculation of infected blood containing 1 times 10⁸ parasites of B bovis, followed by B bigemina and then A marginale. To assess resistance, measurements were made of parasitaemia, rectal temperature, packed cell volume and the number within a group requiring chemotherapy to control infection. There was a recovery period between each infection. Results Infection with B bovis showed that pure B indicus steers were significantly more resistant to B bovis infection than the other groups, with none of this group requiring treatment. There was no significant difference between fi B indicus cross and/B indicus cross with 30% and 20%, respectively, of steers in these groups requiring treatment. The pure B taurus steers were significantly more affected then those in the other three groups with 80% requiring treatment. Infections of B bigemina produced a mild response in comparison to that of B bovis and none of the steers required treatment. However, the pure B taurus group was significantly more affected than the other three groups for all other measurements. After the A marginale infection, B indicus steers were moderately affected with 50% requiring treatment, whereas 70% of the fi B indicus group, 80% of the /B indicus cross group and 100% of the pure B taurus group required treatment. Conclusions All breeds of cattle, ranging from pure B indicus to pure B taurus may be at risk of severe disease if exposed to virulent A marginale. The results confirm that pure B indicus cattle are relatively resistant to B bovis, but there could be a significant risk of severe mortalities if cross-bred herds are exposed to virulent infection.     

Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere

Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited. Some modern schemes incorporate biogeochemical and ecological knowledge and, when coupled with advanced climate and ocean models, will be capable of modeling the biological and physical responses of the Earth system to global change, for example, increasing atmospheric carbon dioxide.     

Field application of PAM as an amendment in deep-tilled US southeastern coastal plain soils

In sandy soils of the southeastern USA coastal plains, crop production is limited by low water holding capacity and compacted soil layers that reduce root growth and productivity. Polyacrylamide (PAM) was added to sandy coastal plain soils to improve physical properties and yield. Soils were amended with linear and cross-linked PAMs. Treatments and controls included the following: (1) spraying a 600 mg kg⁻¹ solution of linear PAM behind a subsoil shank at a rate of 3.93 kg ha⁻¹, (2) spraying a 100 mg kg⁻¹ solution at 0.66 kg ha⁻¹, (3) spraying only water at 13.1 m³ ha⁻¹, (4) dropping a dry PAM powder formulation (3005 KB) behind a subsoil shank at 300 kg ha⁻¹, (5) dropping another dry PAM powder formulation (3005 K2) at 230 kg ha⁻¹, (6) dropping a dry PAM powder formulation 3005 K2 at a lower rate of 55 kg ha⁻¹, (7) applying nothing behind a subsoil shank, and (8) not subsoiling. In each of the 3 years of the experiment, new sets of treatments were set up while the old ones were maintained to look at longevity of the PAM effect. Though treatment effects were dominated by the tillage, the cross-linked PAMs were the only treatments more effective than tillage alone. The cross-linked PAMs may have been more effective because we could add more in dry form than in the spray form. The effect diminished with time similar to or faster than the results seen in tillage only. Though some PAM applications may have reduced cone indices, yields were not affected.     

乳酸菌添加剂对青藏高原燕麦青贮品质的影响

[目的]研究乳酸菌添加剂对青贮燕麦发酵品质的影响,为燕麦的青贮提供技术条件。[方法]按0．005g／kg燕麦的添加量,将乳酸菌粉剂直接加入燕麦,采用捆裹青贮系统进行青贮。处理80d后,观察其感官特征并测定品质,与普通青贮燕麦和青刈燕麦进行比较。[结果]乳酸菌青贮燕麦的气味、色泽和手感均优于普通青贮燕麦,其pH值低于3．8,乳酸与乙酸的比值下降,乳酸占总酸的比例增加,DM、CP和Ash含量增加,NDF、ADF含量降低。[结论]乳酸菌添加剂改善了青贮燕麦的品质,所得燕麦属于优质青贮料。     

Matrix-Based Fertilizers Reduce Pesticide Leaching in Soil

The presence of pesticides in groundwater has been documented in several large-scale studies and numerous small-scale investigations. Pesticide leaching through soil has been identified as a major cause for the occurrence of these chemicals in surface and groundwater. We developed matrix-based fertilizers (MBFs) that have been shown to reduce N and P leaching. We tested the efficacy of the ionic bonds in the MBFs to reduce 2,4-dichlorophenoxyacetic acid (2,4-D), metolachlor, thiophanate methyl, carbaryl, diazinon, and malathion leaching in soil columns. After 7 days 2,4-D, thiophanate methyl, carbaryl, and malathion did not leach in sufficient quantities to determine if the MBF fertilizers reduced leaching compared with the control and the slow-release fertilizer Polyon®. The MBF fertilizers leached from five to 30 times less metolachlor than the control and Polyon® treatment. Treatments with MBF fertilizers leached from two to 72 times less diazinon than the control treatment. The MBF fertilizer treatment leached from eight to 268 less diazinon than columns receiving Polyon®. The MBF formulations allow compounds with both anionic and cationic charges to bind with the Al(SO₄)₃ 3H₂O and/or Fe₂(SO₄)₃ 3H₂O-lignin-cellulose matrix. When pesticides are added to the soil amended with matrix-based fertilizers, the ion exchange matrix will likely bind the metolachlor and diazinon to the Al(SO₄)₃ 3H₂O and/or Fe₂(SO₄)₃ 3H₂O-starch-cellulose-lignin matrix thereby substantially reducing leaching. The MBFs could be used to limit both nutrients and pesticide leaching from agricultural fields.     

In vivo administration of acepromazine or promethazine to horse decreases the reactive oxygen species production response of subsequently isolated neutrophils to stimulation with phorbol myristate acetate

The previous experiments have shown that some phenothiazines have antioxidant and anti-inflammatory properties in vitro . In this study the inhibition of the production of reactive oxygen species (ROS) by neutrophils was studied in two groups of horses, which received a dose of 0.1 mg/kg of either acepromazine or promethazine intravenously. Blood samples were collected before (T0) and 0.5, 1, 3 and 5 h after drug administration. The chemiluminescence (CML) response of neutrophils was measured ex vivo in the presence of luminol for a period of 10 min and the maximum CML value (peak value) recorded. There was a significant inhibition of the ROS production in the acepromazine treated group (49% inhibition) at 5 h after administration and in the promethazine group (24% inhibition) at 3 h after administration ( P  < 0.05 vs. T0). These findings are of therapeutic relevance in the use of phenothiazines in equine patients with inflammatory diseases where neutrophil activation and ROS production are implicated.