Multiple diagnostic tests to identify cattle with Bovine viral diarrhea virus and duration of positive test results in persistently infected cattle

Several tests for Bovine viral diarrhea virus (BVDV) were applied to samples collected monthly from December 20, 2005, through November 27, 2006 (day 0 to day 342) from 12 persistently infected (PI) cattle with BVDV subtypes found in US cattle: BVDV-1a, BVDV-1b, and BVDV-2a. The samples included clotted blood for serum, nasal swabs, and fresh and formalin-fixed ear notches. The tests were as follows: titration of infectious virus in serum and nasal swabs; antigen-capture (AC) enzyme-linked immunosorbent assay (ELISA), or ACE, on serum, nasal swabs, and fresh ear notches; gel-based polymerase chain reaction (PCR) testing of serum, nasal swabs, and fresh ear notches; immunohistochemical (IHC) testing of formalin-fixed ear notches; and serologic testing for BVDV antibodies in serum. Of the 12 animals starting the study, 3 died with mucosal disease. The ACE and IHC tests on ear notches had positive results throughout the study, as did the ACE and PCR tests on serum. There was detectable virus in nasal swabs from all the cattle throughout the study except for a few samples that were toxic to cell cultures. The serum had a virus titer ≥ log₁₀ 1.60 in all samples from all the cattle except for 3 collections from 1 animal. Although there were several equivocal results, the PCR test most often had positive results. The BVDV antibodies were due to vaccination or exposure to heterologous strains and did not appear to interfere with any BVDV test. These findings illustrate that PI cattle may be identified by several tests, but differentiation of PI cattle from cattle with acute BVDV infection requires additional testing, especially of blood samples and nasal swabs positive on initial testing. Also, calves PI with BVDV are continual shedders of infectious virus, as shown by the infectivity of nasal swabs over the 11-mo study.     

Minerals controlling arsenic distribution in floodplain soils

As a consequence of intensive mining of the western Erzgebirge since medieval times, floodplain soils of the Mulde river contain large concentrations of arsenic (As) (>50 mg kg⁻¹). Arsenic in soil is often bound to poorly crystalline Fe and Mn (hydr)oxides, which may dissolve under reducing conditions. Part of the As may also exist in primary minerals, predominately sulphides, or in secondary minerals formed upon weathering. In order to better understand the impact of seasonal flooding, we surveyed As‐bearing mineral phases, especially of iron (Fe) (hydr)oxides. Because Fe (hydr)oxides are clay‐sized, soil samples were fractionated into six particle‐size fractions. The fractions were digested with aqua regia for determination of total element concentrations, extracted with hydroxylammonium chloride (NH₃OHCl; selective for Mn (hydr)oxides and NH₄ oxalate), and analysed by X‐ray diffraction and scanning electron microscopy. The largely similar distribution of As and lead (Pb) suggested the potential co‐existence of the two elements in primary or secondary mineral phases. However, neither As–Pb minerals nor any other As mineral were detected. Association with Mn oxides was negligible. The predominant As‐bearing phases were poorly crystalline Fe (hydr)oxides, which also incorporated large amounts of Pb and were affected by redox dynamics.     

Alteration of secondary minerals along a time series in young alkaline soils derived from carbonatic wastes of soda production

Industrial activities result in increasing amounts of technical substrates being deposited in landfills. These substrates are subject to weathering and pedogenic processes. We studied the chemical and mineralogical transformations on naturally weathered waste deposits of soda industry. Four sites differing in age (15, 19, 57, and 70 years) and derived from carbonatic slurry (mainly CaO^.H₂O, CaCO₃, NaCl) were selected. The formed soils, calcareous spolic Regosols, are weakly to strongly alkaline with pH values ranging from 8 to 12. Within 15 years, the substrate's initial pH of 12 drops rapidly in the topsoil due to the reaction of dissolved Ca either with CO₂ from the atmosphere or evolved by microbial respiration and finally stabilizes at around 8.1. All soils show high electrical conductivity, up to 12.3 mS cm^− 1 at the youngest site. The electrical conductivity strongly decreases within 70 years of weathering due to leaching processes and the formation of less soluble secondary minerals. The content of organic C in the studied soils ranges from 2.4 to 70.8 g kg^− 1 and stocks increase with site age. Soil structure and soil color change distinctly. The binding of CO₂ results in large amounts of carbonate, increasing with time. Seventy years after deposition, calcite [CaCO₃] dominates the topsoil (0–30 cm depth), comprising about 80% of the soil material. The mineral composition was characterized by X-ray diffraction. Besides calcite, we found different quantities and different distributions of the less common minerals ettringite [Ca₆(Al(OH)₆)₂(SO₄)₃  26H₂O], thaumasite [Ca₆(Si(OH)₆)₂(CO₃)₂(SO₄)₂  24H₂O], hydrocalumite [Ca₂Al(OH)₇  2H₂O] and hydrotalcite [Mg₆Al₂(CO₃)(OH)₁₆  4H₂O]. Formation and alteration of these minerals are basically influenced by changes in the soil pH. With progressing weathering neither thaumasite nor ettringite are stable due to the non-favorable soil reaction (pH  8.1). In contrast, hydrocalumite and hydrotalcite exist in all investigated soils. They are stable also under weakly alkaline conditions and thus may exist in all carbonatic soils. Results indicate a surprisingly rapid soil development driven by the highly dynamic formation and alteration of minerals in carbonatic substrates under alkaline conditions.     

Thrombelastography in 26 healthy horses with and without activation by recombinant human tissue factor

Objectives – To develop a standardized technique for thrombelastography (TEG) analysis in healthy adult horses, with and without the ex vivo addition of tissue factor (TF) as an activator. To determine reference intervals for TEG parameters in the horse, and to determine if traditional coagulation tests correlate with TEG. Design – Prospective, observational. Setting – Veterinary teaching hospital. Animals – Twenty‐six healthy adult horses. Interventions – None. Measurements and Main Results – Thrombelastography with (TF‐TEG) and without (TEG) the addition of TF performed by 4 operators. Coagulation profiles (prothrombin time, activated partial thromboplastin time, platelet count, fibrinogen, antithrombin, and fibrinogen degradation products) were assessed in a subset of horses. Mean values (SD) for TEG parameters in healthy horses were: reaction time (R)=17.0 minutes (3.0 min), K time (K)=5.8 minutes (2.3 min), clotting rate (Ang)=42° (14°), maximum clot strength (maximum amplitude [MA])=60.3 mm (5.7 mm), CL30=97.0% (2.0%), LY30=0.8% (0.6%), CL60=92% (5.9%), LY60=3.2% (2.5%). Mean values (SD) for TF‐TEG parameters were: R‐TF=6.6 minutes (1.4 min), K‐TF=3.1 minutes (1.0 min), Ang‐TF=50.9° (9°), MA‐TF=62.3 mm (5.1 mm), CL30‐TF=97.8% (1.6%), LY30‐TF=0.6% (0.5%), CL60‐TF=90.8% (4.2%), and LY60‐TF=3.6% (1.9%). The addition of TF decreased R and K and increased Ang. TF‐TEG had a narrower SD for R, K, Ang, CL60 and LY60 compared with TEG. Interoperator differences were reduced by the addition of TF. Regression analysis indicated a positive relationship between MA and fibrinogen concentrations (P=0.02) and R‐TF time and prothrombin time (P=0.03). Conclusion – TF‐TEG using the described protocol may minimize variability in data obtained across institutions or users. However, due to the variability associated with different operators, it is recommended that each laboratory set up individual reference intervals with the personnel who will perform the assay, and that the assay protocols and data obtained are compared on a regular basis.     

Membrane fusion intermediates via directional and full assembly of the SNARE complex

Cellular membrane fusion is thought to proceed through intermediates including docking of apposed lipid bilayers, merging of proximal leaflets to form a hemifusion diaphragm, and fusion pore opening. A membrane-bridging four-helix complex of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediates fusion. However, how assembly of the SNARE complex generates docking and other fusion intermediates is unknown. Using a cell-free reaction, we identified intermediates visually and then arrested the SNARE fusion machinery when fusion was about to begin. Partial and directional assembly of SNAREs tightly docked bilayers, but efficient fusion and an extended form of hemifusion required assembly beyond the core complex to the membrane-connecting linkers. We propose that straining of lipids at the edges of an extended docking zone initiates fusion.     

Parameter estimates from generation means in swedes (Brassica napus ssp. rapifera L.)

From an experiment involving swede (Brassica napus ssp. rapifera L.) material resulting from a 4 × 4 diallel cross and a 4 × 9 factorial mating design better parent heterosis for dry matter and marketable yield was found in the majority of the hybrids. For breeders preference the better parent heterosis was not that pronounced and the majority of the hybrids were inferior when compared to their better parent. The generation means showed that models containing the mean, m, and the dominance parameter, h, generally resulted in the best fit. In some cases the additive parameter, d, improved the fit. In those cases, however, the additive parameter was substantially smaller than the dominance parameter. The probability of occurrence of recombinant inbred lines that outperform the source F₁-hybrid was, with very few exceptions, found to be low. Implications for swede breeding are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Combination of micro suction cups and time-domain reflectometry to measure osmotic potential gradients between bulk soil and rhizosphere at high resolution in time and space

A prerequisite to investigate the importance of osmotic potential (Ψ_o) in relation to matric potential (Ψ_m) in the soil for water uptake is the existence of a method that measures the temporal and spatial dynamics of Ψ_o in the vicinity of roots. One method for measuring Ψ_oin situ is the collection of soil solution with micro suction cups, the spatial resolution of which is suitable for rhizosphere studies. A major drawback of soil solution sampling is the disturbance of soil solution equilibrium, which makes frequent measurements impossible, so another method is required to provide information on the temporal dynamics of Ψ_o. The time‐domain reflectometry (TDR) technique might be suitable as the signal attenuation (σ) shows a close linear correlation with the salt concentration for a known soil water content. The temporal resolution of the TDR technique is high and the measurement has no impact on soil solution equilibrium. However, the spatial resolution of the TDR technique is too coarse to be used on its own in rhizosphere studies. We used a combination of TDR (fine temporal resolution) and micro suction cups (fine spatial resolution) to measure Ψ_o in a model system with Zea mays grown in quartz substrates. Osmotic potential changed continuously with time, and a steep gradient between bulk soil and the root compartment developed during the 39‐day growing period. The steepest gradient measured over a distance of 6 mm across the nylon net, separating the bulk soil from the root compartment, was ?365 kPa. The combination of both methods made it possible to extend the time interval between micro suction cup samplings and thus minimize the impact of sampling on soil solution equilibrium. Problems of separate calibration were avoided by calibrating the TDR measurements against the results obtained with the micro suction cups within the same experiment.