Untersuchung zur Anwendbarkeit von Sorptionskoeffizienten für die Simulation der Verlagerung von 2, 4, 5-T und LAS in Böden

Investigations for the use of sorption coefficients for simulation of the transport of 2, 4, 5-T and LAS in soils The use of sorption coefficients for the prediction of the transport of 2, 4, 5-trichlorophenoxy-acetic acid (2, 4, 5-T) and of n-dodecylbenzene-sulfonate (LAS) was investigated for four different soil types with the simulation model EXSOL. Linear equilibrium sorption coefficients of 2, 4, 5-T determined in batch studies are not suited for the prediction of the transport wheras values derived from the retention in soil columns better fit the experimental profiles of 2, 4, 5-T in the field. Sorption coefficients for LAS from batch studies with a soil-solution ration of 1:2 and a shaking period of 4 h gave the best results for prediction of LAS transport in the field.     

Differences in manganese efficiency of wheat (Triticum aestivum L.) and raya (Brassica juncea L.) as related to root‐shoot relations and manganese influx

Manganese efficiency is a term used to describe the ability of plants to obtain higher relative yields at low Mn supply compared to other species. To evaluate Mn efficiency of wheat (Triticum aestivum L.) and raya (Brassica juncea L.), a greenhouse pot experiment was conducted using Mn deficient Typic Ustochrept loamy sand soil, treated with 0, 50, and 100 mg Mn (kg soil)^–1. In the no‐Mn treatment, wheat had produced only 30 % of its maximum dry matter yield (DMY) with a shoot concentration of 10.8 mg Mn (kg DM)^–1 after 51 days of growth, while raya had produced 65 % of its maximum DMY with 13.0 mg Mn (kg DM)^–1. Taking relative shoot yield as a measure of Mn efficiency, raya was more efficient than wheat. Both crops produced the maximum DMY with 50 mg Mn (kg soil)^–1. Even though raya had a lower root length : DMY ratio and a higher shoot growth rate, it acquired higher Mn concentrations in the shoot than wheat under similar soil conditions, because of a 2.5 times higher Mn influx. Model calculations were used to calculate the difference of Mn solution concentration (ΔC_L) between the bulk soil (C_Li) and the root surface (C_L0) that is needed to drive the flux by diffusion equal to the measured influx. The results showed that ΔC_L was smaller than C_Li, which indicates that chemical mobilization of Mn was not needed to explain the observed Mn uptake even for raya. According to these calculations, the higher Mn influx of raya was caused by more efficient uptake kinetics, allowing for a 4.5 times higher Mn influx at the same Mn concentration at the root surface.     

Spatial risk assessment of herd sero-status of Aujeszky's disease in a county in Hungary

A Geographic Information System (VetEpiGIS) was used to analyze the ADV (Aujeszky's disease virus) sero-status in large-scale pig units regarding certain geographical features in a county of southern Hungary. The ADV sero-statuses were collected from all swine units in Csongrád county in 1998-2000. The units' coordinates were combined with a vector graphical digital map of the county, with a resolution of 1:100,000. Logistic regression tested the associations between sero-status of large-scale units and presence of topographical features, other units and villages in the neighborhood. "Neighborhood" was defined by circular zones with radius 1-10km around the unit (in 1km increments; one logistic regression for each radius). The following topographical features showed significant positive association with the ADV seropositivity: lake (3km OR: 5.7; 5km OR: 7.5; 6km OR: 6.1; 10km OR: 5.4) and highway (5km OR: 4.2; 6km OR: 5.3). Other features had negative association with ADV seropositivity: forest (3km OR: 0.13; 4km OR: 0.15; 5km OR: 0.15; 6km OR: 0.10; 7km OR: 0.10; 8km OR: 0.23) and uninfected large-scale unit (4km OR: 0.07; 5km OR: 0.27; 6km OR: 0.32; 7km OR: 0.31).     

Clinical evaluation of a powder of quality elk velvet antler for the treatment of osteoarthrosis in dogs

A powder of quality elk velvet antler (QEVA) was evaluated on client-owned dogs with osteoarthrosis (OA) in a clinical, double-blind, and placebo-controlled study. Thirteen dogs received a placebo for 30 days and then QEVA for 60 days. Twenty-five other dogs received QEVA for 60 days. Gait analysis measured with a force plate, clinical signs assessed by an orthopedic surgeon, performances in daily life activities and vitality assessed by the owners, and complete blood analyses were obtained at days 0, after 30 days of placebo and/or 60 days of QEVA. On placebo, the 13 dogs did not show significant improvement (P < 0.05); however, their gait, their performances in daily life activities, and their vitality were significantly improved on QEVA, based on changes in values exceeding those observed when placebo was administered. The 25 dogs on QEVA for 60 days showed similar improvements. No clinical changes were revealed on blood analyses. Administration of QEVA was effective in alleviating the condition in arthritic dogs.     

New methods and strategies for monitoring susceptibility of fleas to current flea control products

A flea larval bioassay was developed by an international team of scientists to monitor the susceptibility of fleas (Ctenocephalides felis) to imidacloprid (Advantage, Bayer HealthCare). The assay was validated using laboratory and field isolates of C. felis. Flea eggs representing different field isolates of C. felis were collected by veterinarians in the United States, United Kingdom, and Germany. Of the 972 flea isolates obtained during the 5-year study, 768 contained sufficient numbers of eggs to conduct the larval bioassay. Greater than 5% survival occurred for only six of the field isolates evaluated. Further evaluation and analysis of these isolates demonstrated that they did not differ significantly in their susceptibility to imidacloprid from the reference strains used to develop the assay. Collections of field flea isolates will continue in an attempt to detect and document any change in the susceptibility of field flea populations to imidacloprid.     

BKCa-Cav channel complexes mediate rapid and localized Ca2+-activated K+ signaling

Large-conductance calcium- and voltage-activated potassium channels (BKCa) are dually activated by membrane depolarization and elevation of cytosolic calcium ions (Ca2+). Under normal cellular conditions, BKCa channel activation requires Ca2+ concentrations that typically occur in close proximity to Ca2+ sources. We show that BKCa channels affinity-purified from rat brain are assembled into macromolecular complexes with the voltage-gated calcium channels Cav1.2 (L-type), Cav2.1 (P/Q-type), and Cav2.2 (N-type). Heterologously expressed BKCa-Cav complexes reconstitute a functional "Ca2+ nanodomain" where Ca2+ influx through the Cav channel activates BKCa in the physiological voltage range with submillisecond kinetics. Complex formation with distinct Cav channels enables BKCa-mediated membrane hyperpolarization that controls neuronal firing pattern and release of hormones and transmitters in the central nervous system.     

Formation of pyrazines and a novel pyrrole in Maillard model systems of 1,3-dihydroxyacetone and 2-oxopropanal

Alkylpyrazines are a very important class of Maillard flavor compounds, but their mechanism of formation is complex and consists of different pathways. The model reaction of 20 different amino acids with 1,3-dihydroxyacetone, as a precursor of 2-oxopropanal, was studied by means of SPME-GC-MS to investigate the involvement of the amino acid side chain in the substitution pattern of the resulting pyrazines. 2,5-Dimethylpyrazine was quantitatively the most important pyrazine formed from all of the amino acids. The amino acid side chain is not involved in its formation. The substituents of other less abundant pyrazines resulted mainly from the incorporation of the Strecker aldehyde or aldol condensation products in the intermediate dihydropyrazine. The importance of different reaction mechanisms was evaluated, taking into account the pattern of pyrazines identified. In the solvent extracts of aqueous model reactions of 2-oxopropanal with amino acids, the main reaction product was not a pyrazine but a novel pyrrole. This pyrrole was identified as 2,5-diacetyl-3-methyl-1 H-pyrrole by means of spectral analysis, secured by chemical synthesis. A reaction mechanism for its formation was proposed and evaluated. The influence of various reaction conditions on the formation of 2,5-diacetyl-3-methyl-1 H-pyrrole and 2,5-dimethylpyrazine in the model reaction of alanine with 2-oxopropanal was studied. These results underscore the importance of the ratio of the different reagents and the presence of water in the resulting flavor formation in the Maillard reaction.     

Application of 10% imidacloprid/50% permethrin to prevent Ehrlichia canis exposure in dogs under natural conditions

Canine monocytic ehrlichiosis (CME) caused by Ehrlichia canis is the most known canine tick-borne disease (TBD) spread throughout the world. Preventing tick bites is a priority to reduce the risk of TBDs and it was the aim of the present study to evaluate the efficacy of a combination of imidacloprid 10% and permethrin 50% (ImPer) (Advantix; Bayer AG, Germany) in a spot-on formulation to control CME under field conditions. On January-March 2005, 845 dogs from two kennels in southern Italy (kennels of Bari (KB)- and Ginosa (KG)), with a history of tick infestation were initially tested by serology and PCR assay for E. canis infection. Data on Leishmania infantum infection were also available from a previous study carried out on the same dog population. One hundred twenty-six dogs (14.9%) presented anti-E. canis antibodies with a relative prevalence of 15.6% (n=65 dogs in KB) and 14.2% (n=61 dogs in KG). Five hundred thirty-five animals found negative both for E. canis and L. infantum infections were enrolled in three groups (Group A--treated with ImPer once a month; Group B--treated every 2 weeks; and Group C--untreated control animals) and monitored for E. canis infection by serology and PCR in November 2005 (first follow-up) and in March 2006 (second follow-up). The E. canis infection was serologically revealed, at the first and/or second follow-up, in 26 animals from Group C in KB and KG (mean incidence density rate (IDR), 13.24%) while in none of the animals from Group A (KB and KG) and only in one animal from Group B (IDR 1.13%) in KG. The final protection efficacy of ImPer ranged from 95.57% to 100% in Groups B and A. At PCR only 15 dogs from KG were positive for Rickettsiales only at the first follow-up and at the sequence analysis two (both in Group C) revealed 100% homology with E. canis sequences while 13 with Anaplasma platys. Four out of 13 A. platys PCR-positive dogs were also seropositive for E. canis at one or both follow-ups. ImPer, by virtue of its repellent and acaricidal activity against ticks, has been shown to be efficacious to prevent E. canis infection in treated dogs living under natural conditions in endemic areas.     

Comparison of arterial and central venous cannulations using ultrasound guidance in pigs

OBJECTIVE: To evaluate the feasibility of ultrasound guided vascular access in pigs by comparing central venous and arterial cannulation techniques. ANIMALS: Twenty-two healthy female Pietrain pigs, 14-18 weeks old and weighing 51.1 +/- 4.3 kg (mean +/- SD). STUDY DESIGN: Comparative animal trial. MATERIALS AND METHODS: After induction of general anaesthesia, cannulation of the external jugular vein and internal carotid artery was attempted using real-time ultrasound guidance. The quality of the ultrasound picture was assessed on an analogue scale from 1 (excellent) to 5 (insufficient). Vessel size, cannulation success rate, number of puncture attempts and time from first puncture attempt until insertion of the Seldinger wire were recorded. RESULTS: Cannulation was successful in all but one animal in which a cut-down technique was performed. The arteries were significantly smaller than the veins (p < 0.001) resulting in a significantly prolonged cannulation time (p = 0.032) for insertion of arterial catheters without differences in success rate. In 89% of attempted cannulations, the Seldinger wire was inserted within 5 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: In anaesthetized pigs undergoing instrumentation for biomedical research, ultrasound-guided vascular access is a simple and rapid alternative to surgical cut-down. In veterinary anaesthesia, the technique might be useful in sedated or anesthetized pigs in which arterial or central venous access is required.     

RADIX: rhizoslide platform allowing high throughput digital image analysis of root system expansion

Background

Phenotyping of genotype-by-environment interactions in the root-zone is of major importance for crop improvement as the spatial distribution of a plant’s root system is crucial for a plant to access water and nutrient resources of the soil. However, so far it is unclear to what extent genetic variations in root system responses to spatially varying soil resources can be utilized for breeding applications. Among others, one limiting factor is the absence of phenotyping platforms allowing the analysis of such interactions.

Results

We developed a system that is able to (a) monitor root and shoot growth synchronously, (b) investigate their dynamic responses and (c) analyse the effect of heterogeneous N distribution to parts of the root system in a split-nutrient setup with a throughput (200 individual maize plants at once) sufficient for mapping of quantitative trait loci or for screens of multiple environmental factors. In a test trial, 24 maize genotypes were grown under split nitrogen conditions and the response of shoot and root growth was investigated. An almost double elongation rate of crown and lateral roots was observed under high N for all genotypes. The intensity of genotype-specific responses varied strongly. For example, elongation of crown roots differed almost two times between the fastest and slowest growing genotype. A stronger selective root placement in the high-N compartment was related to an increased shoot development indicating that early vigour might be related to a more intense foraging behaviour.

Conclusion

To our knowledge, RADIX is the only system currently existing which allows studying the differential response of crown roots to split-nutrient application to quantify foraging behaviour in genome mapping or selection experiments. In doing so, changes in root and shoot development and the connection to plant performance can be investigated.