Recent advances in the spectroscopic characterization of soil humic substances and their ecological relevance

Non destructive spectroscopic methods such as ¹³C- and ¹⁵N-NMR provide new insights into the structure of humic substances. Solid state NMR is capable of studying complete native soils by the CPMAS-technique. By means of nitrogen 15-enriched composts it is suggested that nitrogen in soil organic matter is mainly located in amide and peptide structures. Most probable assignments are given. The investigation of humification processes in forest soils is possible via an approach which uses several fractionation techniques in combination with degradative and non-degradative analytical techniques. Besides structure analysis, the ¹³C-NMR-spectroscopy provides important information about the functions of humic substances. By using ¹³C-enriched xenobiotics the binding mechanism to organic matter can be elucidated on a molecular basis. Molecular fluorescence spectrometry, a non-invasive method, is a powerful tool for the quantitative characterization of metal ion complexation by dissolved organic matter in aqueous leaf litter extracts in terms of conditional stability constants and metal binding capacities.     

Unique genotypes of Mycobacterium avium subsp. paratuberculosis strains of Type III

Mycobacterium avium subsp. paratuberculosis (MAP) strains with two new IS900 restriction fragment length polymorphism (RFLP) BstEII types intermediate suspected to belong to the MAP Type III group were isolated from migrating sheep in Germany. Such strains have only been sporadically identified in a few studies. For a better understanding of the genomic diversity of MAP with regard to specific host associations, geographic origin, and the discussed classification into Type I, Type II and Type III, these isolates were further characterized.Using IS900-RFLP, the isolates showed unique fingerprint patterns after BstEII-, PstI-, PvuII- and BamHI-digestion which had not been published before. Additionally, using gyrB-PCR-restriction endonuclease analysis (PCR/REA) and mycobacterial interspersed repetitive unit (MIRU)-PCR, the two strains showed differences to known patterns of the Type I as well as the Type II group. Unique genotypes were also obtained with multilocus short sequence repeat (MLSSR) sequencing and MIRU-variable-number tandem-repeat (VNTR) typing.As expected, genomic profiles identical to the Type I and different from the Type II group were detected by IS1311-PCR/REA, IS1311 sequencing as well as by Large Sequence Polymorphism analysis (LSP^A 8, 17, 20, 4-II, and 18).In addition to distinct growth characteristics, the unique genotypes of the studied sheep strains support their affiliation to the assumed third group within the MAP subspecies and suggest the existence of different genotypes within this Type III group. The results could serve as further evidence that Type I and Type III groups are more closely related to each other than to the bovine Type II group.     

Serum cardiac troponin I and cardiac troponin T concentrations in dogs with gastric dilatation-volvulus

OBJECTIVE: To determine whether serum concentrations of cardiac troponin I (cTnI) and cardiac troponin T (cTnT) are increased in dogs with gastric dilatationvolvulus (GDV) and whether concentrations correlate with severity of ECG abnormalities or outcome. DESIGN: Prospective case series. ANIMALS: 85 dogs with GDV. PROCEDURE: Serum cTnl and cTnT concentrations were measured 12 to 24, 48, 72, and 96 hours after surgery. Dogs were grouped on the basis of severity of ECG abnormalities and outcome. RESULTS: cTnl and cTnT were detected in serum from 74 (87%) and 43 (51%) dogs, respectively. Concentrations were significantly different among groups when dogs were grouped on the basis of severity of ECG abnormalities (none or mild vs moderate vs severe). Dogs that died (n = 16) had significantly higher serum cTnI (24.9 ng/ml) and cTnT (0.18 ng/ml) concentrations than did dogs that survived (2.05 and < 0.01 ng/ml, respectively). Myocardial cell injury was confirmed at necropsy in 4 dogs with high serum cardiac troponin concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that concentrations of cTnI and cTnT suggestive of myocardial cell injury can commonly be found in serum from dogs with GDV and that serum cardiac troponin concentrations are associated with severity of ECG abnormalities and outcome.     

Local knowledge helps select species for forest restoration in a tropical dry forest of central Veracruz, Mexico

Species for restoration forestry on degraded lands in the tropics are often restricted to a few well-known exotic timber species. This selection frequently leads to failed projects, as local people expect trees to cover a number of uses, not only timber. We studied local knowledge of the usefulness, scarcity and importance for wildlife of native tree species in central Veracruz, Mexico, a region with mainly secondary vegetation and remnants of tropical dry forest. Data were obtained from several workshops, in depth interviews of 40 key informants, field walks with informants, and botanical collections. Analysis included indices for cultural importance, scarcity and wildlife relevance. We documented 76 species in one or more of the categories, from primary, secondary, agroforestry and riparian habitats. Fabaceae was the most important family. All of the species were useful for humans, mainly for rural construction, food, fence posts and fuel. Two-thirds of the species were considered scarce though they were not necessarily rare??some were highly useful, overexploited species with populations insufficient for demand; this category included five of the ten most important species culturally. Also, two-thirds of the tree taxa were considered important for wildlife, especially species of Moraceae. The study shows that the local population is highly aware of the varying functions of trees in the landscape. However, few of the important species are available from regional nurseries. We propose a number of species for restoration forestry, agroforestry systems and enrichment plantings that would be valued by landowners.     

Comparison of different laboratory methods with lysimetry for soil solution composition — experimental and model results

Compositions of soil solution obtained by the following methods were compared with those obtained by lysimetry: centrifugation; 2:1 extracts of air dried (2:1_dried) and field moist (2:1_moist) samples; saturation extracts; the ‘equilibrium soil pore solution’︁ method using columns with undisturbed (ESPS) and composited soil (ESPS_comp); and a method using pressure. Two soil depths of a Spodic Dystric Cambisol at Solling, Germany, were sampled with 10 to 12 replications. A coupled equilibrium model was used to describe the effect of soil to solution ratio on the solution composition. The model included multiple cation exchange and inorganic complexation, and for the subsoil solubility products of AlOHSO₄ and Al(OH)₃. Saturation extracts gave similar results as lysimetry and thus may be useful for calculating output fluxes. However, biological transformations (N mineralisation, solubilisation of organic matter) occurred during the preparation of saturation extracts. Composition of soil solutions obtained by either 2:1_dried extracts or centrifugation differed greatly from the results of other methods, indicating that these two methods may not be the best means to investigate equilibrium soil solutions. The values of molar ion ratios depended largely on the method used to obtain soil solutions: Ca²⁺/Al³⁺ ratios for each depth ranged from less than 0.3 (which suggests that liming is required urgently) to greater than 1 (liming not necessary). Modelling described the effect of soil to solution ratio on element concentrations for the methods pressure, saturation extracts, ESPS_comp and 2:1_moist extracts qualitatively with a few exceptions. The model suggested that differences in element concentrations using these methods may be mainly due to dilution, cation exchange and solubilisation of sparingly soluble salts, depending on the soil to solution ratio used.     

Effects of deoxynivalenol exposure time and contamination levels on rainbow trout

The trend toward using plant‐based ingredients in aquafeeds is set to intensify; however, mycotoxin contamination might be a challenge. Two diets, with deoxynivalenol (DON) levels of 1,166 μg/kg (1.1 DON) and 2,745 μg/kg (2.7 DON), were prepared for short‐term DON exposure (50 days). A third diet with a low DON level of 367 μg/kg (0.3 DON) was prepared for long‐term DON exposure (168 days). Ingestion of DON by trout during both short‐term/high‐dosage exposure (50 days; 1,166 μg/kg and 2,700 μg/kg DON) and long‐term/low‐dosage exposure (168 days; 367 μg/kg DON) impacted growth performance and, to a lesser extent, liver enzyme parameters (2.7 DON). Histopathology showed mild to moderate changes in the liver but not in the other sampled tissues (intestine and kidney). Despite these effects, short‐term exposure of rainbow trout to high doses of DON did not result in increased susceptibility to Yersinia ruckeri. In both the short‐ and long‐term studies, the effects of DON showed a high interindividual variability. The present study confirms that subclinical levels of mycotoxins affect rainbow trout. The effects of such low mycotoxin levels could be masked by other production challenges while still negatively affecting productivity.     

Microscale-scale measurement of potential nitrification rates of soil aggregates

To improve our knowledge about the effect of soil structure on potential nitrification (PN) rates in different soil aggregate fractions, we adapted and validated the standard method based on International Organization of Standardization (ISO) 15685 to small sample volumes. This assay was used to determine the distribution of PN in soil aggregates obtained from three different sites (natural grassland, agricultural land and forest). Overall, the external surface layers of the aggregates showed higher PN rates than the interior fractions of the aggregates. These differences were more clear in clayey than in sandy soils.     

Radiation exposure of the staff during standardised radiography of dogs and cats

The knowledge of the radiation exposure of the staff involved in X-ray examinations is one precondition for an optimisation of radiation protection. Hence the radiation exposure of the staff during X-ray examinations of dogs and cats was investigated in the Clinic for Small Animals. The study includes at least ten measurements for each of thirteen X-ray examinations of a dog and four of a cat. The equivalent doses of eye lens, thyroid, chest, hands, gonads, and lower leg were measured using TLD (LiF:Mg,Cu,P). The maximum values of 44.3 and 48.3 microSv were measured on the eye lens and the thyroid, respectively. The median and mean values of the equivalent doses on the seven measuring positions with the exception of eye lens (6.0 microSv) are lower than 5 microSv per radiograph. More than 95% of the equivalent doses on chest, hands, gonads, and lower leg are smaller than 2 microSv. Particularly eye lenses and thyroid are exposed to measurable doses. Altogether the radiation exposure of the staff is relatively low. Hence a manual fixation of animals is justifiable if the fundamental rules of radiation protection are observed.     

Quantitative resistance level (MIC) of Pasteurella multocida isolated from pigs between 2004 and 2006: national resistance monitoring by the BVL

The National Resistance Monitoring of the Federal Office of Consumer Protection and Food Safety (BVL) is to determine the prevalence of resistance of bacterial pathogens from animals using a valid database. From 2004 to 2006, a total of 1,472 Pasteurella multocida strains isolated from pigs with acute respiratory tract diseases was submitted to the BVL and examined. Of these, 1,11 (75.5 %) were included in the study and tested using 24 different antimicrobial substances. The results showed that the resistance level is generally low, with the exception of the substances tetracycline, trimethoprim, and the combination trimethoprim/sulfamethoxazole. It also became clear that resistance data need to be evaluated separately for each of the animal production categories, so that a realistic figure of the current resistance level can be presented. This knowledge provides information about the resistance situation in Germany, and helps deduce the necessary management measures that must be taken to minimize resistance to antibiotics. Furthermore, it provides valuable information that can form the basis for empirical therapy, so that the National Resistance Monitoring makes an important contribution to the safety of food derived from animals and consequently aids the improvement of consumer protection.