Negligible contribution from roots to soil-borne phospholipid fatty acid fungal biomarkers 18:2ω6,9 and 18:1ω9

The phospholipid fatty acid biomarkers 18:1ω9, 18:2ω6,9 and 18:3ω3,6,9 are commonly used as fungal biomarkers in soils. They have, however, also been found to occur in plant tissues, such as roots. Thus, the use of these PLFAs as fungal biomarkers in sieved soil, which may still contain small remains of roots, has been questioned. We used data from a recent beech tree girdling experiment to calculate the contribution of roots to these biomarkers and were able to demonstrate that not more than 0.61% of 18:1ω9 and 18:2ω6,9 in sieved soil samples originated from roots (but 4% of 18:3ω3,6,9). Additionally, the abundance of the biomarker 18:2ω6,9 in the soil was found to be highly correlated to ectomycorrhizal root colonization, which further corroborates its fungal origin. PLFA biomarkers were substantially reduced in vital roots from girdled trees compared to roots of control trees (by up to 76%), indicating that the major part of PLFAs measured in roots may actually originate from ectomycorrhizal fungi growing inside the roots. We calculated, that even a near to 50% reduction in fine root biomass - as observed in the girdling treatment - accounted for only 0.8% of the measured decrease of 18:2ω6,9. Our results demonstrate that both 18:1ω9 and 18:2ω6,9 are suitable biomarkers for detecting fungal dynamics in soils and that especially 18:2ω6,9 is a reliable biomarker to study mycorrhizal dynamics in beech forests.     

Body and claw measurements and pressure distribution under the claws in calves of different cattle breeds

In 58 female calves of the three breeds German Holstein (GH), German Brown (GB) and German Red (GR) the body weight and height were determined at the age of 79 to 188 days. At the right front limb and the left hind limb the following claw measurements were taken: dorsal border length, diagonal length, heel length and height, angle of the dorsal border and hardness of the claw horn. Furthermore, the punctual pressure under the medial and the lateral claw of the right front limb and the left hind limb were determined using an electronic measuring system. The GH calves weighing 136.8 kg were heavier than GB, which was the tallest breed with 106.2 cm height at the sacral bone. GR calves were the smallest (99.1 cm) and weighed 121.1 kg. The length of the diagonal and the angle of the dorsal border were smaller at the hind limb of all breeds which resulted in a smaller area of ground surface for the claw of this limb. The GR calves had the longest and flattest claws. The GB showed the highest pressures per cm2 at the front limb with 25.6 N/cm2 under both claws as well as at the hind limb with 26.7 N/cm2. The AR had the smallest pressure load with 20.8 N/cm2 at the front limb and 20.2 N/cm2 at the hind limb. The animals showed a larger relative weight load and area of ground surface on the medial claws of the front and hind limbs than on the lateral claws. The highest pressures were found underneath the rear part of the medial claw in all breeds. GB calves showed the highest average pressures (33.3 N/cm2 at the front limb) while GR calves had the lowest (26.3 N/cm2 at the hind limb). GR calves had the highest claw hardness at all measuring positions.     

Diagnostic determination of melamine and related compounds in kidney tissue by liquid chromatography/tandem mass spectrometry

In 2007, it was determined that melamine, ammeline, ammelide, and cyanuric acid (abbreviated as MARC for melamine and related contaminants) had been added to wheat gluten and rice protein that were subsequently incorporated into pet food. The consumption of food tainted by MARC compounds was implicated in numerous instances of renal failure in cats and dogs. A method for the analysis of MARC compounds in kidney tissue using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) has been developed. MARC analytes were extracted by homogenization of kidney tissue in 50/40/10 acetonitrile/water/diethylamine. The homogenate was centrifuged, and an aliquot of supernatant was diluted with acetonitrile, concentrated, and fortified with a stable isotope-labeled analogue of melamine. Analytes were detected using atmospheric pressure chemical ionization and multiple reaction monitoring. Quantitation of positive samples was performed using the internal standard method and five-point calibration curves ranging between 50 and 1000 ng/mL of each analyte. The method was validated by analysis of replicate kidney tissue samples fortified with the individual analytes and by analysis of kidney samples fortified with melamine cyanurate powder at two different concentrations. This method was successfully used for routine postmortem diagnosis of melamine toxicosis in animals. Melamine was also detected by this method in paraffin-embedded tissue from animals suspected to have died of melamine toxicosis.     

Diagnosis of Taxus (yew) poisoning in a horse.

A 2-year-old bay Thoroughbred colt was found dead overnight in its stall without a known history of any illness, existing disease, or toxicant exposure. No information on the clinical signs before this animal's death was reported. A full necropsy was performed the next morning and revealed a mild to moderate degree of endocardial hemorrhages in both ventricles. Microscopic examination of the heart showed an acute mild multifocal necrosis of papillary muscles and ventricles. The stomach content contained approximately 2% Taxus alkaloids as determined by gas chromatography/mass spectrometry. In the past, diagnosis of Taxus poisoning has been mainly based on history of exposure and the presence of plant parts in the gastrointestinal tract. Pathological lesions associated with Taxus poisoning have not been published for horses. Therefore, this is the first report of cardiac lesions in a horse after lethal exposure to Taxus. On the basis of these findings, it is suggested that Taxus exposure needs to be considered in the differential diagnosis of horses that die suddenly or have cardiac lesions suggestive of Taxus exposure, even if intact plant parts are not identified in the stomach by the naked eye.     

Efficacy of milbemycin oxime in the treatment of canine generalized demodicosis: a retrospective study of 99 dogs (1995-2000)

Ninety-nine dogs diagnosed with generalized demodicosis were treated with milbemycin oxime. Cases diagnosed before two years of age were classified as juvenile-onset (53%) and those diagnosed after two years of age as adult-onset (47%). Dogs were considered cleared of mites when none could be demonstrated in scrapings and cured if no relapse was seen for 12 months. Eighty-five per cent (84/99) were cured with milbemycin oxime used for 1-6 months (mean 2.3 months) at a dosage of 0.5-1.6 mg kg-1 body weight (mean 0.75 mg kg-1). No significant difference in dosage or treatment time was seen between juvenile and adult cases. Chance of cure was significantly better in young animals (cured cases mean age 2.97 years) than in older animals (not cured cases mean age 8.02 years). Start of treatment early in the course of disease gave a significantly better chance of cure. Cases with severe pododemodicosis had less chance of a cure (9/11 not cured).     

Treatment of demodicosis in dogs: 2011 clinical practice guidelines

Background and Objectives – These guidelines were written by an international group of specialists with the aim to provide veterinarians with current recommendations for the diagnosis and treatment of canine demodicosis. Methods – Published studies of the various treatment options were reviewed and summarized. Where evidence in form of published studies was not available, expert consensus formed the base of the recommendations. Results – Demodicosis can usually be diagnosed by deep skin scrapings or trichograms; in rare cases a skin biopsy may be needed for diagnosis. Immune suppression due to endoparasitism or malnutrition in young dogs and endocrine diseases, neoplasia and chemotherapy in older dogs are considered predisposing factors and should be diagnosed and treated to optimize the therapeutic outcome. Dogs with disease severity requiring parasiticidal therapy should not be bred. Secondary bacterial skin infections frequently complicate the disease and require topical and/or systemic antimicrobial therapy. There is good evidence for the efficacy of weekly amitraz rinses and daily oral macrocyclic lactones such as milbemycin oxime, ivermectin and moxidectin for the treatment of canine demodicosis. Weekly application of topical moxidectin can be useful in dogs with milder forms of the disease. There is some evidence for the efficacy of weekly or twice weekly subcutaneous or oral doramectin. Systemic macrocyclic lactones may cause neurological adverse effects in sensitive dogs, thus a gradual increase to the final therapeutic dose may be prudent (particularly in herding breeds). Treatment should be monitored with monthly skin scrapings and extended beyond clinical and microscopic cure to minimize recurrences. Editor’s Note – A brief review article by R. Mueller has been published: Evidence‐based treatment of canine demodicosis, Tierarztl Prax Ausg K Kleintiere Heimtiere 2011; 39: 419–24. This is not considered to constitute duplication of the article published here in Veterinary Dermatology.     

Grain yield of wheat (Triticum aestivum L.) under long‐term heat stress is sink‐limited with stronger inhibition of kernel setting than grain filling

The aim of the study was to investigate source‐sink relations of wheat under continuous heat stress and to identify bottle necks of yield formation. A pot experiment was conducted in two climatic chambers exposing wheat plants (Triticum aestivum L. cv. Thasos) either to day/night temperatures of 20/20°C (control conditions) or of 30/25°C (heat stress) during the whole vegetation period in the absence of plant water deficit. Plants were harvested at four phenological stages: three‐node stage (DC 33), start of flowering (DC 61), grain filling (DC 75) and maturity (DC 94). Heat stress shortened the development phases of the plants and caused a significant decrease in total above‐ground biomass between 19% and 41%. At grain filling and at maturity, the reductions in total shoot biomass mainly resulted from grain yield depressions by 77% and 58%, respectively. The ear number per plant was significantly higher under heat stress in comparison with the control, at maturity it was more than doubled. On the contrary, under heat stress, the kernel number per ear was strongly decreased by 83% and 75% during grain filling and at maturity, respectively. The decrease in individual kernel weight was 23% at maturity. Thus, the heat‐stressed plants were able to strongly increase the number of ear‐bearing tillers which were able to set only a small number of kernels, yet these kernels showed good grain filling. The harvest index (HI) of heat‐stressed plants was significantly reduced by 36% (control: HI = 50.1% ± 0.4, heat: HI = 32.2% ± 0.9***). The plants in the stress treatment adapted to the adverse conditions by less biomass production which presumably allowed a higher transpiration without an increase in total water consumption. Nevertheless, under heat stress, the water use efficiency (WUE_grain) was strongly decreased by 62% as a result of a small grain yield. In ears and grains, the sucrose, glucose and fructose concentrations were not significantly different between control and heat stress at start of flowering and during grain filling. Thus, the supply of assimilates was not restricted (no source limitation). Sink capacity was reduced by heat stress, as lesser and smaller kernels were produced than in the control. Concerning sink activity, the sink‐limiting step during kernel set is probably the active transport of hexoses across the plasma membrane into the developing kernels, which could also affect grain filling. This needs to be investigated in more detail in further studies.     

Changes in compact bone microstructure of rats subchronically exposed to cadmium

Background

Chronic exposure to cadmium (Cd), even at low concentrations, has an adverse impact on the skeletal system. Histologically, primary and secondary osteons as basic structural elements of compact bone can also be affected by several toxicants leading to changes in bone vascularization and mechanical properties of the bone. The current study was designed to investigate the effect of subchronic peroral exposure to Cd on femoral bone structure including histomorphometry of the osteons in adult male rats.In our study, 20 one-month-old male Wistar rats were randomly divided into two experimental groups. In the first group, young males received a drinking water containing 30 mg of CdCl₂/L, for 90 days. Ten one-month-old males without Cd intoxication served as a control group. After 90 days of daily peroral exposure, body weight, femoral weight, femoral length, cortical bone thickness and histological structure of the femora were analysed.

Results

We found that subchronic peroral application of Cd had no significant effect on body weight, femoral length and cortical bone thickness in adult rats. On the other hand, femoral weight was significantly increased (P < 0.05) in Cd-intoxicated rats. These rats also displayed different microstructure in the middle part of the compact bone where vascular canals expanded into central area of substantia compacta and supplied primary and secondary osteons. Additionally, a few resorption lacunae which are connected with an early stage of osteoporosis were identified in these individuals. Histomorphometrical evaluations showed that all variables (area, perimeter, maximum and minimum diameter) of the primary osteons’ vascular canals, Haversian canals and secondary osteons were significantly decreased (P < 0.05) in the Cd group rats. This fact points to alterations in bone vascularization.

Conclusions

Subchronic peroral exposure to Cd significantly influences femoral weight and histological structure of compact bone in adult male rats. It induces an early stage of osteoporosis and causes reduced bone vascularization. Histomorphometrical changes of primary and secondary osteons allow for the conclusion that the bone mechanical properties could be weakened in the Cd group rats. The current study significantly expands the knowledge on damaging action of Cd on the bone.