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21.
Dwarf shrub litter is thought to be of poor quality and palatability for macro-decomposers. In laboratory feeding experiments, however, it was found that this litter type represents a potential food source for earthworms and millipedes. Here we tested whether this is true under natural conditions by conducting a 1 year field experiment on an abandoned alpine pasture in Tyrol (Austria). As the natural isotopic signatures of plant litter do not allow discriminating between different plant species, dwarf shrub litter, artificially enriched in 15N, was offered in experimental plots to the macro-decomposer community. Both the earthworm Lumbricus rubellus and the millipede Cylindrojulus fulviceps fed on dwarf shrub litter as indicated by their increased δ15N signatures, but IsoError analysis indicated a clear preference for grass litter for all macro-decomposer species investigated.Soil δ15N signatures were only marginally affected by the experimental provision of 15N-enriched dwarf shrub litter, whereas litter from other, unlabelled, plants became enriched by the isotopic tracer to some extent. Except for one grass species, plants harvested at the end of the experiment were not enriched in 15N, suggesting that the N-uptake from decomposing litter material by plants on abandoned alpine pastureland is slow.  相似文献   
22.
Toona ciliata (Australian red cedar), a valuable hardwood species, requires a nurse-tree overstorey to prevent damage from frost and drought in some regions of north-eastern Argentina. Different nurse-species offer different degrees of protection, resource competition, and thinning revenues. In addition, choice of nurse-species will influence trade-offs between T. ciliata establishment success, stem quality and productivity as well as revenue from intermediate and final harvests. We tested the effects of overstorey species and planting density on underplanted T. ciliata survival, stem morphology and growth. Initial stand densities of nurse-species Pinus taeda (625 stems/ha), P. elliottii × P. caribaea (625 stems/ha), and Grevillea robusta (833 stems/ha) were thinned by 0%, 25%, 50%, and 75% in three experiments, each using a randomized block design. Initial mortality, light availability and growth of T. ciliata, as well as growth of its nurse-trees, were measured before and two years after thinning. In the third year, we characterized T. ciliata stem morphology (straightness and height-to-diameter-ratio) and destructively harvested a subsample of T. ciliata in order to investigate T. ciliata biomass production and allocation patterns in response to overstorey species, thinning density and light availability. T. ciliata mortality was lower when planted under G. robusta than the pines, and increased in plots with greater exposure to solar radiation. T. ciliata productivity was also greater under G. robusta than under the pines, and was generally greatest where any of the nurse-species were thinned by 75%. Stem form was best when growing under P. taeda and in stands thinned by 50%, regardless of nurse-species. With the exception of early mortality, light levels appeared to have limited effects on T. ciliata growth dynamics. Neither growth rate nor stem morphology was strongly correlated with light availability. Total overstorey basal-area was highest in P. taeda stands and individual overstorey tree growth generally increased with decreasing stand densities, except for slower height growth of G. robusta in more open stands. Thinning operations resulted in sawn-wood revenue for the pine species only. Because stand productivity and stem quality were optimized under different nurse-species and thinning treatments, we conclude that the choice of nurse-species and thinning intensity will depend on management objectives and will change with market preferences and conditions.  相似文献   
23.
Investigations of 1167 dairy cows out of 105 herds with fertility disorders on secretion of Coxiella burnetii (C. burnetii) by the genitals as well as serological studies of these animals using ELISA demonstrated that C. burnetii infections are significantly associated with abortions but not with repeated inseminations without success or vaginal excretions. The demonstration of an increased risk of infections for persons caring for those dairy herds could be shown by a total of 253 serological studies. A comparison of these studies of farmers caring for dairy herds suffering from abortions a seroprevalence of > or = 20% showed that these persons revealed significantly more frequent antibodies against C. burnetii than farmers of the group compared with. Further studies showed that in herds suffering from abortions a seroprevalence of > or = 20% means an additional risk of infections of farmers. Vice versa abortions of the cows in herds with a seroprevalence of > or = 20% imply an additional infectious risk.  相似文献   
24.
The aim of this study was to evaluate the accuracy of serum beta-hydroxybutyrate (beta-OHB) measurements for the diagnosis of diabetic ketoacidosis (DKA) in dogs. One hundred sixteen diabetic dogs were prospectively enrolled in the study: 18 insulin-treated (IT) diabetic dogs that had a positive urine ketone test and 88 untreated, newly diagnosed diabetic dogs. Venous blood gas tensions and pH, serum glucose and urea nitrogen (SUN), and electrolyte (Na+, Cl-, and K+) and urine acetoacetate (AA) concentrations were measured concurrently with serum beta-OHB concentrations. On the basis of laboratory findings, the patients were assigned to I of 3 groups: diabetic ketoacidosis (n = 43); diabetic ketosis (DK, n = 41); and nonketotic diabetes (NDK, n = 31). Serum beta-OHB concentrations differed significantly (P < .001) among the study groups. Although marked differences in beta-OHB concentrations were found, a considerable overlap exists between the distributions of dogs with DK and those with DKA. The overall accuracy of beta-OHB determination as a diagnostic test for DKA, determined by the area under the receiver operating characteristic (ROC) curve, was 0.92. In the 1.9- to 4.8-mmol/L range, serum beta-OHB determination sensitivity varied from 100 to 35.7%, whereas specificity varied from 39 to 100%. The cutoff value of 3.8 mmol/L showed the best equilibrium between specificity (95%), sensitivity (72%), and likelihood ratio (14.8). We concluded that the quantitative measurement of serum beta-OHB may be a potential tool for diagnosing and monitoring ketosis and ketoacidosis in diabetic dogs.  相似文献   
25.
Progressive multisystemic disease caused by Blastomyces dermatitidis was diagnosed in a 17-year-old Quarter horse broodmare. The mare had been treated unsuccessfully with antibiotics for mastitis 3 months postpartum. The disease progressed to exudative cutaneous lesions affecting the ventrum, pectoral region, and limbs accompanied by weight loss across several months. Yeast bodies were observed in swabs of the cutaneous exudate, suggesting a clinical diagnosis of blastomycosis. Following referral, pleural effusion, cavitated lung lesions, and hyperproteinemia were identified, and the mare was euthanized because of poor prognosis. Necropsy revealed extensive pyogranulomas in the mammary gland, skin, subcutaneous tissues, and lungs, accompanied by thrombi in major blood vessels of the lungs and hind limbs. Histologically, pyogranulomatous inflammation was evident in many tissues, and fungal organisms were seen in sections of mammary gland, skin, subcutis, pericardium, and lung. Blastomyces dermatitidis was cultured from mammary tissue, lungs, lymph node, and an inguinal abscess. Although blastomycosis is endemic in the area of origin of the mare in northwestern Wisconsin, the disease is extremely rare in horses and hence easily misdiagnosed. Unique features of this case included the extent of mammary gland involvement and the presence of thrombi in multiple sites.  相似文献   
26.
27.
We have studied the effect of artificial modification of leaf area on inflorescence and floral quality in Antirrhinum majus. We used two treatments where we clipped all the leaves except the first three pairs of true leaves, or we cut every leaf visible by the time the plant had six leaf pairs. Decreased leaf area caused a decrease in stem elongation that could be traced back to a decrease in internode elongation. Leaves left on the plant increased their size beyond control. Inflorescence quality was strongly affected since total floral number showed a strong decrease with reduced leaf area. In contrast, floral size hardly changed. Breeding programs in Antirrhinum should take into account growth conditions affecting leaf area when searching for changes in inflorescence quality while floral size can be screened independently of this factor.  相似文献   
28.
Lateral thoracic nerve reflex latencies values were measured in ponies using a simple, non-invasive technique. The reflex was elicited using an external triggering hammer attached to an electrodiagnostic unit. The resulting evoked, compound muscle action potentials were recorded with electrodes, which were placed over the 6th ribs or 11th rib level with the axilla. Two superimposed repeats of 4 signal-averaged sweeps of 50 or 100 milliseconds were recorded and the estimated reflex pathway was measured for each subject in order to calculate the reflex latencies and latency velocities. Mean left and right 6th rib peak latencies were not significantly different from each other ( P = .609), but left 6th rib latencies were shorter than those recorded from the 11th rib ( P < .0001), substantiating the existence of an indirect (central) pathway to the reflex. The calculated left and right 6th rib latency velocities were not significantly different from each other ( P = .58) but left 6th rib latency velocities were different from left 11th rib ( P = .009). The calculated latency velocities were within the broad range for corticospinal tract motor conduction velocities and comparable to magnetic motor evoked latency velocities. The use of lateral thoracic reflex latency measurements to objectively identify the site of spinal cord lesions is discussed.  相似文献   
29.
Relatively little is known about soil organic carbon (SOC) dynamics in montane ecosystems of the semi-arid western U.S. or the stability of current SOC pools under future climate change scenarios. We measured the distribution and quality of SOC in a mosaic of rangeland-forest vegetation types that occurs under similar climatic conditions on non-calcareous soils at Utah State University's T.W. Daniel Experimental Forest in northern Utah: the forest types were aspen [Populus tremuloides] and conifer (mixture of fir [Abies lasiocarpa] and spruce [Picea engelmannii]); the rangeland types were sagebrush steppe [Artemisia tridentata], grass-forb meadow, and a meadow-conifer ecotone. Total SOC was calculated from OC concentrations, estimates of bulk density by texture and rock-free soil volume in five pedons. The SOC quality was expressed in terms of leaching potential and decomposability. Amount and aromaticity of water-soluble organic carbon (DOC) was determined by water extraction and specific ultra violet absorbance at 254 nm (SUVA) of leached DOC. Decomposability of SOC and DOC was derived from laboratory incubation of soil samples and water extracts, respectively.

Although there was little difference in total SOC between soils sampled under different vegetation types, vertical distribution, and quality of SOC appeared to be influenced by vegetation. Forest soils had a distinct O horizon and higher SOC concentration in near-surface mineral horizons that declined sharply with depth. Rangeland soils lacked O horizons and SOC concentration declined more gradually. Quality of SOC under rangelands was more uniform with depth and SOC was less soluble and less decomposable (i.e., more stable) than under forests. However, DOC in grass-forb meadow soils was less aromatic and more bioavailable, likely promoting C retention through cycling. The SOC in forest soils was notably more leachable and decomposable, especially near the soil surface, with stability increasing with soil depth. Across the entire dataset, there was a weak inverse relationship between the decomposability and the aromaticity of DOC. Our data indicate that despite similar SOC pools, vegetation type may affect SOC retention capacity under future climate projections by influencing potential SOC losses via leaching and decomposition.  相似文献   

30.
The INHAND Proposal (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) has been operational since 2005. A Global Editorial Steering Committee (GESC) manages the overall objectives of the project and the development of harmonized terminology for each organ system is the responsibility of the Organ Working Groups (OWG), drawing upon experts from North America, Europe and Japan.Great progress has been made with 9 systems published to date – Respiratory, Hepatobiliary, Urinary, Central/Peripheral Nervous Systems, Male Reproductive and Mammary, Zymbals, Clitoral and Preputial Glands in Toxicologic Pathology and the Integument and Soft Tissue and Female Reproductive System in the Journal of Toxicologic Pathology as supplements and on a web site – www.goreni.org. INHAND nomenclature guides offer diagnostic criteria and guidelines for recording lesions observed in rodent toxicity and carcinogenicity studies. The guides provide representative photo-micrographs of morphologic changes, information regarding pathogenesis, and key references. During 2012, INHAND GESC representatives attended meetings with representatives of the FDA Center for Drug Evaluation and Research (CDER), Clinical Data Interchange Standards Consortium (CDISC), and the National Cancer Institute (NCI) Enterprise Vocabulary Services (EVS) to begin incorporation of INHAND terminology as preferred terminology for SEND (Standard for Exchange of Nonclinical Data) submissions to the FDA. The interest in utilizing the INHAND nomenclature, based on input from industry and government toxicologists as well as information technology specialists, suggests that there will be wide acceptance of this nomenclature. The purpose of this publication is to provide an update on the progress of INHAND.  相似文献   
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