Amounts and degradability of dissolved organic carbon from foliar litter at different decomposition stages     

Axel Don  Karsten Kalbitz 《Soil biology & biochemistry》2005,37(12):2171-2179

Litter is one of the main sources of dissolved organic carbon (DOC) in forest soils and litter decomposition is an important control of carbon storage and DOC dynamics. The aim of our study was to evaluate (i) effects of tree species on DOC production and (ii) relationships between litter decomposition and the amount and quality of DOC. Five different types of leaves and needles were exposed in litterbags at two neighboring forest sites. Within 12 months we sampled the litterbags five times and leached aliquots of field moist litter in the laboratory. In the collected litter percolates we measured DOC concentrations and recorded UV and fluorescence spectra in order to estimate the aromaticity and complexity of the organic molecules. Furthermore, we investigated the biodegradability of DOC from fresh and decomposed litter during 6 weeks incubations. Fresh sycamore maple litter released the largest amounts of DOC reaching about 6.2% of litter C after applying precipitation of 94 mm. We leached 3.9, 1.6, 1.0 and 3.3% carbon from fresh mountain ash, beech, spruce and pine litter, respectively. In the initial phase of litter decomposition significantly decreasing DOC amounts were released with increasing litter mass loss. However, after mass loss exceeds 20% DOC production from needle litter tended to increase. UV and fluorescence spectra of percolates from pine and spruce litter indicated an increasing degree of aromaticity and complexity with increasing mass loss as often described for decomposing litter. However, for deciduous litter the relationship was less obvious. We assume that during litter decomposition the source of produced DOC in coniferous litter tended toward a larger contribution from lignin-derived compounds. Biodegradability of DOC from fresh litter was very high, ranging from 30 to 95% mineralized C. DOC from degraded litter was on average 34% less mineralizable than DOC from fresh litter. Taking into account the large DOC production from decomposed needles we can assume there is an important role for DOC in the accumulation of organic matter in soils during litter decomposition particularly in coniferous forests.  相似文献   

Feline lymphocytes: observations on surface membrane concanavalin A receptor mobility     

W S Nichols  J E Dunlap  L C Hebebrand  L E Mathes  R G Olsen 《American journal of veterinary research》1979,40(7):959-961

The mechanics of concanavalin A receptor mobility of the feline lymphocyte surface membrane were investigated, utilizing fluorescein-labeled lectin to quantitate lymphocyte capping. The results of this study indicated that lectin concentration and buffer selection were critical for extensive receptor redistribution with cap formation of feline lymphocytes. Maximal capping was obtained with 50 microgram of concanavalin A/ml of minimal essential medium. The mean capping rate of peripheral blood lymphocytes increased significantly with colchicine exposure at 10(-7) M concentration. The mean values of capping increased slightly with advancing age of feline donors, although this difference was not statistically significant. Concurrent work has indicated that concanavalin A capping may be useful in the study of immunosuppression in feline leukemia virus-infected cats.  相似文献   

Bur buttercup poisoning of sheep     

J D Olsen  T E Anderson  J C Murphy  G Madsen 《Journal of the American Veterinary Medical Association》1983,183(5):538-543

Bur buttercup (Ceratocephalus testiculatus) has not been considered to be poisonous, but the sudden death loss of 150 ewes while grazing it prompted study of the plant. It was found that bur buttercup can be highly toxic to sheep, with a lethal dose being as little as 500 g of green plant for a 45-kg sheep. Clinical signs of bur buttercup poisoning are weakness, depression, diarrhea, labored breathing, anorexia, and occasional fever. Postmortem findings include inflammation and edema of the rumen; hemorrhage in the left ventricle of the heart; congestion of the lungs, liver, and kidneys; and excessive fluid in the thoracic and abdominal cavities.  相似文献   

Feline leukemia virus vaccine: new developments     

M G Lewis  L J Lafrado  K Haffer  J Gerber  R L Sharpee  R G Olsen 《Veterinary microbiology》1988,17(3):297-308

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Feed aversion induced by intraruminal infusion with larkspur extract in cattle     

J D Olsen  M H Ralphs 《American journal of veterinary research》1986,47(8):1829-1833

Twelve Hereford heifers were infused with larkspur extract (group 1, n = 4), lithium chloride solution (group 2, n = 4), or sodium chloride solution (group 3, n = 4). After 3 weeks of being fed basal ration (meadow grass hay), all heifers were offered a ration of alfalfa pellets (3,400 g) in a 2-phase, single-day feeding regimen. In phase 1, the amount eaten within 45 minutes was measured by weigh-back of uneaten pellets. In phase 2, cattle that ate greater than 150 g of pellets in phase 1 were offered the balance of uneaten pellets and were infused with their respective designated solution. Five pairings of pellet feedings and appropriate infusions were given at 2- or 3-day intervals to initially induce feed aversion. Heifers in groups 1 and 2 developed a strong aversion to pellets by the 5th feeding. Persistence of aversion was tested twice at weekly intervals. Infusion of cattle with larkspur extract or lithium chloride solution induced a persistent aversion to an otherwise palatable feed.  相似文献   

Plasma growth hormone concentrations in cows before, during, and after parturition     

J D Olsen  A Trenkle  D A Witzel  J S McDonald 《American journal of veterinary research》1974,35(8):1131-1134

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Validation of the Fluorescence Polarisation Assay (FPA) for the serological diagnosis of brucellosis     

Bahn P  Nöckler K 《Berliner und Münchener tier?rztliche Wochenschrift》2005,118(9-10):372-376

In order to evaluate suitability of Fluorescence Polarisation Assay (FPA) for serological Brucella diagnostic, 1739 samples of sera from cattle, pigs, sheep and goats (65 Brucella-positive, 960-negative and 714 false-positive sera) were investigated at a dilution of 1:10. The cut-off was adjusted by means of ROC analysis. Furthermore, the serum samples were examined for Brucella antibodies using SAT, CFT and ELISA and the results were evaluated regarding sensitivity and specificity. FPA, SAT, CFT and ELISA attained a sensitivity of 92.3, 98.5, 84.6 and 86.2%. In comparison, specificity varied with 87.8, 72.6, 92.5 and 85.8%, respectively. Accordingly, FPA is a suitable test for serodiagnosis of brucellosis.  相似文献   

The use of sarmazenil in the treatment of a moxidectin intoxication in a foal     

Müller JM  Feige K  Kästner SB  Naegeli H 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2005,19(3):348-349

A13-day-old Arabian Thoroughbred filly weighing 40 kg (88 1b) was presented to the University of Zurich Equine Clinic with a history of depression after deworming with moxidectin at a dose of 2 mg/kg (recommended dose 0.4 mg/kg body weight)^a the day before admission. The foal was found recumbent 12 hours after drug administration and was in an unconscious state 6 hours later  相似文献   

Isolation of methicillin-resistant Staphylococcus aureus from a non-healing abscess in a cat     

Bender JB  Torres SM  Gilbert SM  Olsen KE  LeDell KH 《The Veterinary record》2005,157(13):388-389

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Use of real-time reverse transcriptase polymerase chain reaction assay and cell culture methods for detection of swine influenza A viruses   总被引：4，自引：0，他引：4  

Landolt GA  Karasin AI  Hofer C  Mahaney J  Svaren J  Olsen CW 《American journal of veterinary research》2005,66(1):119-124

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