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51.
The authors visited some deer farms in Northeastern China in 1991 and 1993. The seven subspecies of Asian Wapiti (Cervus elaphus) were detected by observing the animal’s appearance and analyzing the video information. The status of taxonomy research
in China was also discussed. 相似文献
52.
Assessment of allometric algorithms for estimating leaf biomass, leaf area index and litter fall in different-aged Sitka spruce forests 总被引:1,自引:0,他引:1
Tobin Brian; Black Kevin; Osborne Bruce; Reidy Brian; Bolger Tom; Nieuwenhuis Maarten 《Forestry》2006,79(4):453-465
The relationship between leaf area and diameter at breast height(d.b.h.) or sapwood area (AS) has been used to estimate standleaf area or biomass of forest canopies. It has been suggestedthat intra-specific variations in the relationship between standleaf area and d.b.h. or AS can introduce a systematic errorin these estimates for younger and older stands unless additionalparameters relating to canopy structure are included in allometricfunctions. We collected data from a Sitka spruce chronosequenceto parametrize and test different algorithms for the estimationof foliar biomass (FB) and litter inputs over a range of forestages. FB estimates were significantly improved when additionalbiometric information relating to crown structure (canopy opennessand height of live crown) was included in the models. Althoughthe use of the relationship between leaf area and AS for theestimation of leaf area is justified by theoretical considerations(pipe model theory), we show that d.b.h. and other canopy parametersprovided the most robust estimation of leaf area across different-agedstands. Our results also suggest that the accuracy of litterinput estimates depends on needle retention time and annualturnover rate, particularly immediately before and after canopyclosure. 相似文献
53.
Effects of forest floor planting and stock type on growth and root emergence of Pinus contorta seedlings in a cold northern cutblock 总被引:1,自引:0,他引:1
D. Bruce Campbell Steven Kiiskila Leanne J. Philip Janusz J. Zwiazek Melanie D. Jones 《New Forests》2006,32(2):145-162
A two-year field trial was conducted to determine the growth response, and root emergence pattern of interior lodgepole pine
(Pinus contorta Dougl. var. latifolia Engelm.) seedlings in response to container type and forest floor removal. Seedlings were grown in StyroblocksTM, CopperblocksTM, or AirBlocksTM, and were planted directly into the undisturbed forest floor or into manually prepared planting spots where the forest floor
had been scraped away to expose the mineral soil. Seedlings planted into scalped planting spots exhibited marginally but significantly
(7%) greater above-ground growth rates (seedling stem volume); whereas seedlings planted into the forest floor produced significantly
more (11%) new roots. There were no differences in above- or below-ground biomass. Seedlings grown in CopperblockTM containers produced a higher proportion of roots near the top of the plug when tested at lifting, however this pattern was
not observed in the field. Given that scalping is more costly than forest floor planting, and that the increased shoot growth
was relatively small, we recommend that forest floor planting be considered as an alternative to manual spot scalping for
sites, such as the site tested here: those with cold, but well-drained soils and where competition from other plants is not
a serious problem. 相似文献
54.
A VALENTINE‐SHAPED CARDIAC SILHOUETTE IN FELINE THORACIC RADIOGRAPHS IS PRIMARILY DUE TO LEFT ATRIAL ENLARGEMENT
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Trisha J. Oura Aisha N. Young Bruce W. Keene Ian D. Robertson Dennis E. Jennings Donald E. Thrall 《Veterinary radiology & ultrasound》2015,56(3):245-250
Conflicting information has been published regarding the cause of a valentine‐shaped cardiac silhouette in dorsoventral or ventrodorsal thoracic radiographs in cats. The purpose of this retrospective, cross‐sectional study was to test the hypothesis that the valentine shape is primarily due to left atrial enlargement. Images for cats with a radiographic valentine‐shaped cardiac silhouette and full echocardiography examination were retrieved and independently reviewed. A subjective scoring system was used to record severity of radiographic valentine shape. Subjective radiographic evidence of left atrial enlargement in a radiographic lateral projection and a final diagnosis based on medical records were also recorded. A total of 81 cats met inclusion criteria. There was a strong positive correlation (P < 0.001) between echocardiographic left atrial size and severity of radiographic valentine shape. There was no effect of echocardiographic right atrial size on the severity of valentine shape, except when concurrent with severe left atrial enlargement. In this situation, right atrial enlargement increased the likelihood of observing a severe valentine shape. There was no effect of right atrial enlargement on the shape of the cardiac silhouette when left atrial enlargement was absent or only mild to moderate. There was no correlation between the category of final diagnosis of cardiac disease and the severity of valentine shape. Findings from this study supported the hypothesis that a valentine‐shaped cardiac silhouette in radiographs is due primarily to left atrial enlargement in cats, with right atrial enlargement only impacting the shape if concurrent with severe left atrial enlargement. 相似文献
55.
56.
Bruce K. Wobeser 《The Canadian veterinary journal. La revue veterinaire canadienne》2015,56(4):359-360
During a widespread anthrax outbreak in Canada, miniature horses were vaccinated using a live spore anthrax vaccine. Several of these horses died from an apparent immune-mediated vasculitis temporally associated with this vaccination. During the course of the outbreak, other miniature horses from different regions with a similar vaccination history, clinical signs, and necropsy findings were found. 相似文献
57.
Nora Denk Vikram Misra Lynne S. Sandmeyer Bianca B. Bauer Jaswant Singh George W. Forsyth Bruce H. Grahn 《Canadian journal of veterinary research》2015,79(1):31-38
The objective of this study was to develop a murine retinal/choroidal/scleral explant culture system to facilitate the intravitreous delivery of vectors. Posterior segment explants from adult mice of 2 different age groups (4 wk and 15 wk) were cultured in serum-free medium for variable time periods. Tissue viability was assessed by gross morphology, cell survival quantification, activated caspase-3 expression, and immunohistochemistry. To model ocular gene therapy, explants were exposed to varying transducing units of a lentiviral vector expressing the gene for green fluorescent protein for 48 h. Explant retinal cells remained viable for approximately 1 wk, although the ganglion cell layer developed apoptosis between 4 and 7 d. Following vector infusion into the posterior segment cups, viral transduction was noted in multiple retinal layers in both age groups. An age of donor mouse influence was noted and older mice did not transduce as well as younger mice. This explant offers an easily managed posterior segment ocular culture with minimum disturbance of the tissue, and may be useful for investigating methods of enhancing retinal gene therapy under controlled conditions. 相似文献
58.
Gabhan Chalmers John McLean D. Bruce Hunter Marina Brash Durda Slavic David L. Pearl Patrick Boerlin 《Canadian journal of veterinary research》2015,79(2):129-135
Pododermatitis is a disease of concern for mink breeders in Canada and worldwide, as it causes discomfort and lowers the breeding rates on farms affected by the disease. Unfortunately, the etiology and pathogenesis of pododermatitis are still unknown. In this study, we compared Staphylococcus spp. and Streptococcus canis isolates from healthy mink with isolates from animals with pododermatitis on 2 farms in Ontario. Almost all hemolytic Staphylococcus spp. isolated were shown to be Staphylococcus delphini Group A by 16S ribosomal ribonucleic acid (rRNA) sequence analysis and polymerase chain reaction (PCR). Pulsed-field gel electrophoresis (PFGE) did not reveal any S. delphini or S. canis clonal lineages specifically associated with pododermatitis, which suggests that these bacteria do not act as primary pathogens, but does not dismiss their potential roles as opportunistic pathogens. While S. delphini and S. canis were the most prevalent bacterial pathogens in mink pododermatitis, they were also present in samples from healthy mink. Arcanobacterium phocae is occasionally isolated from pododermatitis cases, but is difficult to recover with conventional culture methods due to its slow growth. A quantitative real-time PCR was developed for the detection of A. phocae and was tested on 138 samples of footpad tissues from 14 farms. The bacterium was detected only in pododermatitis-endemic farms in Canada and was at higher concentrations in tissues from infected footpads than in healthy tissues. This finding suggests that A. phocae is involved in the pathogenesis of pododermatitis. 相似文献
59.
60.
LoCascio RG Ninonuevo MR Freeman SL Sela DA Grimm R Lebrilla CB Mills DA German JB 《Journal of agricultural and food chemistry》2007,55(22):8914-8919
The molecular basis by which human breast milk supports the development of a protective intestinal microbiome in infants is unknown. After lactose and lipids, human milk oligosaccharides (HMOs) are quantitatively the third largest and most diverse component of breast milk. In this work, glycomic profiling of HMO consumption by bifidobacteria using Fourier transform ion cyclotron resonance mass spectrometry reveals that one species, Bifidobacterium longum biovar infantis ATCC 15697, an isolate from the infant gut, preferentially consumes small mass oligosaccharides, representing 63.9% of the total HMOs available. These HMOs were detected in human breast milk at the onset and constantly through the first month of lactation by use of high performance liquid chromatography-chip time-of-flight mass spectrometry. Further characterization revealed that strain ATCC 15697 possesses both fucosidase and sialidase activities not present in the other tested strains. This work provides evidence that these small mass HMOs are selectively metabolized by select bifidobacterial strains and represent a potential new class of bioactive molecules functioning as prebiotics to facilitate a protective gut colonization in breast-fed newborns. 相似文献