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101.
R.D. Jolly F.J. Allan M.G. Collett T. Rozaklis V.J. Muller J.J. Hopwood 《New Zealand veterinary journal》2013,61(5):144-148
Aim: To investigate the nature of a progressive ataxia in a New Zealand Huntaway dog. Methods: The affected dog was examined clinically before being humanely killed and necropsied. Selected tissues were submitted to light and electron microscopy and to biochemical analyses. Results: The histological lesions were interpreted as indicative of one of the forms of mucopolysaccharidosis type-III (dMPS-III), a lysosomal storage disease. Biochemically there was a deficiency of heparan sulphamidase. All the heparan sulphate chains had non-reducing-end glucosamine-N-sulphate residues. Conclusion: The disease is dMPS-IIIA (Sanfilippo syndrome). An autosomal recessive mode of inheritance can be provisionally assumed from the nature of this disease in other species. 相似文献
102.
103.
The effect of fertility control on the transmission of bovine tuberculosis in wild brushtail possums
AIM: To determine the effect of fertility control on the rate of transmission of bovine tuberculosis (Tb), caused by Mycobacterium bovis, in brushtail possums (Trichosurus vulpecula). METHODS: At two study sites with a history of Tb infection in the resident possum population, a sample of adult male and female possums (n=50), determined by palpation to be Tb-free, was surgically sterilised by gonadectomy. A sample of untreated Tb-free male and female possums (n=54) served as controls. Each study site was trapped every 2 months over a 3-year period, and the Tb status of the individuals in the trial assessed. At the conclusion of the trial, all remaining experimental individuals were killed, necropsied and examined for characteristic lesions typical of Tb. The rate of transmission of Tb infection was estimated using the incidence of tuberculous cases in the experimental animals and comparing it between sites, sex and sterilisation treatment. RESULTS: Sterilisation by gonadectomy resulted in a reduction in the rate of transmission of Tb in male possums by 53%, but a corresponding increase in sterilised females for reasons that are still unclear. However, this interaction was statistically weak (p=0.10). When the sexes were combined, there was no overall effect of sterilisation on the rate of transmission of Tb (p=0.43). Sterility treatment notwithstanding, there was a highly significant difference in the rate of transmission between the sexes (p=0.01), being almost one order of magnitude higher in untreated males compared with untreated females. CONCLUSIONS: Although lacking strong statistical support, these results suggest that fertility control that targets endocrine control of fertility may provide some additional benefits for disease control over that achieved by reductions in population density, by reducing the rate of transmission of M. bovis in male possums. However, additional studies are needed to confirm the validity of these results. The large difference in the rate of transmission of M. bovis in untreated males compared with untreated females suggests that transmission of Tb among males may be an important driver of the dynamics of Tb infection in possums. 相似文献
104.
Michel Anderson Almeida Colmanetti Allan Lopes Bacha Pedro Luis da Costa Aguiar Alves Rinaldo Cesar de Paula 《林业研究》2019,(2):537-543
In silvopasture system, the coexistence of eucalyptus seedlings with other species may result in growth reduction, especially during eucalyptus early development.Therefore, studies elucidating how forage species affect the eucalyptus growth can provide important information for their rational management aiming to obtain the maximum gain of the system. The aim of this work was to evaluate the effect of increasing densities of Urochloa brizantha cv.Marandu in the early development of Eucalyptus urograndis. An experiment was conducted in 20 L pots, in an open and semi-controlled area, during 90 days after planting of eucalyptus. A completely randomized design with four replications was used, in a 6 9 7 factorial system, meaning six evaluation periods and seven densities of U. brizantha: 0(control), 22, 33, 44, 67, 89 and111 plants m-2. Fortnightly, eucalyptus height, stem diameter and chlorophyll fluorescence(Fv/Fm) were evaluated. At the end of experimental period, the net assimilation rate, stomatal conductance and transpiration rate of eucalyptus plants were determined, in addition to the dry matter of eucalyptus(leaves and stem) and U. brizantha (leaves). In coexistence with 111 plants m-2, eucalyptus had reduction of 63.9% on total dry matter and 72.7% on leaf area, compared to the control. From the density of22 plants m-2, U. brizantha negatively interfere significantly the growth of E. urograndis. Up to 8 plants m-2 there are no reductions greater than 5% in eucalyptus height and stem diameter. 相似文献
105.
Luciano Rodrigo Lanssanova Sebastião do Amaral Machado Alexandre Techy de Almeida Garrett Izabel Passos Bonete Allan Libanio Pelissari Afonso Figueiredo Filho 《Southern Forests》2019,81(2):167-173
This study evaluated the efficiency of taper functions and the application of mixed-effect modelling for diameter estimation along the stems of Tectona grandis. We sampled 266 trees of Tectona grandis, measuring the diameter at relative heights for volume determination, grouping the data according to three form-factor classes. Six taper functions were fitted, selecting the function with better fit performance. Six taper functions were fitted, selecting the function with better fit performance. The selected function was fitted in its basic formulation, and with the mixed non-linear modelling technique in different scenarios, and for the stem stratified in three portions of the total height. The precision and selection of the adjusted models were evaluated regarding the coefficient of determination, standard error of estimate, the Akaike information criterion, bias, quadratic error and absolute bias. According to the statistical criteria used, the model of Kozak was selected for the adjustments. For diameter estimation, the scenario with two coefficients as random effects provided an accuracy increase of 11.91%, and the mixed non-linear modelling better estimated the stem diameter for the stratified stems. In conclusion, the model of Kozak can be used to describe the stem shape of Tectona grandis, and the mixed-effect non-linear model approach was the best technique to estimate diameter along the stem of Tectona grandis. 相似文献
106.
Eric Paterson Barry Thornton Andrew J. Midwood Shona M. Osborne Allan Sim Pete Millard 《Soil biology & biochemistry》2008,40(9):2434-2440
Plants link atmospheric and soil carbon pools through CO2 fixation, carbon translocation, respiration and rhizodeposition. Within soil, microbial communities both mediate carbon-sequestration and return to the atmosphere through respiration. The balance of microbial use of plant-derived and soil organic matter (SOM) carbon sources and the influence of plant-derived inputs on microbial activity are key determinants of soil carbon-balance, but are difficult to quantify. In this study we applied continuous 13C-labelling to soil-grown Lolium perenne, imposing atmospheric CO2 concentrations and nutrient additions as experimental treatments. The relative use of plant- and SOM-carbon by microbial communities was quantified by compound-specific 13C-analysis of phospholipid fatty acids (PLFAs). An isotopic mass-balance approach was applied to partition the substrate sources to soil respiration (i.e. plant- and SOM-derived), allowing direct quantification of SOM-mineralisation. Increased CO2 concentration and nutrient amendment each increased plant growth and rhizodeposition, but did not greatly alter microbial substrate use in soil. However, the increased root growth and rhizosphere volume with elevated CO2 and nutrient amendment resulted in increased rates of SOM-mineralisation per experimental unit. As rhizosphere microbial communities utilise both plant- and SOM C-sources, the results demonstrate that plant-induced priming of SOM-mineralisation can be driven by factors increasing plant growth. That the balance of microbial C-use was not affected on a specific basis may suggest that the treatments did not affect soil C-balance in this study. 相似文献
107.
Saman Bowatte Russell Tillman Andrew Carran Allan Gillingham David Scotter 《Biology and Fertility of Soils》2008,44(6):805-813
This paper explored the potential of application of in situ ion exchange resin membrane (IEM) technique for assessing soil
nitrogen (N) availability and spatial distribution in New Zealand grazed pastures. Field and incubation experiments conducted
to test the technique proved IEM technique to be a useful approach to monitoring the continuous changes in soil mineral N
in pasture soils. The field testing showed that the IEM technique reflects both differences in pool size and mineral N flux,
while 2-M KCl extraction reflects only pool size at the sampling. Testing the effects of residence time, temperature, soil
inorganic N content, and soil water content through diffusion modeling offers further support for using IEM to explore the
complex dynamics of nitrogen availability in pasture soils. 相似文献
108.
This study focuses on soils in a mountainous catchment area located in the eastern part of the Southern Alps, South Island, New Zealand. The objective was to check the soils for non- or poorly crystalline constituents (metal organic complexes, short-range-order minerals) and if there is a relationship between pedogenesis and aspect and more recent landscape history. The morphology of the soils indicates brown soils (dystric cambisols, dystrudepts) with only few signs of podsolisation. In contrast, selected chemical properties of the soils reveal very strong weathering and leaching. Feo/Fed ratios are high and exceeding 0.6 in almost every soil horizon. Oxalate-extractable aluminium and silicon show prominent peaks in the lower subsoil horizons with 1.76–2.52% Alo and up to 0.68% for Sio on southern aspects. This is considerably higher than the values measured for soils on northern aspects (0.59% to 1.07% Alo, max. 0.26% Sio). This aspect relationship is also applying to phosphate retention reaching values of more than 90% on southern aspects and not more than 70% for northern aspects. Additionally, significant movement of organic matter in soils on southern aspects is evident by measurements of organic carbon and pyrophosphate-extractable Al and Fe. Thus soil formation can be regarded as more advanced on southern aspects. Allophane in association with organic matter can be considered as an important constituent in southern aspect subsoils being responsible for the typical andic properties. Metal-humus complexes and ferrihydrite are of subordinate significance. Considering the actual soil forming conditions under scrub-grassland (esp. soil acidity), it is unlikely that weathering and leaching is still strong enough today to allow significant podsolisation and the formation of short-range-order minerals. Under consideration of existing soil data from other studies it is proposed that these components and the podsolisation features are relicts caused by more acidic conditions under former forest cover which supported a stronger weathering and leaching. 相似文献
109.
Gerard Allan Amber Williams Pablo D. Rabinowicz Agnes P. Chan Jacques Ravel Paul Keim 《Genetic Resources and Crop Evolution》2008,55(3):365-378
Worldwide genetic diversity in 200 individuals comprising 41 castor bean accessions was assessed using amplified fragment
polymorphisms (AFLPs) and simple sequence repeats (SSRs). We found that, despite surveying five continents and 35 countries,
genetic diversity in castor bean germplasm is relatively low (overall H
e = 0.126 for AFLPs and 0.188 for SSRs) compared to estimates of genetic diversity in other plant species. Our data also show
no geographic structuring of genotypes across continents or countries within continents. An assessment of the congruence between
AFLP and SSRs indicates a low correlation (R
2 = 0.19) between the two data sets, but each marker class nonetheless shows similar patterns of low-genetic diversity and
a lack of geographic structure. Our data do suggest that SSRs yield a higher percentage of polymorphic loci, higher heterozyosity
and a greater range of genetic distances, and are therefore more informative than are AFLPs on a locus-by-locus basis. Based
on comparisons with numerous other plant species, we suggest that the lower genetic variation in this worldwide collection
may be due to one or more factors including: sampling strategies that have not captured the full extent of genetic variation
in the species; artifactual variation due to long-term germplasm storage and seed regeneration; or intense selection followed
by domestic cultivation of a limited number of castor bean genotypes, which are widely propagated for their horticultural
and agro-economic value. 相似文献
110.
Nikki Baggaley Allan Lilly Kirsty Blackstock Karen Dobbie Adam Carson Fraser Leith 《Soil Use and Management》2020,36(1):19-26
Surface runoff, erosion, compaction and the leaching of potential pollutants from land can degrade the soil resource and damage the water environment, reducing crop yields, causing loss of valuable nutrients and organic matter, together with increasing flood risk. Increasingly, it is recognized that scientific information must be translated into practical tools to change practices and protect the soil and water resource. Working alongside agencies in Scotland, we applied a suite of simple, transparent, rule-based models to identify areas most at risk of exporting sediment and pollutants that may degrade water quality based on field-scale (1:25,000) soil maps. The maps have been used by Scottish Environment Protection Agency, Scottish Water and Scottish Government to assess soil risks to waters from field to regional scale. The work brought scientists together with policy makers, agencies and the water industry to pool their knowledge to apply these practical tools for decision-making. It highlights the need to apply existing knowledge to answer salient questions. All three examples described show that providing the right type of information, which is based on fundamental soils data, can directly influence the implementation of policies, investment and monitoring decisions and provide evidence in support of government. However, this requires both researchers and agency scientists to develop skills as knowledge brokers and to normalize the use of soil data in everyday agency settings. 相似文献