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21.
NR Salvetti C Baravalle GA Mira EJ Gimeno BE Dallard F Rey HH Ortega 《Reproduction in domestic animals》2009,44(5):805-814
The purpose of this study was to estimate the expression and relative amounts of estrogen (ER) and progesterone receptors (PR) and their isoforms as well as heat shock protein 70 (HSP70) in ovaries of rats with induced cystic ovarian disease (COD). Primary, secondary, tertiary, atretic and cystic follicles were evaluated by immunohistochemistry and total ovarian proteins were analyzed by Western blot. In the granulosa layer, growing and cystic follicles in the treated group have a higher expression of ERα than growing follicles of control individuals. In the theca interna layer, tertiary follicles presented a significantly higher expression of ERα in the treated group. An increase in total ERα protein was detected in the treated group. Granulosa cells of all growing, atretic and cystic follicles show a lower expression of ERβ in animals with COD, and the total protein expression of ERβ was lower in this group. The expression of PR was lower in the granulosa cell layer of tertiary and cystic follicles in treated animals, and theca interna layer had less intense immunostaining in this group. Although there were no differences in the expression of PR-B by Western blotting, the expression of PR-A was higher and the expression of PR-C was smaller in the treated group. An intense HSP70 immunostaining was observed in the cells of cystic follicles. By Western blotting, higher protein expression of HSP70 was detected in the ovarian samples of the control group than those of the treated ones. Ovaries of animals with COD exhibited an altered steroid receptor expression and subtype balance as compared with control animals, and an increase in HSP70 immunoexpression. 相似文献
22.
Brook RK Kutz SJ Millins C Veitch AM Elkin BT Leighton T 《The Canadian veterinary journal. La revue veterinaire canadienne》2010,51(10):1115-1122
Domestic animal health services are supplied to communities in Canada's Northwest Territories (NT) in diverse ways, including private veterinary practices in 2 of 33 communities, and by mail-order, fly-in, free clinics, and a government-coordinated lay vaccinator program in some of the other 31 communities. We evaluated delivery, needs, and potential uptake of domestic animal health services in the Sahtu Settlement Area, NT by offering free clinics for 225 dogs in 2008 and 2009; and administered questionnaires to 42 dog owners and 67 students in 2008. Owners indicated that 20% of dogs were neutered, 37% had had rabies vaccinations, and 29% had been dewormed. Physical examination of dogs demonstrated that 54% were "thin" and 4% were "emaciated." Owners and youth showed a range of attitudes toward dogs and supported improved domestic animal health services. Future services need to build on existing programs and collaborate with communities to ensure relevance, ownership, and sustainability. 相似文献
23.
The conservation challenges facing mega-biodiverse South and Southeast Asia in the 21st century are enormous. For millennia, much of the habitat of these regions was only lightly modified by human endeavour, yet now it is experiencing rampant deforestation, logging, biofuel cropping, invasive species expansion, and the synergies of climate change, drought, fire and sea-level rise. Although small-scale conservation management might assist some species and habitats, the broader sweep of problems requires big thinking and some radical solutions. Given the long expected lead times between progressive economic development and stabilization of human population size and consumption rates, we argue that ‘technological fixes’ cannot be ignored if we are to address social and fiscal drivers of environmental degradation and associated species extinctions in rapidly developing regions like southern Asia. The pursuit of cheap and abundant ‘clean’ energy from an economically rational mix of nuclear power, geothermal, solar, wind, and hydrogen-derivative ‘synfuels’, is fundamental to this goal. This will permit pathways of high-tech economic development that include intensified (high energy-input) agriculture over small land areas, full recycling of material goods, a transition from fossil-fuel use for transport and electricity generation, a rejection of tropical biofuels that require vast areas of arable land for production, and a viable alternative to the damming of major waterways like the Mekong, Murum and northern tributaries of the Ganges and Brahmaputra Rivers for hydroelectricity. Rational approaches that work at large scales must be used to deal with the ultimate, rather than just proximate, drivers of biodiversity loss in the rapidly developing regions of southern Asia. 相似文献
24.
25.
Michel P. Laforge Ryan K. Brook Floris M. van Beest Erin M. Bayne Philip D. McLoughlin 《Landscape Ecology》2016,31(4):855-863
Context
Spatial scale is an important consideration for understanding how animals select habitat, and multi-scalar designs in resource selection studies have become increasingly common. Despite this, examination of functional responses in habitat selection at multiple scales is rare. The perceptual range of an animal changes as a function of vegetation association, suggesting that use, selection and functional responses may all be habitat- and scale-dependent.Objectives
Our objective was to determine how varying grain size affects our interpretation of functional response in habitat selection and to elucidate scalar and landscape effects on habitat selection.Methods
We quantified the functional response of GPS-collared, female white-tailed deer (Odocoileus virginianus, n = 18) in Riding Mountain National Park, Canada, to different habitat types. Functional responses were quantified at multiple spatial scales by regressing proportion of habitat used against proportion of habitat available at different buffer radii (ranging from 75–1000 m radius) surrounding used (telemetry) locations and available points within the individual’s seasonal home range. We examined how functional responses changed as a function of grain by plotting grain size against the slope of the functional response.Results
We detected functional responses in most habitat types. As expected, functional responses tended to converge towards 1 (use proportional to availability) at large buffer sizes; however, the relationship between scale and functional response was typically non-linear and depended on habitat type.Conclusions
We conclude that a multi-scalar approach to modelling animal functional responses in habitat selection is important for understanding patterns in animal behaviour and resource use.26.
27.
The hydrophilicity of Maritime pine wood surfaces was modified by silicone, an extremely hydrophobic material. A generic
method for the introduction of a variety of silicones at the surface of pre-treated wood was developed. The initial treatment
of wood with maleic anhydride and allyl glycidyl ether resulted in oligoesterified wood bearing terminal alkenes. The hydro-
osilylation of these groups, performed with hydride-terminated silicones, led to very hydrophobic surfaces, even after extensive
soxhlet extraction with good solvents for silicones. Thze presence of silicon, only at the surface of hydrosilylated wood,
was confirmed by ESCA. The silicones appear to be attached to the wood by covalent bonds.
Received 20 December 1998 相似文献
28.
Rinterknecht VR Clark PU Raisbeck GM Yiou F Bitinas A Brook EJ Marks L Zelcs V Lunkka JP Pavlovskaya IE Piotrowski JA Raukas A 《Science (New York, N.Y.)》2006,311(5766):1449-1452
The Scandinavian Ice Sheet (SIS) was an important component of the global ice sheet system during the last glaciation, but the timing of its growth to or retreat from its maximum extent remains poorly known. We used 115 cosmogenic beryllium-10 ages and 70 radiocarbon ages to constrain the timing of three substantial ice-margin fluctuations of the SIS between 25,000 and 12,000 years before the present. The age of initial deglaciation indicates that the SIS may have contributed to an abrupt rise in global sea level. Subsequent ice-margin fluctuations identify opposite mass-balance responses to North Atlantic climate change, indicating differing ice-sheet sensitivities to mean climate state. 相似文献
29.
Kelly P O'Sullivan K Berry D More S Meaney W O'Callaghan E O'Brien B 《Irish veterinary journal》2009,62(1):36-42
Research has shown that total bacterial count (TBC), which is the bacterial growth per ml of milk over a fixed period of time, can be decreased by good hygiene and farm management practices. The objective of the current study was to quantify the associations between herd management factors and bulk tank TBC in Irish spring calving, grass-based dairy herds. The relationship between bulk tank TBC and farm management and infrastructure was examined using data from 400 randomly selected Irish dairy farms where the basal diet was grazed grass. Herd management factors associated with bulk tank TBC were identified using linear models with herd annual total bacterial score (i.e., arithmetic mean of the natural logarithm of bulk tank TBC) included as the dependent variable. All herd management factors were individually analysed in a separate regression model, that included an adjustment for geographical location of the farm. A multiple stepwise regression model was subsequently developed. Median bulk tank TBC for the sample herds was 18,483 cells/ml ranging from 10,441 to 130,458 cells/ml. Results from the multivariate analysis indicated that the following management practices were associated with low TBC; use of heated water in the milking parlour; participation in a milk recording scheme; and tail clipping of cows at a frequency greater than once per year. Increased level of hygiene of the parlour and cubicles were also associated with lower TBC. Herd management factors associated with bulk tank TBC in Irish grazing herds were generally in agreement with most previous studies from confinement systems of milk production. 相似文献
30.
Contemporary fire patterns are considered the most likely cause for regional population decline amongst small to medium mammals in northern tropical Australia. Here we assess the extinction risk faced by a vulnerable north Australian native rodent, the Brush-tailed Rabbit-rat Conilurus penicillatus in relation to fire frequency. This species has recently suffered a significant contraction in range. We provide the first quantitative evidence to demonstrate the immediate threat destructive wildfires and regular annual fire pose to the long-term population persistence of C. penicillatus. We show that late-dry season fires cause a reduction in both juvenile and adult survival probabilities. However, abundance declined at the unburnt as well as a frequently burnt site, suggesting that fire exclusion alone does not guarantee the species’ long-term persistence. Our model projections indicate that the remaining populations of C. penicillatus on the Northern Territory mainland risk extirpation within the next ten years. Conservation requires decisive management action to ameliorate extensive and destructive fires. A multi-faceted management plan needs to focus on restoring a fire management regime which generates a fine-scale mosaic of burnt and unburnt habitat, and the release of captive bred animals into fenced reserves free of exotic predators. 相似文献