Preface     

K.C. Olson 《Veterinary Clinics of North America: Food Animal Practice》2007

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In vitro migration responses of neutrophils from cows and calves     

D P Olson 《American journal of veterinary research》1990,51(7):973-977

The directional (chemotactic) and random migration activities of neutrophils from cows and newborn and 2-week-old calves were determined by use of the chemotaxis-under-agarose assay. Blood samples were stored for 2, 24, or 48 hours and at 4 or 25 C before testing. During the assay, cells were incubated at 17, 27, or 37 C. The assay was found suitable for testing the directional and random migration activities of neutrophils from cattle. Directional migration of neutrophils was diminished (P less than or equal to 0.05) when cells were incubated at 17 or 27 C, compared with data from incubation at 37 C. Random migration of neutrophils was unaffected by test incubation temperature. Significant (P less than or equal to 0.05) differences were found between cows and calves regarding the percentage number and viability and the directional and random migration activities of neutrophils. Neutrophils from cows were adversely affected to a greater extent by prolonged sample storage times or low storage temperature than were neutrophils from calves. Results indicate that a sample storage time of up to 24 hours, a sample storage temperature of 25 C, and a test incubation temperature of 37 C provided optimal conditions for testing the migratory activities of neutrophils from cattle.  相似文献   

Evaluation of biochemical evidence of congenital nutritional myopathy in two-week prepartum fetuses from selenium-deficient ewes     

A Hamliri  W G Olson  D W Johnson  M Kessabi 《American journal of veterinary research》1990,51(7):1112-1115

Muscle damage attributable to selenium (Se)/vitamin E deficiencies is known to develop at birth or later in lambs. The purpose of this study was to determine whether and when muscle damage develops in utero. Thirty pregnant ewes maintained on Se-deficient forages from birth were allotted to 3 equal groups. Half of each group was given a single IM injection of 0.056 mg of Se/kg of body weight, 1 month before parturition. At 3 weeks before parturition, cesarean section-derived fetuses from Se-deficient ewes did not have evidence of muscle damage. At 2 weeks before parturition, fetuses from Se-deficient ewes had biochemical evidence of congenital nutritional myopathy, as evidenced by low blood Se concentration (P less than 0.05) and by increased plasma creatinine kinase (P less than 0.001) and lactate dehydrogenase (P less than 0.01) activities, compared with fetuses from Se-treated ewes. Thus, for optimal protection of fetuses and newborn lambs in Se-deficient areas, Se should be administered to ewes at least 1 month before parturition.  相似文献   

Polymerisation of added coniferyl alcohol by inherent xylem peroxidases and its effect on fungal decay resistance of Norway spruce     

Sanni Raiskila  Kurt Fagerstedt  Tapio Laakso  Pekka Saranpää  Mia Löija  Leena Paajanen  Riitta Mahlberg  Anne-Christine Ritschkoff 《Wood Science and Technology》2006,40(8):697-707

It is known that active peroxidase isozymes exist in mature wood of Norway spruce (Picea abies L. Karst.) and that they remain active for years and are found even in the heartwood (in Scots pine), where all cellular activity has ceased. This peroxidase activity was utilised in the impregnation of wood blocks with a natural monolignol, coniferyl alcohol and hydrogen peroxide. The hypothesis was that the internal wood peroxidases would oxidise the added monolignol and bind it stably into the cell wall matrix, which could hinder fungal decay. Since coniferyl alcohol is not very soluble in water, the impregnation was done under vacuum with an acetone–water solution containing 10% coniferyl alcohol and 0.4 mM H₂O₂ at room temperature (ca. 0.02 g of coniferyl alcohol was added to 1 g of wood). After impregnation, dimers of coniferyl alcohol and free coniferyl alcohol were found in acetone extracts with GC–MS analysis. Penetration of coniferyl alcohol and non-extractable reaction products were studied from the wood blocks with FTIR PAS technique. The wood samples treated were also subjected to a fungal decay test with Coriolus versicolor. This treatment hindered fungal decay in a 60-day experiment and led to a dry weight loss of 8.8% in comparison with 19.9% in the control. The reactions of coniferyl alcohol and H₂O₂ in the presence of peroxidases are discussed as well as the use of monolignols to increase wood decay resistance.  相似文献   

Effects of temperature and nutrient availability on plasma membrane lipid composition in Scots pine roots during growth initiation     

Iivonen S  Saranpää P  Sutinen ML  Vapaavuori E 《Tree physiology》2004,24(4):437-446

We studied the effects of root zone temperature (RZT) and nutrient availability on free sterols and phospholipids in the plasma membrane (PM) and on PM-ATPase activity in roots of 1-year-old Scots pine (Pinus sylvestris L.) seedlings during growth initiation in the spring. Seedlings were grown for 6 weeks in hydroponic cultures with low (0.5 mM N; LN) or high (3 mM N; HN) nutrient availability. The root zone was subjected to slow warming (SW) and fast warming (FW) treatments while maintaining similar air temperatures in both treatments. Decreases in the amount of phospholipids and in the phospholipid/free sterol ratio, an increase in the degree of saturation of phospholipid fatty acids and changes in free sterol composition were observed during root growth initiation. Changes in lipid composition of the PM associated with the cold deacclimation process were detected at RZTs above 9 degrees C. Nutrient availability affected the lipid composition of the PM only when RZT was increased slowly. When RZT increased from 4 to 6 degrees C in the SW treatment, the degree of saturation of phospholipid fatty acids decreased, especially in HN seedlings. The sitosterol/stigmasterol ratio remained higher in HN seedlings than in LN seedlings. After an RZT of 9 degrees C had been reached in the SW treatment, HN caused increases in the saturation of phospholipid fatty acids and root PM-ATPase activity, and a decrease in the phospholipid/free sterol ratio. Possible effects of changes in PM lipid composition on root growth and PM-ATPase activity are discussed.  相似文献   

Influence of forage harvesting regimes on dynamics of biological dinitrogen fixation of a tropical woody legume     

Nygren P  Cruz P  Domenach AM  Vaillant V  Sierra J 《Tree physiology》2000,20(1):41-48

Effects of three forage harvesting regimes-total removal of foliage and branches once (T-12) or twice a year (T-6) and 50% removal every 2 months (P-2)-on growth and biological dinitrogen fixation of Gliricidia sepium (Jacq.) Walp were studied under subhumid tropical conditions in Guadeloupe, French Antilles. Gliricidia sepium was grown in association with the perennial C(4) grass Dichantium aristatum (Poir) C.E. Hubbard in a two-storied fodder production system. The medium-term effects of pruning on N(2) fixation were assessed by the (15)N natural abundance method. Gmelina arborea Roxb. was used as the non-fixing reference. The trees in the T-12 regime followed the natural phenological cycle, and flowering and podfilling at the beginning of the dry season reduced both foliage and nodule biomass. The T-6 regime impeded flowering, and only a few flowers, on older branches, were produced in the P-2 regime. In trees in the T-12, T-6, and P-2 regimes, fixed N comprised 54-87, 54-92, and 60-87%, respectively, of the total N in aboveground biomass, depending on sampling date. Total annual accumulation of N in harvestable aboveground biomass was highest in trees in the T-6 regime at 313 kg ha(-1), of which 204 kg ha(-1) of N was fixed from the atmosphere. In all treatments, about 70% of the N exported per year from the plot in the fodder harvest came from N(2) fixation. Thus, N(2) fixation makes an important contribution to the N economy of the G. sepium-D. aristatum forage production system, and greatly reduces the need for fertilizer application.  相似文献   

Biodiversity management approaches for stream–riparian areas: Perspectives for Pacific Northwest headwater forests,microclimates, and amphibians     

Deanna H. Olson  Paul D. Anderson  Christopher A. Frissell  Hartwell H. Welsh Jr.  David F. Bradford 《Forest Ecology and Management》2007

Stream–riparian areas represent a nexus of biodiversity, with disproportionate numbers of species tied to and interacting within this key habitat. New research in Pacific Northwest headwater forests, especially the characterization of microclimates and amphibian distributions, is expanding our perspective of riparian zones, and suggests the need for alternative designs to manage stream–riparian zones and their adjacent uplands. High biodiversity in riparian areas can be attributed to cool moist conditions, high productivity and complex habitat. All 47 northwestern amphibian species have stream–riparian associations, with a third being obligate forms to general stream–riparian areas, and a quarter with life histories reliant on headwater landscapes in particular. Recent recognition that stream-breeding amphibians can disperse hundreds of meters into uplands implies that connectivity among neighboring drainages may be important to their population structures and dynamics. Microclimate studies substantiate a “stream effect” of cool moist conditions permeating upslope into warmer, drier forests. We review forest management approaches relative to headwater riparian areas in the U.S. Pacific Northwest, and we propose scenarios designed to retain all habitats used by amphibians with complex life histories. These include a mix of riparian and upslope management approaches to address the breeding, foraging, overwintering, and dispersal functions of these animals. We speculate that the stream microclimate effect can partly counterbalance edge effects imposed by upslope forest disturbances, hence appropriately sized and managed riparian buffers can protect suitable microclimates at streams and within riparian forests. We propose one approach that focuses habitat conservation in headwater areas – where present management allows extensive logging – on sensitive target species, such as tailed frogs and torrent salamanders that often occur patchily. Assuming both high patchiness and some concordance among the distribution of sensitive species, protecting areas with higher abundances of these animals could justify less protection of currently unoccupied or low-density habitats, where more intensive forest management for timber production could occur. Also, we outline an approach that protects juxtaposed headwater patches, retaining connectivity among sub-drainages using a 6th-field watershed spatial scale for assuring well-distributed protected areas across forested landscapes. However, research is needed to test this approach and to determine whether it is sufficient to buffer downstream water quality and habitat from impacts of headwater management. Offering too-sparse protection everywhere is likely insufficient to conserve headwater habitats and biodiversity, while our alternative targeted protection of selected headwaters does not bind the entire forest landscape into a biodiversity reserve.  相似文献   

Crystallinity of wood and the size of cellulose crystallites in Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis>)   总被引：5，自引：0，他引：5  

Seppo?Andersson  Ritva?SerimaaEmail author  Timo?Paakkari  Pekka?Saranp??  Erkki?Pesonen 《Journal of Wood Science》2003,49(6):531-537

X-ray diffraction was used to study variations in the crystallinity of wood and the average thickness and length of the crystallites of cellulose as a function of the number of the year ring in Norway spruce [Picea abies (L.) Karst.]. The crystallinity increased from ring 4 to ring 10 from the pith and was constant after ring 10. The crystallinity of mature wood was about 30% ± 5%. The average thickness and average length of the crystallites were 3.2 ± 0.1nm and 28 ± 2nm, respectively; and no systematic variation of these values with the number of the year ring was observed. The mean microfibril angle decreased near the pith but was constant in the mature wood.  相似文献   

Effect of temperature and compression on the mechanical behavior of steam-treated wood   总被引：2，自引：0，他引：2  

Petri P. KÄrenlampi  Pekka TynjÄlÄ  Pasi StrÖm 《Journal of Wood Science》2003,49(4):298-304

The mechanical behavior of steamed spruce wood changes dramatically with compression along the grain, the change being much more moderate perpendicular to the grain. The stiffness decrement due to increased temperature is greatest in the tangential material direction. The stiffness decrement due to compression is greatest along the grain. Compression to 80% compressive strain at 131°C inverts the order of the material directions regarding stiffness, the stiffness being the least along the grain. Plastic strain due to compression is greater at higher temperatures. The compression-induced decrement of stiffness along the grain is greater at higher temperatures, but the off-axis decrement of stiffness is less at higher temperatures.  相似文献   

Effect of fibers on the flow property of turbulent fiber suspensions in a contraction   总被引：1，自引：0，他引：1  

Jianzhong Lin  Shanliang Zhang  James A. Olson 《Fibers and Polymers》2007,8(1):60-65

In the flow of turbulent fiber suspensions flowing through a contraction with rectangular cross-section, the Reynolds averaged Navier-Stokes equation with the term of additional stress resulting from fibers was solved with the Reynolds stress model to get distributions of the mean velocity, mean pressure, turbulent kinetic energy and turbulent dissipation. It is found that the mean velocities at exit are small around the center and large near the wall for higher concentration. Fibers reduce turbulent intensity and turbulent dissipation at central line, but enhance them over the cross section at exit. Fibers have no effect of restraint on the turbulence in the contraction flow. The additional stress resulting from fibers plays a role in the increase of drag.  相似文献