Bordetella bronchiseptica and toxigenic type D Pasteurella multocida as agents of severe atrophic rhinitis of swine

Bordetella bronchiseptica and toxigenic type-D Pasteurella multocida were cultured from pigs in each of five herds diagnosed as having severe atrophic rhinitis (AR). B. bronchiseptica alone, P. multocida alone, or both organisms isolated from four herds were inoculated intranasally into 1-week-old gnotobiotic pigs which were necropsied 4 weeks post-inoculation (PI). Nasal turbinate atrophy in B. bronchiseptica-inoculated pigs was moderate to severe, while P. multocida-inoculated pigs had slight to severe atrophy. Pigs inoculated with both organisms had moderate to complete turbinate atrophy. P. multocida was reisolated at necropsy from all pigs receiving the organism except those having no turbinate damage. B. bronchiseptica and P. multocida from a fifth herd were simultaneously inoculated into six naturally farrowed 6-day-old SPF pigs. Necropsy performed 4 weeks PI revealed severe to complete turbinate atrophy. Nasal turbinates were normal for control pigs in both experiments.     

Simulated acid rain effects on fine roots,ectomycorrhizae, microorganisms,and invertebrates in pine forests of the southern United States

A 2-yr study evaluated the effects of acid precipitation on the forest floor community. Throughfall was collected at weekly intervals, acidified to pH 4.3 and 3.6, and applied to throughfall excluded 1 m² plots in a stand of loblolly pine (Pinus taeda L.) in south Mississippi, and in a longleaf pine (P. palustris Mill.) plantation in east Texas. Control plots received ambient throughfall which ranged from pH 3.7 to 6.2 in Mississippi and pH 3.8 to 6.7 in Texas. Five plots of each treatment at each location were destructively sampled after 1 yr and the 5 remaining plots were sampled after 2 yr. Chemical analyses were conducted for all collections of throughfall and litter leachate, and for the fermentation layer, rhizosphere, and mineral soil. After 2 yr, comparisons of the pH 3.6 plots with the controls indicated significant decreases in the number, length and biomass of lateral roots, and the percent and number of ectomycorrhizae. Decreases in these root characteristics for plots subjected to applications of throughfall acidified to near-ambient pH 4.3 were also significant or bordered on significance. Numbers of herbivorous mites increased significantly with decreasing pH, but the predaceous mites appeared insensitive. Treated plots had fewer numbers of some groups of the larger invertebrates, especially earthworms, but variation was generally too great to show significance. The acid treatments had little effect on numbers of nematodes, saprophytic fungi or endomycorrhizal fungi.     

Body composition and fasting heat production from birth to 14 months of age for three biological types of beef heifers.

Thirty heifers were randomly sampled at five ages from each of the Hereford, Charolais, and Simmental herds at the U.S. Meat Animal Research Center to estimate association of fasting heat production (FHP) with body composition. Replicated measures of respiratory exchange were obtained for six heifers per breed at ages 2 d, 3 mo, 7 mo, 10 mo, and 14 mo using open-circuit calorimetry. Regression adjustment of FHP/live weight.75 to zero activity (AFHP) reduced the mean by 12% and variance among periods for the same animal by 42%. Daily AFHP (kcal/kg.75) was highest at 2 d (122), lowest at 10 mo (92) (P less than .01), and intermediate (103 to 106) at other ages and averaged 109, 106, and 102 for Charolais, Simmental and Hereford over all ages (P less than .05). Pooled within-age correlations of AFHP were .77 with weight of carcass (CAR) nonfat or water and .75 with live and empty body weight (EBW) but were only .13 with fat weight. Prediction of AFHP within age groups was most accurate from multiple regression on the nonfat weight in visceral organs and blood (VOB), gastrointestinal tract (GIF), head, hide, and shanks (HHS), and CAR fractions (R2 = 61%, error SD = 21.5), from regression on nonfat in CAR alone (60%, 21.6), or from regression on chemical components in each of the four fractions (59%, 22.0), relative to EBW (55%, 22.9) or its four chemical components (58%, 22.3). Partial regressions were largest for water or nonfat (P less than .01) and were negligible for fat. Importance in predicting AFHP was two to eight times greater for nonfat in CAR than in other fractions because CAR was 60 to 65% of EBW. Lean mass is clearly a major predictor of nutrient requirement that is useful to evaluate effects of body composition on the efficiency of beef production.     

The landscape ecology of large disturbances in the design and management of nature reserves

Large disturbances such as fires and floods are landscape processes that may alter the structure of landscapes in nature reserves. Landscape structure may in turn influence the viability of species and the functioning of ecosystems. Past reserve design and management strategies have been focussed on species and ecosystems rather than on landscape-scale processes, such as disturbance.An essential feature of a natural disturbance regime is the variation in disturbance attributes (e.g., size, timing, intensity, spatial location). Although some past reserve management policies have included natural disturbances, perpetuating disturbance variation has not been the explicit goal of either reserve design or management.To design a reserve to perpetuate the natural disturbance process requires consideration of: (1) the size of the reserve in relation to maximum expected disturbance size, (2) the location of the reserve in relation to favored disturbance initiation and export zones and in relation to spatial variation in the disturbance regime, and (3) the feasibility of disturbance control at reserve boundaries, or in reserve buffers.Disturbance management possibilities are constrained by the design of the reserve and the reserve goals. Where a natural disturbance regime is not feasible, then it is important that the managed disturbance regime mimic historical variation in disturbance sizes and other attributes as well as possible. Manipulating structure on the landscape scale to restore landscapes thought to have been altered by historical disturbance control is premature given our understanding of spatial disturbance processes in landscapes.     

Composition and proposed structure of a water-soluble glycan from the Keumsa Sangwhang Mushroom (Phellinus linteus)

Phellinus linteus is a mushroom which has been prized in Korea for its medicinal properties since ancient times. A glycan preparation from this source has shown promise in experimental anti-tumour and metastasis studies, but the glycan has not been well characterized. In the present work, the glycan fraction of a hot water extract from P. linteus (Keumsa Sangwhang Mushroom, Korea) has been isolated following ammonium sulfate precipitation, dialysis/concentration and anion exchange chromatographic steps. Analyses for monosaccharide composition showed glucose and mannose to be the major constituents. Digestion of the glycan fraction with specific glycosidases and by linkage analysis allowed us to propose a core beta(1-3) linked glucan heavily substituted via (1-6) links with beta(1-3) linked mannose chains. Significant levels of galactose and xylose, present in the glycan fraction, may be associated with this glucomannan or not. These findings are consistent with the view that a core beta(1-3)-linked glucan chain with beta(1-6) branch points is a common feature of mushroom glycans possessing anti-tumour activity.