Genetic similarity of natural populations and plantations of Pinus roxburghii Sarg. in Nepal

? Genetic structures of five population pairs each consisting of one natural population and one neighbouring plantation of Pinus roxburghii Sarg. in Nepal were assessed using nuclear (nSSRs) and chloroplast microsatellite loci (cpSSRs).

? The mean number of alleles at nSSRs loci in natural populations was 5.0 compared to 4.93 in plantations while the average observed heterozygosities were the same in both groups (H ₀ = 0.50). Most of the alleles were common to all the populations, indicating that the populations correspond to a single genetic entity. Similarly forty-seven haplotypes were observed in natural populations compared to fifty haplotypes in plantations. Mean haplotype diversities of natural populations (0.953) and plantations (0.955) were very similar. Genetic diversity of Pinus roxburghii was relatively high with low or no evidence of inbreeding while genetic differentiation among all populations was very low (about 1%).

? The very low differentiation among natural populations indicates efficient long-distance gene flow among populations resulting in homogeneous genetic structures at least at selectively neutral loci. Even though the harvest and production of seeds and seedlings was largely uncontrolled, genetic structures of most plantations show no signs of reduced variation, inbreeding or other negative effects compromising the adaptedness or adaptability of planted forests.

     

Mastication and prescribed fire impacts on fuels in a 25-year old ponderosa pine plantation, southern Sierra Nevada

Due to increases in tree density and hazardous fuel loading in Sierra Nevadan forests, land management is focusing on fuel reduction treatments to moderate the risk of catastrophic fires. Fuel treatments involving mechanical and prescribed fire methods can reduce surface as well as canopy fuel loads. Mastication is a mechanical method which shreds smaller trees and brush onto the surface fuel layer. Little data exist quantifying masticated fuel beds. Despite the paucity of data on masticated fuels, land managers desire fuel loading, potential fire behavior and fire effects such as tree mortality information for masticated areas. In this study we measured fuel characteristics before and after mastication and mastication plus prescribed burn treatments in a 25-year old ponderosa pine (Pinus ponderosa C. Lawson) plantation. In addition to surface fuel characteristics and tree data collection, bulk density samples were gathered for masticated material. Regressions were created predicting masticated fuel loading from masticated fuel bed depth. Total masticated fuel load prior to fire treatment ranged from 25.9 to 42.9 Mg ha⁻¹, and the bulk density of masticated fuel was 125 kg m⁻³. Mastication treatment alone showed increases in most surface fuel loadings and decreases in canopy fuel loads. Masticated treatment in conjunction with prescribed burning reduced both surface and canopy fuel loads. Detailed information on fuel structure in masticated areas will allow for better predictions of fire behavior and fire effects for fire in masticated fuel types. Understanding potential fire behavior and fire effects associated with masticated fuels will allow managers to make decisions on the possibility of mastication to create fuel breaks or enhance forest health.     

德国牧羊犬协会繁殖价值估算

1998年5月23日至24日,德国牧羊犬协会在莱比锡召开的会员大会上一致通过了实施繁殖价值的估算,同时通过了防治髋关节异常的繁殖计划.     

Wedge-shaped vertebral formation as the cause of leg weakness syndrome in swine--a case report

We report about two cases of hemivertebrae in pigs. The malformations appeared in the T2/3, respectively in the T10. One case showed clinical apparent signs, namely ataxia and leg weakness. The productivity of the affected pig was reduced. Both cases are of unclear genesis. A hereditary predisposition could not be proved.     

Canine borreliosis: a laboratory diagnostic trial

The aim of this study was to investigate samples from dogs suggestive of active canine borreliosis (group A) by culture and PCR and the detection of antibodies against Borrelia burgdorferi sensu lato in order to confirm a presumptive clinical diagnosis of canine borreliosis by laboratory results. Criteria for such a diagnosis were: history of tick exposure, lameness, neurological signs, nephropathy, lethargy, anorexia, and fever. A total of 302 samples comprising EDTA blood, urine, synovial fluid, cerebrospinal fluid, and tissue (skin, synovial membrane, kidney) from 98 dogs (26 with arthritis, 46 with neurological signs, 21 with nephropathy, 5 with non-specific symptoms) were collected and examined. Moreover, 55 healthy dogs (group B) and 236 dogs with symptoms or injuries unlikely to be associated with borreliosis (group C) were included in this study. Blood serum samples collected from all individuals (n=389) were analysed by ELISA. Twenty-one (21%) out of 98 dogs from group A, 4 (7%) out of 55 from group B and 15 (6%) out of 236 dogs from group C were positive for antibodies against B. burgdorferi sensu lato. The seroprevalences between groups A, B and C differed significantly. None of the corresponding samples investigated by PCR and culture were positive for spirochetal DNA or viable spirochetes. Borrelia afzelii was grown from one EDTA-blood sample but the corresponding blood serum sample remained antibody-negative. Consequently, the etiologic role of B. afzelii in this case is unclear. In approximately 40% of the presumptive canine borreliosis cases, other lesions have been found to be responsible for clinical signs. This study affirms that a definitive diagnosis of canine borreliosis cannot be made by clinical symptoms and serology based on a single consultation. Moreover, this study clearly revealed that the diagnostic sensitivity is enhanced by a thorough consideration and exclusion of other diseases.