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排序方式: 共有1024条查询结果,搜索用时 31 毫秒
91.
Amadou Traoré Luis J. Royo Adama Kaboré Lucía Pérez-Pardal Isabel álvarez Iván Fernández Laya Sawadogo Hamidou H. Tamboura Félix Goyache 《Tropical animal health and production》2012,44(7):1469-1472
A total of 162 individuals, belonging to three Burkinabé and one Niger sheep populations, were analysed for prion protein (PrP) gene polymorphism at codons 136, 154 and 171. The ARQ allele was the most frequent in both the Burkinabé (86.7%) and the Niger (67.5%) sheep populations. The highly sensitive allele VRQ was not found in the sampled individuals. The highly resistant ARR allele was in very low frequency in the Burkina-Sahel (4.4%) and Mossi (3.2%) populations and was not present in the Djallonké and Touareg populations. Only 4 out of 15 possible PrP genotypes were identified in the sampled individuals. No favourable ARR/ARR genotypes were found in either of the breeds. Sequencing a subgroup of the samples allowed the identification of other five polymorphisms on the PrP gene sequence at codons 116, 138, 151, 237 and 240. The very low frequency of the ARR allele in the West African sheep should dissuade the implementation of a preventive selection programme aimed to increase resistance to scrapie, to avoid an extreme erosion of the genetic stock. 相似文献
92.
We describe the case of a 14-year-old Domestic Short Hair male cat that presented with a single mammary tumour one centimetre in diameter, classified as invasive micropapillary carcinoma. Histology and immunohistochemistry revealed a high mitotic index, a KI-67 index of 10%, a lack of reactivity to myoepithelial markers, and a dense infiltration with T and B lymphocytes at the periphery of the tumour. Micrometastases were detected in the regional lymph node at the time of surgery. Overall survival time was 10 months with a disease-free interval of 7.5 months. Distant metastases in the sublumbar lymph nodes confirmed the aggressiveness of this tumour, which has recently been subtyped in female cats. This is the first case reported in male cats with a complete follow-up, highlighting the importance of prompt and aggressive treatment in the presence of mammary tumours in male cats. 相似文献
93.
Ana Isabel Moreno-Calles Alejandro Casas Eduardo García-Frapolli Ignacio Torres-García 《Agroforestry Systems》2012,84(2):207-226
Agroforestry systems (AFS) derived from the cactus forest “chichipera” and cultivated with “milpa”, the traditional multi-crop
system of maize-beans-squash were studied in the Tehuacán Valley, Mexico. Plant management types practiced by people, role
of agricultural and forest resources in households’ subsistence, and consequences of changes in AFS were investigated through
ethnobotanical, ecological, and economic approaches. People maintain in this AFS 122 plant species that provide useful products
for 14 different purposes. Nearly 90% of useful plants are native to the region, representing 54% of all plant species recorded
in the chichipera forest. Management strategies were identified occurring on 63 species at landscape, parcel, and individual
plant levels. About 67% of managed plant species are left standing during clearance of vegetation; 35% are transplanted to
the parcels’ surrounding area, 32% receive particular protection, and 10 species from other areas are cultivated inside the
fields. During years of higher rainfall (~745 mm) AFS supply nearly 75% of the maize grain and 50% of the maize straw used
as fodder by households. AFS with intermediate vegetation cover have higher economic value than monocultures and forest. However,
plots with low forest cover and monocultures are progressively more common as consequence of socio-cultural processes. Local
traditional ecological knowledge and management techniques are crucial for managing resilience of these AFS. 相似文献
94.
Isabel Dorado Li?án Emilia Gutiérrez Ingo Heinrich Laia Andreu-Hayles Elena Muntán Filipe Campelo Gerhard Helle 《European Journal of Forest Research》2012,131(4):933-944
Aging in trees implies a progressive reduction in the growth rate, related to a shortening of the growing period and changes in the photosynthetic capability and efficiency. These changes may continue during the old-growth life stages following the juvenile phase and are reflected in tree-ring properties such as growth increment, density or stable isotopes. We studied possible climate age effects in time series of several tree-ring parameters (ring width, wood density and stable carbon and oxygen isotopes) of mature individuals from two age groups of Pinus uncinata and P. nigra at two locations in Spain. The aim was to test whether age differences in trees in the old-growth life stages could lead to diverging climate responses. The results show some differences in response to climate between age groups at a monthly level, but most of these divergences are not significant for seasonal climate variables. Regardless of the age group, the main limiting climate factors constrained tree growth equally. Although our findings do not support the idea of an age-dependent response to climate that may lead to inaccurate climate reconstructions, further studies using tree-ring density and stable isotope series are urgently needed to verify the current results. 相似文献
95.
Insects respond to changes in microhabitat caused by canopy disturbance, and thus can be used to examine the ecological impacts of harvesting. Single-tree selection harvesting is the most common silvicultural system used to emulate local small-scale natural disturbance and maintain uneven-aged forest structure in temperate forests. Here, we test for differences in richness, abundance, and composition of hymenopteran and saproxylic insect assemblages at four different taxon levels (selected insect orders; and all hymenopteran families, and braconid subfamilies and morphospecies) between the canopy and understory of unharvested and single-tree selection harvested sites in a northern temperate forest from central Canada. Harvesting had no effect on insect assemblage richness, composition or abundance at the three highest taxon levels (order, family and subfamily). Similarly, richness and abundance at the lowest-taxon level (braconid morphospecies) were similar, although composition differed slightly between unharvested and harvested stands. Insect assemblages were vertically stratified, with generally higher abundance (for Diptera, Hymenoptera, some hymenopteran families and braconid subfamilies) and richness (for braconid morphospecies) in the understory than the canopy. In particular, composition of the braconid morphospecies assemblage showed relatively low similarity between the understory and canopy. Single-tree selection harvesting appears to influ-ence wood-associated insect taxa only subtly through small changes in community composition at the lowest taxon level, and thus is recommended as a conservative approach for managing these northern temperate forests. 相似文献
96.
Patrizia Erre Innocenza Chessa Concepción Muñoz-Diez Angjelina Belaj Luis Rallo Isabel Trujillo 《Genetic Resources and Crop Evolution》2010,57(1):41-54
The genetic relationships within and between wild and cultivated olives were examined and clarified in an isolated and restricted
area, such as the Mediterranean island of Sardinia. Wild (21 individuals) and cultivated olive trees (22 local cultivars from
a germplasm collection and 35 ancient trees) were genotyped by means of 13 SSR loci. Five cases of synonymy were observed
and nine distinct genotypes were identified in the collection. Five novel genotypes were also detected among the ancient trees.
Differences on the allelic composition and heterozygosity levels were found between wild and cultivated trees. Model-based
clustering method classified the olive trees into two major gene pools: (a) wild genotypes and (b) local cultivars from the
collection and from heritage olives. Regarding the cultivated plant material, we observed that: (a) most of the Sardinian
cultivars shared the same allelic profiles with the ancient cultivated trees and (b) the majority of these cultivars and all
the novel genotypes were not related to any other cultivars included in this study. These findings as well as the detection
of unique alleles and a certain wild genetic background at some cultivars revealed by the Bayesian analysis may indicate their
autochthonous origin. The synonymy cases found between local cultivars and Italian mainland cultivars indicate interchange
of genetic material among these growing areas, suggesting thus a possible allochthonous origin. The information obtained can
assist in the management of an olive collection and sheds some light on the survival of true oleasters and the origin of Sardinian
cultivars. 相似文献
97.
Maria Isabel Ferraz de Oliveira Elsa Lamy Miguel N. Bugalho Margarida Vaz Cristina Pinheiro Manuel Cancela d’Abreu Fernando Capela e Silva Elvira Sales-Baptista 《Agroforestry Systems》2013,87(6):1421-1437
Montados are agro-silvo-pastoral ecosystems, typical of the Southwest Iberian Peninsula, of high socio-economic and conservation importance, where grazing is a dominant activity. Montados are characterized by an open tree canopy of Quercus sp. and a diverse undercover of shrubs and grasslands that constitute the plant food resources for grazing animals. Plant food resources of Montados are highly variable, both spatially and seasonally, in quantity and quality. Reliable and easy to use methods to monitor grazing are necessary to allow proper understanding of foraging strategies of grazing animals and to set sustainable grazing management. We describe the main characteristics of the plant food resources available for grazing animals, striking its variability, and revise the potential of using N-alkanes and saliva proteome methods to assess foraging strategies in Montados. In a scenario of dynamic multiple choices, we discuss the use of n-alkane methodology for the simultaneous estimation of diet composition and voluntary intake and saliva proteome as a mean of increasing the knowledge on diet adjustments. 相似文献
98.
Wouter van Wyngaardt Cordelia Mashau Isabel Wright Jeanni Fehrsen 《Journal of veterinary science (Suw?n-si, Korea)》2013,14(1):95-98
There is an ongoing need for standardized, easily renewable immunoreagents for detecting African horsesickness virus (AHSV). Two phage displayed single-chain variable fragment (scFv) antibodies, selected from a semi-synthetic chicken antibody library, were used to develop double antibody sandwich enzyme-linked immunosorbent assays (DAS-ELISAs) to detect AHSV. In the DAS-ELISAs, the scFv previously selected with directly immobilized AHSV-3 functioned as a serotype-specific reagent that recognized only AHSV-3. In contrast, the one selected with AHSV-8 captured by IgG against AHSV-3 recognized all nine AHSV serotypes but not the Bryanston strain of equine encephalosis virus. Serving as evidence for its serogroup-specificity. These two scFvs can help to rapidly confirm the presence of AHSV while additional serotype-specific scFvs may simplify AHSV serotyping. 相似文献
99.
Isabel M. Gamondès Moyano Richard K. Morgan Guillermo Martínez Pastur 《Journal of Sustainable Forestry》2013,32(1):37-59
AbstractThe intensive forest use has caused a significant transformation around the world. Sustainable forest management (SFM) has emerged as an alternative to address concerns regarding resource use, conservation, and socioeconomic benefits. Evidence suggests that its application remains inconsistent. In Argentina, the national government passed a law addressing management aiming to provide guidelines and incentives to steer practices into a sustainable framework. The objectives were: (a) understand what the concept of SFM means to participants in Tierra del Fuego; (b) identify and assess how different factors influence the adoption of SFM; (c) review the stakeholder perceptions on recent regulatory changes; and (d) identify the steps required for improving management. We conducted 52 semi-structured interviews with stakeholders and parties at the national level. New regulatory arrangements were implemented for a short-time before this research was undertaken, and we could not evaluate the success of reform. The study provided deep insight into the policy-making process, and the views held by different stakeholders. The historical mismanagement of the resource, together with an unfavorable past relationship with authorities, has promoted short-term perspectives which resulted in behaviors inconsistent with SFM. Moreover, the characteristic demographic composition brings a social component not identified in the broader literature as relevant for SFM adoption. 相似文献
100.
Daniel Moreno-Fernández Isabel Cañellas Rafael Calama Javier Gordo Mariola Sánchez-González 《Annals of Forest Science》2013,70(8):761-768