抗氧化剂与基因表达

近来 ,对日粮中起抗氧化作用物质的兴趣越来越大。抗氧化物质可降低心血管病、癌症的发病率 ,而这些疾病的发生与自由基介导的氧化反应有关 ,并可被抗氧化剂抑制。对自由基的早期研究结果发现 ,自由基可损害细胞 ,导致细胞变性和突变 ( Gey,1 987;Slater,1 985)。近来集中抗氧化剂保护细胞对抗自由基的机制。日粮中抗氧化剂对组织中自由基活性有重要调节作用 ,但对其机制还所知甚少。许多研究者认为多摄取抗氧化剂如VC、VE、β-胡萝卜素 ,使组织中抗氧化剂浓度升高对细胞有利 ,但有研究者对此提出疑问。Woodal( 1 996)在一个精确控制添加…     

Bovine Cells Infected in Vivo with Theileria Annulata Express CD11b,the C3bi Complement Receptor

Forsyth, L.M.G., Jackson, L.A., Wilkie, G., Sanderson, A., Brown, C.G.D. and Preston, P.M., 1997. Bovine cells infected in vivo with Theileria annulata express CD11b, the C3bi complement receptor. Veterinary Research Communications, 21 (4), 249-263Bovine cells from cattle infected with Theileria annulata were phenotyped with monoclonal antibodies recognizing bovine leukocyte antigens. Macroschizont-infected, transformed cell lines prepared from peripheral blood mononuclear cells of cattle, infected with sporozoites, were assessed by flow cytometry; parasitized cells in tissues from infected cattle were examined by immunocytochemical techniques. Co-expression of markers for different cell lineages by the cell lines precluded a definite conclusion as to their phenotypic origins. For, while the pattern of leukocyte antigens expressed by these in vivo-derived schizont-infected cells, which included CD11b, was indicative of a myeloid origin, the possibility that they were NK cells could not be excluded. The monoclonal antibody (MAb) IL-A15, which recognizes CD11b, reacted with a high proportion of parasitized cells in sections of tissues from infected cattle at all stages of acute disease. Mononuclear cells infected with parasites at all stages of differentiation, from macroschizont to microschizont, expressed CD11b. Such parasitized cells occurred throughout the lymphoid tissues, being found in the thymus, spleen and lymph nodes, particularly the prescapular node draining the site of infection, the hepatic, mesenteric and precrural nodes, as well as in the reticulo-endothelial tissue of the liver, kidney, lung, abomasum, adrenal and pituitary glands. These observations provided the first evidence for a myeloid origin for the parasitized T. annulata cells found in infected bovine tissues and blood and suggested a mechanism whereby schizonts could transfer from cell to cell during mechanical infection with schizont-infected cells.     

Genetic relationships between attributes in sugarcane clones closely related to Saccharum spontaneum

Summary Saccharum spontaneum is being used in sugarcane breeding programs in attempt to improve characteristics such as ratooning ability and stress tolerance. A population of F₁ (Saccharum officinarum or commercial variety x S. spontaneum) and F₁ x F₁ sugarcane clones was evaluated for sugar yield and a range of yield components in a plant and two ratoon crops. The aim was to determine genetic correlations between attributes in clones with a large component of S. spontaneum, that could be used to help derive appropriate selection indices in such populations.There were close associations between the same attributes measured in different crop-years and the associations between different attributes were generally similar across crop-years. Stalk number and fibre content were positively correlated, as were stalk weight and CCS. The latter two attributes (which are low in S. spontaneum but high in S. officinarum) were negatively correlated with the former two (high in S. spontaneum, low in S. officinarum). Sugar yield was more closely associated with stalk weight and CCS than with stalk number but became more closely associated with stalk number with successive ratoon crops.CCS was positively correlated (r_g=0.55) with cane yield in the plant crop but showed a small negative correlation with cane yield (r_g=–0.20) in the second ratoon crop. CCS (measured in any crop) also had a negative correlation with cane yield in the ratoon crops expressed as a percentage of plant cane yield. This suggests that CCS is negatively correlated with levels of traits contributing to ratooning ability. Intensive selection among such populations for CCS without consideration of ratooning performance may reduce the frequency of favourable specific ratooning characteristics.Abbreviations CCS commercial cane sugar     

Changing positions and interests of stakeholders in environmental conflict: A New Zealand transport infrastructure case

Abstract: Stakeholders are an integral part of environmental conflict. Analysing the positions and interests of stakeholders is vital in effective environmental conflict management. This paper reviews the literature related to stakeholders and their dynamics in environmental conflict. It also presents the results of a study relating to a New Zealand transport infrastructure project where the positions and interests of stakeholders have kept on changing during the life of the project. This study plots the changing positions of some of the key stakeholders, towards this project. These stakeholders include a policy manager, a community stakeholder, an environmental stakeholder and a political stakeholder. The paper also analyses the changing positions by identifying and classifying the key drivers for these changes.     

利用AFLP进行“甘蔗属复合体”系统演化和亲缘关系研究

采用AFLP分子标记技术，对“甘蔗属复合体”中4个属16个种的69份来自中国和澳大利亚的甘蔗种质资源材料进行系统演化和亲缘关系分析。2对AFLP引物共检测到173个标记，其中172个为多态标记，多态率达99.4%；通过计算Jaccard相似性系数，用UPGMA和PCA法构建了分子系统树和效应图。结果表明：(1)属间亲缘关系中，甘蔗属与芒属较     

Degradation Kinetics of Perchlorate in Sediments and Soils

This study investigated the intrinsic perchlorate (ClO₄ ^-)degradation kinetics of sediments and soils from multiple sites in microcosm studies, including the influence of varying nitrate concentration (NO₃ ^--N from 1 to 22.8 ppm) and up to 300 ppm sulfate. The first-order degradation rates and lag times of both ClO₄ ^- and NO₃ ^- degradation were site-specific and dependent on environmental conditions such as organic substrate availability, nitrate, initial ClO₄ ^- concentration, and prior ClO₄ ^- exposure. At an initial ClO₄ ^- concentration of 5 ppm, ClO₄ ^- degradation rates ranged from 0.13 to 0.46 day^-1, and lag times of ClO₄ ^- degradation ranged from 0 to 60.0 days; while NO₃ ^- degradation occurred at rates ranging from 0.03 to 1.42 day^-1, with lag times ranging from 0 to 29.7 days. Under the same treatment conditions, NO₃ ^- degradation rates were relatively higher than that of ClO₄ ^-. Perchlorate degradation rates remained constant at both lower (0.5 ppm) and higher (5 ppm) ClO₄ ^- concentrations. Generally, ClO₄ ^- rates were affected by the availability of organic substrate, which was represented here by Total Volatile Solids (TVS) of sediments and soils, and not by NO₃ ^-. Nitrate did increase the lag time of ClO₄ ^- degradation, which may account for the persistence of ClO₄ ^- in the environment, especially when ClO₄ ^- is typically ppb levels in the environment compared to ppm levels of NO₃ ^-. This study showed rapid intrinsic ClO₄ ^- degradation in sediments and soils of contaminated sites, and highlighted the potential for natural attenuation of ClO₄ ^- in the environment.