沙棘叶子提取物对白化病白鼠由铬诱导氧化胁迫的抗氧化活性评估

本研究报道沙棘(胡颓子科)对雄性白化病白鼠由铬诱导氧化胁迫的抗氧化活性。氧化胁迫通过对小白鼠进行强制性喂养30 d,以浓度为30 m g/kg的铬相对体重比例的重铬酸钾盐实现。铬促使体重下降,而却明显增加了器官与体重比例。铬处理明显减少了谷胱甘肽的降低,增加了丙二醛和肌氨酸磷酸激酶的水平;而且它还加强了血清中谷氨酸草酰乙酸转移酶和谷氨酸丙酮酸转移酶的浓度。用不同剂量的沙棘叶子提取物(乙醇提取)对保护铬元素诱导的氧化胁迫进行了评估,结果表明叶子提取物在浓度为100到250 m g/kg铬与体重比的情况下可以明显保护动物避免由铬所诱导的氧化伤害。     

四个亚高山森林树种的叶面积、叶生物量与边材面积的关系

了解植物的叶面积,对于计算植物生产率、研究气体交换现象、测定林冠郁闭度等许多方面有用。叶面积计用于测定植株上摘下的或连在小枝上的一片阔叶的面积是有效的。然而,问题是缺乏直接测定全株总叶面积的方法。Grier 和 Waring(1974)、Snell 和 Brown(1978)等人的研究表明,木本植物叶的生物量与茎中输导组织的横切面面积是紧密相关的。而且,因为叶表面积和干重之间的关系紧密,所以,叶或针叶面积与边材面积也是紧密相关的(Rogers Hinckley,1979;Waring 和 Others,1977)。于是,只要测出树干中边材面积,就可估算全株叶面积。我们在研究森林树木的耗水量及其在水文循环中的作用方面,需要叶面积的资料。就洛基山中部的亚高山森林树种来说一般缺乏这些资料。研究株冠各个部分的气体交换现象。还需估计叶的垂直分布。叶面积和茎的输导组织面积的相关性,可能是以株冠的需水量与茎的导水能力之间的生理平衡为基础的。于是可以设想,不仅可以确定全树冠的叶面积与该树冠之下茎的     

Economic Benefit Analysis of Sedimentation Reduction by Forests in Miyun Watershed, Beijing

Soil erosion causes the loss of the fertilized surface soil. The eroded soil can be transported into rivers, lakes and reservoirs. The sedimentation raises the riverbed. It also reduces the flood discharge ability of rivers and the storage ability of reservoirs(Sun Lida, et al, 1995; Yu Zhimin, et al, 1999). Various researches proved that forests could reduce soil erosion. Forests in the watershed can decrease the sedimentation of the reservoir (Guo Zhongwei, et al, 1998; Qing Yongsheng, 2…     

植物生物技术:苏云金杆菌抗虫基因的研究和它对未来树木遗传工程的影响

许多不同的技术可以促进农业生产力的持续增长，生物技术是其中最重要和最有前途的方法。因为生物技术不仅可以增加生产力。而且在环境和自然资源的保护中起重要作用，应用生物技术可以生产高产、优质、高抗性和无病植物，同时也可以提高育种效率和促进食品的工业化生产。苏云金杆菌抗虫基因是目前生物技术领域中应用最广泛的例子之一。由此而产生的抗虫植物正在广泛应用于世界各地的商业化生产。本文综述了苏云金杆菌抗虫基因的研究进展和它在未来林木遗传工程中的应用。表4参68。     

Construction of cDNA Library from Populus euphratica

1 Introduction Populus euphratica is a salt tolerant tree species, which is mainly distributed in the desert regions in northwest China (Wei 1993). Moreover, it is the only large tree species, which can survive and develop into forest in these arid and saline-alkali areas. P. euphratica forest plays a very important role in restraining the expansion of desert, maintaining ecological environment in west China, protecting the biological diversity and raising the local people抯 living standard…     

Researches and Application of Fuelbreaks in China

The fuelbreaks were established in south China from 1950s. With the active work of local communities and state government, the fuelbreaks have been built for 398,000 kilometers. In some areas, fuelbreaks and firebreaks have constructed a network primarily, such as in the provinces of Fujian, Guangdong, Guangxi. The fuelbreaks can prevent forest fire effectively. That has been approved by actual examples and burning tests. The fuelbreaks also benefit the forest ecosystem and environment. This paper makes a review on fuelbreaks research and application in China, discussed present research achievements about fuelbreaks mechanism and its development. In the future, the Chinese government and local communities will increase investment in the construction of firebreaks network with fuelbreaks as focal points.     

Impact of Land Tenure Change on Land Use

China is a public ownership country. At present, theownership of land belongs to the country andcollectivity. In China, the meaning of ownership ofland is the light that the owners of land can possessthe land, use the land, get some interest from the landand deal with the land according to laws. The 4 sectionsof ownership of land can either be combined or beseparated to carry out. In practice, these 4 sections ofownership are usually separated to carry out. The tenureof land is an independent…     

Ultrastructural and Extracellular Protein Changes in Cell Suspension Cultures of Populus euphratica Associated with Low Temperature-induced Cold Acclimation

Populus euphratica Olive is the only tree species that can grow in the saline land and also survive cold winters in northwest China, and it plays a very important role in stabilizing the vulnerable ecosystem there. A cell suspension culture was initiated from callus derived from plantlets of Populus euphratica. Cold acclimation was induced (LT50 of-17.5 ℃) in cell suspension at 4-5 ℃ in the dark for 30 days and the freezing tolerance increased from LT50 of-12.5 ℃ in nonacclimated cells to LT50 of-17.5 ℃ in cold-acclimated cells. Microvacuolation, cytoplasmic augmentation and accumulation of starch granules were observed in cells that were cold-acclimated by exposure to low temperatures. Several qualitative and quantitative changes in proteins were noted during cold acclimation. Antibodies to carrot extracellular (apoplastic) 36 kD antifreeze protein did not cross react on immunoelectroblots with extracellular proteins in cell suspension culture medium of Populus euphratica, indicating no common epitopes in the carrot 36 kD antifreeze protein and P euphratica extracellular proteins. The relationship of these changes to cold acclimation in Populus euphratica cell cultures was discussed.     

Study on Growth and Genetic Gains of Different Families in Eucalyptus urophylla Second Generation Seed Orchards

A second-generation seedling seed orchard including 32 open-pollinated families of Eucalyptus urophylla was built at Gaoyao City, Guangdong Province to examine the genetic performance of the orchard, which were selected from the superior trees in an improvement seed orchard. Compared to the characteristics of height, DBH, individual volume, stem form, branch and blossom quantities among different families at 22 months. The results indicate that: (1) The most superior families in individual volume and blossom quantities include No. 11,8,40,27 and 2 families; (2) With the 50%-selected rate, the genetic gain of individual volume of the superior families from seed orchard was estimated to be 4.84%.     

Tropical Timber Trade Flows in P.R. China

The historical transition of timber distribution pattern in China was presented firstly with main parts of timber flows in China, which included timber markets, timber transport system and regulations of timber transport. Based on the overview on tropical timber flows in China, the trade flows of tropical timber from production and imports of tropical timber to export of tropical timber products were analyzed by vivid illustrations. At the same time, problems in timber trade flows in China were analysed in the end.