Reactive Oxygen and Nitrogen Species in Defense/Stress Responses Activated by Chitosan in Sycamore Cultured Cells

Chitosan (CHT) is a non-toxic and inexpensive compound obtained by deacetylation of chitin, the main component of the exoskeleton of arthropods as well as of the cell walls of many fungi. In agriculture CHT is used to control numerous diseases on various horticultural commodities but, although different mechanisms have been proposed, the exact mode of action of CHT is still unknown. In sycamore (Acer pseudoplatanus L.) cultured cells, CHT induces a set of defense/stress responses that includes production of H₂O₂ and nitric oxide (NO). We investigated the possible signaling role of these reactive molecules in some CHT-induced responses by means of inhibitors of production and/or scavengers. The results show that both reactive nitrogen and oxygen species are not only a mere symptom of stress conditions but are involved in the responses induced by CHT in sycamore cells. In particular, NO appears to be involved in a cell death form induced by CHT that shows apoptotic features like DNA fragmentation, increase in caspase-3-like activity and release of cytochrome c from the mitochondrion. On the contrary, reactive oxygen species (ROS) appear involved in a cell death form induced by CHT that does not show these apoptotic features but presents increase in lipid peroxidation.     

Simulated recruitment of riparian trees and shrubs under natural and regulated flow regimes on the Wisconsin River,USA

Models that link ecological responses to hydrologic changes are important for assessing the effects of flow regulation on aquatic and riparian ecosystems. Based on the Recruitment Box Model, a graphical model used to prescribe environmental flows for cottonwood (Populus spp.) recruitment, we designed a simulation model to represent the influence of river flow dynamics on seedling recruitment of riparian pioneer woody plants. The model simulates the influence of temporal patterns of river stage on dispersal, germination, initial recruitment and over‐winter survival of first‐year seedlings of riparian pioneer shrubs and trees. We used the model to simulate seedling recruitment patterns for five species (Acer saccharinum, Betula nigra, Populus deltoides, Salix nigra and Salix exigua) on the Wisconsin River (Wisconsin, USA) under three flow scenarios: historic (1935–2002), simulated natural (1915–1975) and simulated regulated flows (1915–1975). Simulation results agreed well with field‐observed relative differences among years (1997–2000) in seedling densities for the five focal species. Simulated successful recruitment years were highly synchronous among species, but species differed in their sensitivity to flows at different times during the growing season, consistent with among‐species differences in seed dispersal timing. Comparison of simulated natural and regulated flows for 1915–1975 showed that flow regulation decreased monthly flow variability, increased late summer to winter baseflow and reduced the magnitude of spring peaks. Simulated recruitment and over‐winter survival of tree seedlings of all species was enhanced under the regulated flow scenario, likely due to increased summer baseflow and reductions in peak flood magnitude. Our analyses show the utility of extending the Recruitment Box Model to include multiple species of riparian shrubs and trees, and the effects of post‐colonization flows on their recruitment success. However, some key functional relationships between flow patterns and woody seedling demography (e.g. shear stress thresholds for seedling mortality) have not been adequately quantified and merit further study. Copyright © 2006 John Wiley & Sons, Ltd.     

用VBA开发基于Excel的数据统计

Excel是广泛应用的电子数据表格程序,如在Excel中使用VBA（Visual Basic for Application）编程将有很多机会开发出有价值的应用程序,本文介绍一种基于Excel的VBA编程方法,来扩展Excel的功能,以实现学生评优和奖学金评选的数据统计的计算功能。     

FA composition and regiospecific analysis of Acer saccharum (sugar maple tree) and Acer saccharinum (silver maple tree) seed oils

GC analysis was performed to determine regiospecific distribution and FA composition in seed oils of the Aceraceae species, Acer saccharum and A. saccharinum. The oil content in the seeds was low at 5.0% in A. saccharum and 5.8% in A. saccharinum, and the main FA were linoleic (30.8 and 29.4%), oleic (21.3 and 27.6%), palmitic (10.1 and 10.5%), and cis-vaccenic (9.4 and 7.9%) acids, respectively. In addition, both oils contained long-chain monoenes of the n−9 and n−7 groups, including 11-eicosenoic, 13-docosenoic, 15-tetracosenoic, 13-eicosenoic, and 15-docosenoic acids, whereas γ-linolenic acid accounted for 0.8% of total FA in A. saccharum, and 0.5% in A. saccharinum. Regiospecific analysis, performed using the methodology of dibutyroyl derivatives of MAG, indicated that linoleic, oleic, and linolenic acids were mainly esterified at the internal position of TAG in both seed oils, whereas long-chain monoenes of the n−7 group were almost exclusively esterified on the external positions.     

元宝枫的综合开发利用

综述了元宝枫的生长特性 ,分布 ;含有的营养成分 ,生物活性成分及其保健作用 ;生物活性成分提取方法 ;在食品、医药、化工行业上的开发和应用     

元宝枫叶总黄酮的提取研究

用乙醇作为溶剂，采用常规浸提法及超声辅助法对元宝枫叶总黄酮的提取进行了对比研究。通过单因素及正交试验结果得到浸提法的优化条件为：溶剂为体积分数50％的乙醇溶液，料液比1g：25mL，提取时间1．5h，浸提温度70℃。按照此条件提取两次，第一次提取率94．16％，第二次1．36％；超声辅助法的优化条件为：溶剂为体积分数50％的乙醇溶液，料液比1g：15mL，提取时间0．5h，浸提温度60℃。按照此条件提取两次，第一次提取率为96．29％，第二次提取率为3．11％．     

Kinetics of Hydrolysis of Erythro-Guaiacylglycerol β-(2-Methoxyphenyl) Ether and Its Veratryl Analogue Using Hc1 and Aluminum Chloride As Catalysts

The rates of hydrolysis of the β-aryl ether bond were determined in the temperature range 130° to 155°C for guaiacylglycerol-P (2-methoxyphenyl) ether and its veratryl analogue using both HC1 and AICI₃ as catalysts in a mixed ethanol-water medium. The data, based on quantitative determinations of guaiacol liberated in the process, demonstrate the absence of competing intramolecular condensation processes. The rates of HCl-catalyzed hydrolyses are first-order with respect to both catalyst and substrate concentrations, higher in dioxane-water than in aqueous or ethanol-water media, and the activation energies were nearly identical for both model compounds, 36.1 and 35.5 kcal/mol, respectively. In general, the hydrolysis of the guaiacyl model was four times faster than that of the veratryl analogue. The catalytic effect of AICI3 appears to be based on HCI released at higher temperatures by gradual hydrolysis.     

Conflicts between Perception and Reality in the Management of Alien Species in Forest Ecosystems: A Norwegian Case Study

The vegetation dynamics and landscape management during 20 years of a temperate deciduous forest protected as a nature reserve in western Norway are analysed. Sycamore (Acer pseudoplatanus), an alien species in northern Europe, has become abundant in parts of the forest and the paper discusses how nature management has formulated and interpreted the introduction of sycamore. Scientists and nature managers regard the species as aggressive and a threat to the local natural biodiversity, but in this respect empirical evidence has been replaced by assumption and prejudice, and this is critically reviewed in the paper. The development of the forest has been monitored annually since 1988 and the long-term forest dynamics and behaviour of sycamore are discussed in relation to the attitudes of nature managers. The views held by nature managers are based on their own values and ideas regarding what is valuable nature, and alien species are often assumed to be invasive and aggressive, yet with no reference being made to site ecology and human local history. As an alternative to an a priori understanding of the role of alien species, the paper suggests that proper knowledge of ecosystem dynamics can only be achieved through analysis of ecological variation in space and time. The management of any species should not be according to its status as native or alien, but according to a judgment of its role and long-term behaviour. The values of nature conservationists should not be confused with the intrinsic values of nature.     

元宝枫油中神经酸乙酯的分离提纯

将元宝枫油制成混合脂肪酸乙酯,分别利用多级分子蒸馏提纯和分子蒸馏与尿素包合法相结合提纯神经酸乙酯得到高含量的神经酸乙酯产品。六级分子蒸馏直接提纯神经酸乙酯,得到神经酸乙酯含量为78.35%的产品。二级分子蒸馏与尿素包合法相结合时,分子蒸馏脱除甾醇、维生素E、C16、C18、C20及部分C22脂肪酸乙酯,得到神经酸乙酯与芥酸乙酯比例为1∶1的初级产品,再在m(脂肪酸乙酯)∶m(尿素)∶V(甲醇)为1∶5∶35、包合温度35℃、包合时间8 h条件下,经过二次尿素包合处理,可得到神经酸乙酯含量为66.21%的产品。     

元宝枫油制备生物柴油

以精炼元宝枫油为原料、固体超强酸为催化剂,通过甲醇酯交换反应制备脂肪酸甲酯(生物柴油)。采用气相色谱法测定反应体系中脂肪酸甲酯的含量。应用正交实验法找出精炼元宝枫油酯交换反应的最佳反应条件为:反应温度60℃,醇油物质的量比6∶1,催化剂用量1.0%,反应时间80 min。在此反应条件下原料油转化率可达98.14%。放大实验所得的生物柴油主要质量指标已达到国家0#柴油质量标准。