专一转化人参二醇类皂苷Rb1为Rd的真菌菌株的筛选

于2009年的7－10月间在辽宁省的桓仁,吉林省的集安、靖宇、抚松等药材产区采集人参及人参根际土壤样品45份。通过真菌分离和培养,共获得真菌菌株105株,经形态学鉴定分属于15属48种。通过活性筛选,得到具有转化人参总皂苷活性的菌株25株,其中菌株SR87和SR105对人参皂苷Rb1具有专一转化活性。通过TLC和HPLC检测,其转化产物为人参皂苷Rd。经形态学鉴定,确定阳性菌株SR87为莫勒接霉Zygorhynchus moelleri,SR105为灰绿犁头霉Absidia glauca。这两株真菌均有较高的转化潜力,可以应用于制备人参皂苷Rd。     

竹亚科刚竹属植物的修订(Ⅲ)

作为对刚竹属 (Phyllostachys Sieb.et Zucc.)一些类群加以评注的第三部分 ,讨论了金竹 (Ph.sul-phurea(Carr.) A.et C.Riv.)在中国的分布 ,明确了它的具体产地 ,确认了它在华东皖浙赣毗邻地区仍然存在着一定数量的野生居群 ;同时还对本种种下变异类型重新作了分类学处理 ,承认其下包括 1变种 3变型 ,作出 1个新组合 ,归并了 2个不可靠的变型的拉丁学名和 5个命名上多余的拉丁学名。     

北大西洋大青鲨种群统计分析

大青鲨是金枪鱼延绳钓渔业中最主要的兼捕鱼种,在海洋食物网中属于顶端物种,在海洋生态系统中处于重要地位.由于数据限制,传统的资源评估方法很难准确描述大青鲨的资源动态.本研究基于大青鲨的生活史参数,应用种群统计分析法评估大青鲨的种群参数和资源状态,并探讨了内禀增长率为0时对应的临界捕捞死亡系数F_c与开捕年龄t_c的关系.结果表明： 未开发状态下,大青鲨存活率为0.719～0.820;大青鲨的内在瞬时增长率(r₀)为0.250～0.381,种群倍增时间(t_x2)为1.819～2.773年,种群的净繁殖力(R₀)为6.600～22.255,世代间期时间(G)为8.498～〖JP2〗10.162年,种群资源状态良好.生活史参数的敏感性检验显示,大青鲨初始年龄的自然死亡系数、种群性成熟年龄及寿命的不确定性对种群统计参数的意义影响不大;临界捕捞死亡系数伴随开捕年龄的增大而增大,当t_c≥5时,F_c值与t_c无显著相关关系.     

紫胶虫四种寄主树次生韧皮部与周皮的解剖学观察

紫胶虫的4种寄主树钝叶黄檀、南岭黄檀、木豆和苏门答腊金合欢的次生韧皮部轴向系统均由筛管、伴胞、韧皮薄壁细胞、纤维组成,径向系统由射线组成。木豆、苏门答腊金合欢中尚有少量石细胞。苏门答腊金合欢筛管分子端壁较倾斜,具复筛板,无明显的 P-蛋白质。其余3种筛管分子端壁均为横向,具单筛板,具 P-蛋白质。根据观察结果分析,4种寄主树2—3年生枝条或具表皮,或木栓层很薄;次生韧皮部的筛管看来均具相对较长的寿命;4种寄主中有3种筛管与伴胞均属特化程度高的类型。     

Taste receptor activity and feeding behaviour reveal mechanisms of white spruce natural resistance to Eastern spruce budworm Choristoneura fumiferana

The pattern of feeding of Eastern spruce budworm Choristoneura fumiferana (Clem.) (Lepidoptera, Tortricidae) is compared on foliage from white spruce Picea glauca (Moench) Voss. (Pinaceae) trees previously determined to be susceptible and resistant to defoliation by budworm. No differences are observed in electrophysiological responses from taste sensilla to aqueous extracts of the two foliage types, nor is there a preference for either extract type in a choice test. Acetone extracts from the two foliage types are both preferred to a control sucrose solution, although neither elicits a preference relative to the other. These results suggest that there is no difference in phagostimulatory power of internal leaf contents of the two foliage types. Longer‐term observation of feeding behaviour in a no‐choice situation shows no difference in meal duration, confirming the lack of difference in phagostimulatory power. However, on average, intermeal intervals are twice as long on the resistant foliage, leading to an overall lower food consumption during the assay. This result suggests an anti‐digestive or toxic effect of the resistant foliage that slows behaviour and limits food intake. Previous research has shown that waxes of the resistant foliage deter initiation of feeding by the spruce budworm and that this foliage contains higher levels of tannins and monoterpenes. The data suggest that the resistant foliage contains a post‐ingestive second line of defence against the spruce budworm.     

Do mycorrhizal network benefits to survival and growth of interior Douglas-fir seedlings increase with soil moisture stress?

Facilitation of tree establishment by ectomycorrhizal (EM) networks (MNs) may become increasingly important as drought stress increases with climate change in some forested regions of North America. The objective of this study was to determine (1) whether temperature, CO(2) concentration ([CO(2)]), soil moisture, and MNs interact to affect plant establishment success, such that MNs facilitate establishment when plants are the most water stressed, and (2) whether transfer of C and water between plants through MNs plays a role in this. We established interior Douglas-fir (Pseudotsuga menziesiivar.glauca) seedlings in root boxes with and without the potential to form MNs with nearby conspecific seedlings that had consistent access to water via their taproots. We varied temperature, [CO(2)], and soil moisture in growth chambers. Douglas-fir seedling survival increased when the potential existed to form an MN. Growth increased with MN potential under the driest soil conditions, but decreased with temperature at 800 ppm [CO(2)]. Transfer of (13)C to receiver seedlings was unaffected by potential to form an MN with donor seedlings, but deuterated water (D(2)O) transfer increased with MN potential under ambient [CO(2)]. Chlorophyll fluorescence was reduced when seedlings had the potential to form an MN under high [CO(2)] and cool temperatures. We conclude that Douglas-fir seedling establishment in laboratory conditions is facilitated by MN potential where Douglas-fir seedlings have consistent access to water. Moreover, this facilitation appears to increase as water stress potential increases and water transfer via networks may play a role in this. These results suggest that conservation of MN potential may be important to forest regeneration where drought stress increases with climate change.     

Electrical impedance of white spruce shoots in relation to pressure-volume analysis and free sugar content

Electrical impedance measurements made on white spruce, Picea glauca (Moench) Voss, stems were related to shoot free sugar contents and to osmotic, turgor and water potential. During seasonal dormancy induction, there were commensurate increases in free sugar contents, osmotic potential at full turgor and impedance which resulted in linear relationships among these variables. When measured over the course of laboratory drying, impedance increased curvilinearly with decreasing relative water content. There was a linear increase in impedance with decreasing water potential, with a break point coincident with the turgor loss point, possibly attributed to disruption to current flow through broken plasmodesmatal connections between adjacent cells. This technique offers a non-destructive method to measure tissue free sugar content, and therefore, short- and long-term shifts in parameters historically derived from pressure-volume analysis.     

Non‐parametric habitat models with automatic interactions

Questions: Can a statistical model be designed to represent more directly the nature of organismal response to multiple interacting factors? Can multiplicative kernel smoothers be used for this purpose? What advantages does this approach have over more traditional habitat modelling methods? Methods: Non‐parametric multiplicative regression (NPMR) was developed from the premises that: the response variable has a minimum of zero and a physiologically‐determined maximum, species respond simultaneously to multiple ecological factors, the response to any one factor is conditioned by the values of other factors, and that if any of the factors is intolerable then the response is zero. Key features of NPMR are interactive effects of predictors, no need to specify an overall model form in advance, and built‐in controls on overfitting. The effectiveness of the method is demonstrated with simulated and real data sets. Results: Empirical and theoretical relationships of species response to multiple interacting predictors can be represented effectively by multiplicative kernel smoothers. NPMR allows us to abandon simplistic assumptions about overall model form, while embracing the ecological truism that habitat factors interact.     

VISUALIZATION OF GOLGI APPARATUS IN METHACRYLATE EMBEDDED CONIFER EMBRYO TISSUE USING THE MONOCLONAL ANTIBODY JIM 84

Methacrylate embedding followed by resin removal has been used for the first time to visualize a membrane-associated antigen at the tissue level. Monoclonal antibody JIM 84 was used to stain the Golgi apparatus of gymnosperm (conifer) embryos by light microscope immunocytochemistry. Specificity of labelling was confirmed by electron microscope immunocytochemistry using LR-white resin. GA staining was evident in all stages of white spruce somatic embryo development from immature to mature. Some regions of the somatic embryos (e.g. root cap/suspensor region) stained more vigorously than other regions (hypocotyl/cotyledon end). GA also stained in roots of Monterey pine and Douglas fir. Unlike the situation in most angiosperms, JIM 84 antigen appears to be absent from the conifer plasma membrane. However, it appears to be present in representatives of both major classes of higher plants.