胞外三磷酸腺苷对铅胁迫下植物细胞损伤和过氧化氢及其清除酶水平的调节

细胞外三磷酸腺苷（extracellular adenosine-5'-triphosphate）是植物细胞的重要信号分子。以烟草悬浮细胞BY-2（Nicotiana tabacum L.cv.Bright Yellow-2）为材料,探讨了胞外三磷酸腺苷对铅胁迫下细胞损伤、H₂O₂（过氧化氢）含量及H₂O₂清除酶活性的影响。结果显示,随着Pb（NO₃）₂浓度的不断提高（30~400 μmol·L^-1）,细胞外三磷酸腺苷含量呈现出逐渐下降的趋势,但胞内三磷酸腺苷含量及细胞的受损伤程度逐渐增大;同时,H₂O₂含量和过氧化氢酶的活性均有所上升,并在200 μmol·L^-1 Pb（NO₃）₂处理下达到最大值,而过氧化物酶的活性则不断降低。较之Pb（NO₃）₂胁迫下的细胞,对Pb（NO₃）₂胁迫的细胞加入外源三磷酸腺苷使得细胞受损伤程度显著降低,H₂O₂含量减少,过氧化氢酶活性减弱,而过氧化物酶活性增强。实验结果表明,Pb（NO₃）₂胁迫诱导的植物细胞损伤和H₂O₂及其清除酶水平的变化能受到细胞外三磷酸腺苷水平的调节。     

THE EXTRAORDINARY TRILOBITE FENESTRASPIS (DALMANITIDAE, SYNPHORIINAE) FROM THE LOWER DEVONIAN OF BOLIVIA

Abstract:  The hitherto poorly known, monotypic trilobite genus Fenestraspis from the Lower Devonian of Bolivia is revised and its original assignment to the Synphoriinae supported. The thoracic morphology of the genus remains very poorly known. Fenestraspis is morphologically unusual because of the development of extensive fenestrae in the pleural region of the pygidium and apparently of the thorax; the presence of upwardly directed spines on the cephalon, thorax and pygidium; and the exceptionally large and highly elevated eyes with the palpebral rim projecting outwards above the visual surface. The function of the fenestrae remains uncertain. If they formed openings in the body of the trilobite in life they may have allowed circulation of oxygenated water to the limb exites so that respiration could have been maintained while the trilobite was enrolled. If they were covered with a flexible membrane, they may have been secondary respiratory structures or had a sensory function. The Synphoriinae is regarded as a subfamily of the Dalmanitidae rather than as an independent family of the Dalmanitoidea as proposed by some authors. The type species of the poorly known monotypic genus Dalmanitoides from the Lower Devonian of Argentina is illustrated photographically for the first time and compared with Fenestraspis .     

Phylogenetic and phenotypic originality and abundance in a cerrado plant community

The originality of a species is how much that species contributes to the rarity of traits in a community. Here we tested the relation between abundance and both phylogenetic and phenotypic originality. We measured nine traits associated with defence against herbivory, as well as phylogenetic information and abundance for woody plant species in a woodland cerrado in southeastern Brazil. About 90% of the species accounted for about 50% of the phylogenetic and phenotypic originality: most woody species had low originality. Abundance was related to tougher leaves, lower specific leaf area and lower originality based on nutritional quality. Our results suggest that herbivory may reduce the abundance of species with low resistance to herbivory and with different nutritional quality. Nevertheless, abundance was not related to either phylogenetic or phenotypic originality, so extinction of rare species may not endanger overall community function as long as more abundant species are retained. We argue that this is a consequence of the low complementarity of a large number of woody species.     

STAT1 is involved in signal transduction in the EPO induced HEL cells

Erythropoietin(EPO) is the major regulator of mamalian erythropoisis,which stimulates the growth and differentiation of hematopoietic cells through interaction with its receptor(EPO-R),Here we use HEL cells (a human erythro-leukemia cell line) as a model to elucidate the pathway of signal transduction in the EPO-induced HEL cells.Our data show that the EPOR (EPO receptor) on the surface of HEL cells interacts with the Janus tyrosine protein kinase(Jak2) to transduce intracellular signals through phosphorylation of cytoplasmic proteins in EPO-treated HEL cells.Both STAT1 and STAT5 in this cell line are tyrosine-phosphorylated and translocated to nucleus following the dinding of EPO to HEL cells.Furthermore,the dinding of both STAT1 and STAT5 proteins to specific DNA elements(SIE and PIE elements) is revealed in an EPO-dependent manner,Our data demonstrate that the pathway of signal transduction following the binding of EPO to HEL cells is similar to immature eryhroid cell from the spleen of mice infected with anemia strain of Friend virus.     

Effects of the geomorphometric characteristics of the local terrain on floristic composition in the central Brazilian Amazon

The objective of this study was to identify the effects of local geomorphometry on the abundance, richness and floristic composition of tree species in the central Brazilian Amazon. Forty‐six 0.25‐ha plots in different phyto‐ecologic sites were sampled, and their trees were inventoried. Geomorphometric data (elevation, slope, aspect, plan and profile curvatures) were derived from Shuttle Radar Topography Mission data. A detrended correspondence analysis (DCA) was used to examine the floristic distribution patterns among plots. In addition, geomorphometric variables were submitted to multiple regression analysis to identify the variables influencing floristic composition (represented by the first DCA component), abundance and species richness. Correlation analyses between the number of individuals from each species and the first DCA component were performed to evaluate the contribution of each species. Analysis of the results could not confirm an effect of geomorphometry alone on species richness and abundance, although floristic composition was significantly influenced by profile curvature and elevation. Despite the relatively low variation in altitude at the study site, species were found to be sensitive to terrain peculiarities such as elevation and profile curvature, which can constrain particular ecologic niches and contribute to the spatial distribution patterns of species.     

Floral biology of Eriope blanchetii (Lamiaceae) in coastal sand dunes of NE Brazil

Abstract The floral biology of the sand dune shrub Eriope blanchetii (Benth) Harley was investigated in a wild population located within an environment protection area near Salvador, NE Brazil. Inflorescence and flower development were monitored, and the reproductive biology was assessed. Inflorescences are terminal panicles, each bearing from one to 38 small, zygomorphic flowers. The duration of an inflorescence is about 2 months, with few new flowers each day. The rewards to visitors are pollen and nectar, the latter being produced in small quantities at the corolla base, near the stylopodium. Three sequential phases of flower development were identified, based on colour changes, pollen and nectar availability, and stigmatic receptivity. Anthesis takes place throughout the day within each plant, and flowers are strongly protandrous. Flowers are short‐lived, with individual variations of 7–30 h until corolla abscission. This variation is probably associated to a post‐pollinating response, which reduces the length of the female phase and could be advantageous for the economy of nectar production and for increased efficient pollination of the remaining flowers on a plant. The results of the pollination tests (apomixis, spontaneous and manual autogamy, manual cross‐pollination, and control) reinforced the role of pollinators for the reproductive success of E. blanchetii, given that the production of fruits from spontaneous pollination is unlikely to be resulting from protandry and given the morphological floral features. Taken together, the morphological and physiological aspects of E. blanchetii floral biology favour cross‐pollination, and it is likely that most of the fruits in nature are produced by outcrossing.     

Distribution of Epitopes of Trypanosoma cruzi Amastigotes During the Intracellular Life Cycle within Mammalian Cells

ABSTRACT. In this study we have examined the distribution of epitopes defined by monoclonal antibodies raised against Trypanosoma cruzi amastigotes during the intraceullar life cycle of the parasite. We have raised monoclonal antibodies towards amastigote forms and performed preliminary immunochemical characterization of their reactivities. MAB 1D9, 3G8, 2B7, 3B9, and 4B9, and 4B9 react with carbohydrate epitopes of the parasite major surface glycoprotein—Ssp-4 defined by MAB 2C2 [5]: MAB 4B5 reacts with a noncarbohydrate epitope in all developmental stages of the parasite, and MAB 3B2 also detects a noncarbohydrate epitope preferentially in T. cruzi flagellared forms. Vero cells infected with tissue culture-derived trypomastigotes of clone D11 (G strain) were fixed at different times during the intraceullular proliferation of parasites, and processed for immjno-electron microscopy and confocal immunoflurescence with the different monoclonal antibodies. We observed that while the surface distribution of MAB 2C2 and 4B9 epitopes was uniform throughout the cycle, MAB 1D9, 3G8, and 2B7 reacted with cytoplasmic membrance-bound compartments of the amastigotes. MAB 3B9 displayed a unique surface dentate pattern in some amastigotes. MAB 4B5 recognized a curved-shaped structure at the flagellar pocket region in some intracellular amastigotes and localized to the membrane in dividing forms. In intracellular trypomastigotes, MAB 4B5 also displayed a punctate pattern near the flagellar pocket.     

上海乡土水生植物资源及其在水生态恢复与水景观建设中的应用潜力

水生植物作为水生生态系统的主体, 对发挥水生生态系统的自维持、自循环功能有重要作用。研究通过相关资料的查阅, 建立上海地区乡土水生植物名录, 并对其科属组成、区系特征、生活型、生长型等进行统计分析。结果表明上海地区乡土水生植物共计35 科83 属160 种(含变种), 单属科、单种属的比例较高, 均达65%以上; 植物区系组成丰富、成分复杂, 以热带成分占优势, 达64.6%; 生活型以挺水植物为主, 沉水植物次之, 浮水植物最少; 生长型类型丰富, 以草本型、禾草型居多, 20 种生长型可进一步归为表征相似生态学特征和功能地位的6 个生长型组。在水生态恢复与水景观建设中, 仅有68.8%的景观水体有水生植物应用,且应用种类在2 种以下的占79.2%。乡土水生植物应用不足, 一半以上为观赏性强的外来物种, 应用频率较高的为挺水植物, 对具有良好净化效果的沉水植物重视不够。因此, 在水生态恢复与水景观建设中, 建议加强乡土水生植物资源的繁育栽培, 在充分利用乡土水生植物资源配置群落的基础上, 根据水质的富营养及基底状况, 通过不同生长型组水生植物的应用, 构建沉水-浮水-挺水植物群落复合体, 并通过近自然型护岸的营造, 形成水生-湿生复合生态系统。运用植被工程学的原理和方法, 采用生态浮岛、生态沉岛等技术营造水生植被, 将强人工化的水景观建成具生命的水生生态系统。       

Regeneration of plants from callus tissues of hairy roots induced by Agrobacterium rhizogenes on Alhagi pseudoalhagi

INTRoDUCTIONThe hairy root disease is a patholOgical syndromeof dicotyledonous plants fOllowing wounding and in-fection with Agrobacterum rhjZOgenesI1]. The rhi-zogenicity is conferred to p1ant cel1s by a fragmentof DNA (Ri T-DNA), which is transferred from thelarge root--inducting (Ri) plasmid, haJrboured by thebacterium, to the genome, where it is stably inte-grated and expressed. Illtegration of a DNA segment(T-DNA) of pRi into the host genome 1eads to ac-tive proliferation of…