AIM To analyze the association of HCV-RNA with peripheral blood mononuclear cells (PBMC)and to answer the question whether HCV-RNA positivity in PBMC is due to viral replication,METHODS HCV-RNA was monitored in seruma...AIM To analyze the association of HCV-RNA with peripheral blood mononuclear cells (PBMC)and to answer the question whether HCV-RNA positivity in PBMC is due to viral replication,METHODS HCV-RNA was monitored in serumand PBMC preparations from 15 patients with chronic HCV infection before, during and after an IFN-α therapy using a nested RT/ PCRtechnique. In a second approach, PBMC from healthy donors were incubated in HCV positive plasma.RESULTS In the IFN-α responding patients,HCV-RNA disappeared first from total RNApreparations of PBMC and then from serum. In contrast, in relapsing patients, HCV-RNAreappeared first in serum and then in PBMC. A quantitative analysis of the HCV-RNAconcentration in serum was performed before and after transition from detectable to nondetectable HCV-RNA in PBMC-RNA and vice versa. When HCV-RNA was detectable in PBMCpreparations, the HCV concentration in serum was significantly higher than the serum HCV-RNA concentration when HCV-RNA in PBMC was not detectable. Furthermore, at no time during the observation period was HCV specific RNA observed in PBMC, if HCV-RNA in serum was under the detection limit. Incubation of PBMCfrom healthy donors with several dilutions of HCV positive plasma for two hours showed a concentration-dependent PCR-positivity for HCV-RNA in reisolated PBMC.CONCLUSION The detectability of HCV-RNA in total RNA from PBMC seems to depend on the HCV concentration in serum. Contamination or passive adsorption by circulating virus could be the reason for detection of HCV-RNA in PBMCpreparations of chronically infected patients.展开更多
AIM To report on the efficacy, safety and tolerability of interferon alfa-2a combined with a "low dose" of ribavirin for relapsers and non responders to alpha interferon monotherapy.METHODS Thirty-four chron...AIM To report on the efficacy, safety and tolerability of interferon alfa-2a combined with a "low dose" of ribavirin for relapsers and non responders to alpha interferon monotherapy.METHODS Thirty-four chronic hepatitis C virus-infected non-responders to interferon alfa2a monotherapy (a course of at least 3 months treatment) and 13 relapsers to interferon alfa 2a monotherapy (a dose of 3 to 6 million units three times per week for at least 20 weeks but not more than 18 months) were treated with the same dose of interferon alfa-2a used before (3 to 6 million units three times per week) and ribavirin (10 mg/ kg daily) for 6 months. In complete responders, interferon alfa-2a was administered for further 6 months at the same dose used before as monotherapy.RESULTS Seven (20.6%) of 34 non-responders stopped the combined therapy due to adverse events, including two patients with histological and clinical Child A cirrhosis. In 17/27 (63%)non-responders, the combined therapy was stopped after three months because of non-response. Ten of the 27 non-responders completed the 1;2-month treatment course. At a mean follow up of 28 months (16- 37 months)after the treatment, 4/10 (15%) previous non-responders still remained complete responders,All 13 previous relapsers completed the 12-month treatment course. At a mean follow up of 22months (9 - 36 months) after treatment, 6/13(46%) the previous relapsers were stillsustained complete responders.CONCLUSION Our treatment schedule of the combined therapy for 6 months of interferon alfa2a with a low dose of ribavirin (10 mg/kg/day)followed by 6 months of interferon alfa-2amonotherapy is able to induce a sustainedcomplete response rate in 15% of non-responders and 46% of relapsers with chronic hepatitis C virus-related liver diseases comparable to those obtained with the standarddoses of ribavirin 1000 - 1200 mg/day.Randomized prospective controlled trials using lower total amounts of ribavirin in combination with interferon should be performed.展开更多
Geological,geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana.Although the classical geodynamic scenario assumed for the period 8...Geological,geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana.Although the classical geodynamic scenario assumed for the period 800-700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins,a significantly different tectonic evolution can be inferred for most Western Gondwana cratons.These cratons occupied a marginal position in the southern hemisphere with respect to Rodinia and recorded subduction with back-arc extension,island arc development and limited formation of oceanic crust in internal oceans.This period was thus characterized by increased crustal growth in Western Gondwana,resulting from addition of juvenile continental crust along convergent margins.In contrast,crustal reworking and metacratonization were dominant during the subsequent assembly of Gondwana.The Rio de la Plata,Congo-Sao Francisco,West African and Amazonian cratons collided at ca.630-600 Ma along the West Gondwana Orogen.These events overlap in time with the onset of the opening of the Iapetus Ocean at ca.610-600 Ma,which gave rise to the separation of Baltica,Laurentia and Amazonia and resulted from the final Rodinia break-up.The East African/Antarctic Orogen recorded the subsequent amalgamation of Western and Eastern Gondwana after ca.580 Ma,contemporaneously with the beginning of subduction in the Terra Australis Orogen along the southern Gondwana margin.However,the Kalahari Craton was lately incorporated during the Late Ediacaran-Early Cambrian.The proposed Gondwana evolution rules out the existence of Pannotia,as the final Gondwana amalgamation postdates latest connections between Laurentia and Amazonia.Additionally,a combination of introversion and extroversion is proposed for the assembly of Gondwana.The contemporaneous record of final Rodinia break-up and Gondwana assembly has major implications for the supercontinent cycle,as supercontinent amalgamation and break-up do not necessarily represent alternating episodic processes but overlap in time.展开更多
The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl...The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl: 0, 100, 200 and 500 mmol·L^-1. Growth of MAJ and NAU was enhanced by 100 mmol·L^-1 NaCl but severely inhibited at the concentration of 500 mmol·L^-1. NAU exhibited a greater capacity to exclude Na^+ and Cl^- under all salinity levels, whereas the salt-includer MAJ had a higher capacity in nutrient uptake under salt stress. The ratios Na^+/K^+, Na^+/Ca^2+ and Na^+/Mg^2+ in NaCl-treated MAJ and NAU did not increase at levels of 100 and 200 mmol·L^-1 NaCl but markedly increased at 500 mmol·L^-1. This suggests that the two strains, especially MAJ, enhanced nutrient uptake corresponding to the increased Na^+ influx at moderate salinity. We conclude that both MAJ and NAU are able to tolerate 500 mmol·L^-1 NaCl but there are species-specific differences in retaining ionic homeostasis in the two Paxillus strains. NAU is a salt-excluder, MAJ is a salt-includer but retains a high capacity in nutrient selectivity under saline conditions. Their definite mechanisms to enhance salt tolerance of mycorrhizal hosts need further study.展开更多
Background and aims: Activation of T cells by dendritic cells (DC) is thought to play a pivotal role in induction and maintenance of Crohn’s disease. Detailed analyses however concerning the phenotype and maturation ...Background and aims: Activation of T cells by dendritic cells (DC) is thought to play a pivotal role in induction and maintenance of Crohn’s disease. Detailed analyses however concerning the phenotype and maturation of DC as well as the mechanisms underlying their recruitment are still lacking for Crohn’s disease. Methods: Different myeloid and plasmacytoid DC subsets were characterised by immunohistochemistry. Expression of the so-called “lymphoid" chemokines CCL19, CCL20, and CCL21 was determined by real time reverse transcription-polymerase chain reaction in Crohn’s disease and normal controls. Furthermore, expression of CCL19, CCL20, and CCL21 as well as their receptors CCR6 (for CCL20) and CCR7 (for CCL19 and CCL21) was characterised by immunohistochemistry and, in addition, their cellular localisation was determined by double immunofluorescence investigations. Results: Colonic tissue affected by Crohn’s disease was characterised by an increased number of mature myeloid DC forming clusters with proliferating T cells. In keeping with their advanced maturation, DC possess the chemokine receptor CCR7. Increased expression of the CCR7 ligands CCL19 by DC themselves as well as CCL21 by reticular cells and lymphatic vessels was observed in Crohn’s disease, thereby causing the matured DC to be trapped at the site of inflammation. Conclusion: Our results demonstrate that autocrine and paracrine actions of lymphoid chemokines in Crohn’s disease may lead to increased numbers of mature DC away from their usual migration to lymphoid organs and result in the development of a tertiary lymphatic tissue within the bowel wall maintaining the autoimmune inflammation in Crohn’s disease.展开更多
Forests over limestone in the tropics have received little attention and limestone forests in Vietnam have been overlooked to an even greater extent in terms of tree physiology. In Ba Be National Park, Vietnam, soil w...Forests over limestone in the tropics have received little attention and limestone forests in Vietnam have been overlooked to an even greater extent in terms of tree physiology. In Ba Be National Park, Vietnam, soil water availability in limestone forests seems to be the most limiting factor in the dry season. Therefore, in order to enhance the preliminary knowledge of choosing native tree species for enrichment planting in the restoration zone, characteristics of the 20 native tree species to soil water stress were investigated in a limestone forest. One-ha plot each consisting of twenty-five 20 m × 20 m plots was established in undisturbed forests. All trees ≥ 10 cm DBH were measured in 20 m × 20 m plots, while twenty-five 5 m × 5 m subplots were established in order to sample the regeneration of tree species with a DBH < 10 cm. The Scholander apparatus and freezing point osmometry were used in order to measure the leaf water potential (Ψw) and leaf osmotic potential (Ψπ) of the 20 native tree species, respectively in this study. 61 species belonging to 34 families of all trees with a DBH ≥ 10 cm were recorded in one ha, while 31 species representing 18 families of trees < 10 cm DBH were identified in 625 m2. The 20 species’ leaf water and osmotic potential values revealed significant differences among species. The maximum leaf water potential was not affected by any anticipated sources of variation, while the minimum water potential, however, showed significant variation to soil water stress. The results in the study area emphasized the importance of water factors in influencing tree species distribution;it could be concluded that native species with wide water potential ranges would be better able to withstand water changes and might be thus good candidates for reforestation (enrichment planting) in limestone areas.展开更多
The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a ...The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.展开更多
Important functions of the plant hormone abscisic acid (ABA) in stress reactions, growth and photosynthetic processes are extensively studied in the model plant Arabidopsis thaliana. This paper investigates the import...Important functions of the plant hormone abscisic acid (ABA) in stress reactions, growth and photosynthetic processes are extensively studied in the model plant Arabidopsis thaliana. This paper investigates the importance of Moco-sulphurase ABA3 and aldehyde oxidase (AO) on ABA-biosynthesis in Populus × canescens. ABA3 is essential for activation of the molybdenum enzymes AO and xanthine dehydrogenase (XDH). AO itself catalyzes the last step in ABA-biosynthesis. Generation of transgenic poplar plants altered in ABA3 and AO-activity using RNAi knock down and overexpression was performed. Whereas RNAi-AO plants show a specific loss of AO activity, the RNAi-ABA3 plants has a strongly reduced activity of both molybdenum enzymes: AO and XDH. Constructs of AO and ABA3-promoters fused to β-glucuronidase provide the basis to investigate transcriptional regulation of ABA-biosynthetic processes under stress conditions. Application of high salt concentrations and different drought stress intensities does change the endogenous AO or XDH neither on the side of transcription nor on protein activity. On phytohormone level however, water loss leads to increased ABA-amounts regardless of whether transgenic or wildtype plants are studied. Salt application resulted in higher ABA-levels in all analyzed plant lines. The down regulation of AO in the two different RNAi-plant lines strongly prevented a wildtype-like increase of ABA-levels. Whereas the WT plants accumulated up to 6000 ng ABA g<sup>-1</sup> FW<sup>-1</sup> after 16 h of salt stress exposure, plants of the RNAi lines revealed a markedly lower increase of only up to 2000 ng ABA g<sup>-1</sup> FW<sup>-1</sup>. Opposing to these observations, ABA-levels increased during drought without any influence by the RNAi-effect. These results revealed that although stresses did not result in a visible increased AO-activity, ABA-production was influenced by AO and ABA3 at least under salinity.展开更多
The long awaited cloud computing concept is a reality now due to the transformation of computer generations.However,security challenges have become the biggest obstacles for the advancement of this emerging technology...The long awaited cloud computing concept is a reality now due to the transformation of computer generations.However,security challenges have become the biggest obstacles for the advancement of this emerging technology.A well-established policy framework is defined in this paper to generate security policies which are compliant to requirements and capabilities.Moreover,a federated policy management schema is introduced based on the policy definition framework and a multi-level policy application to create and manage virtual clusters with identical or common security levels.The proposed model consists in the design of a well-established ontology according to security mechanisms,a procedure which classifies nodes with common policies into virtual clusters,a policy engine to enhance the process of mapping requests to a specific node as well as an associated cluster and matchmaker engine to eliminate inessential mapping processes.The suggested model has been evaluated according to performance and security parameters to prove the efficiency and reliability of this multilayered engine in cloud computing environments during policy definition,application and mapping procedures.展开更多
Cobaltaelectrocatalysis set the stage for sustainable C—H acyloxylations in biomass-derived γ-valerolactone as a renewable solvent. The sustainable electrocatalysis regime featured ample scope, along with high level...Cobaltaelectrocatalysis set the stage for sustainable C—H acyloxylations in biomass-derived γ-valerolactone as a renewable solvent. The sustainable electrocatalysis regime featured ample scope, along with high levels of chemo- and position-selectivity.展开更多
Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fr...Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fringe of the hyperarid Taklamakan Desert(north-west China).Methods In the foreland of the river oasis of Qira(Cele),we determined meteorological variables,plant biomass production,plant water potentials(WL)and the water flux through the plants.We calculated the hydraulic conductance on the flow path from the soil to the leaves(kSL)and tested the effects of kSL,WL and the leaf-to-air difference in the partial pressure of water vapour(Dw)on stomatal regulation using regression analyses.Important Findings Despite high values of plant water potential at the point of turgor loss,all plants sustained WL at levels that were high enough to maintain transpiration throughout the growing season.In A.sparsifolia,stomatal resistance(rs;related to leaf area or leaf mass)was most closely correlated with kSL;whereas in P.euphratica,~70%of the variation in rs was explained by Dw.In T.ramosissima,leaf area-related rs was significantly correlated with WL and kSL.The regulation mechanisms are in accordance with the growth patterns and the occurrence of the species in relation to their distance to the ground water.展开更多
The immunologically mediated disease is a big family which affects many people in the world, since the cures are not yet available for most immune diseases, the patients face a lifetime of illness and treatment. Chine...The immunologically mediated disease is a big family which affects many people in the world, since the cures are not yet available for most immune diseases, the patients face a lifetime of illness and treatment. Chinese medicine inspires us to develop new methods for the treatment of immune diseases. Previous researches of immune system have revealed that an immune network exists. The immune system is like a complex highway; if we travel on these highways, we must have a map to avoid travelling in the wrong direction. Drawing the map of immune network will provide new tools for us to look directly at the basis of the immune system.展开更多
Lacustrine stromatolites were widespread in the Miocene Wudaoliang Group(stromatolites of the Wudaoliang Group), northern Tibetan Plateau;but only at one location nearby the Wudaoliang Town, they occurred intensively ...Lacustrine stromatolites were widespread in the Miocene Wudaoliang Group(stromatolites of the Wudaoliang Group), northern Tibetan Plateau;but only at one location nearby the Wudaoliang Town, they occurred intensively in thick, laterally traceable beds(Wudaoliang stromatolites). Although deposited in lacustrine environment, the lack of fossils in these rocks hampers determining whether the stromatolites formed in freshwater or saline conditions.To address this problem, and in an attempt to identify criteria to distinguish differences of freshwater and saline conditions, we studied the laminae microfabrics, stable carbon and oxygen isotope ratios, rare earth element patterns and biomarkers of the stromatolites. These stromatolites can be divided into fenestral stromatolites and agglutinated stromatolites. The fabric of fenestral stromatolites is formed by microcrystalline carbonate enclosing spar-cemented, angular crystal traces. Essentially, this fabric is interpreted as pseudomorph after former formed evaporite crystals. Faecal pel ets identical to that of the present-day brine shrimp Artemia, lack of other eukaryotic fossils,and stable isotopic signals point to a shal ow, evaporation-dominated hypersaline lake setting. Covariation of carbon and oxygen isotopes indicates hydrological y closed conditions of the Miocene lake on northern Tibetan Plateau.However, if compared to other lacustrine carbonates of the Wudaoliang Group, the high δ13 C values of the investigated Wudaoliang stromatolites reveal an additional photosynthetic effect during the deposition of the stromatolites.Furthermore, although no direct evidence is available from field observations and microfabrics, a positive europium anomaly of Wudaoliang stromatolites indicates that a palaeo-hydrothermal inflow system had existed in the outcrop area.These new results favour a hypersaline lake setting subject to hot spring inflow for the Wudaoliang stromatolites, in contrast to earlier interpretations suggesting a freshwater lake setting(e.g. Yi et al., Journal of Mineralogy and Petrology28: 106-113, 2008;Zeng et al., Journal of Mineralogy and Petrology 31: 111–119, 2011). This approach may be appropriate for other lacustrine, unfossiliferous microbialites in settings where the environmental conditions are difficult to determine.展开更多
Understanding the rate of snowmelt helps inform how water stored as snow will transform into streamflow. Data from 87 snow telemetry (SNOTEL) stations across the Southern Rocky Mountains were used to estimate spatio...Understanding the rate of snowmelt helps inform how water stored as snow will transform into streamflow. Data from 87 snow telemetry (SNOTEL) stations across the Southern Rocky Mountains were used to estimate spatio-temporal melt factors. Decreases in snow water equivalent were correlated to temperature at these monitoring stations for eight half-month periods from early March through late June. Time explained 70% of the variance in the computed snow melt factors. A residual linear correlation model was used to explain subsequent spatial variability. Longitude, slope, and land cover type explained further variance. For evergreen trees, canopy density was relevant to find enhanced melt rates; while for all other land cover types, denoted as non- evergreen, lower melt rates were found at high elevation, high latitude and north facing slopes, denoting that in cold environments melting is less effective than in milder sites. A change in the temperature sensor about mid-way through the time series (1990 to 2013) created a discontinuity in the temperature dataset. An adjustment to the time series yield larger computed melt factors.展开更多
基金Supported by a grant of DFG (SFB 402 Teilprojekt C1 (Mihm))by a grant of Hoffmann La Roche (Grenzach-Wyhden, Germany)Part of the data has been presented as poster at the 1999 EASL-meeting in Neaples
文摘AIM To analyze the association of HCV-RNA with peripheral blood mononuclear cells (PBMC)and to answer the question whether HCV-RNA positivity in PBMC is due to viral replication,METHODS HCV-RNA was monitored in serumand PBMC preparations from 15 patients with chronic HCV infection before, during and after an IFN-α therapy using a nested RT/ PCRtechnique. In a second approach, PBMC from healthy donors were incubated in HCV positive plasma.RESULTS In the IFN-α responding patients,HCV-RNA disappeared first from total RNApreparations of PBMC and then from serum. In contrast, in relapsing patients, HCV-RNAreappeared first in serum and then in PBMC. A quantitative analysis of the HCV-RNAconcentration in serum was performed before and after transition from detectable to nondetectable HCV-RNA in PBMC-RNA and vice versa. When HCV-RNA was detectable in PBMCpreparations, the HCV concentration in serum was significantly higher than the serum HCV-RNA concentration when HCV-RNA in PBMC was not detectable. Furthermore, at no time during the observation period was HCV specific RNA observed in PBMC, if HCV-RNA in serum was under the detection limit. Incubation of PBMCfrom healthy donors with several dilutions of HCV positive plasma for two hours showed a concentration-dependent PCR-positivity for HCV-RNA in reisolated PBMC.CONCLUSION The detectability of HCV-RNA in total RNA from PBMC seems to depend on the HCV concentration in serum. Contamination or passive adsorption by circulating virus could be the reason for detection of HCV-RNA in PBMCpreparations of chronically infected patients.
文摘AIM To report on the efficacy, safety and tolerability of interferon alfa-2a combined with a "low dose" of ribavirin for relapsers and non responders to alpha interferon monotherapy.METHODS Thirty-four chronic hepatitis C virus-infected non-responders to interferon alfa2a monotherapy (a course of at least 3 months treatment) and 13 relapsers to interferon alfa 2a monotherapy (a dose of 3 to 6 million units three times per week for at least 20 weeks but not more than 18 months) were treated with the same dose of interferon alfa-2a used before (3 to 6 million units three times per week) and ribavirin (10 mg/ kg daily) for 6 months. In complete responders, interferon alfa-2a was administered for further 6 months at the same dose used before as monotherapy.RESULTS Seven (20.6%) of 34 non-responders stopped the combined therapy due to adverse events, including two patients with histological and clinical Child A cirrhosis. In 17/27 (63%)non-responders, the combined therapy was stopped after three months because of non-response. Ten of the 27 non-responders completed the 1;2-month treatment course. At a mean follow up of 28 months (16- 37 months)after the treatment, 4/10 (15%) previous non-responders still remained complete responders,All 13 previous relapsers completed the 12-month treatment course. At a mean follow up of 22months (9 - 36 months) after treatment, 6/13(46%) the previous relapsers were stillsustained complete responders.CONCLUSION Our treatment schedule of the combined therapy for 6 months of interferon alfa2a with a low dose of ribavirin (10 mg/kg/day)followed by 6 months of interferon alfa-2amonotherapy is able to induce a sustainedcomplete response rate in 15% of non-responders and 46% of relapsers with chronic hepatitis C virus-related liver diseases comparable to those obtained with the standarddoses of ribavirin 1000 - 1200 mg/day.Randomized prospective controlled trials using lower total amounts of ribavirin in combination with interferon should be performed.
基金S.Oriolo thanks DAAD for a long-term PhD scholarship(A/12/75051)
文摘Geological,geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana.Although the classical geodynamic scenario assumed for the period 800-700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins,a significantly different tectonic evolution can be inferred for most Western Gondwana cratons.These cratons occupied a marginal position in the southern hemisphere with respect to Rodinia and recorded subduction with back-arc extension,island arc development and limited formation of oceanic crust in internal oceans.This period was thus characterized by increased crustal growth in Western Gondwana,resulting from addition of juvenile continental crust along convergent margins.In contrast,crustal reworking and metacratonization were dominant during the subsequent assembly of Gondwana.The Rio de la Plata,Congo-Sao Francisco,West African and Amazonian cratons collided at ca.630-600 Ma along the West Gondwana Orogen.These events overlap in time with the onset of the opening of the Iapetus Ocean at ca.610-600 Ma,which gave rise to the separation of Baltica,Laurentia and Amazonia and resulted from the final Rodinia break-up.The East African/Antarctic Orogen recorded the subsequent amalgamation of Western and Eastern Gondwana after ca.580 Ma,contemporaneously with the beginning of subduction in the Terra Australis Orogen along the southern Gondwana margin.However,the Kalahari Craton was lately incorporated during the Late Ediacaran-Early Cambrian.The proposed Gondwana evolution rules out the existence of Pannotia,as the final Gondwana amalgamation postdates latest connections between Laurentia and Amazonia.Additionally,a combination of introversion and extroversion is proposed for the assembly of Gondwana.The contemporaneous record of final Rodinia break-up and Gondwana assembly has major implications for the supercontinent cycle,as supercontinent amalgamation and break-up do not necessarily represent alternating episodic processes but overlap in time.
基金supported jointly by the Alexander von Humboldt-Stiftung/Foundation(Germany),German Science Foundation through Poplar Research Group Germany(PRG),the key project of National Natural Science Foundation of China(Grant No.30430430)the Hi-Tech Research and Development Program of China("863"Program,2006AA 10Z 131)+1 种基金a Foundation for the Author of National Excellent Doctoral Dissertation of P.R.China(200152)the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institu-tion of MOE,PRC(2002-323).
文摘The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl: 0, 100, 200 and 500 mmol·L^-1. Growth of MAJ and NAU was enhanced by 100 mmol·L^-1 NaCl but severely inhibited at the concentration of 500 mmol·L^-1. NAU exhibited a greater capacity to exclude Na^+ and Cl^- under all salinity levels, whereas the salt-includer MAJ had a higher capacity in nutrient uptake under salt stress. The ratios Na^+/K^+, Na^+/Ca^2+ and Na^+/Mg^2+ in NaCl-treated MAJ and NAU did not increase at levels of 100 and 200 mmol·L^-1 NaCl but markedly increased at 500 mmol·L^-1. This suggests that the two strains, especially MAJ, enhanced nutrient uptake corresponding to the increased Na^+ influx at moderate salinity. We conclude that both MAJ and NAU are able to tolerate 500 mmol·L^-1 NaCl but there are species-specific differences in retaining ionic homeostasis in the two Paxillus strains. NAU is a salt-excluder, MAJ is a salt-includer but retains a high capacity in nutrient selectivity under saline conditions. Their definite mechanisms to enhance salt tolerance of mycorrhizal hosts need further study.
文摘Background and aims: Activation of T cells by dendritic cells (DC) is thought to play a pivotal role in induction and maintenance of Crohn’s disease. Detailed analyses however concerning the phenotype and maturation of DC as well as the mechanisms underlying their recruitment are still lacking for Crohn’s disease. Methods: Different myeloid and plasmacytoid DC subsets were characterised by immunohistochemistry. Expression of the so-called “lymphoid" chemokines CCL19, CCL20, and CCL21 was determined by real time reverse transcription-polymerase chain reaction in Crohn’s disease and normal controls. Furthermore, expression of CCL19, CCL20, and CCL21 as well as their receptors CCR6 (for CCL20) and CCR7 (for CCL19 and CCL21) was characterised by immunohistochemistry and, in addition, their cellular localisation was determined by double immunofluorescence investigations. Results: Colonic tissue affected by Crohn’s disease was characterised by an increased number of mature myeloid DC forming clusters with proliferating T cells. In keeping with their advanced maturation, DC possess the chemokine receptor CCR7. Increased expression of the CCR7 ligands CCL19 by DC themselves as well as CCL21 by reticular cells and lymphatic vessels was observed in Crohn’s disease, thereby causing the matured DC to be trapped at the site of inflammation. Conclusion: Our results demonstrate that autocrine and paracrine actions of lymphoid chemokines in Crohn’s disease may lead to increased numbers of mature DC away from their usual migration to lymphoid organs and result in the development of a tertiary lymphatic tissue within the bowel wall maintaining the autoimmune inflammation in Crohn’s disease.
基金support by the Open Access Publication Funds of the Gottingen University
文摘Forests over limestone in the tropics have received little attention and limestone forests in Vietnam have been overlooked to an even greater extent in terms of tree physiology. In Ba Be National Park, Vietnam, soil water availability in limestone forests seems to be the most limiting factor in the dry season. Therefore, in order to enhance the preliminary knowledge of choosing native tree species for enrichment planting in the restoration zone, characteristics of the 20 native tree species to soil water stress were investigated in a limestone forest. One-ha plot each consisting of twenty-five 20 m × 20 m plots was established in undisturbed forests. All trees ≥ 10 cm DBH were measured in 20 m × 20 m plots, while twenty-five 5 m × 5 m subplots were established in order to sample the regeneration of tree species with a DBH < 10 cm. The Scholander apparatus and freezing point osmometry were used in order to measure the leaf water potential (Ψw) and leaf osmotic potential (Ψπ) of the 20 native tree species, respectively in this study. 61 species belonging to 34 families of all trees with a DBH ≥ 10 cm were recorded in one ha, while 31 species representing 18 families of trees < 10 cm DBH were identified in 625 m2. The 20 species’ leaf water and osmotic potential values revealed significant differences among species. The maximum leaf water potential was not affected by any anticipated sources of variation, while the minimum water potential, however, showed significant variation to soil water stress. The results in the study area emphasized the importance of water factors in influencing tree species distribution;it could be concluded that native species with wide water potential ranges would be better able to withstand water changes and might be thus good candidates for reforestation (enrichment planting) in limestone areas.
基金the Advisory Group on Inter-national Agricultural Research(BEAF)at the German Agency for International Cooperation(GIZ)within the German Ministry for Economic Cooperation(BMZ)for funding this research(project number 08.7860.3-001.00“Making the Mekong Con-nected”-MMC).
文摘The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.
文摘Important functions of the plant hormone abscisic acid (ABA) in stress reactions, growth and photosynthetic processes are extensively studied in the model plant Arabidopsis thaliana. This paper investigates the importance of Moco-sulphurase ABA3 and aldehyde oxidase (AO) on ABA-biosynthesis in Populus × canescens. ABA3 is essential for activation of the molybdenum enzymes AO and xanthine dehydrogenase (XDH). AO itself catalyzes the last step in ABA-biosynthesis. Generation of transgenic poplar plants altered in ABA3 and AO-activity using RNAi knock down and overexpression was performed. Whereas RNAi-AO plants show a specific loss of AO activity, the RNAi-ABA3 plants has a strongly reduced activity of both molybdenum enzymes: AO and XDH. Constructs of AO and ABA3-promoters fused to β-glucuronidase provide the basis to investigate transcriptional regulation of ABA-biosynthetic processes under stress conditions. Application of high salt concentrations and different drought stress intensities does change the endogenous AO or XDH neither on the side of transcription nor on protein activity. On phytohormone level however, water loss leads to increased ABA-amounts regardless of whether transgenic or wildtype plants are studied. Salt application resulted in higher ABA-levels in all analyzed plant lines. The down regulation of AO in the two different RNAi-plant lines strongly prevented a wildtype-like increase of ABA-levels. Whereas the WT plants accumulated up to 6000 ng ABA g<sup>-1</sup> FW<sup>-1</sup> after 16 h of salt stress exposure, plants of the RNAi lines revealed a markedly lower increase of only up to 2000 ng ABA g<sup>-1</sup> FW<sup>-1</sup>. Opposing to these observations, ABA-levels increased during drought without any influence by the RNAi-effect. These results revealed that although stresses did not result in a visible increased AO-activity, ABA-production was influenced by AO and ABA3 at least under salinity.
文摘The long awaited cloud computing concept is a reality now due to the transformation of computer generations.However,security challenges have become the biggest obstacles for the advancement of this emerging technology.A well-established policy framework is defined in this paper to generate security policies which are compliant to requirements and capabilities.Moreover,a federated policy management schema is introduced based on the policy definition framework and a multi-level policy application to create and manage virtual clusters with identical or common security levels.The proposed model consists in the design of a well-established ontology according to security mechanisms,a procedure which classifies nodes with common policies into virtual clusters,a policy engine to enhance the process of mapping requests to a specific node as well as an associated cluster and matchmaker engine to eliminate inessential mapping processes.The suggested model has been evaluated according to performance and security parameters to prove the efficiency and reliability of this multilayered engine in cloud computing environments during policy definition,application and mapping procedures.
基金Project supported by the National Natural Science Foundation of China(No.21801018)the Beijing Institute of Technology Research Fund Program for Young Scholars(No.1230011181807)~~
文摘Cobaltaelectrocatalysis set the stage for sustainable C—H acyloxylations in biomass-derived γ-valerolactone as a renewable solvent. The sustainable electrocatalysis regime featured ample scope, along with high levels of chemo- and position-selectivity.
基金European Union INCO-DC(Project No.ERBIC18CT980275).
文摘Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fringe of the hyperarid Taklamakan Desert(north-west China).Methods In the foreland of the river oasis of Qira(Cele),we determined meteorological variables,plant biomass production,plant water potentials(WL)and the water flux through the plants.We calculated the hydraulic conductance on the flow path from the soil to the leaves(kSL)and tested the effects of kSL,WL and the leaf-to-air difference in the partial pressure of water vapour(Dw)on stomatal regulation using regression analyses.Important Findings Despite high values of plant water potential at the point of turgor loss,all plants sustained WL at levels that were high enough to maintain transpiration throughout the growing season.In A.sparsifolia,stomatal resistance(rs;related to leaf area or leaf mass)was most closely correlated with kSL;whereas in P.euphratica,~70%of the variation in rs was explained by Dw.In T.ramosissima,leaf area-related rs was significantly correlated with WL and kSL.The regulation mechanisms are in accordance with the growth patterns and the occurrence of the species in relation to their distance to the ground water.
文摘The immunologically mediated disease is a big family which affects many people in the world, since the cures are not yet available for most immune diseases, the patients face a lifetime of illness and treatment. Chinese medicine inspires us to develop new methods for the treatment of immune diseases. Previous researches of immune system have revealed that an immune network exists. The immune system is like a complex highway; if we travel on these highways, we must have a map to avoid travelling in the wrong direction. Drawing the map of immune network will provide new tools for us to look directly at the basis of the immune system.
基金funded by the National Natural Science Foundation of China(Grant Nos.41772105 and 41402099)
文摘Lacustrine stromatolites were widespread in the Miocene Wudaoliang Group(stromatolites of the Wudaoliang Group), northern Tibetan Plateau;but only at one location nearby the Wudaoliang Town, they occurred intensively in thick, laterally traceable beds(Wudaoliang stromatolites). Although deposited in lacustrine environment, the lack of fossils in these rocks hampers determining whether the stromatolites formed in freshwater or saline conditions.To address this problem, and in an attempt to identify criteria to distinguish differences of freshwater and saline conditions, we studied the laminae microfabrics, stable carbon and oxygen isotope ratios, rare earth element patterns and biomarkers of the stromatolites. These stromatolites can be divided into fenestral stromatolites and agglutinated stromatolites. The fabric of fenestral stromatolites is formed by microcrystalline carbonate enclosing spar-cemented, angular crystal traces. Essentially, this fabric is interpreted as pseudomorph after former formed evaporite crystals. Faecal pel ets identical to that of the present-day brine shrimp Artemia, lack of other eukaryotic fossils,and stable isotopic signals point to a shal ow, evaporation-dominated hypersaline lake setting. Covariation of carbon and oxygen isotopes indicates hydrological y closed conditions of the Miocene lake on northern Tibetan Plateau.However, if compared to other lacustrine carbonates of the Wudaoliang Group, the high δ13 C values of the investigated Wudaoliang stromatolites reveal an additional photosynthetic effect during the deposition of the stromatolites.Furthermore, although no direct evidence is available from field observations and microfabrics, a positive europium anomaly of Wudaoliang stromatolites indicates that a palaeo-hydrothermal inflow system had existed in the outcrop area.These new results favour a hypersaline lake setting subject to hot spring inflow for the Wudaoliang stromatolites, in contrast to earlier interpretations suggesting a freshwater lake setting(e.g. Yi et al., Journal of Mineralogy and Petrology28: 106-113, 2008;Zeng et al., Journal of Mineralogy and Petrology 31: 111–119, 2011). This approach may be appropriate for other lacustrine, unfossiliferous microbialites in settings where the environmental conditions are difficult to determine.
文摘Understanding the rate of snowmelt helps inform how water stored as snow will transform into streamflow. Data from 87 snow telemetry (SNOTEL) stations across the Southern Rocky Mountains were used to estimate spatio-temporal melt factors. Decreases in snow water equivalent were correlated to temperature at these monitoring stations for eight half-month periods from early March through late June. Time explained 70% of the variance in the computed snow melt factors. A residual linear correlation model was used to explain subsequent spatial variability. Longitude, slope, and land cover type explained further variance. For evergreen trees, canopy density was relevant to find enhanced melt rates; while for all other land cover types, denoted as non- evergreen, lower melt rates were found at high elevation, high latitude and north facing slopes, denoting that in cold environments melting is less effective than in milder sites. A change in the temperature sensor about mid-way through the time series (1990 to 2013) created a discontinuity in the temperature dataset. An adjustment to the time series yield larger computed melt factors.