Diversity of endophytic bacteria and fungi in seeds of Elymus nutans growing in four locations of Qinghai Tibet Plateau,China

Plant and Soil - Seeds are involved in the transmission of microorganisms from one plant generation to the next, acting as initial inoculum for the plant microbiome, therefore provide a key source...     

Inheritance of gusA and neo genes in transgenic rice

Inheritance of foreign genes neo and gusA in rice (Oryza sativa L. cv. IR54 and Radon) has been investigated in three different primary (T₀) transformants and their progeny plants. T₀ plants were obtained by co-transforming protoplasts from two different rice suspension cultures with the neomycin phosphotransferase II gene [neo or aph (3) II] and the -glucuronidase gene (uidA or gusA) residing on separate chimeric plasmid constructs. The suspension cultures were derived from callus of immature embryos of indica variety IR54 and japonica variety Radon. One transgenic line of Radon (AR2) contained neo driven by the CaMV 35S promoter and gusA driven by the rice actin promoter. A second Radon line (R3) contained neo driven by the CaMV 35S promoter and gusA driven by a promoter of the rice tungro bacilliform virus. The third transgenic line, IR54-1, contained neo driven by the CaMV 35S promoter and gusA driven by the CaMV 35S.Inheritance of the transgenes in progeny of the transgenic rice was investigated by Southern blot analysis and enzyme assays. Southern blot analysis of genomic DNA showed that, regardless of copy numbers of the transgenes in the plant genome and the fact that the two transgenes resided on two different plasmids before transformation, the introduced gusA and neo genes were stably transmitted from one generation to another and co-inherited together in transgenic rice progeny plants derived from self-pollination. Analysis of GUS and NPT II activities in T₁ to T₂ plants provided evidence that inheritance of the gusA and neo genes was in a Mendelian fashion in one plant line (AR2), and in an irregular fashion in the two other plant lines (R3 and IR54-1). Homozygous progeny plants expressing the gusA and neo genes were obtained in the T₂ generation of AR2, but the homozygous state was not found in the other two lines of transgenic rice.     

Inhibition of Human Neutrophil Elastase by Pentacyclic Triterpenes

Scope

Inhibiting human neutrophil elastase (HNE) is a promising strategy for treating inflammatory lung diseases, such as H1N1 and SARS virus infections. The use of sivelestat, the only clinically registered synthesized HNE inhibitor, is largely limited by its risk of organ toxicity because it irreversibly inhibits HNE. Therefore, potent reversible HNE inhibitors are promising alternatives to sivelestat.

Methods and Results

An in vitro HNE inhibition assay was employed to screen a series of triterpenes. Six pentacyclic triterpenes, but not tetracyclic triterpenes, significantly inhibited HNE. Of these pentacyclic triterpenes, ursolic acid exhibited the highest inhibitory potency (IC₅₀ = 5.51 µM). The HNE inhibitory activity of ursolic acid was further verified using a mouse model of acute smoke-induced lung inflammation. The results of nuclear magnetic resonance and HNE inhibition kinetic analysis showed that the pentacyclic triterpenes competitively and reversibly inhibited HNE. Molecular docking experiments indicated that the molecular scaffold, 28-COOH, and a double bond at an appropriate location in the pentacyclic triterpenes are important for their inhibitory activity.

Conclusion

Our results provide insights into the effects of pentacyclic triterpenes on lung inflammatory actions through reversible inhibition of HNE activity.     

Synergistic interactions of arbuscular mycorrhizal fungi and rhizobia promoted the growth of <Emphasis Type="Italic">Lathyrus sativus</Emphasis> under sulphate salt stress

In order to examine the influence of microsymbionts on plants, arbuscular mycorrhizal (AM) fungi and rhizobia were used to examine the growth of Lathyrus sativus under sulphate salt stress. Seedlings of L. sativus were inoculated with a combination of selected microsymbionts. Plants were grown under greenhouse conditions with five Na₂SO₄ concentrations (0, 1%, 2%, 3% and 4% (weight : weight)). The inoculations combinations used were the AM fungus, Glomus mosseae and/or the rhizobium, Mesorhizobium mediterraneum. The results showed that sulphate salinity inhibited plant growth and biomass production. However, compared with the control treatments, dual-inoculation of G. mosseae and M. mediterraneum reduced the harmful influence of sulphate salinity. Parmeters including plant height, the extent of AM colonization, total biomass, nodules biomass, P concentration, N concentration and proline concentration confirmed that dual inoculation plays a vital role in promoting the growth of L. sativus under sulphate salt stress. The results suggested that the use of this dual inoculation could be exploited in grassland plantation establishment and in pastoral ecosystem reclamation programmes in arid and semi-arid areas subject to moderate salt contamination.     

Raman optical activity and circular dichroism reveal dramatic differences in the influence of divalent copper and manganese ions on prion protein folding

The binding of divalent copper ions to the full-length recombinant murine prion protein PrP23-231 at neutral pH was studied using vibrational Raman optical activity (ROA) and ultraviolet circular dichroism (UV CD). The effect of the Cu2+ ions on PrP structure depends on whether they are added after refolding of the protein in water or are present during the refolding process. In the first case ROA reveals that the hydrated alpha-helix is lost, with UV CD revealing a drop from approximately 25% to approximately 18% in the total alpha-helix content. The lost alpha-helix could be that comprising residues 145-156, located within the region associated with scrapie PrP formation. In the second case, ROA reveals the protein's structure to be almost completely disordered/irregular, with UV CD revealing a drop in total alpha-helix content to approximately 5%. Hence, although Cu2+ binding takes place exclusively within the unfolded/disordered N-terminal region, it can profoundly affect the structure of the folded/alpha-helical C-terminal region. This is supported by the finding that refolding in the presence of Cu2+ of a mutant in which the first six histidines associated with copper binding to the N-terminal region are replaced by alanine has a similar alpha-helix content to the metal-free protein. In contrast, when the protein is refolded in the presence of divalent manganese ions, ROA indicates the alpha-helix is reinforced, with UV CD revealing an increase in total alpha-helix content to approximately 30%. The very different influence of Cu2+ and Mn2+ ions on prion protein structure may originate in the different stability constants and geometries of their complexes.     

放牧草地健康管理的生理指标

依据草地对席子和牧的生理响应,用牧草生理低限（PLL）,生理上限（PUL）和再生长期（R期）长度/放牧期（G期）长度的比值（R/G）等指标。构建了放牧草地健康评价的生理阈限双因子法,并以光合作用及其相关参数分析了多年生黑麦草轮牧草地的健康指标。维持草地适宜的双因子生理阈限的R/G比值,旨在放牧后草地功能与健康的完全恢复,是放牧草地可持续经营的目标。     

黄土高原退耕地的生态恢复

在刈割干扰下,黄土高原退耕地恢复进程中植被从沙蓬（Agriophyllum arenarium)单优群落向以达乌里胡枝子（Lespedeza davurica)为优势种的群落演替。物种增加速度初期快,后期慢,退耕后恢复初期的新增物种主要是沙蓬和白草（Pennisetum flaccidum);中前期主要是茵陈蒿（Artemisia capillaris),可成为群落的次优势种;中后期新增物种主要是多年生豆科植物,只是群落的伴生种,群落中1年生和多年生植物地上生物量分别以8.8%的年平均速率减少或增加,豆科植物地上生物量及所占比例上升,在退耕地恢复过程中,上层土壤中植物地下生物量比例与变化幅度增加,表现出浅层化趋势,退耕地恢复演替1-7年,土壤粘粒和粉粒减少,砂粒增加,7年后变化趋势相反,退耕地0-100cm土壤含水量在恢复期间呈逐渐上升趋势,中期增幅显著,全N和速效N在恢复前期减少,后期增加,在刈割利用下,退耕地恢复过程中土壤全P,速效P和有机C持续衰竭,退耕地恢复到当前稳定的群落所需时间分别为优势种群8-9年,群落9-11年和土壤11-12年。     

草地农业生态学研究进展与趋势

阐述了草地农业生态学的内涵,发展过程,前沿领域和发展趋势,草地农业生态系统的界面理论,结构与功能,系统耦合与系统相悖以及系统健康评价是该学科的4个前沿领域,草地农业生态系统存在3个基本界面,即草丛-地境,草地-动物以及草畜生产-经营管理界面,研究发生于各个界面的一系列生态学过程,是揭示系统行为特征的关键,草地农业生态系统有4个生产层,即前植物,植物,动物和外生物生产层,系统耦合与系统相悖是生产层之间互作的2个重要概念,不同生产层之间的系统耦合,可产生系统进化,多方面释放系统潜势,生态系统健康水平是其结构和功能的反映,健康评价是对其有序度和服务价值的度量。     

Effects of sheep urine on growth characteristics of different life form plants in a Chinese steppe grassland

The effects of sheep urine deposition volume (0, 1, 2 or 4 L/m²) and deposition stage of plant growth (vegetative or reproductive) on the number and size of tillers/branches and the biomass of Stipa bungeana, Artemisia capillaries and Lespedeza davurica in a Chinese steppe grassland were determined. The results indicate that the response of the three plant species to sheep urine deposition differs, and is influenced by both urine deposition volume and deposition stage of plant growth. Urine deposition had a short-term scorch effect on grassland plants, which mainly occurred in the inner zone of urine patches. Urine application had a long-term positive effect on S. bungeana and a long-term negative effect on A. capillaries and L. davurica, which lasted at least two years and decreased with decrease in urine deposition volume. All species growing in the inner zone of urine patches were scorched by sheep urine deposition, some species in the marginal zone of patches were also scorched, while no species were scorched in the outer zones. The reproductive and vegetative stages of A. capillaries and the reproductive stages of S. bungeana and L. davurica were sensitive to sheep urine deposition.