棉花内生细菌数量动态及其对棉花黄、枯萎病菌的拮抗作用

摘要：【目的】了解棉花内生细菌数量动态,从棉花中获得拮抗黄、枯萎病菌的内生细菌资源【方法】对棉花根、茎、叶表面灭菌,采用稀释平板法分离棉花内生细菌;通过对峙培养法体外鉴定分离的棉花内生细菌对棉花黄、枯萎病菌的拮抗作用,并对拮抗棉花黄、枯萎病菌的内生细菌16S rDNA序列进行了分析【结果】棉花根中内生细菌的数量显著高于茎、叶;根的苗期总体内生细菌数量低于开花期、吐絮期,茎、叶中的内生细菌数量在不同生育期呈现一定的波动性,但趋势性不明显;6个棉花品种根中内生细菌平均数量差异并不显著,但茎、叶中内生细菌数量不同品种间呈现一定程度差异。平板对峙鉴定显示:棉花根中具有较高比例的拮抗棉花黄、枯萎病菌的内生细菌,拮抗强致病落叶型黄萎病菌（V107）的内生细菌比例不仅低于枯萎病菌（F108）,而且低于非落叶型黄萎病菌（V396）。同时拮抗棉花黄、枯萎病菌的内生细菌有44株,16S rDNA分子序列分析表明：这些拮抗内生细菌的类群包括了两个门(变形杆菌门、拟杆菌门)8个属,其中10个菌株与已报道菌株相似性<97%,可能是新的种（属）,优势种群为肠杆菌属（18株）、泛菌属（15株）。【结论】棉花的品种、生育期与器官影响棉花内生细菌数量;棉花拮抗黄、枯萎病菌的内生细菌具有优势种群,且具多样性。     

A novel UASB–MFC–BAF integrated system for high strength molasses wastewater treatment and bioelectricity generation

An up-flow anaerobic sludge blanket reactor–microbial fuel cell–biological aerated filter (UASB–MFC–BAF) system was developed for simultaneous bioelectricity generation and molasses wastewater treatment in this study. The maximum power density of 1410.2 mW/m² was obtained with a current density of 4947.9 mA/m² when the high strength molasses wastewater with chemical oxygen demand (COD) of 127,500 mg/l was employed as the influent. The total COD, sulfate and color removal efficiencies of the proposed system were achieved of 53.2%, 52.7% and 41.1%, respectively. Each unit of this system had respective function and performed well when integrated together. The UASB reactor unit was mainly responsible for COD removal and sulfate reduction, while the MFC unit was used for the oxidation of generated sulfide with electricity generation. The BAF unit dominated color removal and phenol derivatives degradation. This study is a beneficial attempt to combine MFC technology with conventional anaerobic–aerobic processes for actual wastewater treatment.     

Diminished photoinhibition is involved in high photosynthetic capacities in spring ephemeral Berteroa incana under strong light conditions

Berteroa incana (B. incana), a spring ephemeral species of Brassicaceae, possesses very high photosynthetic capacities at high irradiances. Exploring the mechanism of the high light use efficiency of B. incana under strong light conditions may help to explore mechanisms of plants' survival strategies. Therefore, the photosynthetic characteristics of B. incana grown under three different light intensities (field conditions (field): 200-1500μmolphotonsm(-2)s(-1); greenhouse high light (HL) conditons: 600μmolphotonsm(-2)s(-1); and greenhouse low light (LL) conditions: 100μmolphotonsm(-2)s(-1)) were investigated and compared with those of the model plant Arabidopsis thaliana (A. thaliana). Our results revealed that B. incana behaved differently in adjusting its photosynthetic activities under both HL and LL conditions compared with what A. thaliana did under the same conditions, suggesting that the potential of photosynthetic capacity of B. incana might be enhanced under strong light conditions. Under LL conditions, B. incana reached its maximum photosynthetic activity at a much higher light intensity than A. thaliana did, although their maximum photochemical efficiency of photosystem II (PSII) (F(v)/F(m)) was almost the same. When grown under HL conditions, B. incana showed much higher photosynthetic capacity than A. thaliana. A detailed analysis of the OJIP transient kinetics of B. incana under HL and LL conditions revealed that HL-grown B. incana possessed not only a high ability in regulating photosystem stoichiometry that ensured high linear electron transport, but also an enhanced availability of oxidized plastoquinone (PQ) pool which reduced non-photochemical quenching (NPQ), especially its slow components qT and qI, and increased the photochemical efficiency, which in turn, increased the electron transport. We suggest that the high ability in regulating photosystem stoichiometry and the high level of the availability of oxidized PQ pool in B. incana under strong light conditions play important roles in its ability to retain higher photosynthetic capacity under extreme environmental conditions.     

Extraction, purification and antitumor activity of a water-soluble polysaccharide from the roots of Polygala tenuifolia

One polysaccharide PTP was isolated and purified from the roots of Polygala tenuifolia. It consisted of galactose, glucose and galactose in the ratio of 3.1:3.7:2.5, and a small amount of rhamnose, mannose and xylose. 17 general amino acids were identified to be components of the protein-bound polysaccharide analyzed by automatic amino acid analyzer. In order to test the anti-cancer activity of PTP, we investigated its effect against the growth of human ovarian cancer cells SKOV3 in vitro and in ovarian cancer rats. The intracellular reactive oxygen species (ROS) and glutathione (GSH) in SKOV3 cells following PTP treatment were also quantified to explore the possible mechanism underlying the antitumor activity of the polysaccharide. The result showed that PTP is effective on inhibiting the proliferation of SKOV3 cells in a concentration-dependent manner. Furthermore, treatment with PTP caused a rapid depletion of intracellular GSH content and accumulation of intracellular ROS, thus resulting in the apoptosis, which may prove to be a pivotal mechanism for its cancer protection action. In addition, a significant tumor growth inhibition effect was observed in nude mice after PTP administration for 7 weeks. All above indicated PTP could be beneficial towards ovarian cancer therapy.     

Analysis of Aztreonam-Inducing Proteome Changes in Nondividing Filamentous Helicobacter pylori

When stressed, bacteria can enter various nondividing states. In the present study, nondividing filamentous form in Helicobacter pylori was induced by a β-lactam antibiotic, aztreonam. In order to find possible cell division checkpoints in H. pylori, 2-DE was used to compare the proteomic profile of nondividing filamentous H. pylori with its spiral form. In total, 21 proteins involved in various cellular processes showed differential expression. One protein induced by aztreonam was a cell division inhibitor (minD), related to cell division. We then constructed the deletion mutant of minD in H. pylori 26695. Scanning electron microscope observation showed that the deletion of this protein provoked some bacteria to change into a short rod-shape and the viability of the mutant is lower than that of the wild type. Moreover, sequence comparison showed that minD of H. pylori and that of Escherichia coli share 50?% amino acid identity. This suggested that this protein possibly plays the similar part in H. pylori as in E. coli.     

A solid-phase approach to novel purine and nucleoside analogs

This paper describes a method for the preparation of purine analogs using the solid-phase approach. Nucleoside bases were constructed on Merrifield resin by sequential displacement of purine dichloride with amines, and after detachment, the purine analogs were condensed with d,l-ribofuranoside compounds by the Vorbrüggen method. Thereof, l-ribofuranoside was prepared from l-arabinose via the selective oxidation-reduction procedure of the 2-OH group. Some compounds exhibited moderate activity against HIV-1 in PBM cells.     

甘蓝型油菜雌性不育突变体FS-M1乳突细胞的细胞学观察

雌性不育突变体FS-M₁是从甘蓝型油菜(Brassica napus)品种宁油10号中发现的。为了从细胞学角度研究FS-M₁的雌性不育机理, 利用荧光显微镜、扫描和透射电子显微镜观察分析了FS-M₁柱头乳突细胞的授粉行为和超微结构。结果表明: 花粉粒能在FS-M₁乳突细胞上附着和萌发形成花粉管, 但花粉管无法穿越柱头乳突细胞; 开花后的FS-M₁乳突细胞迅速衰退而呈干瘪萎蔫状, 在衰退过程中, FS-M₁柱头乳突细胞的细胞器数量减少, 细胞液泡化明显, 高尔基体、内质网和线粒体等一些细胞器结构被逐渐破坏。因此, 推测FS-M₁的雌性不育性是由于柱头乳突细胞发育异常造成的。     

Agrobacterium-mediated genetic transformation of a Dendrobium orchid

A protocol was developed to obtain stable transgenic orchids (Dendrobium nobile) via Agrobacterium-mediated transformation of protocorm-like bodies (PLBs). Agrobacterium tumefaciens strains AGL1 and EHA105 were used, with each containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing -glucuronidase gene (gus-int) as a reporter gene. PLBs were co-cultivated with A. tumefaciens, which had been activated with 100 M acetosyringone (AS), for 2–3 days until the growth of A. tumefaciens was observed on co-cultivation medium containing 100 M AS. Following co-cultivation, PLBs were cultured on selective medium containing 30 mg l^–1 hygromycin and 250 mg l^–1 cefotaxime. Proliferating PLBs were repeatedly selected for hygromycin resistance. A high efficiency of transformation (18%) was obtained with a total of 73 stably transformed lines produced. Incorporation and expression of the transgenes were confirmed by Southern blot analysis and GUS histochemical assay.