苹果根际自毒物质降解菌的筛选鉴定及降解特性研究

【目的】从苹果根际土壤筛选苹果根系自毒物质降解细菌,并探究分离菌株对根皮苷、邻苯二甲酸、对羟基苯甲酸以及焦性没食子酸的降解能力。【方法】分别采用邻苯二甲酸、焦性没食子酸为唯一碳源富集并筛选其降解菌株。通过对分离菌株的生理生化特征测定及16S r RNA基因序列分析,采用MEGA 5构建系统发育树,进行菌株鉴定。采用紫外分光光度法和高效液相色谱法测定分离菌株对4种自毒物质的降解能力。【结果】共分离5株有降解能力的细菌,编号为BL1、BL2、BL3、BJ1和BJ2,经鉴定BL1为钩虫贪铜菌Cupriavidus necator,BL2为生脂固氮螺菌Azospirillum lipoferum,BL3为氧化烃微杆菌Microbacterium hydrocarbonoxydans,BJ1为Paenibacillus phyllosphaerae,BJ2为Ochrobactrum cytisi。BL1、BL2、BL3菌株对邻苯二甲酸、对羟基苯甲酸、根皮苷、焦性没食子酸的降解率均高于50%。其中BL2菌株的降解效果最好,分别达到66%、72%、84%和84%。【结论】首次发现钩虫贪铜菌、生脂固氮螺菌和氧化烃微杆菌对4种自毒物质均具有很好的降解能力,对缓解自毒物质引起的连作障碍具有潜在的应用价值。     

THE BIOTRANSFORMATION,BIODEGRADATION, AND BIOREMEDIATION OF ORGANIC COMPOUNDS BY MICROALGAE1

Rapid growth in the biotechnological industry and production has put tremendous pressure on the biological methods that may be used according to the guidelines of green chemistry. However, despite continuing dramatic increases in published research on organic biotransformation by microorganisms, more research exists with microalgae. Our efforts in transforming chemicals such as organic compounds for the production of functionalized products help to lessen the environmental effects of organic synthesis. These biotransformations convert organic contaminants to obtain carbon or energy for growth or as cosubstrates. This review aims to focus on the potential of microalgae in transformation, conversion, remediation, accumulation, degradation, and synthesis of various organic compounds. However, these technologies have the ability to provide the most efficient and environmentally safe approach for inexpensive biotransforming of a variety of organic contaminants, which are most industrial residues. In addition, the recent advances in microalgal bioactivity were discussed.     

GA3和Spd对杜鹃开花期光合特性和抗氧化系统的影响

为探讨GA_3和Spd对杜鹃(Rhododendron simsii)开花花期和开花品质的影响,研究了外源GA_3和Spd对杜鹃开花期光合特性和抗氧化系统的变化。结果表明,外源GA_3对花期有显著的提前作用,Spd对花期有明显的延迟作用,但两者均使花期延长、花径增大且成花率提高。GA_3和Spd处理提高了花期叶片的光合色素含量和净光合速率(Pn)、气孔导度(Gs)和胞间CO_2浓度(Ci);GA_3处理提高了叶片的蒸腾速率(Tr),而Spd使叶片的Tr下降,两者均有效缓解了末花期叶绿素含量的下降。GA_3和Spd处理显著降低了花瓣MDA含量,提高了抗氧化酶SOD、POD和CAT活性,并减缓了末花期SOD的下降,有效延缓了衰老进程,延长花期。以1 600 mg L~(–1) GA_3和0.10 mmol L~(-1) Spd处理效果较好,能有效提高杜鹃花的观赏品质。     

Oxidative stress during exercise: Implication of antioxidant nutrients

Research evidence has accumulated in the past decade that strenuous aerobic exercise is associated with oxidative stress and tissue damage in the body. There is indication that generation of oxygen free radicals and other reactive oxygen species may be the underlying mechanism for exercise-induced oxidative damage, but a causal relationship remains to be established. Enzymatic and nonenzymatic antioxidants play a vital role in protecting tissues from excessive oxidative damage during exercise. Depletion of each of the antioxidant systems increases the vulnerability of various tissues and cellular components to reactive oxygen species. Because acute strenuous exercise and chronic exercise training increase the consumption of various antioxidants, it is conceivable that dietary supplementation of specific antioxidants would be beneficial.     

Hypoxia Increases the Susceptibility to Oxidant Stress and the Permeability of the Blood-Brain Barrier Endothelial Cell Monolayer

Abstract: Using a cell culture model of the blood-brain barrier (BBB), we investigated the brain capillary endothelial cell (EC) response to hypoxia. The activities of antioxidant enzymes such as glutathione peroxidase, glutathione reductase, catalase, and superoxide dismutase and the GSH level of brain capillary ECs alone or in coculture with astrocytes, as well as those of pericytes, were compared with those obtained with freshly isolated microvessels. These results demonstrated that brain capillary ECs cocultured with astrocytes and used in the presence of a coculture-conditioned medium provided a relevant in vitro model for studying the effect of hypoxia-reoxygenation at the BBB level. The effect of hypoxia on antioxidant enzymes, GSH, and ATP levels was studied, as well as the modification of the permeability to small weight molecules. A decrease in all enzymes and the GSH level could explain an increase in the susceptibility of the brain capillary ECs to further oxidant injury. Second, profound rearrangements of F-actin filaments of the ECs and a decrease in the ATP level could be associated with an increase in the permeability of the monolayer. Furthermore, an apoptotic process was detected by in situ end labeling of DNA. These results indicate that hypoxia distorts the function of ECs and that these cells in culture provide a valuable tool for exploring mechanisms after hypoxia-reoxygenation.     

Membrane oxidation assay--a novel lipoxygenase-based evaluation of membrane oxidizability

A membrane oxidation assay is presented which uses isolated erythrocyte membranes ("ghosts") and lipoxygenase as a selective catalyst for the transfer of oxygen to cis - cis -1,4-pentadiene-moieties. The latter are, for instance, present in linoleic and arachidonic acids, both of which are integral parts of membranes. These non-conjugated double bonds represent energetically favorable sites for oxidative attack and therefore, may be rearranged and partially consumed during oxidative stress. Consequently, the measurement of oxygen consumption in the course of the lipoxygenase-mediated oxidation provides a tool for the quick and reliable determination of such double bonds. Significant inter-individual differences have been noted in 11 subjects, which also correlate to the total radical antioxidant parameter (TRAP) values obtained. This assay will be helpful in the assessment of oxidizable structures in erythrocyte membranes that may be diminished as a consequence of oxidative damage suffered by an individual. In conclusion, a simple and rapid assay for the assessment of the oxidizability of erythrocyte membranes is presented complementing the TRAP assay for plasma antioxidative status.     

Behavioural response of Lucilia sericata to a decaying body infested by necrophagous insects

Numerous insect species are necrophagous, with Dipterans and Coleopterans being the most abundant on a corpse. Whether the presence of necrophageous species on a corpse affects the attraction of adult blowflies to the corpse is sparsely studied. We test the hypothesis that Lucilia sericata can discriminate the odour of a noncolonized cadaver from the odour of a cadaver on which conspecific and/or heterospecific necrophagous insects are feeding. The volatile organic compounds are collected from decomposing rats under four modalities: (i) in the absence of insects; (ii) in the presence of L. sericata adults; (iii) in the presence of Dermestes frischii adults; (iv) and in the presence of both D. frischii adults and L. sericata adults. During a multiple‐choice bioassay, blowflies are exposed to the four odour samples, and are shown to prefer the odour of a corpse where conspecific larvae are present. We also expect blowflies to avoid cadavers on which predators where present, although L. sericata are not repulsed by the odour of a cadaver colonized by hide beetles. We then compare the average quantities of all 61 volatile molecules identified, finding that the presence of necrophagous insects impacts some of them. However, none of the volatile organic compounds previously reported in the literature as being attractive for L. sericata adults are impacted by the presence of necrophagous insects. The results of the present study suggest that blowfly larvae modify the volatilome of a corpse, enabling adults to discriminate a colonized from a noncolonized corpse.     

西藏仲巴五彩沙漠放线菌资源勘探及生物活性筛选

【背景】细菌耐药性问题日益严峻,新抗生素的研发速度远远落后于临床需要,从特殊生境中挖掘微生物药物资源有望解决以上问题。【目的】勘探西藏仲巴五彩沙漠土壤放线菌多样性并进行生物活性筛选,为发现药用放线菌资源、开发新型抗生素奠定基础。【方法】采用8种分离培养基,通过平板稀释涂布法分离放线菌;根据分离菌株的16S r RNA基因序列同源性分析放线菌多样性;采用PCR技术对分离的放线菌菌株进行II型聚酮合酶(PKS-II)酮缩酶结构域KS、非核糖体多肽合成酶(NRPS)腺苷酸化结构域A、安莎类抗生素生物合成前体3-氨基-5-羟基-苯甲酸合酶(AHBA)保守区、黄素腺嘌呤二核苷酸卤化酶(Halo)保守区抗生素生物合成基因检测;对生物合成基因检测阳性的菌株进行液体发酵,发酵液经乙酸乙酯萃取、菌体经丙酮浸提,获得提取浓缩物样品进行抑菌活性和抗氧化活性筛选。【结果】从4份土样中分离纯化到231株放线菌,分布于7个属,其中链霉菌为优势菌属。68株放线菌的生物合成基因分析显示至少具有1种生物合成基因簇,其中6株同时具有4种生物合成基因簇;进一步的抑菌活性检测显示所有检测的菌株至少表现为对1株检定菌具有抑菌活性,其中8株具有广谱抗菌活性;抗氧化活性筛选结果为13株显示总抗氧化能力阳性,10株具有较好的羟自由基清除能力,3株显示较强的氧自由基清除能力。【结论】西藏仲巴五彩沙漠土壤中含有较丰富的放线菌药用资源,具有从中发现放线菌新菌种和开发新抗生素的潜力。     

Investigations of anticholinestrase and antioxidant potentials of methanolic extract,subsequent fractions,crude saponins and flavonoids isolated from Isodon rugosus

Background

Based on the ethnomedicinal uses and the effective outcomes of natural products in various diseases, this study was designed to evaluate Isodon rugosus as possible remedy in oxidative stress, alzheimer’s and other neurodegenerative diseases. Acetylecholinestrase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of crude methanolic extract (Ir.Cr), resultant fractions (n-hexane (Ir.Hex), chloroform (Ir.Cf), ethyl acetate (Ir.EtAc), aqueous (Ir.Aq)), flavonoids (Ir.Flv) and crude saponins (Ir.Sp) of I. rugosus were investigated using Ellman’s spectrophotometric method. Antioxidant potential of I. rugosus was determined using DPPH, H₂O₂ and ABTS free radicals scavenging assays. Total phenolic and flavonoids contents of plant extracts were determined and expressed in mg GAE/g dry weight and mg RTE/g of dry sample respectively.

Results

Among different fractions Ir.Flv and Ir.Cf exhibited highest inhibitory activity against AChE (87.44 ± 0.51, 83.73 ± 0.64%) and BChE (82.53 ± 0.71, 88.55 ± 0.77%) enzymes at 1 mg/ml with IC₅₀ values of 45, 50 for AChE and 40, 70 μg/ml for BChE respectively. Activity of these fractions were comparable to galanthamine causing 96.00 ± 0.30 and 88.61 ± 0.43% inhibition of AChE and BChE at 1 mg/ml concentration with IC₅₀ values of 20 and 47 μg/ml respectively. In antioxidant assays, Ir.Flv, Ir.Cf, and Ir.EtAc demonstrated highest radicals scavenging activities in DPPH and H₂O₂ assays which were comparable to ascorbic acid. Ir.Flv was found most potent with IC₅₀ of 19 and 24 μg/ml against DPPH and H₂O₂ radicals respectively. Whereas antioxidant activates of plant samples against ABTS free radicals was moderate. Ir.Cf, Ir.EtAc and Ir.Cr showed high phenolic and flavonoid contents and concentrations of these compounds in different fractions correlated well to their antioxidant and anticholinestrase activities.

Conclusion

It may be inferred from the current investigations that the Ir.Sp, Ir.Flv and various fractions of I. rugosus are good sources of anticholinesterase and antioxidant compounds. Different fractions can be subjected to activity guided isolation of bioactive compounds effective in neurological disorders.     

Syntheses and structural characterization of rhenium-bis-hydrazinopyrimidine core complexes with thiolate and Schiff base coligands

The reaction of perrhenate with 2-hydrazinopyrimidine in MeOH–HCl yields [ReCl₃(η¹-NNC₄H₃N₂H)(η²-HNNC₄H₃N₂)] (1). The analogous reaction with Na₂MoO₄ yields [MoCl₃(η¹-NNC₄H₃N₂H)(η²-HNNHC₄H₃N₂)] (1a). The reaction of 1 with pyrimidine-2-thiol and triethylamine produces [Re(η¹-C₄H₃N₂S)(η²-C₄H₃N₂S)(η¹-NNC₄H₃N₂)(η²-HNNC₄H₃N₂)] (2), while reaction of 1 with the Schiff base HSC₆H₄N=C(H)C₆H₄OH provides [Re(η³-SC₆H₄N=C(H)C₆H₄O)(η¹-NNC₄H₃N₂)(η²-HNNC₄H₃N₂)]·0.6CH₂Cl₂ (3·0.6CH₂Cl₂). The analogous hydrazinopyridine complex of the Schiff base, [Re(η³-SC₆H₄N=C(H)C₆H₄O)(η¹-NNC₅H₄N)(η²-HNNC₅H₄N)] (4), was also synthesized by reacting [ReCl₃(η¹-NNC₅H₄NH)(η²-HNNC₅H₄N)] with HSC₆H₄N=C(H)C₆H₄OH. The crystal structures of 1–4 have been determined.