NMR, HPLC-ESI-MS, and MALDI-TOF MS analysis of condensed tannins from Delonix regia (Bojer ex Hook.) Raf. and their bioactivities

The structures of the condensed tannins isolated from leaf, fruit, and stem bark of Delonix regia (Bojer ex Hook.) Raf. have been investigated with (13)C nuclear magnetic resonance ((13)C NMR) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) coupled with thiolysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. The results showed that these condensed tannins from D. regia possessed structural heterogeneity in monomer units and degree of polymerization. Propelargonidin (PP) and procyanidin (PC) were found in the leaf, fruit, and stem bark of D. regia, while prodelphinidin (PD) was found only in the leaves. The polymer chain lengths of condensed tannins from leaf and fruit organs were detected to be trimers to hexadecamers but from trimers to tridecamers for stem bark. B-type linkages were present in all these compounds. Condensed tannins from different parts of D. regia can be explored as tyrosinase inhibitors and food antioxidants because of their potent antityrosinase and antioxidant activities. The inhibitor concentration leading to 50% enzyme activity (IC(50)) was estimated to be 38 ± 1, 73 ± 2, and 54 ± 1.5 μg/mL for the condensed tannins of leaf, fruit, and stem bark. Condensed tannins extracted from stem bark exhibited the highest antioxidant activity; the DPPH scavenging activity (IC(50)) and the FRAP values were 90 ± 2 μg/mL and 5.42 ± 0.09 mmol AAE/g, respectively.     

中国草原鼠害防治现状、问题及对策

草原是我国重要的自然资源,承担着生产、生态和生活等多种功能,在构建生态屏障、促进牧业经济以及维系社会稳定等方面具有重要意义。近几十年来,受全球气候变化和人为过度利用草原的共同影响,我国草原发生大范围退化。草原退化提高了啮齿动物栖息地适合度,促使其种群数量增加,最终导致草原鼠害发生。草原害鼠采食牧草降低草地生产力,掘洞造丘消弱草原固碳、水土保持等生态功能,携带病菌威胁人畜健康。因此,控制草原鼠害事关退化草原治理修复和社会经济的可持续发展。尽管国家开展了一系列草原鼠害研究和工程实践,取得了阶段性成果,但由于草原生态系统的复杂性和社会经济发展需求的不断提升,现有草原鼠害防治成果难以满足草原生态保护与建设的需求,相关理论和技术体系尚未完全形成,学科交叉、技术集成等亟待加强。本文总结了中国草原鼠害发生和防治的现状,并对草原鼠害防治存在的问题进行了讨论,最后从管理和技术层面对加强草原鼠害防治工作进行了展望。     

皮尔瑞俄类芽胞杆菌ZF390对黄瓜细菌性软腐病的防治效果

针对黄瓜细菌性软腐病发生严重且难以防治的问题,本研究以活体防治效果为指标,筛选更加有利于田间应用的高效生防菌株。采用梯度稀释法分离纯化病害发生严重地块的健康黄瓜植株根际中的细菌菌株,再利用双层培养法筛选到6株黄瓜细菌性软腐病菌拮抗菌株,最终通过喷雾接种法筛选得到能够有效防治黄瓜细菌性软腐病的生防菌株ZF390,其防效可达77.94%,且该菌株能够有效抑制8种病原细菌的生长,抑菌谱广。结合形态学特征、生理生化特性和多位点序列分型分析,鉴定菌株ZF390为皮尔瑞俄类芽胞杆菌Paenibacillus peoriae。采用单因素试验对菌株ZF390摇瓶发酵工艺进行优化,最终发酵液菌体浓度提高了4个数量级,可达2.94×10⁹ CFU/mL。菌株ZF390是一株能够有效防治黄瓜细菌性软腐病的生防菌株,具有进一步开发成生防制剂的应用潜力。     

我校公共选修课现状及其应对分析

本文通过我校开设公共选修课的实践经验,阐述了校级选修课在培养大学生科学文化素质方面所起到的重要作用,以及现阶段我校公共选修课面临的各种问题。并针对所出现的问题提出解决措施。     

Assessment of the stability of chromium in remedied soils by Pannonibacter phragmitetus BB and its risk to groundwater

Purpose

Acid rain can accelerate the acidification of the chromium-contaminated soils, resulting in chromium releasing into soil solution and causing ecological risk. The current study aims to investigate the release of chromium in the remedied soils by Pannonibacter phragmitetus BB under the simulated acid rain leaching and to assess its risk to groundwater.

Materials and methods

P. phragmitetus BB was utilized to remedy the Cr(VI)-contaminated soils at two levels (80 and 1,276 mg kg^?1) by the column leaching experiment, and the chemical remediation with ferrous sulfate was used as a control. The remedied soils by P. phragmitetus BB and ferrous sulfate were leached under the simulated acid rain to evaluate the release of chromium. Furthermore, the risk of chromium release from the remedied soils to the groundwater was assessed by a fuzzy comprehensive evaluation method.

Results and discussion

The average concentrations of water-soluble Cr(VI) in the remedied soils by P. phragmitetus BB were reduced to less than 5.0 mg kg^?1. Under leaching situation with the simulated acid rain, the release of total chromium and Cr(VI) from the remedied soils by P. phragmitetus BB and ferrous sulfate declined rapidly with the extended leaching time. However, the release amounts of total chromium and Cr(VI) from the remedied soil by P. phragmitetus BB more efficiently deceased as compared with that by ferrous sulfate remediation. Carbonate-bounded, exchangeable, and organics-bonded chromium were the major chromium-releasing sources under the simulated rain leaching. After microbial remediation with P. phragmitetus BB and chemical remediation with ferrous sulfate, the risk grades of the remedied soils to groundwater declined from classes 11 to 5 and 6, respectively.

Conclusions

The risks of the remedied soils by both microbial remediation with P. phragmitetus BB and chemical remediation with ferrous sulfate to groundwater effectively decreased and microbial remediation more significantly declined the chromium risk to groundwater than chemical remediation.     

氯霉素多克隆抗体的制备及其免疫学特性鉴定

将氯霉素(CAP)进行化学修饰引入羧基活性基团,合成具有半抗原结构特征的氯霉素半琥珀酸酯(CAP-HS);采用混合酸酐(MA)法将CAP-HS与牛血清白蛋白(BSA)和卵清蛋白(OVA)偶联合成人工免疫原BSA-CAP-HS和包被原OVA-CAP-HS,用红外(IR)、紫外(UV)、凝胶电泳(SDS-PAGE)进行鉴定;用BSA-CAP-HS免疫新西兰白兔和SPF鸡制备多克隆抗体(pAb),间接ELISA测定其效价,阻断ELISA鉴定其敏感性,琼脂双扩散试验、WestGold膜杂交试验和交叉反应试验鉴定其特异性。结果表明,BSA-CAP-HS偶联成功,其分子结合比为15.6∶1,获得了高价、敏感、特异的CAPpAb,为CAP残留免疫学检测方法的建立奠定了基础。     

水稻雄性不育系天然异交率与花器性状的遗传相关 Ⅱ.基因型值分析及其与双列杂交分析结果的比较

采用7对不育系(A)、保持系(B)配制7(A)×7(B)完全双列杂交(F_1雄性不育),进行天然异交试验。应用基因型值分析方法估算相关系数。回归分析表明高异交不育系的花器性状为:柱头外露良好、花时较早和颖花窄细。其中柱头外露对异交起决定佳作用。基因型值分析和双列杂交分析结果比较,两种方法所得的相关系数阵相似,但由此导出的决定异交的性状组合不尽相同。     

湖北光敏核不育水稻在福建的生育期和育性变化

1987年在沙县、福州分期播种湖北光敏核不育水稻(HPGMR)农垦58,5月下旬至10月中旬均可连续抽穗.3月10日(x=10)至6月30日(x=132)期间播种,至抽穗天数(y)可用回归方程 y=108.5-0.36x 估计.观察到可育—不育—可育的育性转变.不育—可育转变的临界日期基本稳定在8月10日左右.可育向不育转变的临界日期由于春末夏初天气多变、低温阴雨的影响,依地点、年份而变化不定.稳定不育持续期约为7月22日至8月10日.     

一种快速低廉的PCR探针标记方法

【研究目的】探针标记技术是分子生物学和基因工程研究中常用实验技术,需要发展高效、快速、低成本、安全、简捷的DNA探针标记方法;【方法】利用普通的Taq酶进行PCR探针标记,电泳和Southern杂交检测探针标记结果;【结果】电泳检测发现标记产物在电泳时相对非标记的对照表现明显滞后,表明探针标记成功;电泳条带清晰明亮,表明探针标记效率高;Southern杂交条带清晰,说明该方法标记的探针可用于Southern等分子杂交实验;【结论】利用普通的Taq酶进行PCR探针标记,是一种低成本、高效、快速的DNA探针标记方法。     

A Silicon Single-Electron Transistor Memory Operating at Room Temperature

A single-electron memory, in which a bit of information is stored by one electron, is demonstrated at room temperature. The memory is a floating gate metal-oxide-semiconductor transistor in silicon with a channel width ( approximately 10 nanometers) smaller than the Debye screening length of a single electron and a nanoscale polysilicon dot ( approximately 7 nanometers by 7 nanometers) as the floating gate embedded between the channel and the control gate. Storing one electron on the floating gate screens the entire channel from the potential on the control gate and leads to (i) a discrete shift in the threshold voltage, (ii) a staircase relation between the charging voltage and the shift, and (iii) a self-limiting charging process. The structure and fabrication of the memory should be compatible with future ultralarge-scale integrated circuits.