Identification of Two Novel Anti-Fibrotic Benzopyran Compounds Produced by Engineered Strains Derived from Streptomyces xiamenensis M1-94P that Originated from Deep-Sea Sediments

The benzopyran compound obtained by cultivating a mangrove-derived strain, Streptomyces xiamenensis strain 318, shows multiple biological effects, including anti-fibrotic and anti-hypertrophic scar properties. To increase the diversity in the structures of the available benzopyrans, by means of biosynthesis, the strain was screened for spontaneous rifampicin resistance (Rif), and a mutated rpsL gene to confer streptomycin resistance (Str), was introduced into the S. xiamenensis strain M1-94P that originated from deep-sea sediments. Two new benzopyran derivatives, named xiamenmycin C (1) and D (2), were isolated from the crude extracts of a selected Str-Rif double mutant (M6) of M1-94P. The structures of 1 and 2 were identified by analyzing extensive spectroscopic data. Compounds 1 and 2 both inhibit the proliferation of human lung fibroblasts (WI26), and 1 exhibits better anti-fibrotic activity than xiamenmycin. Our study presents the novel bioactive compounds isolated from S. xiamenensis mutant strain M6 constructed by ribosome engineering, which could be a useful approach in the discovery of new anti-fibrotic compounds.     

Efficient Screening of Marine Extracts for Protease Inhibitors by Combining FRET Based Activity Assays and Surface Plasmon Resonance Spectroscopy Based Binding Assays

The screening of extracts from marine organisms is a widely used strategy to discover new drug leads. A common problem in the screening process is the generation of false positive hits through unspecific effects from the complex chemical composition of the crude extracts. In this study, we explored a combination of a fluorescence resonance energy transfer (FRET) based activity assay and a surface plasmon resonance (SPR) based binding assay to avoid this problem. An aqueous extract was prepared from rest raw material of the Norwegian spring spawning herring, and further fractionated by methanol solubility and solid phase extraction. FRET based activity assays were used to determine the influence of each extract on the activity of different proteases. Several extracts showed more than 50% inhibition. The inhibition mechanisms were elucidated by SPR based competition experiments with known inhibitors. For the secreted aspartic proteases 1, 2, 3 and HIV-1 protease, the results indicated that some extracts contain inhibitors interacting specifically with the active site of the enzymes. The study shows that a combination of an activity assay and an SPR based binding assay is a powerful tool to identify potent inhibitors in marine extracts. Furthermore, the study shows that marine vertebrates offer an interesting source for new bioactive compounds, although they have rarely been explored for this purpose.     

城市滨水区绿地生态空间的设计理念探析

在对上海、北京、哈尔滨三地滨水区绿地进行实地调查的基础上,通过借鉴生态学理论以及相关的景观规划设计理论,围绕自然空间、亲水空间、交通空间、情节空间4个方面阐述了城市滨水区绿地生态空间的构成,初步提出了城市滨水区绿地生态空间的设计理念。     

白皮松天然群体遗传多样性的EST-SSR分析

为探讨白皮松群体间遗传变异规律,使用7对EST-SSR引物对分布区内21个白皮松天然群体的遗传多样性及遗传分化水平进行了研究。结果表明:7对引物在21个白皮松天然群体的663个单株中共检测到14个多态性位点。各群体间有效等位基因数(Ne)、Shannon’s信息指数(I)、观测杂合度(Ho)、期望杂合度(He)、Nei’s期望杂合度(Nei’s)分别为1.156 5 1.601 9、0.133 5 0.492 5、0.138 4 0.397 3、0.0860 0.342 8、0.084 6 0.337 4。白皮松群体间遗传分化系数(Fst)平均为0.215 2,基因流(Nm)值平均为0.911 9,群体间基因交流总体较少,遗传分化较大。白皮松多样性水平在分布区内呈规律性变化,多样性分布的中心区域主要在西部、南部,具有从西向东,从南向北依次减少的趋势。     

宁夏防沙治沙及沙产业技术开发研究

针对宁夏自治区银川平原绿洲腹部沙地、中卫腾格里沙漠和盐池毛乌素沙地三种类型,进行防沙治沙及沙产业技术开发的试验研究。着重突出沙产业技术开发,坚持以经济效益促进防沙治沙生态建设的可持续发展,以提高水资源的利用率为核心,紧密结合当地的自然环境条件,以新技术、少用水、高投入、高产出为主要手段,开发沙产业,实现可持续发展的战略目标。在3个示范区按8个专题进行了研究与开发,建立试验示范区0.13万hm²、辐射推广2.67万hm²;培植杨树短轮伐期速生丰产优质纸浆用材林、鲜食葡萄为主的果品生产与加工、沙地植物资源利用为主的沙旱生植物开发与繁育、沙地设施栽培4种沙产业,申报3项专利,形成多项新技术,撰写30余篇论文及研究报告。     

保水剂用量对胡杨幼苗生长、光合特性和抗逆生理的影响

[目的]探究极端干旱区保水剂对荒漠植物生长与生理特性的影响,明确荒漠植物生长所需适宜保水剂用量,促进抗旱保墒造林技术在干旱荒漠区生态恢复中的应用.[方法]以胡杨2年生幼苗为研究对象,通过田间干旱试验研究5个聚天冬氨酸(PASP)保水剂用量(0、5、10、15、20 g/株)对胡杨幼苗生长、光合特性、生物量分配和抗逆生理...     

基于恒力机构的香蕉落梳装置设计与自适应性分析

针对香蕉机械化落梳过程中出现的自适应性差的问题,设计了基于恒力机构的可自适应环抱蕉茎插切式香蕉落梳装置,并对落梳装置的径向自适应性和转动自适应性进行了分析。采用两斜置压缩弹簧的结构,引入负刚度,再与正刚度的水平压缩弹簧并联组成恒力机构,提高了落梳刀具组对果轴粗细的径向自适应性,对恒力机构的力-位移特性曲线和刚度-位移特性曲线进行分析,并优选关键参数,得出斜置压缩弹簧的刚度系数k1=12 N/mm,水平压缩弹簧的刚度系数k2=3 N/mm,初始状态斜置压簧的倾斜角θ0=36. 87°,恒力行程对应的落梳刀组包络圆直径范围为80～100 mm,对应的恒力f=180 N。在加载有扭簧的虎克铰链基础上设计了可释放两个转动自由度的落梳刀盘,根据测定的香蕉果轴弯曲度设置刀盘旋转角范围为±10°,根据建立的三维模型中的几何参数得出,落梳刀具末端的工作空间是一个半径为300 mm的球面。对落梳刀具末端的柔度矩阵进行分析,结果显示,落梳刀盘旋转角为0°,即刀盘与机架上底面平行时线柔度最大,最大值为0. 818 2 mm/N,落梳刀盘旋转角为10°时线柔度最小,最小值为0. 77 mm/N,说明落梳刀具末端的线柔度随刀盘旋转角的增大而减小。试验结果表明,梳柄切口符合试验指标的蕉梳占所有样本的81. 25%,切口质量良好,该装置设计合理,且满足实际落梳作业的要求。     

基于阻隔因素的耕地质量分等因素插值方法研究

在山地丘陵区,耕地质量等级调查评价中的分等因素属性值估算受到大、中型山体阻隔影响,造成分等单元各分等因素属性赋值结果的失准。以青海省平安区为研究区,研究基于阻隔因素的分等因素属性值估算方法,并与反距离权重插值、样条函数插值方法进行了交叉验证。结果表明:不同的插值方法对3个分等因素空间分布趋势的模拟基本一致;由于插值原数据的特征与插值原理的不同,导致基于阻隔因素的插值方法对不同的土壤性质表现不一致。土壤有机质和有效土层厚度最适宜的插值方法是基于阻隔因素的样条函数插值,而在土壤pH值插值中,基于阻隔因素的反距离权重插值精度最高;研究区内的土壤有机质含量和有效土层厚度的插值精度比不考虑阻隔因素的样条函数插值的平均绝对误差、平均相对误差、均方根误差、相对均方根误差分别提高了11. 23%、10. 98%、7. 54%、9. 20%和15. 08%、11. 74%、17. 41%、9. 40%;采用基于阻隔因素的样条函数插值方法对有机质含量和有效土层厚度进行插值,二者实测值与预测值之间的决定系数分别为0. 927和0. 901。     

基于车载三维激光雷达的玉米点云数据滤波算法

为支持表型参数测量和数字植物相关研究,对车载三维激光雷达获取的玉米点云数据进行分析处理,提出了一种基于统计分析的两次滤波算法。以大喇叭口期的京农科728和农大84玉米为研究对象,使用VLP-16型三维激光雷达采集田间玉米点云数据;对点云数据进行直通滤波预处理,去除无关点后,进行第1次点云数据滤波处理,设置精确率和召回率阈值,选取参数组合;再对点云进行第2次滤波处理,确定精确率和召回率最优组合(110,0. 9)、(6,1. 2),边际组合(100,1. 0)、(6,1. 2)和(110,0. 8)、(5,0. 9),共3组参数组合;以3组验证集数据进行测试,结果表明:最优组合性能最优,可在京农科728和农大84玉米点云数据滤波中通用。     

基于毛细管网的日光温室主动式集放热系统研究

为了对比日光温室传统保温蓄热后墙与基于毛细管网的主动式集放热系统（AHSCTM）的集放热性能,对AHSCTM的集放热性能进行了测试,构建了AHSCTM水温模型,利用一维差分法对相同环境条件下的外保温复合墙（370mm黏土砖和100mm聚苯乙烯板复合而成）日间储热量和夜间放热量进行了模拟。结果表明,AHSCTM的日间储热量和夜间放热量分别为相同条件下外保温复合墙的84.4%~111.3%和74.8%~100.7%,AHSCTM的COP（Coefficient of performance）为1.1~2.4。在夜间运行期间,AHSCTM放热量是相同时间段内外保温复合墙的98.2%~172.5%。因此,与外保温复合墙相比,AHSCTM有利于提高室内最低气温。改进AHSCTM的日间储热量和夜间放热量得到大幅提升,分别较外保温复合墙高67.6%~112.1%和69.0%~128.3%,COP可达2.8~7.0。改进AHSCTM的储放热性能优于外保温复合墙,说明利用改进AHSCTM配合保温墙体替代传统保温蓄热后墙是可行的。