黑曲霉木聚糖酶结构基因和5'调控区基因克隆及其分析

以黑曲霉(Aspergillus niger)A3的基因组DNA为模板,根据已报道的xynB基因序列设计简并引物,在合适的PCR反应条件下有效地扩增出了xynB的结构基因及其5＇调控区序列片段,并克隆到pBS-T载体上,序列测定表明,该目的片段全长1 611 bp.通过序列分析:结构基因部分长744 bp,其中含有一个66 bp的内含子和18个氨基酸的信号肽序列;xynB基因的cDNA序列大小为678 bp,编码225个氨基酸,与GenBank上检索的木聚糖酶基因的核苷酸序列同源性最高达98%,氨基酸序列同源性达99%.在翻译起始点上游92 bp和118 bp处找到转录起始位点和类"TATA"box的核心启动子区特征元件以及"CAAT"box,表明所克隆的调控区序列具有真核生物启动子特点,这为构建木聚糖酶高效表达载体,用于工业育种奠定了基础.     

基于Landsat和MODIS数据融合的农牧区NPP模拟

天山北坡是中国重要的农牧业发展基地,利用遥感数据准确获取植被净初级生产力(Net primary productivity,NPP)的时空信息,对于合理分配农牧业草地资源具有重要意义。由于受到天气影响及卫星传感器受到时间分辨率和空间分辨率的限制,获取既具有中空间分辨率、又具有高时间分辨率的遥感数据比较困难。本文基于中空间分辨率Landsat 8 OLI数据与高时间分辨率MODIS数据,采用遥感数据时空融合STARFM算法,获取中空间分辨率和高时间分辨率序列的遥感数据,以天山北坡中段区域为实验区,结合CASA模型,对区域内植被NPP进行模拟。结果表明,2016年内8个时期,融合后的NDVI数据与对应时刻的Landsat 8 OLI NDVI数据的相关系数不小于0.759,偏差在0.006 2～0.009 4之间,均方根误差在0.074～0.135之间;利用融合数据与CASA模型协同模拟的NPP具有良好的空间细节信息,NPP模拟值与野外实测值决定系数R~2为0.860 1,表明两者具有较好的相关性。本研究为多源遥感影像融合技术与光能利用率模型协同模拟NPP提供了新的思路。     

Inhibition study of red rice polyphenols on pancreatic α-amylase activity by kinetic analysis and molecular docking

This study sought to investigate the possible inhibition mechanism of red rice polyphenols (RRP) on pancreatic α-amylase (PA) activity. RRP showed strong inhibition against PA activity and the half-inhibitory concentration (IC₅₀) value was 3.61 μg/mL. The fluorescence quenching of PA by RRP was a combination of static quenching and dynamic quenching. RRP could aggregate with PA and the physiochemical properties of the aggregates were closely related to the concentration of RRP. Kinetic analysis suggested that the inhibition mode of RRP on PA was reversible inhibition, which was a mixing of competitive inhibition and noncompetitive inhibition. Molecular docking speculated that RRP could form hydrogen bonds with PA by binding to the catalytic active sites (ASP197, GLU233 and ASP300) and the microenvironments of TRP58 and TRP59 were altered, thus inhibiting PA activity.     

Role of cytokeratin 8 on changes of intestinal epithelial permeability induced by corticotropin-releasing factor

AIM: To investigate the role of cytokeratin 8 (CK8) on the change of intercellular permeability of intestinal epithelial cells induced by corticotropin-releasing factor (CRF). METHODS: The expression levels of CRF receptor 1 (CRFR1) and CRFR2 on human colon adenocarcinoma HT29 cell surface were determined by immunofluorescence staining. After treatment with 100 nmol/L CRF for 72 h, the translocation of FITC-labelled dextran was measured in a Transwell chamber. The structural changes of tight junctions were observed under transmission electron microscope. The expression levels of CK8, and tight junction proteins ZO-1 and occludin were determined by Western blot. The activity of protein kinase C (PKC) was detected by ELISA. Furthermore, the effects of CRF on intestinal epithelial permeability were examined in CK8-silencing HT29 cells, which were constructed by infection with sh-CK8 lentivirus. RESULTS: CRF treatment increased the permeability of FITC-labelled dextran (P<0.05), caused the opening of tight junctions, and induced increased fluorescence intensity of CK8. The expression levels of occludin and ZO-1 were down-regulated (P<0.05). PKC activity was decreased at 1 h after CRF treatment (P<0.05). CRF-induced increase in the permeability and down-regulation of occludin were not blocked by CK8 silencing. Nevertheless,CK8 silencing blocked the effects of CRF regarding the decrease in the expression levels of ZO-1 and the increase in PKC activity (P<0.05). CONCLUSION: CK8 may be involved in CRF-induced increase in intestinal epithelial permeability by inhibiting the activity of PKC, and there may be other signaling pathways involved.     

黑曲霉发酵滤液杀食用菌线虫活性初探

对灭菌的黑曲霉发酵滤液杀线虫作用进行了研究,找到经济有效的发酵滤液培养基为豆芽汁培养基。不同浓度、不同pH值的发酵滤液均能影响其杀线效果。pH为3．0的发酵滤液原液,杀线作用及抑制线虫虫卵孵化均达100％;当pH调为5．0时,杀线校正死亡率仍达73．90％;pH5．5时,杀线校正死亡率下降到8．15％。发酵滤液原液稀释到4倍液时,杀线校正死亡率仍达60．47％;稀释6倍液时下降至25．92％。在蘑菇栽培的防治线虫试验中,蘑菇栽培料添加发酵滤液后能减少线虫的数量,同时还具有促进菌丝生长的作用;仅加发酵滤液处理比未加发酵滤液及线虫处理的生物转化率提高76．30％,加发酵滤液及线虫处理比仅加线虫处理的则提高81．41％。     

黑曲霉酸性β-甘露聚糖酶的纯化及部分性质研究

黑曲霉(Aspergillus niger)WM20-11固态发酵成熟曲,经磷酸缓冲液浸提、硫酸铵分步盐析、DEAE-Sepharose fast flow阴离子交换层析、Sephadex G-100凝胶过滤层析等分离纯化手段,最终获得了Native-PAGE、SDS-PAGE纯的酸性β-甘露聚糖酶组分,其纯化倍数为25.08,收率为5.1%。Sephadex G-100凝胶过滤层析和SDS-PAGE测得纯酶的相对分子质量分别为39 kD和40 kD,表明该酶以单体形式存在;IEF-PAGE测得该酶的等电点为4.0;含糖量测定为19.6%;酶蛋白氨基酸组成中(Asp+Glu)/(Lys+Arg)为3.74。     

A Novel Gelatinase from Marine Flocculibacter collagenilyticus SM1988: Characterization and Potential Application in Collagen Oligopeptide-Rich Hydrolysate Preparation

Although the S8 family in the MEROPS database contains many peptidases, only a few S8 peptidases have been applied in the preparation of bioactive oligopeptides. Bovine bone collagen is a good source for preparing collagen oligopeptides, but has been so far rarely applied in collagen peptide preparation. Here, we characterized a novel S8 gelatinase, Aa2_1884, from marine bacterium Flocculibacter collagenilyticus SM1988^T, and evaluated its potential application in the preparation of collagen oligopeptides from bovine bone collagen. Aa2_1884 is a multimodular S8 peptidase with a distinct domain architecture from other reported peptidases. The recombinant Aa2_1884 over-expressed in Escherichia coli showed high activity toward gelatin and denatured collagens, but no activity toward natural collagens, indicating that Aa2_1884 is a gelatinase. To evaluate the potential of Aa2_1884 in the preparation of collagen oligopeptides from bovine bone collagen, three enzymatic hydrolysis parameters, hydrolysis temperature, hydrolysis time and enzyme-substrate ratio (E/S), were optimized by single factor experiments, and the optimal hydrolysis conditions were determined to be reaction at 60 ℃ for 3 h with an E/S of 400 U/g. Under these conditions, the hydrolysis efficiency of bovine bone collagen by Aa2_1884 reached 95.3%. The resultant hydrolysate contained 97.8% peptides, in which peptides with a molecular weight lower than 1000 Da and 500 Da accounted for 55.1% and 39.5%, respectively, indicating that the hydrolysate was rich in oligopeptides. These results indicate that Aa2_1884 likely has a promising potential application in the preparation of collagen oligopeptide-rich hydrolysate from bovine bone collagen, which may provide a feasible way for the high-value utilization of bovine bone collagen.     

基于地表高光谱与OLI影像的土壤含盐量和pH值估测

针对宁夏银北地区大面积土壤盐碱化监测的需要,利用实测植被冠层光谱与Landsat 8 OLI影像相结合进行土壤含盐量和pH值估测研究.对实测植被冠层高光谱与影像多光谱反射率进行倒数、对数、三角函数及其一阶微分等一系列变换,确定最佳光谱变换形式,筛选敏感植被指数和敏感波段,分别建立基于实测植被光谱与Landsat 8 O...     

昭通不同种植模式对苹果‘烟富8号’树体生长及 果实品质的影响

摘 要：【目的】明确烟富8号在昭通地区适宜的种植模式,为昭通地区烟富8号在种植模式、科学管理上提供理论依据。【方法】本试验以M9-T337矮化自根砧嫁接烟富8号、八棱海棠上嫁接M9-T337并嫁接烟富8号、八棱海棠上嫁接烟富8号为材料。调查对比不同种植模式对苹果树生长的影响。【结果】不同种植模式对烟富8号树体长势、早果丰产性影响差异显著,变异系数为9.13%~94.12%。矮化自根砧显著提高烟富8号的中短枝比例,显著降低2年生树体冠幅,显著提高2年生、3年生的单株产量及亩产量;矮化中间砧显著降低烟富8号树体主枝数、总枝量及短枝比例;乔砧提高了烟富8号长枝比例,显著降低2年生、3年生的单株产量及亩产量。不同种植模式对烟富8号果实品质影响差异不显著。【结论】矮化自根砧在控制果树长势、促进早果丰产方面综合评价最佳。     

黑曲霉NRRL3135菌株植酸酶基因在毕赤酵母GS-115系统中的表达

将黑曲S（Aspergillus riger）NRRL3135中的植酸酶基因转入毕赤酵母GS-115中,并整合到染色体DNA上,然后进行诱导表达。通过SDS-PAGE对表达产物进行鉴定,发现重组毕赤酵母GS-115分泌了1个约100kD的蛋白,分泌的蛋白较大。用脱糖基化酶endoglycosidase H降解后,形成了约50kD的蛋白,与植酸酶基因产物的理论值相符。通过对表达产物的酶学性质研究,发现该表达产物在pH2．5和pH5．5时具有较高植酸酶活性,同时该表达产物的最适温度约为55℃。这说明植酸酶得到正确的分泌表达。