Plant extracts from natural sources are an excellent choice for food additives and natural antioxidants.In this study,the active components of Tulipa edulis were extracted and analysed,and their antioxidant capacity was measured.Then,the crude extract mixture was separated and purified using a Sephadex LH-20 gel,and the antioxidant activity of the purified products was determined.Human umbilical vein endothelial human umbilical vein endothelial cells(HUVEC)cells were treated with 35 mmol/L glucose to construct a model of oxidative stress.Then,the cells were treated with the active component to observe whether the products of T.edulis could have a good protective effect on HUVEC cells induced by glucose.Transcriptome analysis was also performed on HUVEC cells after same treatment to explore the possible mechanism of the component F2 protecting HUVEC cells from oxidative stress induced by high glucose.The results showed that component F2 obtained from T.edulis has strong antioxidant activity.Moreover,F2 can play a strong antioxidant protective role in HUVEC cells.Meanwhile,the gene expression of heme oxygenase 1(HO-1),γ-glutamyl cysteine ligase catalytic subunit(GCLC)and NAD(P)H quinone oxidoreductase-1(NQO1)in HUVEC cells was up-regulated after treated with F2.This study provides reference value for the further development and application of T.edulis and the d evelopment of functional food.
【目的】研究西南不同地区的高山湖泊中可培养细菌的多样性及其产胞外蛋白酶、纤维素酶和胞外多糖的能力。【方法】以西南4个不同地区的高山湖泊:雷波的马湖(LB)、中缅边境的凯邦亚湖(ZM)、沙德的莲花湖(SD)、腾冲的青海湖(TC)的水样为研究对象,利用稀释涂布平板方法对可培养细菌进行分离筛选,然后通过对可培养细菌的生理生化指标和16S r RNA基因序列进行分析,初步确定细菌属别;对分离得到的菌株进行产胞外蛋白酶和纤维素酶活性测定和产胞外多糖能力检测。【结果】从西南地区4个湖泊中共分离筛选得到41株细菌,其中LB 15株、ZM 13株、SD 7株、TC 6株。根据16S r RNA基因序列的系统进化分析,4个地区可培养细菌的组成和丰度存在明显差异,其中LB和ZM的优势菌属是芽孢杆菌属(Bacillus),其次是气单胞菌属(Aeromonas)和假单胞菌属(Pseudomonas),分离的TC菌株全部属于芽孢杆菌属(Bacillus),分离的SD菌株特异性较强。进一步酶活性和胞外多糖检测表明,分离得到的41株细菌中有28株菌的发酵产物具有蛋白酶活性,6株具有纤维素酶活性,17株可产胞外多糖(Exopolysaccharides,EPS)。其中有2株细菌同时产蛋白酶、纤维素酶和胞外多糖,10株细菌同时产蛋白酶和胞外多糖,2株细菌同时产蛋白酶和纤维素酶,1株细菌同时产纤维素酶和胞外多糖。【结论】西南4个高山湖泊中存在丰富的微生物菌种资源,且4个湖泊中筛选的可培养细菌受所处环境的影响大。其中莲花湖由于高海拔和较偏僻等特点,人为干扰小,分离得到的细菌类群与其他湖泊相比明显不同;而马湖、凯邦亚湖和青海湖3个湖泊的海拔相对较低,受人类活动影响较大,分离得到的细菌均较常见。此外高山湖泊中的可培养细菌具有分泌多种胞外活性物质特性,为工业化应用奠定了资源基础,极具更深入的开发和研究价值。
This work described a new method for the detection of humic acid(HA) based on the poly(thymine)(polyT)-templated copper nanoparticles(CuNPs). Without the presence of HA, the formation of poly Ttemplated CuNPs could take place, resulting in strong fluorescence emission peaks at 610 nm(upon excitation at 340 nm). On the other hand, when HA was present, strong interaction between HA and Cu^(2+)took place, which then hampered the effective formation of fluorescent CuNPs, leading to the decrease in fluorescence intensity. Furthermore, under the optimal experimental conditions, the method exhibited a high specificity to HA with a detection limit of 0.4 mg/L. This work has demonstrated a low-cost and convenient method that could be accomplished within 10 min. The method could provide a simple, rapid,and sensitive fluorescent platform for the detection of HA.
Changbei MaMingjian ChenHaisheng LiuKefeng WuHailun HeKemin Wang
In this assay, a label-free fluorescent sensing platform based on triple-helix molecular switch(THMS) and G-quadruplex was developed for the detection of tetracycline. We demonstrated this approach by using THMS, which consists of a central section with a shortened 8-mer aptamer sequence with high affinity to tetracycline and flanked by two arm segments. G-rich oligonucleotide can specifically bind to thioflavin T(Th T) as a signal transduction probe(STP). In the absence of tetracycline, THMS remains stable, the fluorescence of background is low. By the addition of target tetracycline, the aptamer-target binding results in the formation of a structured aptamer-target complex, which disassembles the THMS and releases the STP. The free STP self-assembles into G-quadruplex and specifically binds to Th T which generates a obvious fluorescence enhancement. Using the triple-helix molecular switch, the developed aptamer-based fluorescent sensing platform showed a linear relationship with the concentration of tetracycline ranging from 0.2 to 20.0 nmol/L. The detection limit of tetracycline was determined to be970.0 pmol/L. The assay avoids complicated modifications or chemical labeling, making it simple and cost-effective. So, it is expected that this aptamer-based fluorescent assay could be extensively applied in the field of food safety inspection.
Tian-Xiao ChenFeng NingHai-Sheng LiuKe-Feng WuWei LiChang-Bei Ma
