Effects of extraction solvent mixtures on antioxidant activity evaluation and their extraction capacity and selectivity for free phenolic compounds in barley (Hordeum vulgare L.)

Four kinds of solvent extracts from three Chinese barley varieties (Ken-3, KA4B, and Gan-3) were used to examine the effects of extraction solvent mixtures on antioxidant activity evaluation and their extraction capacity and selectivity for free phenolic compounds in barley through free radical scavenging activity, reducing power and metal chelating activity, and individual and total phenolic contents. Results showed that extraction solvent mixtures had significant impacts on antioxidant activity estimation, as well as different extraction capacity and selectivity for free phenolic compounds in barley. The highest DPPH* and ABTS*+ scavenging activities and reducing power were found in 80% acetone extracts, whereas the strongest *OH scavenging activity, O2*- scavenging activity, and metal chelating activity were found in 80% ethanol, 80% methanol, and water extracts, respectively. Additionally, 80% acetone showed the highest extraction capacity for (+)-catechin and ferulic, caffeic, vanillic, and p-coumaric acids, 80% methanol for (-)-epicatechin and syringic acid, and water for protocatechuic and gallic acids. Furthermore, correlations analysis revealed that TPC, reducing power, DPPH* and ABTS*+ scavenging activities were well positively correlated with each other (p < 0.01). Thus, for routine screening of barley varieties with higher antioxidant activity, 80% acetone was recommended to extract free phenolic compounds from barley. DPPH* scavenging activity and ABTS*+ scavenging activity or reducing power could be used to assess barley antioxidant activity.     

Effects of tallowtree seed coat on seed germination

We measured physiological parameters including water uptake, in-vitro embryo germination ratio, and seed coat structure observed by scanning electron microscopy (SEM) to explore the influence of seed coat on the germination of seeds of tallow tree (Sapium sebiferum (Linn) Roxb.). Tallow tree seeds had good water permeability. We found that germination of cabbage seeds was inhibited when cabbage seeds were soaked in extracted solutions from tallow tree seed coat. Seed coat structure at the side of the radicle appeared to be a barrier to seed germination. We tested methods to break tallow tree seed dormancy. Dormancy of tallow tree seeds was overcome by soaking the seeds in 500 mg·L-1 or 1000 mg·L-1 GA3, followed by 100 days of cold stratification.     

Estimating vertical vegetation density through a SPOT5 imagery at multiple radiometric correction levels

There is growing concern about remote sensing of vertical vegetation density in rapidly expanding peri-urban interfaces.A widely used parameter for such density,i.e.,leaf area index (LAI),was measured in situ in Nanjing,China and then correlated with two vegetation indices (VI) derived from multiple radiometric correction levels of a SPOT5 imagery.The VIs were a normalized difference vegetation index (NDVI) and a ratio vegetation index (RVI),while the four radiometric correction levels were i) post atmospheric correction reflectance (PAC),ii) top of atmosphere reflectance (TOA),iii) satellite radiance (SR) and iv) digital number (DN).A total of 157 LAI-VI relationship models were established.The results showed that LAI is positively correlated with VI (r varies from 0.303 to 0.927,p < 0.001).The R 2 values of "pure" vegetation were generally higher than those of mixed vegetation.The average R 2 values of about 40 models based on DN data (0.688) were higher than that of the routinely used PAC (0.648).Independent variables of the optimal models for different vegetation quadrats included two vegetation indices at three radiometric correction levels,indicating the potential of vegetation indices at multiple radiometric correction levels in LAI inversion.The study demonstrates that taking heterogeneities of vegetation structures and uncertainties of radiometric corrections into account may help full mining of valuable information from remote sensing images,thus improving accuracies of LAI estimation.     

Botulinum neurotoxin is shielded by NTNHA in an interlocked complex

Botulinum neurotoxins (BoNTs) are highly poisonous substances that are also effective medicines. Accidental BoNT poisoning often occurs through ingestion of Clostridium botulinum-contaminated food. Here, we present the crystal structure of a BoNT in complex with a clostridial nontoxic nonhemagglutinin (NTNHA) protein at 2.7 angstroms. Biochemical and functional studies show that NTNHA provides large and multivalent binding interfaces to protect BoNT from gastrointestinal degradation. Moreover, the structure highlights key residues in BoNT that regulate complex assembly in a pH-dependent manner. Collectively, our findings define the molecular mechanisms by which NTNHA shields BoNT in the hostile gastrointestinal environment and releases it upon entry into the circulation. These results will assist in the design of small molecules for inhibiting oral BoNT intoxication and of delivery vehicles for oral administration of biologics.     

响应面法优化大肠杆菌CD-2产偶氮还原酶培养基的条件

在摇瓶条件下,对大肠杆菌CD-2发酵生产过程中的主要培养基组成对产偶氮还原酶的影响进行了研究。根据响应面法,以单因子试验结果为基础,利用Plackett-Burma设计对影响E.coli CD-2产偶氮还原酶的相关因子进行了评估,并筛选出具有显著效应的3个因子:pH值、MgCl2、Na2HPO4。用最陡爬坡试验逼近以上3个因子的最大响应区域后,采用design expert 7.0统计软件的Box-Behnken设计以及响应面分析法,确定E.coli CD-2优化后的最佳培养基组成:甘露醇2 g.L-1、氯化铵3 g.L-1、接菌量5%、pH值为6.5、KH2PO42 g.L-1、Na2HPO46 g.L-1、MgCl20.99 g.L-1,优化后的酶活达到2.429 U.mL-1,是初始酶活的2.85倍。从而增强了E.coli CD-2所产的偶氮还原酶实际应用于污水处理的能力。     

Effects of different activation regimens on pronuclear formation and developmental competence of in vitro-matured porcine oocytes after intracytoplasmic sperm injection

To improve the activation protocol for in vitro-maturated porcine oocytes after intracytoplasmic sperm injection (ICSI), we examined the combined effect of U0126, a specific inhibitor of mitogen-activated protein kinase kinases, and an electrical pulse on pronuclear formation and developmental competence. Two approaches were tested: (i) 6-h treatment of ICSI oocytes with U0126 applied at different intervals (0, 2, 3 or 4 h) after the electrical pulse and (ii) treatment of ICSI oocytes with U0126 applied 4 h after the electrical pulse over an additional 4, 6 or 8 h. Another protein kinase inhibitor, 6-dimethylaminopurine, was used as a chemical activator in control experiments. The highest rates of diploid embryo formation, normal fertilization and blastocyst formation were observed after 6 h of exposure to U0126 starting 4 h after the electrical pulse. Therefore, U0126 can be used as an activating agent for porcine oocytes fertilized by ICSI.     

The trophic effect of cholecystokinin on the pancreas declines in rats on total parenteral nutrition

Total parenteral nutrition (TPN) results in atrophy of the pancreas, while cholecystokinin (CCK) can significantly stimulate the exocrine pancreas in rodents. This study was designed to examine whether CCK may improve the atrophy of the pancreas in rats on TPN treatment. Forty-eight Sprague-Dawley rats were divided into orally fed and TPN groups and were infused with CCK at a dose of 5 μg/kg/h or the CCK-receptor antagonist devazepide at a dose of 200 μg/kg/h for 10 days. Infusion of CCK caused hypercholecystokininemia (hyperCCKemia) and decreased the atrophy of the pancreas resulting from TPN. The hyperplastic response to CCK in orally fed rats was decreased in the rats given TPN. Devazepide did not influence the pancreatic variables. This study further confirmed that CCK stimulates the exocrine pancreas and decreases the atrophy of the exocrine pancreas resulting from TPN. Our present findings suggest that the trophic effect of CCK on the exocrine pancreas declines in TPN.     

Toxicarioside M, a new cytotoxic 10β-hydroxy-19-nor-cardenolide from Antiaris toxicaria

A new 10β-hydroxy-19-nor-cardenolide, named toxicarioside M (1), was isolated from the trunk bark of Antiaris toxicaria (Pers.) Lesch (Moraceae), along with six known cardenolides (convallatoxin (2), convallatoxol (3), convalloside (4), 3-O-ß-D-xylopyranosylstrophanthidin (5), glucostrophanthidin (6) and strophanthidin (7)). Their structures were elucidated on the basis of HR-MSⁿ analysis, spectroscopic methods (IR, UV, 1D and 2D NMR) and by comparison with data reported in the literature. The cardenolides were evaluated for their cytotoxic activity against KB, HCT-116, SF-268, MCF-7, HL-60, PC-3 and MRC-5 cell lines.