SARS-COV S蛋白在大肠杆菌和家蚕中的表达

将SARS-CoV S蛋白基因的部分序列(accession number为AY304495的22 908-23 542 nt区域),克隆到表达载体pET28 a(+)中,并在大肠杆菌BL21中诱导表达。SDS-PAGE、W estern b lotting分析表明,重组S蛋白的分子量约为27 kD,与理论分子量相符。将S蛋白基因的部分序列克隆入杆状病毒转移载体pBacPAK-H is后,与线性化家蚕杆状病毒BmBacPAK-6共转染BmN细胞,经空斑筛选获得重组杆状病毒BmBac-S,并将其在细胞和家蚕中进行表达。SDS-PAGE、W estern b lotting分析表明,表达产物的分子量约30 kD,用金属螯合亲和层析纯化得到家蚕细胞表达的重组S蛋白。     

Molecular genetic and chemical assessment of radix Angelica (Danggui) in China

The roots of Angelica sinensis (Danggui), a traditional Chinese medicine, have been used for invigorating blood circulation for over 2000 years in China. Three common species of Angelica roots are found in Asia: A. sinensis from China, A. acutiloba from Japan, and A. gigas from Korea. By using a molecular genetic approach, the 5S-rRNA spacer domains of the three species of Angelica were amplified, and their nucleotide sequences were determined. Diversity in DNA sequences among various species was found in their 5S-rRNA spacer domains, which could serve as markers for authentic identification of Angelica roots. In chemical analyses, the main constituents of Angelica roots including ferulic acid and Z-ligustilide were determined by HPLC; roots of A. sinensis were clearly distinct in that they contained approximately 10-fold higher levels of ferulic acid and Z-ligustilide as compared to roots of A. acutiloba and A. gigas. In addition, the amounts of main constituents in roots of A. sinensis varied according to different regions of cultivation and different methods of preservation. The chemical profile determined by HPLC therefore could serve as a fingerprint for quality control of Angelica roots.     

Derivative potentiometric stripping analysis (dPSA) used for the determination of cadmium,copper, lead,and zinc in Sicilian olive oils

Derivative potentiometric stripping analysis (dPSA) was utilized to evaluate the Cd(II), Cu(II), Pb(II), and Zn(II) content in olive oil samples produced in Sicily in the crop year 2000-2001. The repeatability of the method was attested at 86.36% for cadmium, at 94.94% for copper, at 99.00% for lead, and at 98.92% for zinc. Recovery tests were carried out, both on cleanup procedures and on extraction steps, on olive oil spiked at different levels; obtained recoveries were 84.52 +/- 9.86 for cadmium, 97.34 +/- 2.72 for copper, 100.68 +/- 0.67 for lead and 83.35 +/- 1.72 for zinc. Theoretic detection limits were 1.2 ng g(-1) for Cd, 3.6 ng g(-1) for Cu, 5.9 ng g(-1) for Pb, and 14.3 ng g(-1) for Zn. Found concentrations range were 15.94-58.51 ng g(-1) for Cu, 32.64-156.48 ng g(-1) for Pb, and 157.00-385.22 ng g(-1) for Zn. Copper, lead, and zinc were found in all samples. The main advantage of this determination consists of a not too aggressive metals extraction procedure using hydrochloric acid, which avoids losses of elements typical of sample calcinations methods.     

Characterization of flavonoids and pectins from bergamot (Citrus bergamia Risso) peel, a major byproduct of essential oil extraction

Bergamot peel is an underutilized byproduct of the essential oil and juice-processing industry. As with other Citrus peels, it still contains exploitable components, such as pectins and flavonoids. Commercial glycoside hydrolases, specifically a combination of pectolytic and cellulolytic enzymes, solubilized a high percentage of the material (81.94%). The flavonoid profile of the peel consisted of characteristic Citrus species flavanone rutinosides and neohesperosides derived from naringenin, eriodictyol, and hesperetin. In addition, a number of minor flavanone and flavone glycosides, not found in orange and lemon peels, were identified. The majority of flavonoids were extracted in the two 70% v/v EtOH extractions. Processing this material clearly has economic potential leading to low environmental impact.     

Comparison of cardioprotective abilities between the flesh and skin of grapes

Recent studies have documented that grapes and grape juices are equally cardioprotective as red wine. The existing reports implicate that the skin and seeds of the grapes containing polyphenolic antioxidants are instrumental for the cardioprotective properties of grapes. The present study examines if the flesh of grapes also possesses any cardioprotective abilities. Three groups of randomly selected rats were fed, water only (control), flesh of the grapes (2.5 mg/kg b. wt.) or the skins (2.5 mg/kg b. wt.) for 30 days. At the end of the 30 days, isolated perfused hearts were made ischemic for 30 min followed by 2 h of reperfusion in the working mode. The results demonstrated that both flesh and skin of the grapes could protect the hearts from ischemic reperfusion injury as evidenced by improved postischemic ventricular recovery and reduced myocardial infarct size. High performance liquid chromatography (HPLC) revealed that skin and flesh contained comparative amounts of glucose, fructose, tartaric acid, malic acid, shikimic acid, and trans-caftaric acid. In addition, the flesh contained reduced amounts (compared to skin) of cis-coutaric, trans-coutaric, caffeic, p-coumaric, cinnamics, and catechin/epicatechin. Total polyphenolic index was also lower in flesh compared to skin. The anthocyanins were present exclusively in the skin. Electron paramagnetic resonance (EPR) spectrometry of hydroxy radicals indicated that both flesh and skins possessed equal amount of ROS scavenging activities. Total malonaldehyde content in the heart was reduced comparatively with either flesh or skin. The results indicate for the first time that the flesh of grapes are equally cardioprotective as skin, and antioxidant potential of skin and flesh of grapes are comparable with each other despite of the fact that flesh does not possess any anthocyanin activities.     

Steam-blanched highbush blueberry (Vaccinium corymbosum L.) juice: phenolic profile and antioxidant capacity in relation to cultivar selection

High-quality standards in blueberry juice can be obtained only taking into account fruit compositional variability and its preservation along the processing chain. In this work, five highbush blueberry cultivars from the same environmental growing conditions were individually processed into juice after an initial blanching step and the influence was studied of the cultivar on juice phenolic content, distribution and relative antioxidant activity, measured as scavenging capacity on the artificial free-radical 2,2-diphenyl-1-picrylhydrazyl (DPPH*). A chromatographic protocol was developed to separate all main phenolic compounds in berries. A total of 15 glycosylated anthocyanins, catechin, galactoside, glucoside, and rhamnoside quercetin 3-derivatives, and main benzoic and cinnamic acids were identified. The total content and relative distribution in anthocyanins, chlorogenic acid, and quercetin of each juice were dependent upon cultivar, and the total content was highly correlated (rxy=0.97) to the antioxidant capacity. A selective protective effect of berry blanching in juice processing can be observed on more labile anthocyanin compounds.     

Long-term tillage and crop rotation effects on weed seedbank size and composition

Size and composition of the weed seedbank was assessed after 12 years of application of four tillage systems in two crop rotations. Mouldboard and chisel ploughing at 45 cm, minimum tillage at 15 cm and no tillage were compared in continuous winter wheat and a pigeon bean/winter wheat 2-year rotation. Weed control was based upon post-emergence herbicide application. Weed seedling emergence from soil samples taken at 0–15, 15–30 and 30–45 cm depths was assessed in a non-heated glasshouse for 12 months. The tillage system influenced weed seedbank size and composition to a much greater extent than crop rotation. Total weed seedling density was higher in no tillage, minimum tillage and chisel ploughing plots in the 0–15, 15–30 and 30–45 cm layers respectively. Density in the whole (0–45 cm) layer did not differ significantly among tillage systems. With no tillage, more than 60% of the total seedlings emerged from the surface layer, compared with an average 43% in the other tillage systems. Crop rotation did not influence either weed seedbank size or seedling distribution among soil layers, and only had a small influence on major species abundance. The weed seedbank was dominated (>66%) by Conyza canadensis (L.) Cronq. and Amaranthus retroflexus (L.), which thrived in chisel ploughing and no tillage respectively. Results suggested that crop rotation and substitution of mouldboard ploughing by non-inversion tillage (especially by minimum tillage) would not result in increased weed problems, whereas use of no tillage might increase weed infestations because of higher seedling recruitment from the topsoil.     

Seed phosphorus remobilization is not a major limiting step for phosphorus nutrition during early growth of maize

Phosphorus (P) is the least mobile nutrient in the soil as compared to other macronutrients and therefore frequently limits crop growth. During germination and early growth, seed‐phytate hydrolysis and seed‐P remobilization is the major P source for developing seedlings. The objective of this paper was to investigate whether seed‐P hydrolysis and remobilization of nonphytate P are sufficient for seedling P nutrition during early growth stages of maize. A large part of initial maize endogenous seed P reserves are mainly in the form of phytate. Till 70 cumulated degree days after sowing, nearly all the phytate (98%) was hydrolyzed and caused an increase in nonphytate P in seeds. Phytate hydrolysis and remobilization of nonphytate P was the main source of P supply for the newly growing seedlings and was not a limiting step for seedling P nutrition during the first four weeks of early growth.