酶联适体分析法检测葡萄酒中的赭曲霉素A

建立了竞争取代酶联适体分析方法,检测葡萄酒中的赭曲霉素A(OTA)。核酸适体和OTA特异性结合导致与核酸适体杂交的短链DNA解链,解离的DNA作为捕获元素,进一步特异性结合辣根过氧化物酶(HRP),HRP催化四甲基二苯胺(TMB)底物显色,测定A450nm与浓度的线性关系,确定OTA的检出限。考察了DNA包被浓度、杂交温度和封闭液等因素对检测的影响。结果表明,在优化的条件下,所建立的竞争取代酶联适体分析法对OTA检测有高灵敏度,检测限0.88μg/L,线性范围1~100μg/L在葡萄酒中添加时,加标回收率为92.03%~106.6%,相对标准偏差RSD(n=5)小于2.1%,此方法可用于葡萄酒中OTA的快速测定。     

Bioassay-guided isolation and identification of antifungal components from propolis against Penicillium italicum

The present study was aimed at identification of antifungal components against Penicillium italicum from Chinese propolis with bioassay-guided fractionation technique. Propolis ethanolic extract (PEE) was separated and purified by liquid–liquid extraction and thin layer chromatography (TLC) and the most active band was subjected to HPLC–MS/MS to identify the antifungal compounds. The results showed PEE and its fractions had strong antifungal activity against P. italicum. Among the fractions of PEE partitioned by petroleum ether, ethyl acetate, n-butanol and water, ethyl acetate fraction (E-Fr) exhibited the most effective activity against P. italicum. Further bioautographic TLC assay showed Band I, with Rf value of 0.70, had an inhibitive zone, which showed the strongest antifungal activity and completely inhibited the growth of P.italicum at 200 mg/L. Bioactive components found in Band I were further identified as pinobanksin, pinocembrine, chrysin and galangin. This study exhibited Chinese propolis and its main flavonoids was potential natural alternatives for the control of citrus blue mould caused by P.italicum.     

肉及肉制品中莱克多巴胺的ELISA检测方法的建立

建立一种肉及其制品中莱克多巴胺的酶联免疫分析方法。对莱克多巴胺残留量进行选择性(交叉反应)、特异性与检测限以及回收率和精密度测试。结果显示,选择酶联免疫法来检测样品中的莱克多巴胺准确性较好,其对莱克多巴胺结构类似物的交叉反应率都小于1%,出口猪肉罐头和牛肉中的检测限(LOD)分别为(0.28±0.30)μg/kg和(0.26±0.21)μg/kg,样品平均回收率在82.9%～91.1%之间,相对标准偏差为4.3%～8.7%,经高效液相色谱(HPLC)确证假阳性率小于等于2.0%,表明酶联免疫分析定量法可快速、准确实现对食品中莱克多巴胺残留量的快速筛选。     

Enzymatic Synthesis and Antioxidant Activity of 1‐Caffeoylglycerol Prepared from Alkyl Caffeates and Glycerol

Caffeic acid (CA) as a strong antioxidant has lower solubility in nonpolar media, which limits its application in the food industry. To increase the lipophilicity of CA, 1‐caffeoylglycerol (1‐CG) was synthesized by lipase‐catalyzed transesterification of alkyl caffeates in solvent‐free system and its antioxidant capacity was investigated. Methyl caffeate was screened as the appropriate substrate from tested alkyl caffeates with a yield of 90.63%. Ethyl acetate was used for extracting 1‐CG from enzymatic reactants and could be easily recycled. The produced 1‐CG had 2.5‐ and 10‐fold lower values of half maximal inhibitory concentration (IC₅₀) (10.86 and 3.99 μM) than butylated hydroxyanisole by 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging and β‐carotene‐linoleic acid assays, respectively. Thus, 1‐CG is an excellent antioxidant for application in the functional food industry. Using alkyl caffeates and glycerol as substrates to produce 1‐CG catalyzed by immobilized lipase in a solvent‐free system is a simple, selective, and safe bioprocess that can readily be achieved in the food industry, and the product 1‐CG could be widely applied in food, nutraceutical, and biotechnological products.     

Chemical Defenses Against Fish Predation in Three Brazilian Octocorals: 11β,12β-Epoxypukalide as a Feeding Deterrent in Phyllogorgia dilatata

The feeding-deterrence properties of crude extracts of three Brazilian octocoral species, Neospongodes atlantica Kükenthal (Alcyonacea, Nephtheidae), Plexaurella regia Castro (Gorgonacea, Plexauridae), and Phyllogorgia dilatata Esper (Gorgonacea, Gorgoniidae), were investigated. All the extracts were incorporated into food strips at the concentrations occurring in the living organisms. Crude extract and its ethyl acetate fraction obtained from P. dilatata collected in Armação dos Búzios (Rio de Janeiro State), when incorporated into artificial diets and tested in the habitat of origin, reduced consumption of food strips by fishes, relative to controls. Crude extracts from two octocoral species collected at the National Marine Park of Abrolhos (Bahia State), N. atlantica and P. regia, had no apparent feeding-deterrence properties; in fact, they seemed to stimulate feeding. Bioassay-guided fractionation of the bioactive P. dilatata crude extract revealed that the deterrent property was restricted to a medium polarity fraction. Field palatability experiments with two pure compounds isolated from this fraction revealed that the furanocembranolide 11,12-epoxypukalide is a potent feeding deterrent produced by P. dilatata against fish. Apparently, furanocembranolides are a particular class of compounds with feeding deterrent properties, protecting some octocorals from potential fish predator species in both tropical and temperate environments.     

苯酚-硫酸显色法测定多糖

芦荟多糖是芦荟的主要生物活性组分,其含量是芦荟制品的重要理化检验指标之一。文章研究了测定芦荟中多糖含量的测定方法。用紫外可见分光计,经苯酚-硫酸显色,对多糖进行测定。该法测定芦荟多糖含量,简单、快速、灵敏,而且结果满意。     

First Identification of a Putative Sex Pheromone in a Praying Mantid

Praying mantids are models for a wide variety of behavioral, physiological, and ecological studies, and sex pheromones have been assumed to be important components of their biology. However, no mantid pheromone has ever been identified. We collected volatiles emitted by females of the mantid, Sphodromantis lineola, via solid phase microextraction (SPME). Mass spectral analysis revealed the collected volatiles to be a mixture of pentadecanal and tetradecanal. We prepared a synthetic mixture of these compounds, and found that males were both attracted to this mixture and stimulated to exhibit typical precopulatory behavior. We then examined male antennae with scanning electron microscopy, and confirmed the presence of porous antennal sensilla typical of insect pheromone receptors, i.e., that male mantids are equipped with the appropriate morphological apparatus to receive volatile chemical signals. Pheromones, in conjunction with visual and tactile cues, are thus an important feature of the reproductive biology of this, and undoubtedly other species of mantids. In addition to adding a crucial aspect of behavioral biology to our knowledge of this group, identification and synthesis of mantid pheromones may be a first step in attracting and aggregating these generalist predators for use in pest control.     

Activity and Tissue Expression of Tyrosine Phosphatase PTP-MEG2

Protein tyrosine phosphatases(PTPs) are crucial regulators of signal transduction. Among them,PTP-MEG2 is an intracellular enzyme of 593 amino acid residues with a putative lipid-binding domain at the N-terminus. In the present study, we cloned the full-length form of the enzyme and expressed it in E. coli cells as a 6xHis-tagged protein. The majority of the expressed enzyme was found in the inclusion body of E. coli cell extracts.Upon extraction with a buffer containing urea, the recombinant enzyme was purified to near homogeneity on a single Ni-NTA-agarose column. This procedure resulted in the production of over 100 mg of purified recombinant PTP-MEG2 from 1 L E. coli cell culture. The purified protein displayed a single polypeptide band with expected molecular size on SDS-polyacrylamide gel electrophoresis under reducing conditions. Isolated under denatured conditions in urea, the purified enzyme was re-natured by dialyzing against a refolding buffer. The re-natured enzyme effectively dephosphorylated the common PTP substrate para-nitrophenylphosphate with a specific activity of 2000units/mg. Meanwhile, the denatured enzyme was used to immunize a rabbit to produce antibodies. The resulting antiserum had extremely high sensitivity and specificity. When used for Western blot analysis, the anti-serum revealed a wide expression of PTP-MEG2 in many tissues of mice. Together, we developed a highly effective way to purify a large amount of PTP-MEG2 and generated highly sensitive antibodies that can specifically detect endogenous expression of the enzyme in tissues.     

电痛阈测定法对光敏剂亚甲兰镇痛效果的评定

目的:利用电痛阈测定法精确评定光敏剂亚甲兰的镇痛效应.方法:50只SD大鼠随机分为5组:生理盐水组、0.25%亚甲兰组、0.5%亚甲兰组、0.75%亚甲兰组、1%亚甲兰组.将清醒大鼠的右下肢给予刺激,左肢引导,给予以0.28mA为起始强度、0.02mA为阶梯值的5个串长的连续递增的电刺激,观察给予一定的刺激强度后经过一定的潜伏期后出现第一个复合波形后的相对应的电流值,作为动物给药前之基础痛阈值.选择靠近刺激电极中枢段的右侧坐骨神经为阻断点,神经刺激器定位,注射药物,同样的方法观察记录给药后的1h、2h、3h、4h、6h、8h、12h、24h的痛阈的变化,来确定约物的镇痛效果及药物的起效时间和作用高峰时间.结果:0.25%组亚甲兰无效应,0.5%组在4小时起效,与对照组比较有显著差异,但是很快又恢复至对照水平.0.75%组滓射后3d小时起效果,与对照组比较有显著差异,且这种效果可以持续12小时:1%组注射后2小时起效果,与对照组比较有显著差异,且这种效果可以持续24小时之久.结论:亚甲兰可以提高大鼠的痛阈值,且有浓度递增效应.0.75%组和1%组阻滞效果显著,2小时至3小时起效,4小时达高峰.