低植酸作物突变体研究进展

植酸是玉米(Zea mays)、小麦(Triticum aestivum)、大麦(Hordeum vulgare)、水稻(Oryza sativa)和大豆(Glvcine max)等籽粒中广泛存在的一种有机酸(6-肌醇磷酸),其与K 、Ca2 、Mg2 和Fe3 等金属离子形成的植酸盐是微量营养元素的重要贮存形式.植酸及植酸盐不能被人和非反刍动物所吸收利用;植酸摄入体内后还会和其他来源的微量营养元素结合形成植酸盐,造成这些营养元素的生物有效性下降,从而造成微量元素缺乏症.此外,大量的植酸及植酸盐随粪便排出,造成严重的环境污染,尤其是水体富营养化.由于土壤中缺乏分解微生物,即使畜禽粪便作有机肥还田仍不能被作物吸收利用.近年来,利用理化诱变与转基因技术已成功地获得了玉米、大麦、水稻和大豆等作物的低植酸突变体.本文对植酸的生物合成过程、低植酸突变体的诱发与研究、低植酸突变体的遗传特征与可能机理及营养评价进行了综述,并对低植酸作物的应用前景进行了简要分析.     

玉米中植酸代谢研究的策略

作物尤其是玉米的种子中积累了丰富的植酸。早先的研究侧重于降低种子中植酸的含量,但是随着人们对植酸认识的深入,发现植酸对于动、植物而言具有不可替代的生物功能。对于人和动物而言,植酸有抗营养作用,但也是重要的健康因子;对于植物而言,植酸及其代谢中间体的生物学功能却缺乏明确的研究。若要明确把握植酸的育种方向,就必须对植酸在植物中的合成过程有明确的认识。但自植酸被发现至今,人们对于其在高等植物中的合成过程仍然知之甚少,对其生物学功能更是缺乏全面的了解。本文综述了植酸代谢研究的现状,分析并总结了植酸的代谢通路,指出了植酸代谢研究的突破点,结合植酸代谢的研究特点和进展,比较了基因同源克隆、关联分析等4种最具潜力的研究策略。     

植酸酶基因工程研究进展

植酸酶是催化植酸及植酸盐水解成肌醇和无机磷酸的一类酶的总称.添加于食品和饲料中,能消除植酸所引起的抗营养作用,可提高蛋白质和矿物质的生物利用率.对植酸酶的生物学特性、基因结构和基因工程的研究进展做了综述.     

低植酸作物突变体研究进展

植酸是玉米(Zea mays)、小麦(Triticum aestivum)、大麦(Hordeum vulgare)、水稻(Oryza sativa)和大豆(Glvcine max)等籽粒中广泛存在的一种有机酸(6-肌醇磷酸), 其与K+、Ca2+、Mg2+和Fe3+等金属离子形成的植酸盐是微量营养元素的重要贮存形式。植酸及植酸盐不能被人和非反刍动物所吸收利用; 植酸摄入体内后还会和其他来源的微量营养元素结合形成植酸盐, 造成这些营养元素的生物有效性下降, 从而造成微量元素缺乏症。此外, 大量的植酸及植酸盐随粪便排出, 造成严重的环境污染, 尤其是水体富营养化。由于土壤中缺乏分解微生物, 即使畜禽粪便作有机肥还田仍不能被作物吸收利用。近年来, 利用理化诱变与转基因技术已成功地获得了玉米、大麦、水稻和大豆等作物的低植酸突变体。本文对植酸的生物合成过程、低植酸突变体的诱发与研究、低植酸突变体的遗传特征与可能机理及营养评价进行了综述, 并对低植酸作物的应用前景进行了简要分析。     

离子交换法分离制备植酸的研究

本文研究了离子交换法直接从米糠酸溶液中吸附分离制备植酸的条件和方法。与植酸盐沉淀法相比,工艺简单,生产周期短,产品纯度高,为植酸的离子交换特性的理论研究和应用开发提供了重要依据。     

转基因植物表达植酸酶研究进展

植酸是植物体内磷的主要存在形式,其绝大部分不能被单胃动物消化吸收,而随粪便排出体外造成环境污染;同时,植酸又是一种抗营养因子,它通过络合植物体内的一些营养成分而降低植物的营养价值。通过植物转基因方法使植物自身表达足量的植酸酶,以减小植酸带来的不利影响,是提高植物性饲料营养价值和控制环境磷污染的一种经济有效的措施。就转基因植物植酸酶的优势、研究现状、存在的问题及其发展前景进行了综述。     

植酸的制备

植酸(Phytic Acid)或称环已六醇六磷酸脂.分子组成:C_6H_(18)O_24P_6分子量660.08,分子式:C_6H[OPO(OH)_2]_6,含磷28.16%,分子结构式可表示为:在华工,医药部门以及食品工业     

蒲公英植酸对沙门氏菌抑制作用及其抑菌机理研究

为探究蒲公英植酸对沙门氏菌的抑制作用及其抑菌机理。本文利用沉淀法和离子交换法提取蒲公英植酸,滤纸片法分析蒲公英植酸对沙门氏菌(Salmonella)的抑菌作用,倍比稀释法研究蒲公英植酸的最低抑菌浓度。通过分析沙门氏菌的细胞通透性和生长动力学,结合扫描电镜和荧光显微镜研究了蒲公英植酸对沙门氏菌的抑菌机理,表明蒲公英植酸对沙门氏菌具有很好的抑菌能力,其最小抑菌浓度为0.2 mg/mL。而且植酸对沙门氏菌的抑制作用是通过破坏细胞膜达到抑菌的效果,并且植酸浓度越高,抑菌效果越显著。这表明蒲公英植酸可以有效地抑制沙门氏菌生长,其主要是通过破坏菌体细胞膜完整性,增加细胞薄膜的通透性,使细胞内容物外溢达到抑制细菌生长的目的。     

滴定法快速测定发酵液中植酸酶活性

目前植酸酶发酵液中植酸酶活测定方法主要采用比色法,但此方法受到发酵液中磷的严重干扰,大大降低了检测的准确性.为避免传统方法中磷对检测过程的影响,笔者基于酶活性可用单位时间、单位体积中底物的减少量来表示的原理,通过自动滴定检测植酸钠浓度变化并建立分析模型计算出植酸酶活性.结果显示:在200～1 000 U/mL范围内,不...     

水稻种子植酸含量的地域差异

植酸及植酸盐是种子中普遍存在的物质。植酸是肌醇六磷酸脂,谷物种子中的磷大部分以这种形式贮存于皮层、胚,尤其是糊粉层中,它在细胞中主要存在于蛋白体内。在油质种子中植酸的含量很高［１］,且在相同的生态条件下含量恒定［２］。有作者认为,杂交水稻种子中植酸的含量主要受母体基因型控制［３］。但是,同一品系水稻在不同地域栽种后,其种子植酸含量的差异则未见研究报道。本文就这方面的问题进行了初步研究。１　材料与方法１．１供试材料　进行实验栽种的水稻品系共有１９个,分别为湖北大学生命科学学院选育出的Ｒ１８．Ｒ３２…     

Production of polymalic acid and malic acid by Aureobasidium pullulans fermentation and acid hydrolysis

Malic acid is a dicarboxylic acid widely used in the food industry and also a potential C4 platform chemical that can be produced from biomass. However, microbial fermentation for direct malic acid production is limited by low product yield, titer, and productivity due to end‐product inhibition. In this work, a novel process for malic acid production from polymalic acid (PMA) fermentation followed by acid hydrolysis was developed. First, a PMA‐producing Aureobasidium pullulans strain ZX‐10 was screened and isolated. This microbe produced PMA as the major fermentation product at a high‐titer equivalent to 87.6 g/L of malic acid and high‐productivity of 0.61 g/L h in free‐cell fermentation in a stirred‐tank bioreactor. Fed‐batch fermentations with cells immobilized in a fibrous‐bed bioreactor (FBB) achieved the highest product titer of 144.2 g/L and productivity of 0.74 g/L h. The fermentation produced PMA was purified by adsorption with IRA‐900 anion‐exchange resins, achieving a ～100% purity and a high recovery rate of 84%. Pure malic acid was then produced from PMA by hydrolysis with 2 M sulfuric acid at 85°C, which followed the first‐order reaction kinetics. This process provides an efficient and economical way for PMA and malic acid production, and is promising for industrial application. Biotechnol. Bioeng. 2013; 110: 2105–2113. © 2013 Wiley Periodicals, Inc.     

Separation and simultaneous determination of nalidixic acid, hydroxynalidixic acid and carboxynalidixic acid in serum and urine by micellar electrokinetic capillary chromatography

Separation in capillary electrophoresis is governed by various factors, including buffer type, buffer concentration, pH, temperature, voltage and micelles. Through proper adjustment of these parameters, nalidixic acid and its two major metabolites, 7-hydroxynalidixic and 7-carboxynalidixic, could be separated by micellar electrokinetic capillary chromatography using an electrophoretic electrolyte consisting of 50 mM borate buffer (pH 9) containing 25 mM sodium dodecyl sulphate and 10% acetonitrile. A linear relationship between concentration and peak area for each compound was obtained in the concentration range 0.15–100 μg ml⁻¹, with a correlation coefficient greater than 0.999 and detection limits in the 0.2–0.7 ng ml⁻¹ range. Intra- and inter-day precision values of about 0.8–1.2% RSD (n=11) and 1.3–2.0% RSD (n=30), respectively, were obtained. The method has been applied to the analysis of nalidixic acid and its two major metabolites in serum and urine with limits of sensitivity lower than 0.8 ng ml⁻¹.     

New highly toxic bile acids derived from deoxycholic acid,chenodeoxycholic acid and lithocholic acid

We have prepared a new panel of 23 BA derivatives of DCA, chenodeoxycholic acid (CDCA) and lithocholic acid (LCA) in order to study the effect of dual substitution with 3-azido and 24-amidation, features individually associated with cytotoxicity in our previous work. The effect of the compounds on cell viability of HT-1080 and Caco-2 was studied using the 3-[4,5-dimethylthizol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Compounds with high potency towards reduction of cell viability were further studied using flow cytometry in order to understand the mechanism of cell death. Several compounds were identified with low micromolar IC₅₀ values for reducing cell viability in the Caco-2 and HT1080 cell lines, making them among the most potent BA apoptotic agents reported to date. There was no evidence of relationship between overall hydrophobicity and cytotoxicity supporting the idea that cell death induction by BAs may be structure–specific. Compounds derived from DCA caused cell death through apoptosis. There was some evidence of selectivity between the two cell lines studied which may be due to differing expression of CD95/FAS. The more toxic compounds increased ROS production in Caco-2 cells, and co-incubation with the antioxidant N-acetyl cysteine blunted pro-apoptotic effects. The properties these compounds suggest that there may be specific mechanism(s) mediating BA induced cell death. Compound 8 could be useful for investigating this phenomenon.     

Analysis of creatinine, vanilmandelic acid, homovanillic acid and uric acid in urine by micellar electrokinetic chromatography

A simultaneous determination of vanilmandelic acid, homovanillic acid, creatinine and uric acid using capillary electrophoresis was investigated. The optimum conditions of buffer concentration, pH and surfactant concentration were studied, and high resolution was obtained using a 30 mM phosphate buffer (pH 7.0) containing 150 mM sodium dodecyl sulfate. The detection was by UV absorbance at 245 nm and the column was a fused-silica capillary of 67 cm×75 μm I.D.. The determination of these metabolites in human urine was completed within 15 min without any interferences.     

Determination of acetylsalicylic acid and salicylic acid in skin and plasma by high-performance liquid chromatography

This study describes a HPLC method to determine the concentrations of acetylsalicylic acid (ASA) and salicylic acid (SA) in human stratum corneum and in plasma. The stratum corneum layers for ASA/SA analysis were removed from three patients with postherpetic hyperalgesia treated with topical and oral aspirin. Blood samples were also collected from the same patients. Tape strippings were placed in acetonitrile and sonicated for 15 min. After centrifuging, aliquots of the supernatant were injected into the chromatograph. ASA and SA from plasma samples were extracted on Isolute C₈ columns. Due to interfering peaks in the tape samples, HPLC conditions were slightly different for tape and plasma samples. ASA and SA were separated on a LiChrospher 100 RP-18 column at 1 ml/min using a water–phosphate buffer (pH 2.5)–acetonitrile mobile phase (35:40:25, v/v/v). A linear response to quantities of ASA from 0.1 to 100 μg/cm² and of SA from 0.1 to 5 μg/cm² in tape and to quantities of ASA 0.1 to 2 μg/ml and 1 to 50 μg/ml was obtained and the recovery from tape and plasma samples was over 98%. The method is sensitive (0.1 μg/cm²) and specific enough to allow the determination of the drugs in the skin not only after topical but also after oral administration. A good sensitivity was also obtained in plasma (0.1 μg/ml) allowing study of the kinetics of ASA and SA in plasma after oral administration. Concentrations of ASA after topical administration were 100–200 times higher than after oral administration. Plasma levels of ASA and SA after oral administration were similar to those previously found. No ASA or SA were detected in plasma after topical ASA administration.     

Sempervirenic acid,a diterpene acid from Solidago sempervirens

Sempervirenic acid, a new diterpene has been isolated from Solidago sempervirens and its structure determined by spectroscopic methods and chemical conversions to be 3β-acetoxy-labda-7,13-diene-15-oic acid.     

Molecularly imprinted polymer using-p-hydroxybenzoic acid, p-hydroxyphenylacetic acid and p-hydroxyphenylpropionic acid as templates.

Molecularly imprinted polymers (MIPs) using p-hydroxybenzoic acid (p-HB), p-hydroxyphenylacetic acid (p-HPA) and p-hydroxyphenylpropionic acid (p-HPPA) as templates were synthesized. The performance of the templates and their analogues on polymer-based high performance liquid chromatography (HPLC) columns was studied. The imprinting effect of the MIP using p-HB as template is more obvious than that of MIP using either p-HPA or p-HPPA as template, and the mixture of p-HB and p-HPA can be well separated on the MIP using p-HB as template, but not on the blank. Interestingly, the recognition of MIP (p-HB as the template) to p-HB showed a synergistic effect. The retention factor of p-HB is not the sum of those of phenol and benzoic acid. We also found that the imprinting effect decreased when increasing the concentration of acetic acid in mobile phase. The possible reason is that acetic acid molecules occupied the binding sites of the polymer, thereby decreasing the concentration of binding sites. Furthermore, polymers, which showed specificity to 3,4-dihydroxybenzoic acid, can be prepared with p-HB as template. It is thus possible to synthesize a specific polymer for a compound that is either expensive or unstable by using a structurally similar compound as template.     

Comparison of hypolipidemic activity of synthetic gallic acid-linoleic acid ester with mixture of gallic acid and linoleic acid, gallic acid, and linoleic acid on high-fat diet induced obesity in C57BL/6 Cr Slc mice

Hyperlipidemia is the major risk factors of heart disease such as atherosclerosis, stroke, and death. In the present study, we studied the effect of gallic acid (GA), linoleic acid (LA), mixture of GA and LA (MGL), and chemically synthesized gallic acid-linoleic acid ester (octadeca-9,12-dienyl-3,4,5-trihydroxybenzoate, GLE) on the ability to ameliorate hyperlipidemia in C57BL/6 mice fed a high-fat diet (HFD). GLE, GA, LA, and MGL were mixed with HFD and the composition of the test compounds were 1% of the diet for 7 weeks. After 7 weeks, the average body weight of ND and GLE groups was lower than that of HFD group (P<0.05). The liver weight of mice decreased (P<0.05) in all treatment groups relative to HFD fed group. The plasma lipids such as triglyceride and LDL-cholesterol were found to be decreased (P<0.05) in GLE, GA, LA, and MGL fed mice when compared to that of HFD fed mice. But high-density lipoprotein (HDL) cholesterol increased (P<0.05) in HFD and GLE fed mice when compared to that of ND fed mice. The hepatic accumulation of fat droplets of GA, LA, GLE, and MGL group showed considerably lower than that of HFD group. Adipose histology showed that GLE supplementation was found to be more effective in decreasing the size of adipocyte relative to those of other treatment groups. In conclusion, the supplementation of synthetic GLE from gallic acid and linoleic acid ester may have a potential hypolipidemic effect on mice fed high-fat diet. Further studies are required to prove GLE as a hypolipidemic agent.     

Lactobionic and cellobionic acid production profiles of the resting cells of acetic acid bacteria

Lactobionic acid was produced by acetic acid bacteria to oxidize lactose. Gluconobacter spp. and Gluconacetobacter spp. showed higher lactose-oxidizing activities than Acetobacter spp. Gluconobacter frateurii NBRC3285 produced the highest amount of lactobionic acid per cell, among the strains tested. This bacterium assimilated neither lactose nor lactobionic acid. At high lactose concentration (30%), resting cells of the bacterium showed sufficient oxidizing activity for efficient production of lactobionic acid. These properties may contribute to industrial production of lactobionic acid by the bacterium. The bacterium showed higher oxidizing activity on cellobiose than that on lactose and produced cellobionic acid.     

Alanyl turnover from lipoteichoic acid to teichoic acid in Staphylococcus aureus

Abstract The metabolism of d -alanyl substituents of lipoteichoic acid (LTA) and teichoic acid was studied in Staphylococcus aureus . Double labelling with [³H]glycerol and d -[¹⁴C]alanine revealed that during the chase LTA was stable whereas its ¹⁴C label rapidly decreased. Half-time comparison indicated an enzyme- rather than a base-catalyzed process. Correlated with the loss of [¹⁴C]alanine from LTA was an increase of the radioactivity in wall-linked alanine ester which, after hydrolysis with HF, proved to be linked to teichoic acid. These results suggest that LTA-alanine is the donor for alanine esterification of teichoic acid. In connection with previous data we hypothesize that the loss of alanine from LTA is compensated by de novo incorporation.