Effect of genetic modification on the distribution of minor constituents in canola oil

Oil derived from different lines of genetically modified canola varieties was analyzed for phospholipids, tocopherols, and phytosterols by various chromatographic techniques. As observed previously in genetically modified soybean oils, there was a decrease in the content and composition of phosphatidic acid in three of the modified canola oils derived from the 12 varieties investigated. Normal-phase high-performance liquid chromatographic (HPLC) analyses showed small variations in the phospholipid content of major classes, despite few differences in their composition. Reversed-phase HPLC data indicated that the molecular species distribution of phosphatidylethanolamine was significantly altered by genetic modification when compared to phosphatidylcholine. Impact of oilseed modification on the tocopherol content was variable, with greater variation in the concentration of α- and γ-tocopherols than δ-tocopherol. Phytosterol composition was markedly affected by genetic modification. Brassicasterol, campesterol, and β-sitosterol levels were consistently lowered in one genotype, whereas increased brassicasterol content was observed in the other variety. In general, genetic modification of canola seeds led to changes in the distribution of phospholipids, tocopherols, and phytosterols. Presented in part at the 89th AOCS Annual Meeting & Expo, Chicago, Illinois, May 10–13, 1998.     

Composition and distribution of individual molecular species of major glycolipids in wheat flour

The distribution of individual molecular species of the main wheat flour glycolipids, digalactosyldiglyceride (DGDG), monogalactosyldiglyceride (MGDG), digalactosylmonoglyceride (DGMG) and monogalactosylmonoglyceride (MGMG) has been investigated by reversed phase high-performance liquid chromatography of their benzoate derivatives after the respective galactosylglyceride classes were obtained by semi-preparative high-performance liquid chromatography. Combinations of linoleic acid at thesn-2 position with linoleic, oleic and palmitic acids at thesn-1 position predominated as major common molecular species of MGDG and DGDG. The pairs 16:0/20:4, 18:3/20:1, 18:0/18:3, 18:0/18:1 and 20:0/18:2 were determined only among MGDG molecular species. Five common molecular species containing 16:0, 18:0, 18:1, 18:2 and 18:3 fatty acids, respectively, were determined in MGMG and DGMG, with 18:2 being the most predominant form, and 18:1 (MGMG) and 16:0 (DGMG) as the next major fatty acids.     

Effect of genetic modification on the content and composition of bioactive constituents in soybean oil

The content and composition of tocopherols, sterols, and phospholipids in soybean oils derived from genetically-modified soybeans were determined by normal and reverse-phase high-performance liquid chromatography and gas-liquid chromatography. Tocopherol content was lowered in oils from soybeans selected to yield high palmitate and stearate contents. However, β-tocopherol, which amounts to less than 1 ppm in control oils, was increased to 25–53 ppm in these oils. Sterol content was higher in one reduced-linolenate oil, which also had the highest oleate content. The greatest variability was observed in the content of β-sitosterol, which ranged from 46.9–151.6 mg/100/g in the modified oils. Although, in general, there was little impact on the phospholipids, the content of phosphatidic acid was elevated in crude oils from three of the lines. Increases in phosphatidic acid are generally associated with storage deterioration of soybeans. Individual major classes of phospholipid were isolated, and the molecular species composition of each was determined. Compositional variations in molecular species indicated that there was an impact of the genetic modification of soybeans at the molecular level of the phospholipids that are primary plant cell components. Presented at 86th AOCS Annual Meeting & Expo, San Antonio, Texas, May 7–11, 1995.     

Supercritical fluid extraction of bacterial and archaeal lipid biomarkers from anaerobically digested sludge

Supercritical fluid extraction (SFE) was used in the analysis of bacterial respiratory quinone (RQ), bacterial phospholipid fatty acid (PLFA), and archaeal phospholipid ether lipid (PLEL) from anaerobically digested sludge. Bacterial RQ were determined using ultra performance liquid chromatography (UPLC). Determination of bacterial PLFA and archaeal PLEL was simultaneously performed using gas chromatography-mass spectrometry (GC-MS). The effects of pressure, temperature, and modifier concentration on the total amounts of RQ, PLFA, and PLEL were investigated by 23 experiments with five settings chosen for each variable. The optimal extraction conditions that were obtained through a multiple-response optimization included a pressure of 23.6 MPa, temperature of 77.6 °C, and 10.6% (v/v) of methanol as the modifier. Thirty nine components of microbial lipid biomarkers were identified in the anaerobically digested sludge. Overall, the SFE method proved to be more effective, rapid, and quantitative for simultaneously extracting bacterial and archaeal lipid biomarkers, compared to conventional organic solvent extraction. This work shows the potential application of SFE as a routine method for the comprehensive analysis of microbial community structures in environmental assessments using the lipid biomarkers profile.     

Bacterial Depuration of The Mexican Scallop,Argopecten Circularis

A Mexican company plans to sell artificially cultured and cleansed adult scallops, Argopecten circularis, to Mexicans and Europeans for human consumption. A series of six experiments, comparing the effectiveness of ozone vs chlorine depuration in adult A. circularis, was performed at the aquaculture facility in La Paz. It was quite difficult to maintain oxidant residuals due to the extreme ambient temperature (+42?C), but experiments did show that both oxidants, chlorine and ozone, reduced total plate count 90–94‰ and chlorine treatment depurated scallops of coliform in the experimental treatment time.     

Antioxidant activity and active sites of phospholipids as antioxidants

Various compounds, representative of the major functional groups in phospholipids, phosphatidylethanolamine and phosphatidylcholine, were tested for antioxidant activity (AA) in a sardine oil system to determine the relationship between molecular structure and the AA of these compounds. AA was found to be attributable not only to the side-chain amino groups but also to the cooperative effect of the hydroxy group in the side chain. Choline and ethanolamine, side-chain moieties of phospholipids, strongly inhibited increases in peroxide values in a sardine oil mixture during storage; however, phosphatidic acid derivatives and glycerol, also major functional groups of phospholipids, did not show AA. Choline and ethanolamine have hydroxy amines as functional groups; therefore, several model reagents that contained amines and alcohols were assayed to compare the activity of the amino group with that of the hydroxy group. All basic alkylamines examined had AA as decomposers of hydroperoxides. The intramolecular hydroxy group in these amines complemented AA of the amino group. Only intramolecular alcohol, which can donate a proton, showed strong synergistic activity with AAof the basic amines, while protected groups, such as methyl ether and phosphate ester, did not show this effect.     

北京市大气颗粒物中多环芳烃的分布特征

用撞击式分级采样器同步采集了北京市城乡结合部、郊区的2003年4个季节的不同粒径大气颗粒物样品,用气相色谱-质谱分析了其中的多环芳烃,并对两个地区大气颗粒物中的多环片烃含量、分布及季节性变化特征进行了探讨。     

Interference of polar lipids with the alkalimetric determination of free fatty acid in fish lipids

An examination of the suitability of an alkalimetric method for the determination of free fatty acid (FFA) contents in fats, oils, and lipid extracts was conducted by comparing AOCS method Ca 5a-40 with a method based on a Chromarod-latroscan thin-layer chromatography-flame-ionization detector (TLC-FID) system. The FFA contents determined by the alkalimetric method were consistently higher than the genuine FFA contents obtained by the latroscan TLC-FID method. Phospholipids were found to be the major components that contributed to the alkali-titratable, nongenuine FFA in the total FFA determined alkalimetrically. Contributions from other polar lipid components were smaller, but they dominated as the proportion of phospholipids fell. The other alkali-titratable polar components may include oxidized lipids and their by-products bound to protein fragments. The accurate determination of FFA contents by alkalimetric methods may only be applicable to those commercially refined fats and oils that contain negligible amounts of phospholipids. Corrections for the alkalimetrically determined FFA contents should be made for those fats and oils with relatively high phospholipid contents by correlating the nongenuine FFA contents and the phospholipid contents.     

Dietary Polyunsaturated Fatty Acids and Inflammation: The Role of Phospholipid Biosynthesis

The composition of fatty acids in the diets of both human and domestic animal species can regulate inflammation through the biosynthesis of potent lipid mediators. The substrates for lipid mediator biosynthesis are derived primarily from membrane phospholipids and reflect dietary fatty acid intake. Inflammation can be exacerbated with intake of certain dietary fatty acids, such as some ω-6 polyunsaturated fatty acids (PUFA), and subsequent incorporation into membrane phospholipids. Inflammation, however, can be resolved with ingestion of other fatty acids, such as ω-3 PUFA. The influence of dietary PUFA on phospholipid composition is influenced by factors that control phospholipid biosynthesis within cellular membranes, such as preferential incorporation of some fatty acids, competition between newly ingested PUFA and fatty acids released from stores such as adipose, and the impacts of carbohydrate metabolism and physiological state. The objective of this review is to explain these factors as potential obstacles to manipulating PUFA composition of tissue phospholipids by specific dietary fatty acids. A better understanding of the factors that influence how dietary fatty acids can be incorporated into phospholipids may lead to nutritional intervention strategies that optimize health.     

Nutrition of rice bran oil in relation to its purification

A comparative nutritive study was made to show that the extent of purification markedly influences the nutritive characteristics of rice bran oil. The coefficient of digestibility was 93.8% when rice bran oil that had been purified by degumming, deacidifying, bleaching and deodorizing was fed to rats; whereas it was 94.8% when extremely pure rice bran oil, which was achieved by including an additional dewaxing step, was used. Rice bran oil without deodorization, but purified by other treatments, showed a 96.2% coefficient of digestibility, which is somewhat lower than that of groundnut oil. However, after a feeding experiment over three months, the highly purified rice bran oil showed better results than the other two purified samples of rice bran oil, and was sometimes better than groundnut oil in terms of total lipid, triglyceride and especially in cholesterol content in serum, liver and heart tissues.     

以分子组份为对象的PTA间歇酯化反应模拟

为了研究对苯二甲酸和乙二醇间歇酯化过程中的低聚合反应，建立了一数学模型，模型能被用以估计转化率、低聚组份的浓度和低聚物的分布，分析了乙二醇／对苯二甲酸摩尔比对转化率、低聚物浓度、低聚物分子量及分子分布的影响。     

基于脂质组学的青年女性早晚面部皮肤表面脂质差异分析

建立了基于脂质组学的面部皮肤表面脂质(SSL)采集、检测及分析方法。通过脂质组学方法采集和检测同一组青年女性早晚不同时间的SSL,运用统计学进行分析。结果表明,早晚面部SSL之间表现出明显的分组趋势,进一步的分析表明,早晚面部SSL的八大类脂质成分和含量均有差异,且常见的甘油三酯、甘油二酯和神经酰胺等脂质成分也有不同,提示这些差异脂质可能与不同节律下的皮肤状态有关。     

Lateral Distribution of NBD-PC Fluorescent Lipid Analogs in Membranes Probed by Molecular Dynamics-Assisted Analysis of F?rster Resonance Energy Transfer (FRET) and Fluorescence Quenching

Förster resonance energy transfer (FRET) is a powerful tool used for many problems in membrane biophysics, including characterization of the lateral distribution of lipid components and other species of interest. However, quantitative analysis of FRET data with a topological model requires adequate choices for the values of several input parameters, some of which are difficult to obtain experimentally in an independent manner. For this purpose, atomistic molecular dynamics (MD) simulations can be potentially useful as they provide direct detailed information on transverse probe localization, relative probe orientation, and membrane surface area, all of which are required for analysis of FRET data. This is illustrated here for the FRET pairs involving 1,6-diphenylhexatriene (DPH) as donor and either 1-palmitoyl,2-(6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino] hexanoyl)- sn-glycero-3-phosphocholine (C6-NBD-PC) or 1-palmitoyl,2-(12-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]dodecanoyl)-sn-glycero-3-phosphocholine (C12-NBD-PC) as acceptors, in fluid vesicles of 1,2-dipalmitoyl-sn-3-glycerophosphocholine (DPPC, 50 °C). Incorporation of results from MD simulations improves the statistical quality of model fitting to the experimental FRET data. Furthermore, the decay of DPH in the presence of moderate amounts of C12-NBD-PC (>0.4 mol%) is consistent with non-random lateral distribution of the latter, at variance with C6-NBD-PC, for which aggregation is ruled out up to 2.5 mol% concentration. These conclusions are supported by analysis of NBD-PC fluorescence self-quenching. Implications regarding the relative utility of these probes in membrane studies are discussed.     

大班授课、小班研讨教学模式的探讨

素质教育要求学生是教学的主体,如何把教与学有机结合起来是值得思考的。本文根据高校教学特点以及自身教学的体会,提出了高校教学中的大班授课、小班研讨的教学模式。并结合实际的教学情况,阐明这种教学模式的重要性,为相关教学改革提供一定的参考。     

动态表面张力破裂磷脂膜的分子动力学模拟

磷脂双层膜在生物传感器、仿生膜和生物膜反应器等领域具有广阔的应用前景。揭示磷脂膜破裂过程规律对于磷脂膜器件设计和应用具有重要的基础意义。以二棕榈酰磷脂酰胆碱(dipalmitoyl phosphatidylcholine, DPPC)和二棕榈酰磷脂酰甘油(dipalmitoyl phosphoglycerol, DPPG)作为磷脂膜组分,采用粗粒化分子动力学模拟研究了磷脂膜组成对其破裂过程的影响规律。首先建立了磷脂膜破裂动力学的临界破裂时间及临界破裂表面张力的识别方法;进而考察了磷脂膜组成对其破裂动力学的影响规律。模拟结果表明随着带负电组分DPPG 含量增加,磷脂膜平均临界破裂时间延迟且分布变宽,即磷脂膜强度提高,磷脂膜破裂呈现非均匀特性。提出了描述动态表面张力作用下磷脂膜破裂过程的\"动态\"微观对抗理论,由该理论可预期磷脂膜的线张力随着DPPG 含量提高而增强,与分子动力学模拟结果相符。为基于磷脂膜的分子器件的设计提供了数值模拟及理论依据。     

山桐子油脱胶工艺研究

文章比较了不同脱胶剂对山桐子油脱胶效果的影响,重点研究了磷酸法脱胶工艺,研究结果表明:适宜的脱胶工艺为反应温度80℃,搅拌15 min,脱酸剂用量为1.2%,本试验中搅拌速度对脱胶效果没有影响;山桐子油中以非水化磷脂为主,磷脂酸与溶血磷脂酸钙镁盐在毛油中所占比例相当。