AROMA PROPERTIES AND THRESHOLDS OF SOME BRANCHED-CHAIN AND OTHER MINOR VOLATILE FATTY ACIDS OCCURRING IN MILKFAT AND MEAT LIPIDS1

Aroma properties of twenty-three branched-chain, odd-numbered, or unsaturated fatty acids which had each been dispersed in acidic aqueous media (pH 2.0) were evaluated. Aroma threshold values were determined using approximately 95 judges for assessing the presence of aromas over dilutions of each fatty acid. Qualitative aroma threshold values for individual fatty acids ranged from 0.006 to 82.4 ppm in the acidic solutions, and 4-ethyloctanoic acid exhibited the lowest threshold of the group tested. Qualitative aroma assessments of dilutions of each fatty acid showed a wide range of unique aroma properties. Fatty acids exhibiting branching at the 4-position had goaty/muttony/sheepy aroma notes as did other fatty acids containing 8-carbon chain structures. Cheese-like aromas were associated with the shorter branched-chain fatty acids.     

新体系下茴脑臭氧化反应制取茴香醛(英文)

以茴脑为原料,乙酸乙酯和水为新型混合溶剂,室温下通过臭氧化分解反应制取茴香醛,并对比了该体系下和传统溶剂体系下茴香醛产率的差别。实验考察了溶剂种类、溶剂用量、臭氧气流量、混合溶剂中水含量和反应时间等工艺参数,并通过红外光谱和紫外分光光度计对反应机理进行了探讨验证。该反应在水的存在下实现了室温下一锅法合成茴香醛,产率可达81.7%,避免了茴脑臭氧化物的分离及还原步骤,工艺简单,洁净环保。     

携带IL-2/NK4双基因减毒沙门氏菌TPIN的遗传稳定性研究

对携带IL-2/NK4双基因减毒沙门氏菌TPIN的遗传稳定性进行研究。将TPIN连续传40代,取10代、20代、30代、40代菌落进行鉴定,包括菌落和菌体的形态、质粒的纯度和浓度、目的基因片段、双酶切结果及转染人肝癌细胞(HepG2)后目的基因体外表达活性。结果表明,每10代的菌落和菌体形态一致,其所含质粒的纯度和浓度在传代过程中无明显变化,PCR扩增的目的基因条带大小一致,双酶切鉴定结果正确,转染HepG2细胞后,每代间所表达目的蛋白浓度无明显差异。TPIN作为消化道肿瘤的生物治疗药物,在遗传方面有较好的稳定性,可进一步进行大量生产。     

Determination of endocannabinoids in nematodes and human brain tissue by liquid chromatography electrospray ionization tandem mass spectrometry

A simple and highly sensitive liquid chromatography/tandem mass spectrometric (LC/MS/MS) method was developed to compare endogenous cannabinoid levels in nematodes and in brains of rats and humans, with and without prior exposure to ethanol. After liquid-liquid extraction of the lipid fraction from homogenized samples, a reversed-phase sub 2 μm column was used for separating analytes with an isocratic mobile phase. Deuterated internal standards were used in the analysis, and detection was made by triple quadrupole mass spectrometer with multiple reaction monitoring (MRM). Ionization was performed with positive electrospray ionization (ESI). The nematode Caenorhabditis elegans fat-3 mutant, that lacks the necessary enzyme to produce arachidonic acid, the biologic precursor to 2-arachidonoyl glycerol and anandamide, was used as an analyte-free surrogate material for selectivity and calibration studies. The matrix effect was further investigated by in-source multiple reaction monitoring (IS-MRM) and standard addition studies. Selectivity studies demonstrated that the method was free from matrix effects. Good accuracy and precision were obtained for concentrations within the calibration range of 0.4-70 nM and 40-11,000 nM for monitored N-acylethanolamides (NAEs) and acyl glycerols, respectively.     

Production and characterization of polyclonal and monoclonal antibodies against Aflatoxin B1 oxime-BSA in an enzyme-linked immunosorbent assay

From a single aflatoxin B₁ oxime — bovine serum albumin conjugate, polyclonal and monoclonal antibody preparations were produced. The four rabbit polyclonal antisera were specific for aflatoxin Bi in a microtitration plate enzyme — linked immunosorbent assay. The monoclonal antibodies showed a wide range of differing specificities, recognizing, for example, aflatoxins B₁, B₂, G₁ and G₂; B₁ and B₂; B₁ and G₁; and G₁ alone. No antibody preparations reacted with aflatoxin M₁. The significance of these results to the strategy of anti-aflatoxin antibody production for use in quantitative enzyme immunoassays is discussed.     

红松人工林优势木竞争指数影响因子

在温带湿润气候区东段不同立地条件下的红松人工林内设置面积为600 m~2(20 m×30 m)的70块矩形固定样地。在每个样地内,选取5颗最高且长势较好的优势木作为研究的对象木,用Voronoi图确定优势木相应的竞争木,测定每一块样地内优势木与竞争木之间的距离。采用Hegyi单木竞争指数模型,分析优势木在不同样地水平上的种内竞争强度,探讨林分生长因子、地形因子、土壤养分因子对优势木竞争指数的影响,并对这3类因子与优势木竞争指数进行相应的拟合和相关性分析。结果表明：红松人工林优势木竞争强度随着优势木胸径的增大而变小,并且两者之间的关系服从幂函数;红松优势木的竞争指数与其树高、胸径、冠幅呈极显著的相关关系(P<0.01);坡向、坡位、海拔对竞争指数影响极显著(P<0.01);红松人工林优势木竞争指数的大小与土壤氮磷钾含量均呈极显著的相关关系(P<0.01);pH值对优势木竞争指数的影响不显著。当红松人工林优势木平均胸径达到45cm,优势木平均树高和冠幅大于周围竞争木时,其对周围资源的利用程度增大,林木会发生自然稀疏现象,其所受的竞争压力减小。红松喜光性强,对水分的要求高,...     

蒙古国喀尔喀部蒙古族4项群体指趾遗传学特征研究

在内蒙古民族大学调查了160例(男66例,女94例)来自蒙古国的喀尔喀蒙古族留学生的拇指类型、环食指长、指甲形状、足趾长4项群体指趾遗传学特征。研究结果:1)直型拇指率为44.38%,环指长率78.13%,指甲形状长型率58.75%、方型率6.88%、扁型率34.38%,足趾类型拇趾长率35.00%;2)指甲形状出现率性别间差异具统计学意义,两两特征间均未表现出明显相关关系;3)与我国10个蒙古族族群相比,多数差异具有统计学意义。     

毛乌素沙地南缘沙丘生物结皮中微生物分布特征

为探明半干旱沙区生物结皮中微生物分布特征,对毛乌素沙地南缘沙丘生物结皮中微生物数量进行了测定。结果表明:微生物总数从丘顶到丘间地呈递增趋势,除丘顶与迎风坡、迎风坡与背风坡结皮层微生物总数差异不显著外,其他各地貌部位结皮层微生物数量之间差异显著。同一地貌部位结皮层、0～5和5～10cm土层微生物垂直分布有变化,其变化规律为:除迎风坡放线菌数量呈先增加后递减、迎风坡微生物总数、细菌、真菌和丘顶真菌数量随剖面的加深呈递减外,其他各地貌部位微生物数量均呈先降低,后增加的趋势。微生物类群的组成表现为细菌最多,放线菌次之,真菌最少。在丘间地细菌所占微生物总数的比例与丘顶相比有所增加,而放线菌和真菌的比例有所减少。结皮下0～5和5～10cm土层微生物分布与土壤含水量的变化同步,说明土壤水分可能是影响微生物垂直分布的重要因子。     

Generation of medaka gene knockout models by target-selected mutagenesis

We have established a reverse genetics approach for the routine generation of medaka (Oryzias latipes) gene knockouts. A cryopreserved library of N-ethyl-N-nitrosourea (ENU) mutagenized fish was screened by high-throughput resequencing for induced point mutations. Nonsense and splice site mutations were retrieved for the Blm, Sirt1, Parkin and p53 genes and functional characterization of p53 mutants indicated a complete knockout of p53 function. The current cryopreserved resource is expected to contain knockouts for most medaka genes.