Physical mapping of a centromere-proximal region of chromosome IV-l defines the placement of genes USO1, MBP1, PSA1 and SLC1

A physical map of a 14·5 kb region close to the centromere on the left arm of chromosome IV of Saccharomyces cerevisiae is presented. This map has been constructed by restriction analysis of a clone from a YCp50 genomic library and by use of pre-existing and new sequence data from this region. The map reveals the following gene order (reading from the most centromere-distal to the most centromere-proximal locus): USO1/INT1–MBP1–PSA1–SLC1–YLA1 and defines the size of the open reading frames and intergenic regions.     

1-羧乙基氨基-1-脱氧-D-果糖在氦气中的热解产物分析

采用在线裂解GC/MS技术研究了1-羧乙基氨基-1-脱氧-D-果糖在300、500和800℃下于氦气中的热解产物。结果表明:①温度不同其热解产物亦不同,高温下热解产物较多;②热解产物大部分为杂环类化合物如吡嗪、甲基吡嗪、吡啶、呋喃酮、吡唑、吡咯和吡喃酮等,这些物质都是卷烟烟气中重要的致香成分。     

Thermodynamic characterization of the PR-10 allergens Bet v 1, Api g 1 and Dau c 1 and pH-dependence of nApi g 1 and nDau c 1

Natural and recombinant Bet v 1, the major birch pollen allergen, and homologous allergens, Api g 1 and Dau c 1, from celery and carrot, respectively, were studied by CD spectroscopy under conditions of varying denaturant concentration, pH and temperature to determine fundamental thermodynamic parameters for conformational stability. Thermodynamic studies increase basic knowledge regarding differences between birch pollen-related allergens and are of importance in choosing processing conditions. The conformational stability determined from guanidine hydrochloride denaturation curves was similar for rBet v 1.0101 and rApi g 1.0101. Conformational responses to chaotropic salt were different for recombinant allergens from different species, but were similar for the natural isoform mixtures. The conformational stabilities of nApi g 1 and nDau c 1, were shown to be similar to rBet v 1.2801 at pH > 4.4 [Mogensen, J. E., Ipsen, H., Holm, J., & Otzen, D. E. (2004). Elimination of a misfolded folding intermediate by a single point mutation. Biochemistry, 43(12), 3357-3367], but nApi g and nDau c 1 were stable to heating at lower pH-values.     

Origin and practical significance of the sticky dough factor in 1BL/1RS wheats

When translocated into wheat, the short arm of the 1R chromosome of rye carries with it linked resistance genes to powdery mildew, stripe rust, leaf rust and stem rust. The translocation is also reported to increase yield potential of hard wheats. However, many doughs made from some 1BL/1RS hard wheats are unacceptable for breadmaking purposes because of excessive stickiness and mixing intolerance. 1BL/1RS wheats may be sticky because of: the inheritance of secalin proteins from rye and absence of key glutenin subunits; higher amounts and/or differences in the composition of cell wall polysaccharides, β‐glucans and pentosans; and/or the presence of a ferulic acid ester moiety residing with the water‐soluble fraction of 1BL/1RS flours. None of these hypotheses has been proven or disproven, to date, as a cause of excessive stickiness. Investigators have found that 1BL/1RS doughs are not uniformly sticky and are in some instances less sticky than non‐1BL/1RS doughs. Significant genotype–environment interactions have been reported for dough stickiness and flour quality characteristics of 1BL/1RS wheats. Investigators have generally failed to find significant differences in the breadmaking performance of 1BL/1RS and non‐1BL/1RS hard wheats despite a report that 1BL/1RS doughs break down and soften during high‐speed mixing. The 1BL/1RS translocation has been shown to reduce cookie spread of soft wheat flours but has no deleterious effects on cake volume or texture. © 2002 Society of Chemical Industry     

甲型H1N1流感解读

2009年3月底墨西哥暴发了"人感染猪流感"疫情,该疫情迅速在全球范围内蔓延,对人类造成了巨大的威胁,引起了世界各国的重视。本文介绍了上世纪以来全球暴发的主要流感疫情,并对此次流感疫情的病原学、流行病学、防控以及治疗措施做了详细介绍。     

Suppression of sdh1 mutations by the SDH1b gene of Saccharomyces cerevisiae

Transformation of the respiratory-defective mutant (E264/U2) of Saccharomyces cerevisiae with a yeast genomic library yielded two different plasmids capable of restoring the ability of the mutant to grow on non-fermentable substrates. One of the plasmids (pG52/T3) contained SDH1 coding for the flavoprotein subunit of mitochondrial succinate dehydrogenase. The absence of detectable succinate dehydrogenase activity in mitochondria of E264/U2 and the lack of complementation of the mutant by an sdh11null strain indicated a mutation in SDH1. The second plasmid (pG52/T8) had an insert with reading frame (YJL045w) of yeast chromosome X coding for a homologue of SDH1. Subclones containing the SDH1 homologue (SDH1b), restored respiration in E264/U2 indicating that the protein encoded by this gene is functional. The expression of the two genes was compared by assaying the β-galactosidase activities of yeast transformed with plasmids containing fusions of lacZ to the upstream regions of SDH1 and SDH1b. The 100–500 times lower activity measured in transformants harbouring the SDH1b-lacZ fusion indicates that the isoenzyme encoded by SDH1b is unlikely to play an important role in mitochondrial respiration. This is also supported by the absence of any obvious phenotype in cells with a disrupted copy of SDH1b. © 1998 John Wiley & Sons, Ltd.     

超高效液相色谱-串联质谱法测定食品中黄曲霉毒素B1和M1的方法研究

应用超高效液相色谱-串联质谱联用技术（UPLC-MS/MS）,在多反应离子检测（MRM）方式下对食品中的黄曲霉毒素B1（AFB1）和M1（AFM1）污染量进行检测.样品经乙腈-水混合试剂提取,中性氧化铝柱净化,经Agilem ZORBAX Eclipse plus C18色谱柱（100 mm×4.6 mm,1.8 μm）,以甲醇和10 mmol/L NH4Ac溶液（含0.1％的甲酸）为流动相洗脱分离,以MRM方式进行定量分析.AFB1和AFM1分别在0.12～6.12 μg/L和0.11～2.28 μg/L质量浓度范围内线性关系良好,相对标准偏差（RSD）＜5％,加标回收率为81.3％～97.2％.该方法具有低成本、准确、快速、简便、灵敏度高等优点,可满足我国对AFB1和AFM1检测限要求.     

紫玉米中黄曲霉毒素B1和富马毒素B1的脱毒研究

为脱除紫玉米中富马毒素B1(FB1)和黄曲霉毒素B1(AFB1),分别采用紫外、超高压、微波和NaCl处理,利用高效液相色谱方法进行检测。结果表明：紫外和超高压处理对两种毒素含量无影响,微波处理12min能去除90%以上的毒素,而30%以上NaCl浸泡10min即可去除99%的毒素。结论：NaCl浸泡是一种简单经济的脱毒方法。     

不同浓度1-MCP和1-OCP处理对青熟期芒果后熟和衰老的影响

研究了不同浓度(1、5和50μl/L)的环丙烯类乙烯效应抑制剂1-MCP(1-甲基环丙烯)和1-OCP(1-辛基环丙烯)常温[(20±2)℃]熏蒸处理20h对青熟期芒果(Mangifera indica L.)后熟和衰老的影响。结果表明:不同浓度的环丙烯类乙烯效应抑制剂均能不同程度地延缓芒果果实可滴定酸、MDA(丙二醛)含量的下降;降低POD(过氧化物酶)、PPO(多酚氧化酶)活性;抑制硬度的下降和SSC(可溶性固形物)含量的上升;减缓果实质量损失和成熟度的进程;呼吸高峰出现的时间与对照相比延迟了3 d。表明1-MCP和1-OCP处理能有效地延缓芒果果实的后熟和衰老,其中以5μl/L 1-MCP和50μl/L 1-OCP的效果较佳。     

足球菌ISK—1的发酵产物足球菌素ISK—1的生产最适化

研究了足球菌ＩＳＫ－１发酵中温度，ｐＨ值以及无机阳离子对足球菌素ＩＳＫ－１活性的影响，３７℃，ｐＨ值为５．５～６．０是产生足球菌素ＩＳＫ－１的较适宜条件，Ｍｎ＾２＋和Ｍｇ＾２＋对足球菌素ＩＳＫ－１的产生是必需要，而Ｎａ＾＋，Ｃａ＾２＋，ＮＨ４等阳离子均能提高足球菌素ＩＳＫ－１的活性，其中以Ｎａ＾＋的效果最显著。     

对溴苄基溴的合成工艺研究

文章给出了对溴甲苯为原料直接溴化合成对溴苄基溴方法中的最适宜反应条件 :对溴甲苯与溴的投料比为 1∶0 95 ,反应温度为 98℃～ 10 2℃ ,后处理采用溶剂淋洗及混合溶剂重结晶的方法 ,得到的产品纯度大于 99% ,收率 6 0 %左右     

利用酶抑制剂固定化磷脂酶A1（PLA1）的研究

在固定化磷脂酶A1时,利用酶抑制剂与磷脂酶A1活性中心氨基酸残基结合,使戊二醛基与磷脂酶A1的非活性氨基残基缩合,从而起到保护酶活性中心基团,提高固定化酶活力作用。实验证明磷酸盐是磷脂酶A1的竞争性抑制剂,并求出Ki值。     

Cell wall composition of 1B/1R translocation wheat grains

The cell wall composition and total dietary fibre content of 12 different winter wheat cultivars both without and with 1B/1R gene were analysed. Translocation wheat (with 1B/1R gene) had higher contents of extractable xylose and unextractable mannose residues than standard wheat (without 1B/1R gene). Three sieved flours of standard wheat, translocation wheat and rye respectively were used for further detailed studies. Water‐extractable arabinoxylan was isolated and fractionated on a DEAE‐cellulose column. The water‐eluted fraction of translocation wheat had a higher proportion of monosubstituted xylose residues than the same fraction of standard wheat, which is a typical feature of rye arabinoxylan. Molecular weight determination showed that rye water‐eluted arabinoxylans were larger than those of wheat. The molecular weight of translocation wheat arabinoxylan was lower than that of standard wheat and had a high polydispersity. Xylanase‐resistant arabinoxylan was extracted from all three flours, and NMR studies showed that wheat xylanase‐resistant arabinoxylan had a lower amount of monosubstituted xylose residues, while the rye fraction was rich in consecutive disubstituted xylose residues. Translocation wheat xylanase‐resistant arabinoxylan resembled that of standard wheat. © 2002 Society of Chemical Industry     

食用香料化合物1-甲硫基-2-丙酮和1-正丁硫基-2-丙酮的合成

分别采用过量甲硫醇和止丁硫醇与氢氧化钠、氯丙酮反应，制得1-甲硫皋-2-丙酮和1-正丁硫基-2-丙酮两种食用香料化合物，产率分别为66．4％和78．4％（按氯丙酮计）。采用元素分析、红外光谱、氧核磁共振、色-质联机等手段对产晶进行了结构表征。