Yeast 14-3-3 proteins

14-3-3 proteins form a family of highly conserved proteins which are present in all eukaryotic organisms investigated, often in multiple isoforms, up to 13 in some plants. They interact with more than 200 different, mostly phosphorylated proteins. The molecular consequences of 14-3-3 binding are diverse: this binding may result in stabilization of the active or inactive phosphorylated form of the protein, to a conformational alteration leading to activation or inhibition, to a different subcellular localization, to the interaction with other proteins or to shielding of binding sites. The binding partners, and hence the 14-3-3 proteins, are involved in almost every cellular process and 14-3-3 proteins have been linked to several diseases, such as cancer, Alzheimer's disease, the neurological Miller-Dieker and spinocerebellar ataxia type 1 diseases and bovine spongiform encephalopathy (BSE). The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe both have two genes encoding 14-3-3 proteins, BMH1 and BMH2 and rad24 and rad25, respectively. In these yeasts, 14-3-3 proteins are essential in most laboratory strains. As in higher eukaryotes, yeast 14-3-3 proteins bind to numerous proteins involved in a variety of cellular processes. Recent genome-wide studies on yeast strains with impaired 14-3-3 function support the participation of 14-3-3 proteins in numerous yeast cellular processes. Given the high evolutionary conservation of the 14-3-3 proteins, the experimental accessibility and relative simplicity of yeasts make them excellent model organisms for elucidating the function of the 14-3-3 protein family.     

Ty3/gypsy-like retrotransposons in Candida albicans and Candida dubliniensis: Tca3 and Tcd3

Ty3/gypsy retrotransposons are a widespread group of eukaryote mobile genetic elements. They are similar in structure to, and may be ancestors of, the vertebrate retroviruses. Here we describe the first Ty3/gypsy retrotransposons from the pathogenic yeasts Candida albicans and Candida dubliniensis, which we refer to as Tca3 and Tcd3, respectively. Tca3 was first identified in a variety of strains as an element lacking a large part of its coding region. Comparative analyses between C. albicans and C. dubliniensis allowed us to identify the closely related full-length Tcd3 element, and, subsequently, the full-length Tca3 elements. The full-length versions of Tca3 and Tcd3 are broadly similar in structure to other Ty3/gypsy elements, but have several features of special interest, e.g. both elements appear to have a novel mechanism for priming minus-strand DNA synthesis, probably involving conserved secondary structures adjacent to the 5' LTRs. Also, while closely related to each other, the two elements appear to be fairly distantly related to other known Ty3/gypsy-like elements. Finally, the occurrence of the internally deleted forms of Tca3 in many strains raises interesting questions concerning the evolution of these transposable elements in Candida and the evolution of Candida itself. The sequences reported in this paper have been assigned GenBank Accession Nos AF499463, AF499464 and AF510498.     

Analysis of the rad3-101 and rad3-102 mutations of saccharomyces cerevisiae: Implications for structure/function of rad3 protein

The mutations rad3-101 and rad3-102 (formerly rem1-1 and rem1-2) of the essential RAD3 gene of Saccharomyces cerevisiae confer a phenotype of semidominant enhancement of spontaneous mitotic recombination and mutation frequencies, but not extreme sensitivity to ultraviolet (UV) light. These properties differ from the previously published observations of other rad3 mutations, which are very UV-sensitive but do not alter recombination frequencies significantly. We have located the position of DNA sequence changes from wild-type RAD3 to the rad3-101 and rad3-102 mutations and have demonstrated that these sequence changes are necessary and sufficient to confer the (Rem^?) mutant phenotype when transferred into otherwise wild-type RAD3 plasmids. The Rem^? mutations are not located in the same region. It is possible that the two regions of the gene in which these mutations map define portions of the molecule which are in contact when folded in the native configuration. To begin to test this hypothesis, we have constructed two double mutant alleles, one with rad3-101 and rad3-102, and one with the UV-sensitive rad3-1 mutation and rad3-102. We find that plasmids carrying these double mutant alleles of RAD3 are no longer able to confer a hyper-recombinational phenotype and do not complement the UV-sensitivity of the excision-defective rad3-2 allele. We conclude that the double mutant alleles are non-functional for excision repair, and may be null. We have also constructed new rad3 alleles by oligonucleotide-directed mutagenesis and have tested their effects on spontaneous mutation and mitotic recombination and on UV repair.     

大叶紫薇总三萜对脂肪细胞葡萄糖和脂肪代谢的影响

为探讨大叶紫薇中总三萜对3T3-L1细胞葡萄糖和脂肪代谢的影响,探讨大叶紫薇中总三萜可能的降血糖作用机制。通过检测大叶紫薇中总三萜对3T3-L1葡萄糖的消耗,油红O染色并通过比色定量分析脂肪含量。结果表明:大叶紫薇中总三萜具有促进脂肪细胞葡萄糖消耗及抑制脂肪形成的作用。大叶紫薇中总三萜具有降血糖的作用。     

三维纺织复合材料的结构特点和应用

本文主要讨论了三维纺织预制件及其复合材料的结构特点。由于三维纺织复合材料的纤维在三维空间相互交织和交叉 ,形成了一个不分层的整体结构 ,所以它和层合复合材料相比具有优良的层间性能和其他力学性能 ,可制作第一承力结构件和高功能制件。本文还介绍了树脂基三维纺织复合材料的复合固化技术以及三维纺织复合材料的一些应用 ,说明它具有广泛的应用前景。     

Kinetics of Thermal Degradation of the Anthocyanins Delphinidin-3-rutinoside and Malvidin-3-glucoside

The kinetics of the thermal degradation of the two anthocyanins delphinidin-3-rutinoside and malvidin-3-glucoside at 78, 88, 98 and 108 °C, depending on the pH and the type of solvent has been investigated. The first order reaction of delphinidin-3-rutinoside and malvidin-3-glucoside degradation has been established. The rate constants (K ± 10^?5s^?1), the activation parameters, factor Q₁₀ and the half-decay period have been calculated. The rate of delphinidin-3-rutinoside degradation is higher than that of malvidin-3-glucoside.     

动植物油脂中3-氯-1,2-丙二醇酯的研究进展

随着对氯丙醇的深入研究和检测技术的不断更新,在越来越多的食品中检测出高含量的氯丙醇。目前,有许多关于在动植物油脂中检测出3-氯-1,2-丙二醇(3-MCPD)酯的报道,并得出油脂精炼过程是产生3-MCPD酯的主要途径,精炼工艺中的脱臭工序是3-MCPD酯形成的关键工序。假设3-MCPD酯的含量按照100%转化,则转化生成的3-MCPD将远远超过每日最大耐受量(TDI)2μg/kg。因此,本文对3-MCPD酯的来源及影响因素、检测方法和其在动植物油脂中的发展趋势进行了综述。     

芹菜素对3T3-L1前脂肪细胞增殖及分化作用研究

目的：研究芹菜素(apigenin,AP)对3T3-L1 前脂肪细胞增殖及分化的影响。方法：采用3T3-L1 前脂肪细胞,利用MTT 比色分析法检测不同质量浓度芹菜素对3T3-L1 前脂肪细胞增殖的影响;采用传统的鸡尾酒诱导剂诱导分化3T3-L1 前脂肪细胞,利用油红O 染色检测,通过比色分析法检测不同质量浓度芹菜素对3T3-L1 前脂肪细胞分化的影响。结果：30、50μg/mL 芹菜素相对于空白组和阳性对照组能够显著抑制3T3-L1 前脂肪细胞增殖和分化,提示其可能具有预防肥胖的作用。     

Interaction of Lupinus angustifolius L. α and γ conglutins with 13-hydroperoxide-11,9-octadecadienoic acid

Food proteins suffer losses of functional and nutritional value due to reaction with lipid peroxidation products. The seed globulins conglutin α and γ from Lupinus angustifolius L. have been incubated with 13-hydroperoxide-11,9-octadecadienoic acid at pH 9 as a model of the interactions between seed storage proteins and lipid peroxidation products during storage and processing of protein-based products. The incubation lead to fragmentation and/or polymerization of the conglutins as determined by chromatographic and electrophoretic analysis. Losses of tryptophan, methionine, cysteine, proline, valine and leucine were shown by amino acid analysis. In vitro digestibility assays did not show clear differences between the digestibilities of the native conglutins before and after incubation with the hydroperoxide. Nevertheless, it is concluded that reaction with 13-hydroperoxide-11,9-octadecadienoic acid lead to a decrease in the nutritional value of the conglutins because the losses of essential amino acids were substantial. In addition, fragmentation and polymerization reactions most likely have a detrimental effect in the functional properties of the conglutins. These results highlight the deleterious effects that lipid peroxidation products have on products such as protein concentrates, isolates and hydrolysates obtained from lipid-rich seeds.     

三维机织预型件的织造技术

纺织复合材料预型件的生产工艺有多种,其生产路径主要由最终用途决定。三维机织物是通过对传统织造原理改进加工而成的。二维机织复合材料是一种由二维织物构成的层合材料,而三维机织复合材料是复杂几何结构的整体构件。三维机织复合材料预型件有许多优点,最重要的优点是它避免了二维层合材料的分层现象。介绍了三维机织预型件的织造方法,为纺织复合材料的开发提供了有益的借鉴。     

Schizosaccharomyces pombe stt3+ is a functional homologue of Saccharomyces cerevisiae STT3 which regulates oligosaccharyltransferase activity

The Saccharomyces cerevisiae STT3 (ScSTT3) gene encodes a protein which is involved in protein glycosylation via the regulation of oligosaccharyltransferase activity. We have cloned and isolated the Schizosaccharomyces pombe STT3 homologous gene (Spstt3+). The Spstt3+ gene encodes a protein consisting of 749 amino acid residues which has significant homology with ScStt3p and the mouse Stt3p-homologue Itm1p. Disruption of the Spstt3+ gene shows that this gene is essential for growth. Like Itm1, Spstt3+ partially suppressed the temperature sensitivity of the stt3-1 mutation of S. cerevisiae, indicating that Spstt3+ is a functional and structural homologue of the ScSTT3 gene.     

3T3-L1前脂肪细胞在功能性成分评价中的应用

脂肪细胞的增殖与分化异常是导致人类肥胖、心血管疾病和Ⅱ型糖尿病等的发生的主要原因,而3T3-L1前脂肪细胞是国际上公认的研究脂肪代谢的细胞模型,因此脂肪细胞的增殖与分化已成为研究的热点。本文主要论述3T3-L1前脂肪细胞的体外培养、增殖与分化及调控及其在功能性成分的评价中的应用,以期为预防和治疗肥胖及糖尿病等并发症提供一定的理论参考。     

多重纬角连锁三维机织物结构设计

分析了用于复合材料预制件的三维机织物的结构与成形类别，阐述了利用普通织机制织的多重纬角连锁三维机织物的结构特征、组织结构设计要点及一种特殊变化。     

Occurrence of 3-chloro-propane-1,2-diol (3-MCPD) and related compounds in foods: a review

A critical review of the occurrence of 3-chloro-propane-1,2-diol (3-MCPD) in foods not known to contain hydrolysed vegetable proteins is presented. The review covers the properties and chemistry of 3-MCPD and the current methods of analysis in foodstuffs. The results of UK surveys of 3-MCPD occurrence in both retail foods and commercial food ingredients are discussed with particular reference to cereal, meat and dairy products. The possible mechanisms for the formation and decay of 3-MCPD in foods are suggested. The review does not cover the detailed toxicology of 3-MCPD and its occurrence in hydrolysed vegetable proteins, which have been considered elsewhere, nor possible issues such as in-vivo formation.     

Effects of yeast stress and pH on 3-monochloropropanediol (3-MCPD)-producing reactions in model dough systems

A major precursor of 3-monochloropropanediol (3-MCPD) in leavened cereal products is glycerol, which is formed as a natural by-product of yeast fermentation. However, yeast metabolism is affected by stresses such as low osmotic pressure from, for example, the incorporation of sugar or salt in the dough recipe. Tests with model doughs have shown that glycerol production was proportional to yeast mass and limited by available sugars, but that high levels of yeast inhibited 3-MCPD formation. The yeast fraction responsible for the inhibition of 3-MCPD in model dough was shown to be the soluble cytosol proteins, and the inhibition mechanism could be explained by the known reactions of 3-MCPD and/or its precursors with ammonia/amino acids (from yeast proteins). Added glucose did not increase the production of glycerol by yeast but it did promote the generation of 3-MCPD in cooked doughs. The latter effect was attributed to the removal of 3-MCPD inhibitors such as ammonia and amino acids by their reactions with added glucose (e.g. Maillard). The thermal generation of organic acids from added glucose also reduced the pH of cooked doughs, so the effect of pH and short-chain organic acids on 3-MCPD generation in dough was measured. There was a good correlation between initial dough pH and the level of 3-MCPD generated. The effect was weaker than that predicted by simple kinetic modelling, suggesting that the involvement of H⁺ and/or the organic acid was catalytic. The results showed that modifications to dough recipes involving the addition of reducing sugars and/or organic acids can have a significant impact on 3-MPCD generation in bakery products.     

Immobilization of selenite on Fe3O4 and Fe/Fe3C ultrasmall particles

The sorption of selenite ions onto Fe3O4 and Fe/Fe3C nanoparticles (NPs) was studied in aqueous solutions under anoxic conditions using gamma spectrometry and X-ray absorption spectrometry (XAS) techniques. This is the first study related to the remedial applications of Fe/Fe3C NPs. FesO4 NPs have been prepared by conventional coprecipitation of Fe(II) and Fe(III) in basic solutions. Stable Fe/Fe3C NPs have been prepared by Fe(CO)5 sonicating in diphenylmethane solutions and subsequently annealing the as-prepared product. Kinetic study demonstrated that Se(IV) sorption is extremely rapid: the equilibrium is reached in approximately 10 and 30 min for Fe3O4 and Fe/Fe3C NPs, respectively, at pH = 4.9-5.1 in solutions of 0.1 M NaCl. The distribution coefficients are also very high for both kinds of NPs (Kd > 3000). Increasing the pH to 10.3 or adsorption of organic ligands, like L-lysine or dodecanoate, at the surface of NPs causes the decrease in Kd values. However, even in these cases Kd values exceed 150. Magnetic NPs loaded with selenium can be easily and completely removed from solution with a 0.4 T permanent magnet. XAS study revealed the absence of Se(IV) reduction during the sorption onto Fe3O4 NPs in the pH range of 4.8-8.0. By contrast, the removal of Se(IV) with Fe/Fe3C NPs in anaerobic conditions occurs via Se(IV) reduction to Se(-II) and subsequent formation of iron selenide at the particle surface. Thus, the Fe/Fe3C NPs are superior to Fe3O4 NPs due to their ability to immobilize rapidly and irreversibly Se(IV) via reductive mechanism. Presumably these particles could be also effective for the removal of other contaminants such as hexavalent chromium, actinides, technetium, and toxic organic compounds.     

n-3多不饱和脂肪酸对疾病的预防与治疗作用

n-3多不饱和脂肪酸主要源于亚麻籽、胡桃仁、大豆以及海洋生物。增加n-3多不饱和脂肪酸摄取量可以促进视网膜、大脑和神经系统发育。n-3多不饱和脂肪酸通过各种途径降低人体心血管疾病和炎症的发生,降低糖尿病患者血清低密度脂蛋白胆固醇(LDL-C)和甘油三酯(TG)水平。膳食中增加n-3多不饱和脂肪酸的含量可以对心血管疾病、糖尿病、炎症等患者有辅助治疗效果;n-3多不饱和脂肪酸可以作用于神经细胞,对注意力不集中、抑郁症、精神分裂症有一定的疗效。n-3多不饱和脂肪酸可抑制体外培养的乳腺、前列腺和结肠癌细胞增生,促进细胞凋亡。     

Isolation of two γ-gliadins from cappelle-desprez

The strongest band in the electrophoretic pattern of Cappelle-Desprez gliadin owes its intensity to the coincidence of two proteins. These have been isolated and characterised. They have a fairly similar amino acid composition, typical of the gliadin class, and appear to be single polypeptide chains, free of SH groups and carbohydrate. Their molecular weights are 38 000 and 44 000. The higher mobility at pH 8.9 of the lighter molecule is attributed to its smaller size though the possibility also exists of its having fewer COO- groups. The equal mobility at acid pH arises because the extra resistance encountered by the larger molecule is balanced by a higher positive charge due to histidine. The proteins appear to correspond to the _γ2 and _γ3 Ponca gliadins isolated at Peoria, and this supports the idea that gliadins of equal mobility from different varieties have very similar structures. A rapid way of calculating recovered protein is mentioned.     

α3-gliadin from Timmo wheat. Isolation and partial structure determination

Ion-exchange chromatography, followed by gel-filtration has been used to separate α₃-gliadin from the hard English wheat, Timmo. Amino acid sequence determination on the protein has revealed 10 N-terminal residues and six C-terminal residues. The gliadin has been cleaved by N-bromosuccinimide into two peptides and another two peptides have been obtained by treatment with cyanogen bromide. The amino acid analyses of the peptides and α₃gliadin are reported.