共查询到20条相似文献,搜索用时 15 毫秒
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P. Krenn F. Berthiller W. Schweiger C. Hametner R. Ludwig G. Adam R. Krska R. Schuhmacher 《Mycotoxin Research》2007,23(4):180-184
The work at hand describes the production of the zearalenone (ZON) metabolites zearalenone-4-glucoside (ZON-4G), a-zearalenol-4-glucoside (oc-ZOL-4G) and ß-zearalenol-4-glucoside (ß-ZOL-4G). In a first step a genetically modified yeast strain, expressing theArabidopsis thaliana UDP-glu-cosyltransferase UGT73C6, was treated with ZON to produce ZON-4G. The substance was purified by solid phase extraction and subsequent reversed phase preparative HPLC prior to the reduction with sodium borohydride to yield 0C-ZOL-4G and ß-ZOL-4G. The identity and purity of the substances were confirmed by13C-and1H-NMR as well as by HPLC-UV. In total, 50 mg of ZON were used to produce 5 mg of a-ZOL-4G with a purity of 98%, 6 mg of ß-ZOL-4G with a purity of 99% and 5 mg of ZON-4G with a purity of 99%. 相似文献
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《Inorganica chimica acta》1987,132(1):37-39
The chemical behavior of the realgar molecule, As4S4, toward various (triphos)M moieties has been investigated. The reaction of As4S4 with [{MCl(cod)}2] (M=Rh or Ir; cod=1,5-cyclooctadiene) in the presence of the ligand triphos [triphos=1,1,1- tris(diphenylphosphinomethyl)ethane] yields compounds of formula [(triphos)M(η3-As3S3)]·C6H6 containing the new As3S3 unit, which is trihapto bonded to the metal atom through one sulfur and two arsenic atoms. Such a As3S3 fragment is the largest one so far extruded from the realgar molecule. The As4S4 molecule undergoes more drastic disruptions in the reactions with Co(BF4)2·6H2O and Ni(BF4)2·6H2O in the presence of triphos. These results suggest that the fragmentation of the As4S4 molecule is controlled by the nature of the metal atom involved in the reaction. 相似文献
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梁玉龙 《国外医学:分子生物学分册》2000,22(6):375-379
p18^INK4C和p19INK4D是细胞周期调控中的两种抑制因子,属于CKIs中的INK4家族蛋白,具有周期依赖性表达模式,特异性抑制G1CDK4/6的激酶活性。同时也参与一些组织的终末分化过程,在细胞增殖周期与分化调控方法发挥偶联作用。 相似文献
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Can Peng ;Weihua Chen ;Yuhong Han ;Tanya Sanders ;Geoffrey Chew ;Jing Liu ;Edward Hawrot ;Chengwu Chi ;Chunguang Wang 《Acta biochimica et biophysica Sinica》2009,(10):858-864
As part of continuing studies of the identification of gene organization and cloning of novel α-conotoxins, the first α4/4-conotoxin identified in a vermivorous Conus species, designated Qcl.2, was originally obtained by cDNA and genomic DNA cloning from Conus quercinus collected in the South China Sea. The predicted mature toxin of Qc1.2 contains 14 amino acid residues with two disulfide bonds (Ⅰ-Ⅲ, Ⅱ-Ⅳ connectivity) in a native globular configuration. The mature peptide of Qcl.2 is supposed to contain an N-terminal post-translationally processed pyroglutamate residue and a free carboxyl C-terminus. This peptide was chemically synthesized and refolded for further characterization of its functional properties. The synthetic Qcl.2 has two interconvertible conformations in aqueous solution, which may be due to the cis-trans isomerization of the two successive Pro residues in its first Cys loop. Using the Xenopus oocyte heterologous expression system, Qcl.2 was shown to selectively inhibit both rat neuronal α3β2 and α3β4 subtypes of nicotinic acetylcholine receptors with low potency. A block of -63% and 37% of the ACh-evoked currents was observed, respectively, and the toxin dissociated rapidly from the receptors. Compared with other characterized α-conotoxin members, the unusual structural features in Qcl.2 that confer to its receptor recognition profile are addressed. 相似文献
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本文报道了用绒毛细胞直接制备染色体的方法,诊断出一个家系中3例染色体异常胎儿。一例核型为:46,XX,rec(4),dup p,inv(4)(P12 q35)pat;另外两例核型为:46,XY,inv(4)(p12 q35)Pat。对此家系2代中8人进行了染色体检查。其中3人核型为46,XY,inv(4)(P12q35)。3例胎儿的异常染色体是来自他们的父亲(4号染色体臂间倒位携带者)。并讨论了臂间倒位染色体携带者对后代的影响。 相似文献
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Xiao-Chun Yang Shi-Jing Qian Li Wang Si-Da Liao Ji Cao Yong-Zhou Hu Qiao-Jun He Hong Zhu Bo Yang 《Translational oncology》2013,6(1):75-82
A novel VP-16 derivative, 4β-[N -(4?-acetyloxyl-phenyl-1?-carbonyl)-4″-aminoanilino]-4′-O-demethyl-4-desoxypodophyllotoxin (GL3), displayed a wide range of cytotoxicity in a panel of human tumor cell lines, with half-maximal inhibitory concentration (IC50) values ranging from 0.82 to 4.88 µM, much less than that of VP-16 (4.18–39.43 µM). Importantly, GL3 induces more significant apoptosis and cell cycle arrest than VP-16. The molecular and cellular machinery studies showed that GL3 functions as a topoisomerase II (Top 2) poison through direct binding to the enzyme, and the advanced cell-killing activities of GL3 were ascribed to its potent effects on trapping Top 2-DNA cleavage complex, Moreover, GL3-triggered DNA double-strand breaks and apoptotic cell death were in a Top 2-dependent manner, because the catalytic inhibitor aclarubicin attenuated these biologic consequences caused by Top 2 poisoning in GL3-treated cells. Taken together, among a series of 4β-anilino-4′-O-demethyl-4-desoxypodophyllotoxin analog, GL3 stood out by its improved anticancer activity and well-defined Top 2 poisoning mechanisms, which merited the potential value of GL3 as an anticancer lead compound/drug candidate deserving further development. 相似文献
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CXCR4–SDF-1 Signalling, Locomotion, Chemotaxis and Adhesion 总被引:23,自引:0,他引:23
Kucia M Jankowski K Reca R Wysoczynski M Bandura L Allendorf DJ Zhang J Ratajczak J Ratajczak MZ 《Journal of molecular histology》2004,35(3):233-245
Chemokines, small pro-inflammatory chemoattractant cytokines, that bind to specific G-protein-coupled seven-span transmembrane receptors present on plasma membranes of target cells are the major regulators of cell trafficking. In addition some chemokines have been reported to modulate cell survival and growth. Moreover, compelling evidence is accumulating that cancer cells may employ several mechanisms involving chemokine-chemokine receptor axes during their metastasis that also regulate the trafficking of normal cells. Of all the chemokines, stromal-derived factor-1 (SDF-1), an alpha-chemokine that binds to G-protein-coupled CXCR4, plays an important and unique role in the regulation of stem/progenitor cell trafficking. First, SDF-1 regulates the trafficking of CXCR4+ haemato/lymphopoietic cells, their homing/retention in major haemato/lymphopoietic organs and accumulation of CXCR4+ immune cells in tissues affected by inflammation. Second, CXCR4 plays an essential role in the trafficking of other tissue/organ specific stem/progenitor cells expressing CXCR4 on their surface, e.g., during embryo/organogenesis and tissue/organ regeneration. Third, since CXCR4 is expressed on several tumour cells, these CXCR4 positive tumour cells may metastasize to the organs that secrete/express SDF-1 (e.g., bones, lymph nodes, lung and liver). SDF-1 exerts pleiotropic effects regulating processes essential to tumour metastasis such as locomotion of malignant cells, their chemoattraction and adhesion, as well as plays an important role in tumour vascularization. This implies that new therapeutic strategies aimed at blocking the SDF-1-CXCR4 axis could have important applications in the clinic by modulating the trafficking of haemato/lymphopoietic cells and inhibiting the metastatic behaviour of tumour cells as well. In this review, we focus on a role of the SDF-1-CXCR4 axis in regulating the metastatic behaviour of tumour cells and discuss the molecular mechanisms that are essential to this process. 相似文献
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《Comparative biochemistry and physiology. C: Comparative pharmacology》1991,98(1-2):161-164
- 1.1. 3,3',4,4'-tetrachlorobiphenyl (PCB 77), but not hexachlorobenzene, induced liver micro-somal cytochrome P-450 (Cyt P-450), ethoxycoumarin-O-deethylase (ECOD) and ethoxyresorufin-O-deethylase (EROD) in rainbow trout. Maximum induction was observed in a PCB 77 injected group of fish (1.0mg/kg, i.p. injection) 13 days after the injections being 2, 10 and 50 times the values of non-induced fish, respectively.
- 2.2. The apparent Km value of ethoxyresorufin of this induced group of fish differed only slightly from that of non-induced fish. The apparent Vmax value (EROD) was 50 times higher.
- 3.3. Freezing small pieces of liver in liquid nitrogen did not produce cytochrome P-420.
- 4.4. Fluorimetric and spectrophotometric measurements of EROD correlated.
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Carmen Valero-Aracama Michael E. Kane Sandra B. Wilson Nancy L. Philman 《In vitro cellular & developmental biology. Plant》2011,47(4):536-552
LATE ABSTRACTS
2011 In Vitro Biology Meeting, June 4–8, Raleigh, North Carolina Late Submission Abstracts 相似文献14.
自从上个世纪60年代末C4光合途径发现以来,人们对工程改造现有C3粮食作物使之具有C4光合能力进行了大量努力。目前,大量分子、生理和基因组水平研究的进展和证据表明,该目标将可能在10~15年之内实现。本综述结合目前国际C4研究的现状,详述了该领域目前所涉各项研究内容的理论依据。我们首先总结过去的经典杂交实验,然后论证新一代测序技术与C4光合研究模式系统狐尾草(Setaria viridis)的发展极大的促进了我们对C4光合特征遗传发育相关基因的发现与鉴定。最后,我们强调虽然C4光合工程改造的研究目前已在世界各国大规模展开,但其最终成功仍有赖于不同国家研究基金及私立慈善基金的大力和长期共同资助。 相似文献
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赤霉素A4,A7的研究进展 总被引:7,自引:0,他引:7
赤霉素A_4、A_7的研究进展颜方贵,秦杰,何增国,李季伦(北京农业大学生物学院,北京100094)赤霉素A_3(GA_3)是目前应用最广的植物生长激素之一。随着研究的深入,对该族的其它同系物,特别是GA_4、GA_7越来越受到重视,这是由于GA_4... 相似文献
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Lydmila D. Garaeva Irina V. Yartseva Stalina Ya. Melnik 《Nucleosides, nucleotides & nucleic acids》2013,32(6):1295-1303
Abstract A synthesis of 4,6-dimethylthio-1-(2-deoxy-β-D-erythro-pentofuranosyl)pyrazolo[3,4-d]pyrimidine-3-carbonitrile (4) is described using the stereospecific sodium salt glycosylation procedure. Condensation of the sodium salt of 4,6-dimethylthiopyrazolo[3,4-d]pyrimidine-3-carbonitrile (1) with 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-α-D-eythro-pentofuranose (2) gave exclusively the corresponding blocked nucleoside (3) with β-anomeric configuration, which on deprotection provided 2′-deoxyriboside 4. Aglycone functional groups transformations of 4 led to related 3,4,6-trisubstituted pyrazolo[3,4-d]pyrimidine-2′-deoxynucleosides. These compounds are devoid of any significant cytotoxic activity in vitro. 相似文献
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Gehad A Al-Banna NA Vaci M Issekutz AC Mohan K Latta M Issekutz TB 《Journal of immunology (Baltimore, Md. : 1950)》2012,189(1):337-346
CCR4 on T cells is suggested to mediate skin homing in mice. Our objective was to determine the interaction of CCR4, E-selectin ligand (ESL), and α(4)β(1) on memory and activated T cells in recruitment to dermal inflammation. mAbs to rat CCR4 were developed. CCR4 was on 5-21% of memory CD4 cells, and 20% were also ESL(+). Anti-TCR-activated CD4 and CD8 cells were 40-55% CCR4(+), and ~75% of both CCR4(+) and CCR4(-) cells were ESL(+). CCR4(+) memory CD4 cells migrated 4- to 7-fold more to dermal inflammation induced by IFN-γ, TNF, TLR agonists, and delayed-type hypersensitivity than CCR4(-) cells. CCR4(+) activated CD4 cells migrated only 5-50% more than CCR4(-) cells to these sites. E-selectin blockade inhibited ~60% of CCR4(+) activated CD4 cell migration but was less effective on memory cells where α(4)β(1) was more important. Anti-α(4)β(1) also inhibited CCR4(-) activated CD4 cells more than CCR4(+) cells. Anti-E-selectin reduced activated CD8 more than CD4 cell migration. These findings modify our understanding of CCR4, ESL, α(4)β(1), and dermal tropism. There is no strict relationship between CCR4 and ESL for skin homing of CD4 cells, because the activation state and inflammatory stimulus are critical determinants. Dermal homing memory CD4 cells express CCR4 and depend more on α(4)β(1) than ESL. Activated CD4 cells do not require CCR4, but CCR4(+) cells are more dependent on ESL than on α(4)β(1), and CCR4(-) cells preferentially use α(4)β(1). The differentiation from activated to memory CD4 cells increases the dependence on CCR4 for skin homing and decreases the requirement for ESL. 相似文献
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Phosphoenolpyruvate carboxylase (PEPCase; EC 4.1.1.31) from Flaveria trinervia Mohr (C4), F. floridana Johnston (C3–C4), and F. cronquistii Powell (C3) leaves were compared by electrotransfer blotting/enzyme-linked immunoassay (Western-blot analysis), mobility of the native enzyme in polyacrylamide gels and in isoelectric focusing (IEF) gels, peptide mapping, and in-vitro translation of RNA isolated from each plant. The PEPCases from the C3 and C3–C4 plants were very similar to each other in terms of electrophoretic mobilities on gels and isoenzyme patterns on IEF gels, and identical in peptide mapping. Quantitative differences were noted, however, in that the C3–C4 intermediate plant contained more PEPCase overall and that the relative activity of individual isoenzymes shifted between the C3 and C3–C4 intermediate PEPCases. The PEPCase from the C4 plant had a different isoenzyme pattern, a different peptide map, and was far more abundant than the other two enzymes. Western blot analysis demonstrated the cross-reactivity of PEPCases from all three Flaveria species with antibody raised against maize PEPCase. The results provide evidence, at the molecular level, that supports the view of C3–C4 intermediate species as C3-like plants with some C4-like photosynthetic characteristics, but there are differences from the C3 plant in the quantity and properties of the PEPCase from the C3–C4 intermediate plant.Abbreviations IEF
isoelectric focusing
- kDa
kilodalton
- PEPCase
phosphoenolpyruvate carboxylase
- Rubisco
Ribulose-1,5-bisphosphate carboxylase/oxygenase 相似文献