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51.
Thomas Ostenfeld Larsen Jørn Smedsgaard Flemming Lund Jens C. Frisvad Manfred Gareis 《Mycotoxin Research》2000,16(1):109
Recent work in our laboratory has demonstrated that the most common contaminating fungi on different types of cheese are;Penicillium commune, P. nalgiovense, P. solitum, P. discolor, P. roqueforti, P. crustosum, P. nordicum andAspergillus versicolor. On blue cheese a new speciesP. caseifulvum has been discovered as a surface contaminant. A large number of known and unknown metabolites have been described from the above mentioned cheese associated fungi from both synthetic media and real samples. Based on chemotaxonomy our laboratory has discovered thatP. roqueforti should be divided into three species:P. roqueforti (from cheese),P. carneum (from meat) andP. paneum (from bread). SimilarlyP. verrucosum should be divided intoP. verrucosum (from cereals) andP. nordicum (from cheese and meat products). Both species produce ochratoxins, however, only the former species produce citrinin. 相似文献
52.
Kristiansen OP Nolsøe RL Holst H Reker S Larsen ZM Johannesen J Nerup J Pociot F Mandrup-Poulsen T;Danish Study Group of IDDM in Childhood 《Immunogenetics》2000,52(1-2):107-111
Type 1 (insulin-dependent) diabetes is a complex trait. The region harboring the ICAM1 gene on 19p13 links to type 1 diabetes, and a growing body of evidence indicates that intercellular adhesion molecule-1 (ICAM-1) could play a role in type 1 diabetes development. Recently, association studies of an ICAM-1 K469E polymorphism in type 1 diabetes populations have reported conflicting results. Hence, we performed a transmission disequilibrium test analysis of the ICAM-1 K469E variations in 253 Danish type 1 diabetes families. Linkage and association was not found between the ICAM-1 K469E variation and type 1 diabetes in Danish patients (P(tdt)> or =0.48), and our data did not indicate an interaction between ICAM1 and IDDM1 in predisposition to type 1 diabetes in Danes (P=0.78). We did not observe significant association with late-onset type 1 diabetes (P(tdt)> or =0.12) or differences in transmission patterns between groups of affected offspring stratified for age at onset (P> or =0.19), as suggested in Japanese patients. Combined analysis of the present and previously reported transmission data comprising 728 affected offspring of Romanian, Finnish, and Danish ancestry suggested association between the ICAM-1 E469 allele and type 1 diabetes (P(tdt)=0.013), but association was not found in the combined Scandinavian material. In conclusion, we found no association of the ICAM-1 K469E polymorphism with type 1 diabetes or its subsets stratified for age at onset and HLA risk in Danish patients. Analysis of ICAM-1 K469E transmissions reported in three populations suggested association to type 1 diabetes, but also demonstrated heterogeneity between populations. 相似文献
53.
Romstad A Kalkanoğlu HS Coşkun T Demirkol M Tokatli A Dursun A Baykal T Ozalp I Guldberg P Güttler F 《Human genetics》2000,107(6):546-553
Dihydropteridine reductase (DHPR) catalyses the conversion of quinonoid dihydrobiopterin (qBH2) to tetrahydrobiopterin (BH4), which serves as the obligatory cofactor for the aromatic amino acid hydroxylases. DHPR deficiency, caused by mutations in the QDPR gene, results in hyperphenylalaninemia and deficiency of various neurotransmitters in the central nervous system, with severe neurological symptoms as a consequence. We have studied, at the clinical and molecular levels, 17 patients belonging to 16 Turkish families with DHPR deficiency. The patients were detected at neonatal screening for hyperphenylalaninemia or upon the development of neurological symptoms. To identify the disease causing molecular defects, we developed a sensitive screening method that rapidly scans the entire open reading frame and all splice sites of the QDPR gene. This method combines PCR amplification and "GC-clamping" of each of the seven exonic regions of QDPR, resolution of mutations by denaturing gradient gel electrophoresis (DGGE), and identification of mutations by direct sequence analysis. A total of ten different mutations were identified, of which three are known (G23D, Y150C, R221X) and the remaining are novel (G17R, G18D, W35fs, Q66R, W90X, S97fs and G149R). Six of these mutations are missense variants, two are nonsense mutations, and two are frameshift mutations. All patients had homoallelic genotypes, which allowed the establishment of genotype-phenotype associations. Our findings suggest that DGGE is a fast and efficient method for detection of mutations in the QDPR gene, which may be useful for confirmatory DNA-based diagnosis, genetic counselling and prenatal diagnosis in DHPR deficiency. 相似文献
54.
High incidence of propionic acidemia in greenland is due to a prevalent mutation, 1540insCCC, in the gene for the beta-subunit of propionyl CoA carboxylase 下载免费PDF全文
55.
Energy transfer and charge separation in photosystem I: P700 oxidation upon selective excitation of the long-wavelength antenna chlorophylls of Synechococcus elongatus. 下载免费PDF全文
L O Plsson C Flemming B Gobets R van Grondelle J P Dekker E Schlodder 《Biophysical journal》1998,74(5):2611-2622
Photosystem I of the cyanobacterium Synechococcus elongatus contains two spectral pools of chlorophylls called C-708 and C-719 that absorb at longer wavelengths than the primary electron donor P700. We investigated the relative quantum yields of photochemical charge separation and fluorescence as a function of excitation wavelength and temperature in trimeric and monomeric photosystem I complexes of this cyanobacterium. The monomeric complexes are characterized by a reduced content of the C-719 spectral form. At room temperature, an analysis of the wavelength dependence of P700 oxidation indicated that all absorbed light, even of wavelengths of up to 750 nm, has the same probability of resulting in a stable P700 photooxidation. Upon cooling from 295 K to 5 K, the nonselectively excited steady-state emission increased by 11- and 16-fold in the trimeric and monomeric complexes, respectively, whereas the quantum yield of P700 oxidation decreased 2.2- and 1.7-fold. Fluorescence excitation spectra at 5 K indicate that the fluorescence quantum yield further increases upon scanning of the excitation wavelength from 690 nm to 710 nm, whereas the quantum yield of P700 oxidation decreases significantly upon excitation at wavelengths longer than 700 nm. Based on these findings, we conclude that at 5 K the excited state is not equilibrated over the antenna before charge separation occurs, and that approximately 50% of the excitations reach P700 before they become irreversibly trapped on one of the long-wavelength antenna pigments. Possible spatial organizations of the long-wavelength antenna pigments in the three-dimensional structure of photosystem I are discussed. 相似文献
56.
Laura J. Mares Alvaro Garcia Helge H. Rasmussen Flemming Cornelius Yasser A. Mahmmoud Joshua R. Berlin Bogdan Lev Toby W. Allen Ronald J. Clarke 《Biophysical journal》2014
The charge-transporting activity of the Na+,K+-ATPase depends on its surrounding electric field. To isolate which steps of the enzyme’s reaction cycle involve charge movement, we have investigated the response of the voltage-sensitive fluorescent probe RH421 to interaction of the protein with BTEA (benzyltriethylammonium), which binds from the extracellular medium to the Na+,K+-ATPase’s transport sites in competition with Na+ and K+, but is not occluded within the protein. We find that only the occludable ions Na+, K+, Rb+, and Cs+ cause a drop in RH421 fluorescence. We conclude that RH421 detects intramembrane electric field strength changes arising from charge transport associated with conformational changes occluding the transported ions within the protein, not the electric fields of the bound ions themselves. This appears at first to conflict with electrophysiological studies suggesting extracellular Na+ or K+ binding in a high field access channel is a major electrogenic reaction of the Na+,K+-ATPase. All results can be explained consistently if ion occlusion involves local deformations in the lipid membrane surrounding the protein occurring simultaneously with conformational changes necessary for ion occlusion. The most likely origin of the RH421 fluorescence response is a change in membrane dipole potential caused by membrane deformation. 相似文献
57.
Magnus Kjaergaard Ann‒Beth Nørholm Ruth Hendus‒Altenburger Stine F. Pedersen Flemming M. Poulsen Birthe B. Kragelund 《Protein science : a publication of the Protein Society》2010,19(8):1555-1564
Structural characterization of intrinsically disordered proteins (IDPs) is mandatory for deciphering their potential unique physical and biological properties. A large number of circular dichroism (CD) studies have demonstrated that a structural change takes place in IDPs with increasing temperature, which most likely reflects formation of transient α-helices or loss of polyproline II (PPII) content. Using three IDPs, ACTR, NHE1, and Spd1, we show that the temperature-induced structural change is common among IDPs and is accompanied by a contraction of the conformational ensemble. This phenomenon was explored at residue resolution by multidimensional NMR spectroscopy. Intrinsic chemical shift referencing allowed us to identify regions of transiently formed helices and their temperature-dependent changes in helicity. All helical regions were found to lose rather than gain helical structures with increasing temperature, and accordingly these were not responsible for the change in the CD spectra. In contrast, the nonhelical regions exhibited a general temperature-dependent structural change that was independent of long-range interactions. The temperature-dependent CD spectroscopic signature of IDPs that has been amply documented can be rationalized to represent redistribution of the statistical coil involving a general loss of PPII conformations. 相似文献
58.
Mette Kristensen Francesco Savorani Gitte Ravn-Haren Morten Poulsen Jaroslaw Markowski Flemming H. Larsen Lars O. Dragsted Søren B. Engelsen 《Metabolomics : Official journal of the Metabolomic Society》2010,6(1):129-136
Risk of cardiovascular disease is related to cholesterol distribution in different lipoprotein fractions. Lipoproteins in
rodent model studies can only reliably be measured by time- and plasma-consuming fractionation. An alternative method to measure
cholesterol distribution in the lipoprotein fractions in rat plasma is presented in this paper. Plasma from two rat studies
(n = 68) was used in determining the lipoprotein profile by an established ultracentrifugation method and proton nuclear magnetic
resonance (NMR) spectra of replicate samples was obtained. From the ultracentrifugation reference data and the NMR spectra,
an interval partial least-square (iPLS) regression model to predict the amount of cholesterol in the different lipoprotein
fractions was developed. The relative errors of the prediction models were between 12 and 33% and had correlation coefficients
(r) between 0.96 and 0.84. The models were tested with an independent test set giving prediction errors between 19 and 46%
and r between 0.96 and 0.76. Prediction of High, Low and Very Low Density Lipoprotein (HDL, LDL and VLDL) and total cholesterol
was conducted in a study where rats had been supplemented with two doses of air-dried apple-powder. No significant difference
in LDL, VLDL and total cholesterol was observed between the groups. The high apple-powder (20%) group had significantly lower
HDL cholesterol (11%, P = 0.0452) than the control group. It is concluded that the iPLS approach yielded excellent regression models and thus univocal
established chemometric analysis of NMR spectra of rat plasma as a strong and efficient way to quantify lipoprotein fractions
in rat studies. 相似文献
59.
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