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1.
Summary A new process for the production of small size dextran is developed in which dextran is produced by cultures of Leuconostoc mesenteroides in the presence of a partially constitutive mutant of Lipomyces starkeyi producing dextranase. Mixed cultures were examined by scanning electron microscopy with ruthenium to show the effects of the mixed culture on low molecular weight dextran (M.W. of 5,000 – 100,000) formation. The presence of the size variation in dextran was confirmed by gel permeation chromatography. 相似文献
2.
3.
Characteristics of a new bacteriophage, Psp231a, infecting Pseudomonas phaseolicola HB10Y.
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Bacteriophage Psp231a infects Pseudomonas phaseolicola, strain HB10Y, which is the host cell for the enveloped bacteriophage phi 6. This paper describes the biophysical characteristics of Psp231a and the physical properties of its nucleic acid. In electron micrographs the virion appears as an icosahedral structure, approximately 55 nm in diameter, with a short tail. The virion density is 1.48 g/cm3 in CsCl, and the sedimentation coefficient is approximately 407S. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of 12 polypeptides ranging in molecular weight from 5,000 to 117,000. The nucleic acid of Psp231a is linear, double-stranded DNA of molecular weight 28 X 10(6). Its density in CsCl is 1.716 g/cm3, and its sedimentation coefficient in 3 M CsCl is 20.0S, corresponding to an S020,W of 34S. 相似文献
4.
DC Chhieng AR Frost S Niwas H Weiss WE Grizzle S Beeken 《Biotechnic & histochemistry》2013,88(1):25-36
Small biopsy samples are used increasingly to assess the biomarker expression for prognostic information and for monitoring therapeutic responses prior to and during neoadjuvant therapy. The issue of intratumor heterogeneity of expression of biomarkers, however, has raised questions about the validity of the assessment of biomarker expression based on limited tissue samples. We examined immunohistochemically the expression of HER-2neu (p185erbB-2), epidermal growth factor receptor (EGFR), Bcl-2, p53, and proliferating cell nuclear antigen (PCNA) in 30 breast carcinomas using archived, paraffin embedded tissue and determined the extent of intratumor heterogeneity. Each section was divided into four randomly oriented discrete regions, each containing a portion of the infiltrating carcinoma. For each tumor, the entire lesion and four regions were analyzed for the expression of these markers. Scores of both membrane and cytoplasmic staining of HER-2neu and EGFR, scores of cytoplasmic staining of Bcl-2, and scores of nuclear staining of both p53 and PCNA were recorded. The intensity of staining and the proportion of immunostained cells were determined. A semiquantitative immunoscore was calculated by determining the sum of the products of the intensity and corresponding proportion of stained tumor cells. We analyzed both invasive (IDC) and in situ (DCIS) carcinomas. The Wilcoxon signed-rank test was used for paired comparisons between overall and regional immunoscores and between overall and regional percentages of stained cells. Spearman's correlation coefficients were used to assess the level of agreement of overall biomarker expression with each of the regions. Generalized linear models were used to assess overall and pair-wise differences in the absolute values of percent changes between overall and regional expression of biomarkers. For IDCs, there were no statistically significant differences in the expression of the biomarkers in terms of either the percentage of cells staining or the immunoscores when comparing the entire tumor with each region except for the lower EGFR expression of arbitrarily selected region 1 and lower p53 expression of region 1 compared to that of the entire tumor section. For DCIS, there were no statistically significant differences in the expression of the biomarkers between the entire tumor and each region except in PCNA of region 2 compared to that of entire tumor section. Positive correlation of immunoscores was observed between the entire tumor and each region as well as across all four regions for IDC. Similar observations were noted with DCIS except for HER-2neu and PCNA. No statistically significant differences were observed in the absolute values of percent changes of biomarker expression between overall and the four regions for both DCIS and IDC. Therefore, no significant intratumor heterogeneity in the expression of HER-2neu, Bcl-2, and PCNA was observed in IDC. Minor regional variations were observed for EGFR and p53 in IDC. Similarly, no significant regional variation in the expression of markers was observed in DCIS except for PCNA. 相似文献
5.
Jin-Ha?Lee Mi-Hwa?Choi Ji-Young?Park Hee-Kyoung?Kang Hwa-Won?Ryu Chang-Sin?Sunwo Young-Jung?Wee Ki-Deok?Park Do-Won?Kim Doman?KimEmail author 《Biotechnology and Bioprocess Engineering》2004,9(4):318-322
Lactic acid is an environmentally benign organic acid that could be used as a raw material for biodegradable plastics if it
can be inexpensively produced by fermentation. Two genes (IdhL andIdhD) encoding the L-(+) and D-(−) lactate dehydrogenases (L-LDH and D-LDH) were cloned fromLactobacillus sp., RKY2, which is a lactic acid hyper-producing bacterium isolated from Kimchi. Open reading frames ofIdhL for andIdhD for the L and D-LDH genes were 962 and 998 bp, respectively. Both the L(+)- and D(−)-LDH proteins showed the highest degree
of homology with the L- and D-lactate dehydrogenase genes ofLactobacillus plantarum. The conserved residues in the catalytic activity and substrate binding of both LDHs were identified in both enzymes. 相似文献
6.
Metabolic acids produced by oral pathogens demineralize tooth surfaces, leading to dental caries. Glucosyltransferases are the key factor in this process. We synthesized various modified oligosaccharides and tested them for their inhibitory effects on glucosyltransferase activity. Oligosaccharides were produced using a mixed-culture fermentation of Lipomyces starkeyi and Leuconostoc mesenteroides and then further modified as iron- and sulfate-oligosaccharides. Iron- and sulfate-oligosaccharides reduced glucosyltransferase activity of Streptococci from 17% to 43% and prevented the formation of insoluble biomass on the surface of glass vials or stainless steel wires in the presence of sucrose. They also reduced the growth and acid productions of oral pathogens including S. mutans, S. sobrinus, Eikenella corrodens, Prevotella intermedia, and Actinobacillus actinomycetemcmitans. 相似文献
7.
Weissella cibaria isolated from human saliva produces a soluble glucan that predominantly has α-1,6-glucosidic type linkages. Using degenerated primers that were selected based on the amino acid sequences of conserved regions from known glucansucrases, a single 2.7-kb fragment was isolated. In subsequent steps, a 4969-bp product was obtained using inverse PCR. The coding region for the glucansucrase gene ( dsrWC ) consisted of a 4419-bp ORF that encoded a 1472-amino acid protein with a calculated molecular mass of 161.998 Da. The produced DSRWC glucansucrases exhibited similarity with the enzymes of the glucosylhydrolase family 70, which includes the Lactobacillus fermentum glucansucrase. The expressed recombinant DSRWC (rDSRWC) synthesized oligosaccharides in the presence of maltose or isomaltose as an acceptor and the synthesized products included α-1,6-linked glucosyl residues in addition to the maltosyl or isomaltosyl residue. rDSRWC synthesized water-soluble polymers using sucrose as substrate. According to the 13 C-nuclear magnetic resonance analysis, the polymer that was synthesized by rDSRWC was a linear dextran, which formed predominately α-1,6-glucosidic linkages. This is the first report on the molecular characterization of glucansucrase from a W. cibaria strain. 相似文献
8.
Biochemical properties of a putative thermostable dextranase gene from Thermotoga lettingae TMO were determined in a recombinant protein (TLDex) expressed in Escherichia coli and purified to sevenfold apparent homogeneity. The 64-kDa protein displayed maximum activity at pH 4.3, and enzyme activity
was stable from pH 4.3–10. The optimal temperature was 55–60°C during 15 min incubation, and the half-life of the enzyme was
1.5 h at 65°C. The enzyme showed higher activity against α-(1 → 6) glucan and released isomaltose and isomaltotriose as main
products from dextran T2000. An unusual kinetic feature of TLDex was the negative cooperative behavior on the reaction of
dextran T2000 cleavage. Enzyme activity was not significantly affected by the presence of metal ions, except for the strong
inhibited by 1 mM Fe2+ and Ag2+. TLDex may prove useful as an enzyme for high temperature sugar milling processes. 相似文献
9.
Moon YH Nam SH Kang J Kim YM Lee JH Kang HK Breton V Jun WJ Park KD Kimura A Kim D 《Applied microbiology and biotechnology》2007,77(3):559-567
Two arbutin glucosides were synthesized via the acceptor reaction of a glucansucrase from Leuconostoc mesenteroides B-1299CB with arbutin and sucrose. The glucosides were purified by Bio-gel P-2 column chromatography and high-performance
liquid chromatography, and the structures were elucidated as 4-hydroxyphenyl β-isomaltoside (arbutin-G1), 4-hydroxyphenyl
β-isomaltotrioside (arbutin-G2), according to the results of 1H, 13C, heteronuclear single-quantum coherence, 1H-1H COSY, and heteronuclear multiple-bond correlation analyses. Arbutin glucoside (4-hydroxyphenyl β-isomaltoside) exhibited
slower effects on 1,1-diphenyl-2-picrylhydrazyl radical scavenging and similar effects on tyrosinase inhibition, and increased
inhibitory effect on matrix metalloproteinase-1 production induced by UVB than arbutin.
Young Hwan Moon and Seung Hee Nam contributed equally to this work. 相似文献
10.
Shalindra Ranasinghe Renu Wickremasinghe Sanjeeva Hulangamuwa Ganga Sirimanna Nandimithra Opathella Rhaiza DC Maingon Vishvanath Chandrasekharan 《Memórias do Instituto Oswaldo Cruz》2015,110(8):1017-1023
Leishmania donovani is the known causative agent of both cutaneous
(CL) and visceral leishmaniasis in Sri Lanka. CL is considered to be under-reported
partly due to relatively poor sensitivity and specificity of microscopic diagnosis.
We compared robustness of three previously described polymerase chain reaction (PCR)
based methods to detectLeishmania DNA in 38 punch biopsy samples
from patients presented with suspected lesions in 2010. Both,
Leishmaniagenus-specific JW11/JW12 KDNA and LITSR/L5.8S internal
transcribed spacer (ITS)1 PCR assays detected 92% (35/38) of the samples whereas a
KDNA assay specific forL. donovani (LdF/LdR) detected only 71%
(27/38) of samples. All positive samples showed a L. donovani
banding pattern upon HaeIII ITS1 PCR-restriction fragment length polymorphism
analysis. PCR assay specificity was evaluated in samples containing
Mycobacterium tuberculosis, Mycobacterium
leprae, and human DNA, and there was no cross-amplification in JW11/JW12
and LITSR/L5.8S PCR assays. The LdF/LdR PCR assay did not amplify M.
leprae or human DNA although 500 bp and 700 bp bands were observed in
M. tuberculosis samples. In conclusion, it was successfully shown
in this study that it is possible to diagnose Sri Lankan CL with high accuracy, to
genus and species identification, using Leishmania DNA PCR
assays. 相似文献