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NG Henry 《Applied microbiology》1976,31(3):395-398
The growth requirements of several yeasts isolated from San Francisco sour dough mother sponges were compared with those of bakers' yeast. The sour dough yeasts studied were one strain of Saccharomyces uvarum, one strain of S. inusitatus, and four strains of S. exiguus. S. inusitatus was the only yeast found to have an amino acid requirement, namely, methionine. All of the yeasts had an absolute requirement for pantothenic acid and a partial requirement for biotin. Inositol was stimulatory to all except bakers' yeast. All strains of S. exiguus required niacin and thiamine. Interestingly, S. inusitatus, the only yeast that required methionine, also needed folic acid. For optimal growth of S. exiguus in a molasses medium, supplementation with thiamine was required. 相似文献
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实时荧光定量PCR技术被广泛应用于实验研究、临床检测中。与普通的PCR相比,实时荧光定量PCR技术具有特异性强、灵敏度高、重复性好、定量准确、速度快、全封闭反应等优点。我们综述了实时荧光定量PCR技术的原理、定量方法,及其在传染性疾病检测研究中的应用。 相似文献
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STEPHEN F. NG 《The Journal of eukaryotic microbiology》1989,36(1):74-81
Removal of the micronuclei of Paramecium tetraurelia and Paramecium jenningsi by micropipetting generates amicronucleate cell lines. These cell lines go through a period of growth depression for several dozen fissions, but they gradually recover. Amicronucleate cells in the depression period characteristically exhibit abnormal oral development, particularly reduction in the length of the buccal cavity and an abnormal pattern of the oral membranelles. To test the notion that the macronucleus is involved in the recovery of amicronucleate cell lines, DNA demethylation drugs were administered to amicronucleates in the depression period. After at least 4 fissions, the treated amicronucleates were assessed for their progress in recovery by scoring the proportion of cells with normal oral membranelles. Cvtidine analogues which demethylate cytosine specifically at the 5 position, namely 5-azacytidine, 5-aza-2'- deoxycytidine and 5-fluoro-2'-deoxycytidine. promoted recovery of the amicronucleates. Cytidine, 6-azacytidine, 2'-fluoro-2'-deoxy-cytidine and cytosine-β-D-arabinofuranoside did not. These results suggest that (i) 5-methylcytosine is present in the macronucleus of these Paramecium species, probably in small amounts and (ii) recovery of amicronucleates involves demethylation of macronuclear DNA. This implies that in normal cells the micronuclei are involved in maintaining the macronuclear DNA in a methylated state and hence the inactivation of the macronuclear sequences that are to be employed for stomatogenic recovery. A general mechanism for the control of gene expression may therefore be employed for the regulation of specific sequences. 相似文献
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C. T. LEE S. L. LEE Q. Z. FARIDAH S. S. SIRAJ K. K. S. NG B. NORLIA M. N. MAT‐ISA 《Molecular ecology resources》2006,6(4):1198-1201
This paper reports the isolation and characterization of 24 polymorphic microsatellite markers in an important tropical timber species, Koompassia malaccensis (Leguminosae). The primers were designed from a genomic library enriched for dinucleotide (CT) repeats and screened on 24 samples from a natural population. The number of alleles detected per locus ranged from two to 13 while the observed heterozygosity ranged from 0.042 to 1.000. Significant departure from Hardy–Weinberg equilibrium (P < 0.05) was detected in two loci. These microsatellite markers were tested across 13 timber species of the same family. The amplification success appeared to be associated with taxonomy classification at the genus but not subfamily levels. 相似文献
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The recently determined crystal structures of two aspartic proteinase zymogens, prophytepsin from barley and proplasmepsin II from the malarial parasite Plasmodium falciparum, have provided new insights into zymogen inactivation. Prophytepsin shows a variation of the mechanism of inhibition used by the well-known gastric aspartic proteinase zymogens, whereas proplasmepsin II uses a completely new mode of inactivation. 相似文献
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S.P. NG Z.G. LI B.W. CHEN Z.K. QIN M.M. GARCIA S.W.K. IM M.H. NG 《Journal of Rapid Methods and Automation in Microbiology》1997,5(4):285-294
We previously described an enrichment-immunoassay utilizing a T6 monoclonal antibody capture enzyme-linked immunosorbent assay. Here we evaluated it for the rapid screening for Salmonella in fishmeal obtained from the national Animal and Plant Quarantine service in the People's Republic of China. In this method, the number of Salmonella present is first expanded by appropriate enrichment cultures, and the pathogens are then directly detected by the T6 immunoassay. In a total of 94 enrichment cultures of fishmeal, we obtained an overall concordance of 98% between the results obtained in parallel by this method and by conventional test method. The positive prediction by this method was 92% and the negative prediction was 100%. The turn around time for the new test was 27 h which is a significant improvement from the turn around time exceeding 96 h required for the conventional test method. This test proved to be compatible with the routine work flow in the practical setting of a quarantine laboratory. 相似文献