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1.
The CMP-N-acetylneuraminic acid (CMP-NeuNAc) synthetase gene of Neisseria meningitidis group B is located on a 2.3-kb EcoRI fragment within the cps gene cluster. Nucleotide sequence determination of the gene encoding the CMP-NeuNAc synthetase revealed a 515-bp open reading frame that can encode a 18.9-kDA protein. A computer data base scan revealed a 59.4% identity to the CMP-NeuNAc synthetase gene of E. coli K1. Enzymatic activity was confirmed in vitro and in vivo. Transformation of the CMP-NeuNAc defective E. coli K1 strain EV5 with the meningococcal CMP-NeuNAc synthetase could complement the defect in E. coli. 相似文献
2.
Ulrike Rosenfellner Franz Zehetner Martin H. Gerzabek 《Soil & Sediment Contamination》2009,18(6):685-687
Data from eight published studies were combined to show that the influence of traffic density on Pb contents in roadside soils increases with proximity to the road. 相似文献
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Summary The reductive cleavage of the aclacinomycins A (I), Y (II), and B (III) by intact mycelia or subcellular fractions of the producer strain S. spec. AM 33352/F43 is suppressed in the presence of uncouplers, complex-forming agents, detergents, and some metal anions such as chromate. Increased concentration of the latter in complete cultures caused rearrangement of I to III. 相似文献
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Summary Pedigree analyses of individual yeast cells recovering from DNA damage were performed and time intervals between morphological landmark events during the cell cycle (bud emergence and cell separation), were recorded for three generations. The associated nuclear behavior was monitored with the aid of DAPI staining. The following observations were made: (1) All agents tested (X-rays, MMS, EMS, MNNG, nitrous acid) delayed the first bud emergence after treatment, which indicates inhibition of the initiation of DNA replication. (2) Cells that survived X-irradiation progressed further through the cell cycle in a similar way to control cells. (3) Progress of chemically treated cells became extremely asynchronous because surviving cells stayed undivided for periods of varying length. (4) Prolongation of the time between bud emergence and cell separation was most pronounced for cells treated with the alkylating agents MMS and EMS. This is interpreted as retardation of ongoing DNA synthesis by persisting DNA adducts. (5) Cell cycle prolongation in the second and third generation after treatment was observed only with MMS treated cells. (6) In all experiments, individual cells of uniformly treated populations exhibited highly variable responses.Abbreviations DAPI
4,6-diamidino-2-phenyl-indole
- EMS
ethyl methanesulfonate
- MMS
methyl methanesulfonate
- MNNG
N-methyl-N-nitro-N-nitrosoguanidine 相似文献
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Summary A new genetic polymorphism of a human serum glycoprotein, the inter--trypsin-inhibitor (ITI), has been demonstrated by population and family studies. Sera were examined after neuraminidase treatment by isoelectric focusing on agarose gels followed by immunoblotting or by immunfixation with specific ITI-antiserum. Using this method, three common ITI phenotypes 1, 1–2 and 2, as well as two further rare ITI types 1–3 and 2–3 were disclosed. Genetically, these phenotypes are controlled by three allelic genes that determine a total of six phenotypes. These alleles are designated ITI*1, ITI*2 and ITI*3. The homozygous form of the third allele ITI*3 has not been found, as yet. The frequencies of ITI were examined in two population samples from Southern Germany (n=248) and from Tyrol, Austria (n=124). The gene frequencies of the common alleles ITI*1 and ITI*2 were 0.575 and 0.417, respectively, in Southern Germany, and 0.577 and 0.423, respectively, in Tyrol, Austria. The third allele ITI*3 was found only in the sample from Southern Germany, thus far, and was calculated to be 0.008. 相似文献