Nejvíce citovaný článek - PubMed ID 689571
The replication map of the chromosome of Mycobacterium phlei
It is generally assumed that genetic research of mycobacteria is delayed as compared with other, more commonly used, bacterial models, particularly in the field of genetic transfers. In the field of mutagenesis the problems have been studied to such an extent that replication maps of the chromosome of M. phlei and M. tuberculosis H37 Rv have already been constructed and a new model of the cell cycle of bacteria exhibiting a slow growth rate has been worked out. When the problems of mycobacterial genetics are looked upon in the light of gene manipulations it may be concluded that mycobacteria belong to a few models whose genes are used for cloning and that problems of practical significance will be studied by means of the most modern approaches.
- MeSH
- mikrobiální genetika * MeSH
- Mycobacterium genetika MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The initial replication region of the chromosome on the replication map of M. phlei constructed by means of sequential mutagenesis in synchronous populations was accurately determined. By following the time shift of the replication moment of the genes bac and met in the control culture and in the culture with the initial inhibition of DNA synthesis by nalidixic acid the start of replication of the chromosome was determined at 15 min before replication of the gene ile. On the basis of the results obtained a scheme of the cell cycle in M. phlei was proposed. Intervals C and D depend on the generation time, become prolonged independently of each other and assume the whole cycle. The ratio C/(C + D) equals to 0.56 and the interval D has a value of 0.76 of the interval C. The mutual ratio of the intervals C : D is 1.3 : 1.0. The obtained results make it possible to form the assumption about mutual ratios between the chromosome replication and cell division in bacteria exhibiting slow growth rates.
- MeSH
- bakteriální chromozomy MeSH
- buněčný cyklus MeSH
- časové faktory MeSH
- DNA bakterií biosyntéza MeSH
- Escherichia coli cytologie MeSH
- kyselina nalidixová farmakologie MeSH
- Mycobacterium phlei cytologie genetika MeSH
- Mycobacterium cytologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- DNA bakterií MeSH
- kyselina nalidixová MeSH
Nalidixic acid was used for describing more accurately the terminal replication region of the Mycobacterium phlei chromosome. Cell division in synchronized cultures was not sensitive to this acid any more between 185-190 min, i.e. about 10 min after replication of the ser gene, the last of 24 genes of the replication map described so far. The replication of the chromosome was controlled by determining the position of the bac gene. Microscopic studies in phase contrast of the cells that were subjected for long time periods to nalidixic acid treatment at a bactericidal concentration showed elongated cells. The electronmicroscopic observation showed that a portion of the population influenced by nalidixic acid lyses, whereas other cells remain intact and resemble control cells.
- MeSH
- bakteriální chromozomy účinky léků metabolismus MeSH
- buněčné dělení účinky léků MeSH
- DNA bakterií biosyntéza MeSH
- kyselina nalidixová farmakologie MeSH
- mapování chromozomů * MeSH
- Mycobacterium phlei účinky léků genetika růst a vývoj MeSH
- Mycobacterium genetika MeSH
- replikace DNA účinky léků MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- DNA bakterií MeSH
- kyselina nalidixová MeSH
N-Methyl-N-nitrosourea was used to induce auxotrophic, scotochromogenic and isonicotinic acid hydrazide resistant mutants in Mycobacterium phlei and its effect was compared with that of nitrosoguanidine. Seventeen auxotrophic mutants requiring amino acids or vitamins and 52 scotochromogenic mutants with orange colonies were induced. The frequency of isonicotinic acid hydrazide-resistant mutants increased by two orders of magnitude.
- MeSH
- aminokyseliny metabolismus MeSH
- antibiotická rezistence MeSH
- biologické pigmenty biosyntéza MeSH
- isoniazid farmakologie MeSH
- methylnitrosomočovina farmakologie MeSH
- mutace * MeSH
- Mycobacterium phlei genetika fyziologie MeSH
- Mycobacterium genetika MeSH
- nitrosoguanidiny farmakologie MeSH
- nitrosomočovinové sloučeniny farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- aminokyseliny MeSH
- biologické pigmenty MeSH
- isoniazid MeSH
- methylnitrosomočovina MeSH
- nitrosoguanidiny MeSH
- nitrosomočovinové sloučeniny MeSH
New facts about the replication map of Mycobacterium phlei chromosome are summarized. Replication positions of two genes located in marginal regions of the replication map, ile close to the origin and ser near the terminus, were determined. Known positions of replication of some genes were defined with more precision within 2.5--5-min intervals using the method of sequential mutagenesis in synchronized cultures (leu, met, bac, pyr, stm, tet, cyc, his). Replication positions of genes responsible for the biosynthesis of thiamine and resistance to tetracycline and vancomycin were further identified. The contemporary replication map contains replication positions of 24 genes.
