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  • 1
    Electronic Resource
    Electronic Resource
    THE INACTIVATION OF THE TRANSPORT MECHANISM FOR β-GALACTOSIDES OF ESCHERICHIA COLI UNDER VARIOUS PHYSIOLOGICAL CONDITIONS (1963)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 102 (1963), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1963.tb13663.x
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  • 2
    Electronic Resource
    Electronic Resource
    WHAT SIZE SHOULD A BACTERIUM BE? A Question of Scale (1996)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Microbiology 50 (1996), S. 317-348 
    Details
    ISSN: 0066-4227
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract There are living prokaryotes (Bacteria and Archaea) that have cell sizes that range from 0.02-400 mum3. Over this tremendous range, various abilities to cope with the environment are needed. This review attempts to formulate some of the problems and some of the solutions. The smallest size for a free-living organism is suggested to be largely set by the catalytic efficiency of enzymes and protein synthetic machinery. Because of fluctuations in the environment, cells must maintain machinery to cope with various catastrophes; these mechanisms increase the minimum size of the cell. On the other hand, the largest cell is reasonably assumed to be limited by the ability of diffusion to bring nutrients to the appropriate part of the cell and to dispose of waste products. To explore the limitation imposed by diffusion, analysis is developed of diffusion processes through stirred and unstirred media, diffusion through media that contains obstacles, and the effect of size and shape.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.micro.50.1.317
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  • 3
    Electronic Resource
    Electronic Resource
    The coupling of wall growth and chromosome replication in Gram-positive rods (1981)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 12 (1981), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1981.tb07642.x
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  • 4
    Electronic Resource
    Electronic Resource
    The three-for-one model for Gram-negative wall growth: a problem and a possible solution (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 162 (1998), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The murein wall in Gram-negative bacteria is so thin that the mechanism of growth is necessarily complicated. From analytical data of murein components, Höltje suggested a model for the growth mechanism that would lead to safe wall enlargement. The model depended on the formation of trimers of peptidoglycan disaccharides linked via their pentapeptides. In the ‘three-for-one’ model three oligopeptidoglycan chains are linked to each other in the usual linkages between the carboxyl group of d-alanine residues and the ε-amino group of diaminopimelic acid residues; these are designated ‘tail-to-tail’ linkages. This three-chained raft is then linked to the stress-bearing wall via the formation of trimers, defined as three peptide chains linked together by tail-to-tail linkages. Then by autolyzing the oldest bonds in each trimer, the old chain is excised and the raft becomes part of the stress-bearing wall and the wall is enlarged. There is a problem with the three-for-one model in that it demands a precise fitting of the prefabricated raft of three crosslinked chains to a stress-bearing chain in the wall fabric to allow the series of trimer linkages to form. Because the wall, when bearing stress, must be pulled into a ‘honeycomb’ structure, the end-to-end distance would be shortened. The possibility is raised here that the glycan chains in the stress-bearing wall are stretched to a sufficient degree by the cell's turgor pressure to compensate for its zig-zag structure; this could allow the model to function. A calculation is presented that assumes that the area of the pores in the fabric, called tessera, is maximized by the cell's turgor pressure. In this case the glycan chain must stretch 10% (and the end-to-end distance of peptide strands stretch 28%) so that the end-to-end distance of a glycan chain in the stress-bearing wall and the unstretched nascent wall can be the same and permit indefinite stable growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1998.tb12989.x
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  • 5
    Electronic Resource
    Electronic Resource
    The wall of bacteria serves the roles that mechano-proteins do in eukaryotes (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 88 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04954.x
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  • 6
    Electronic Resource
    Electronic Resource
    The growth strategy of the Gram-positive rod (1986)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 32 (1986), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Bacteria grow by enlarging their envelope in such a way that osmotic pressure does not normally cause physical rupture. The strategy of Bacillus subtilis for both cylindrical elongation and pole formation is now substantially defined. Side-wall growth takes place by laying down new peptidoglycan, which is then displaced outwards, stretched and discarded; cross walls are laid down in the absence of stress, and then stretched and bulged outward as the septum is split and the pole is formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1986.tb01196.x
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  • 7
    Electronic Resource
    Electronic Resource
    Energized membrane regulates cell pole formation in Bacillus subtilis (1984)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 24 (1984), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The pole of the Gram-positive rod Bacillus subtilis is formed by the construction of a crosswall which is then split. The newly exteriorized wall comes under stress and stretches to form the developing pole. A model is proposed to account for the even bisection of the septum. It is based on an extension of our previous finding that autolysin action on living cells is increased when the protonmotive force is dissipated in any of a number of ways. The first site of enzymatic attack is that region of the peripheral wall that has become farther removed from the cytoplasmic membrane as the result of the envagination of the developing septum. Later, enzymatic action lead to the cleavage midway between the portions of cytoplasmic membrane delimiting the septum as this region is farthest removed from the source of protonmotive force.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1984.tb01294.x
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  • 8
    Electronic Resource
    Electronic Resource
    Primeval cells: Possible energy-generating and cell-division mechanisms (1985)
    Springer
    Journal of molecular evolution 21 (1985), S. 270-277 
    Details
    ISSN: 1432-1432
    Keywords: Origin of cells ; Origin of bioenergetics ; Origin of Darwinian systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary It is proposed that the first entity capable of adaptive Darwinian evolution consisted of a liposome vesicle formed of (1) abiotically produced phospholipidlike molecules; (2) a very few informational macromolecules; and (3) some abiogenic, lipid-soluble, organic molecule serving as a symporter for phosphate and protons and as a means of high-energy-bond generation. The genetic material had functions that led to the production of phospholipidlike materials (leading to growth and division of the primitive cells) and of the carrier needed for energy transduction. It is suggested that the most primitive exploitable energy source was the donation of 2H++2e− at the external face of the primitive cell. The electrons were transferred (by metal impurities) to internal sinks of organic material, thus creating, via a deficit, a protonmotive force that could drive both the active transport of phosphate and high-energy-bond formation. This model implies that proton translocation in a closed-membrane system preceded photochemical or electron transport mechanisms and that chemically transferable metabolic energy was needed at a much earlier stage in the development of life than has usually been assumed. It provides a plausible mechanism whereby cell division of the earliest protocells could have been a spontaneous process powered by the internal development of phospholipids. The stimulus for developing this evolutionary sequence was the realization that cellular life was essential if Darwinian “survival of the fittest” was to direct evolution toward adaptation to the external environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02102359
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  • 9
    Electronic Resource
    Electronic Resource
    Selection and recombination in populations containing tandem multiplet genes (1979)
    Springer
    Journal of molecular evolution 14 (1979), S. 273-285 
    Details
    ISSN: 1432-1432
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Computer simulation for selective conditions that may apply in nature yielded three generalizations for prokaryotic organisms with recombinant mechanisms. (1) Selective forces can suffice to maintain a tandem gene family with the nearly optimum number of genes with little variance within the population. (2) Tandem genes will occur within the population unless the population is frequently cloned or unless the function due to a single copy is capable of over-providing the needs of the organism. (3) Even when there is no selective advantage or disadvantage due to extra gene copies, the population distribution becomes more skewed with time; and organisms with only single copies of the gene comprise a progressively larger fraction of the total. This may be the case with genes that function under strong cellular regulation. Evolutionary implications of these calculations are that the occurrence of unequal recombination of tandem genes would greatly slow evolution via duplication of genetic material. This difficulty and its possible resolutions are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732495
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  • 10
    Electronic Resource
    Electronic Resource
    The protein burden oflac operon products (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 455-462 
    Details
    ISSN: 1432-1432
    Keywords: Protein burden ; Chemostat competition ; Synthesis of useless protein ; Disadvantage of permease possession ; Cost oflac operon products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new approach to measuring the slowing of growth due to the manufacture of proteinsnot needed by a bacterium is presented. An entire single colony ofEscherichia coli was used to start a chemostat culture that was then given a selective pressure by the addition of phenylgalactoside (Φ-gal). This enriched the population for constitutive mutants that produced β-galactosidase without induction and could split Φ-gal, consume the galactose, and grow faster. When the Φ-gal was removed, the constitutives grew slower than the parental strain and were gradually lost. This procedure allows competition experiments to be carried out with minimum effects due to genetic drift. Experiments with both strains having wild-type and mutant permease genes were conducted. With the former the selective disadvantage was initially much greater than expected from the simplest hypothesis that extra unused proteins would slow growth in proportion to their fraction of the total protein synthesis. This phase was followed by a second phase where the selective disadvantage was smaller than predicted by this simple hypothesis. With a very slowly reverting permease negative strain the selective disadvantage, and therefore the protein burden, was found to be much smaller and not statistically different from zero. Thus, while one would expect under carbon and energy limitation in the chemostat the protein burden to be larger than under unlimited conditions, it is so small that that even the refined technique used here could not measure it accurately. It is certainly less than the fraction of ‘waste’ protein synthesis; but it could be between zero and the fraction of the cells' energy and carbon budget spent on manufacture of the proteins of thelac operon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02102321
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