Retention of Episomes During Protoplasting and During Propagation in the L State

Kawakami, M; Landman, Otto E.

doi:10.1128/jb.92.2.398-404.1966

Cited by 15 publications

(7 citation statements)

References 13 publications

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“…The septal mesosome represents one type of mesosome which seems fairly universal in the gram-positive bacilli (244). However, individual bacterial cells may contain several mesosomes located at different sites, although considerable controversy exists concerning this point (34,124,148,246). It appears that variation in the numbers and sites of mesosomes, as well as in their ultrastructural appearance (see above), may be related to species, age of the cells, and methods of fixation for electron microscopy (30, 33, 34, 120-122, 124-127, 198-202).…”

Section: Formation Of Mesosomes In Bac-mentioning

confidence: 99%

Mesosomes: membranous bacterial organelles.

Greenawalt¹,

Whiteside²

1975

Bacteriological Reviews

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And is it not true that the comparatively simple act of looking through a microscope presents the eye with pictures that we should all declare fantastic and far-fetched if we happened upon them by chance. .. (Schmidt, 270) Meditation over an electron micrograph of a bacterial cell wall or the endoplasmic reticulum ofa liver cell brings conviction that the position ofsynthesis within the cell must be as important as the chemical synthesis itself. (Gale, 89

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Section: Formation Of Mesosomes In Bac-mentioning

confidence: 99%

Mesosomes: membranous bacterial organelles.

Greenawalt¹,

Whiteside²

1975

Bacteriological Reviews

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“…Preparation ofspore suspensions. Spores were grown on Oxoid Nutrient Agar containing 5 g of NaCl per liter (14). After 2 days of incubation at 37 C and 3 days at room temperature, sporulation was nearly complete.…”

Section: Materials and Merhodsmentioning

confidence: 99%

Control of the Synthesis of Macromolecules During Amino Acid and Thymine Starvation in Bacillus subtilis

Anraku

Landman

1968

J Bacteriol

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Studies of Maal0e, Lark, and others with amino acidand thymine-starved cultures revealed successive steps in the biosynthesis of Escherichia coli chromosomes. In this study, the corresponding mechanisms in Bacillus subtilis 168 were examined. Using a strain requiring both thymine and tryptophan, we found that, 3 hr after the start of amino acid starvation, when the deoxyribonucleic acid (DNA) content of the culture had increased 40 to 50%, DNA synthesis ceased. After 4 to 5 hr, 100%o of the cells were immune to thymineless death; their chromosomes had presumably been completed. Immune cultures slowly incorporated 3H-thymine. Thymine incorporation increased 20-fold 30 min after readdition of amino acids, indicating reinitiation of chromosome synthesis. Simultaneous presence of amino acids and thymine was required for reinitiation. If 5-bromouracil (5-BU) was added instead of thymine, newly replicated DNA segments could be separated by centrifugation in CsCl. Analysis of the CsCl fractions by a transformation assay showed that the order in which the markers were synthesized was ade-16, thr-5, leu-8, metB5. Less than half the chromosomes started resynthesis synchronously in 5-BU. Nevertheless, chromosome alignment in the amino acid-starved culture is probably very good: marker frequency analysis of its DNA gives the same normalized frequencies as DNA from "perfectly" aligned spores. Full viability is maintained in the chromosome-arrested culture for 10 hr in thymine-free medium in the absence or presence of amino acids. In the latter condition, protein synthesis proceeds, and the cells filament and become more lysozyme-sensitive. Such cells must be incubated and plated on hypertonic or on slow-growth media; otherwise, they undergo "quasiosmotic" thymineless death. This death is thus apparently not directly attributable to any damage of chromosomal DNA. Further, weakening of the teichoic acid portion of the cell wall is not involved, since 32p incorporation into teichoic acid is normal. Chloramphenicol prevents quasiosmotic thymineless death and also inhibits 32P incorporation into teichoic acid. Chromosome-synthesizing cultures suffer thymineless death of two types: quasiosmotic death, and death insusceptible to osmotic rescue. Preceding experiments have shown that deoxyribonucleic acid (DNA) synthesis proceeds sequentially along the chromosome from a fixed starting point in exponentially growing cells of Escherichia coli (5, 19, 26) and Bacillus subtilis (32). In B. subtilis, this demonstration is based on two types of experiments. First, a comparison by transformation of marker frequencies in DNA from exponential cultures with marker frequencies in DNA of stationary

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“…The probability of reversion is very different in different organisms. For example, Salmonella paratyphi B mass conversion stable L forms revert extremely rarely (13,15), whereas those ofBacillus megaterium multiply only briefly in the naked state before reverting (12,13). B. subtilis is intermediate in this respect: depending on the plating medium, the individual L colonies are overgrown in 2 to 20 days by spontaneous revertants within the L colonies (16).…”

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confidence: 99%

Inhibitory protein controls the reversion of protoplasts and L forms of Bacillus subtilis to the walled state

DeCastro-Costa¹,

Landman²

1977

J Bacteriol

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When the cell wall of Bacillus subtilis is removed by lysozyme and the resultant protoplasts are plated on hypertonic soft agar medium, each protoplast forms an L colony. L bodies from such L colonies again plate as L-colony-forming units (CFU). However, if protoplasts or L bodies are "conditioned" by 1 h of incubation in 0.4% casein hydrolysate medium and then incubated in 25% gelatin medium for 1 h, 60 to 100% of the formerly naked cells give rise to bacillary colonies. The present experiments largely explain the mechanism responsible for the "heritable" persistence of the wall-less state in B. subtilis. It is shown that protoplasts produce a reversion inhibitory factor (RIF) which blocks reversion when the cell concentration exceeds 5 x 105 CFU/ml. This inhibitor is nondialyzable and sensitive to trypsin, heat, and detergent. Efficient reversion at 2 x 107 CFU/ml is obtained if the protoplasts are treated with trypsin after conditioning and chloramphenicol is incorporated into the gelatin reversion medium. In the presence of 500 ,ug of trypsin per ml, the requirement for gelatin is sharply reduced, and reversion occurs rapidly in liquid medium containing only 10% gelatin. Trypsin also stimulates reversion in L colonies growing on soft agar. Latent RIF is activated by ,3-mercaptoethanol. This reagent blocks reversion of protoplast suspensions at densities of 5 x 105 CFU/ ml. Comparison of the autolytic behavior ofB. subtilis and of the RIF revealed that several of the properties ofthe two activities coincide: both are inhibited by high concentrations of gelatin, both are activated by (3-mercaptoethanol, and both have high affinity for cell wall. Going on the assumption that REF is autolysin, models for protoplast reversion and L-form stability are proposed. A role of teichoic acid in reversion is suggested by the finding that mutants with altered teichoic acid show altered reversion behavior.When the cell wall is removed from Bacillus subtilis with lysozyme and the resultant protoplasts are plated on hypertonic soft-agar medium, each protoplast gives rise to an L colony consisting of wall-less, irregularly shaped L bodies (16,24). L bodies from suspended L colonies again give rise to L colonies in further platings (16). Thus, a brief transient enzyme treatment produces an alteration in each member of the treated population-namely, walllessness-which is then passed on "heritably" through an indefinite number of cell generations. We have called these naked offspring "mass conversion stable L forms" (13) to underline the distinction between these L forms and certain kinds of gene mutants blocked in peptidoglycan or peptidoglycan precursor biosynthesis, which are also sometimes called stable L forms (see, for instance, 28). We are quite certain that the persistent change induced in mass Present address:

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Retention of Episomes During Protoplasting and During Propagation in the L State

Cited by 15 publications

References 13 publications

Mesosomes: membranous bacterial organelles.

Mesosomes: membranous bacterial organelles.

Control of the Synthesis of Macromolecules During Amino Acid and Thymine Starvation in Bacillus subtilis

Inhibitory protein controls the reversion of protoplasts and L forms of Bacillus subtilis to the walled state

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