Site of Initiation of Cellular Autolysis in Streptococcus faecalis as Seen by Electron Microscopy
01 Aug 1970-Journal of Bacteriology (American Society for Microbiology)-Vol. 103, Iss: 2, pp 504-512
TL;DR: Evidence supporting the involvement of autolysin activity in continued wall extension and in cell separation as well as in the initiation of new sites of wall extension was obtained.
Abstract: Low concentrations of glutaraldehyde (0.1% or higher) blocked cellular and wall autolysis. The site of autolytic activity was studied by allowing cell autolysis to proceed for very short periods (0 to 15 min) before addition of glutaraldehyde. Electron microscopy of ultrathin sections showed that the primary site of autolytic activity was the leading edge of the nascent cross wall. The base of the cross wall seemed more resistant than the tip. Evidence supporting the involvement of autolysin activity in continued wall extension and in cell separation as well as in the initiation of new sites of wall extension was obtained. In cells exposed for 10 min to chloramphenicol, wall dissolution was very much slower but occurred at the same cross wall site.
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195 citations
01 May 1971
TL;DR: Theoretical analysis of Procaryotic Cell Division with Respect to Wall and Membranes and its Applications in Microbiology shows clear trends in prokaryotic cell division towards apoptosis.
Abstract: (1971) Procaryotic Cell Division with Respect to Wall and Membranes CRC Critical Reviews in Microbiology: Vol 1, No 1, pp 29-72
177 citations
TL;DR: The observations that bacteriolysis could be prevented, with the formation of spherical, osmotically fragile bodies, by the provisions of an iso-osmotic environment again demonstrated that autolysis was the result of hydrolysis of a sufficient number of bonds in the protective cell wall peptidoglycan to cause its dissolution and removal from the bacterial surface.
Abstract: Publisher Summary This chapter discusses the microbial peptidoglycan (murein) hydrolases. Studies of the action of lysozyme and of other bacteriolytic enzymes revealed that the bacteriolytic action was a result of hydrolysis of specific bonds in the protective and shape-maintaining bacterial exoskeleton, the peptidoglycan (murein) sacculus of the cell wall. The observations that bacteriolysis could be prevented, with the formation of spherical, osmotically fragile bodies, by the provisions of an iso-osmotic environment again demonstrated that autolysis was the result of hydrolysis of a sufficient number of bonds in the protective cell wall peptidoglycan to cause its dissolution and removal from the bacterial surface. The peptide moieties of peptidoglycan are attacked by exo- as well as by endo-peptidases. DD-carboxypeptidases convert pentapeptide into tetrapeptide moieties by cleaving the terminal D-aIanyl-D-alanine bond of crosslinked and uncrosslinked stem peptides. DD-endopeptidases have been described and isolated which cleave the crucial DD-peptide bond that crosslinks the stem peptides to yield the characteristic peptidoglycan network.
162 citations
TL;DR: Preliminary studies with inhibitors suggest that turnover is dependent on new cell wall deposition, and this work has confirmed that Bacillus subtilis W-23 strain KM in logarithmic growth phase is prone to turnover.
160 citations
TL;DR: Bulge formation, due to the presumed action of an autolysin(s), may be an initial step in the septation sequence when the mucopeptide is modified to allow construction of the sePTum.
Abstract: Septa can be demonstrated in sections of Escherichia coli strains B and B/r after fixation with acrolein and glutaraldehyde. The septum consists of an ingrowth of the cytoplasmic membrane and the mucopeptide layer; the outer membrane is excluded from the septum until the cells begin to separate. Mesosomes have also been observed. The septum is highly labile and, except in the chain-forming strains, E. coli D22 env A and CRT 97, not easily preserved by standard procedures. The labile nature of the septum may be due to the presence of autolysin(s) located at the presumptive division site. Blocking division by addition of ampicillin (2 to 5 μg/ml) to cells of E. coli B/r produces a bulge at the middle of the cells; bulge formation is stopped by addition of chloramphenicol. Cephalosporins also induce bulge formation but may stop cell elongation as well as division. Bulge formation, due to the presumed action of an autolysin(s), may be an initial step in the septation sequence when the mucopeptide is modified to allow construction of the septum. In a nonseptate filament-forming strain, PAT 84, which ceases to divide at 42 C, bulge formation only occurs in the presence of ampicillin at the time of a shift-down at 30 C or at 42 C in the presence of NaCl (0.25 to 0.34 M). Experiments with chloramphenicol suggest that the filaments are fully compartmentalized but fail to divide owing to the inactivation, rather than loss of synthesis, of an autolysin at 42 C.
158 citations
Cites background from "Site of Initiation of Cellular Auto..."
...faecalis, autolysis proceeds from the newly synthesized tip of the growing cross wall, whereas the peripheral wall is less susceptible to autolytic attack (16)....
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References
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TL;DR: The stain reported here differs from previous alkaline lead stains in that the chelating agent, citrate, is in sufficient excess to sequester all lead present, and is less likely to contaminate sections.
Abstract: Aqueous solutions of lead salts (1, 2) and saturated solutions of lead hydroxide (1) have been used as stains to enhance the electron-scattering properties of components of biological materials examined in the electron microscope. Saturated solutions of lead hydroxide (1), while staining more intensely than either lead acetate or monobasic lead acetate (l , 2), form insoluble lead carbonate upon exposure to air. The avoidance of such precipitates which contaminate surfaces of sections during staining has been the stimulus for the development of elaborate procedures for exclusion of air or carbon dioxide (3, 4). Several modifications of Watson's lead hydroxide stain (1) have recently appeared (5-7). All utilize relatively high pH (approximately 12) and one contains small amounts of tartrate (6), a relatively weak complexing agent (8), in addition to lead. These modified lead stains are less liable to contaminate the surface of the section with precipitated stain products. The stain reported here differs from previous alkaline lead stains in that the chelating agent, citrate, is in sufficient excess to sequester all lead present. Lead citrate, soluble in high concentrations in basic solutions, is a chelate compound with an apparent association constant (log Ka) between ligand and lead ion of 6.5 (9). Tissue binding sites, presumably organophosphates, and other anionic species present in biological components following fixation, dehydration, and plastic embedding apparently have a greater affinity for this cation than lead citrate inasmuch as cellular and extracellular structures in the section sequester lead from the staining solution. Alkaline lead citrate solutions are less likely to contaminate sections, as no precipitates form when droplets of fresh staining solution are exposed to air for periods of up to 30 minutes. The resultant staining of the sections is of high intensity in sections of Aralditeor Epon-embedded material. Cytoplasmic membranes, ribosomes, glycogen, and nuclear material are stained (Figs. 1 to 3). STAIN SOLUTION: Lead citrate is prepared by
24,137 citations
"Site of Initiation of Cellular Auto..." refers methods in this paper
...The sections were stained for 20 min with saturated uranyl acetate in 50% ethanol and lead citrate (11) for 5 min....
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TL;DR: Epoxy embedding methods of Glauert and Kushida have been modified so as to yield rapid, reproducible, and convenientembedding methods for electron microscopy.
Abstract: Epoxy embedding methods of Glauert and Kushida have been modified so as to yield rapid, reproducible, and convenient embedding methods for electron microscopy. The sections are robust and tissue damage is less than with methacrylate embedding.
9,741 citations
TL;DR: The studies indicate that this teichoic acid contains choline and is a major structural component of pneumococcal cell wall, since walls prepared from pneumococci in which cell wall choline was replaced by ethanolamine were found to be totally resistant to the action of the autolytic enzyme.
298 citations
"Site of Initiation of Cellular Auto..." refers background in this paper
...Tomasz (21) observed that the substitution of ethanolamine for choline in the wall teichoic acid (8) of Diplococcus pneumoniae resulted, among other things, in growth in extremely long chains....
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195 citations
"Site of Initiation of Cellular Auto..." refers background in this paper
...Tomasz (21) observed that the substitution of ethanolamine for choline in the wall teichoic acid (8) of Diplococcus pneumoniae resulted, among other things, in growth in extremely long chains....
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...Also, it seems likely that the cross-linking transpeptidation reaction takes place outside the permeability barrier of the cell, whereas synthesis of the linear glycan chains takes place, at least partially, in the membrane fraction (21)....
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TL;DR: The cytoloqg of bacterial cellular division in Bacillus cereus is studied by the techniques of ultra-thin sectioning and electron microscopy to remove a little of confusion and point the way to much greater contributions of the method in the future.
Abstract: In the course of cytological studies of a few selected species of bacteria by the techniques of ultra-thin sectioning and electron microscopy, some new and si8nificant information has been obtained concerning cellular division in Bacillus cereus. The cytoloqg of bacterial cellular division inYneS-a_ number of structures aiid ev-ts which are beyond the resolution limit of the light microscope. The complexity of these structures and -the psi'bl1e variatiow whfch differences in species, age of culture, and growth conditions may introduce have made it impossible to make reliable interpretations by indirect methods. This has led to considerable confuwsion as is apparent from any review of the literature. It is hoped that some of the observations made in the present investigation will remove a little of that confusion and point the way to much greater contributions of the method in the future.
175 citations