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K Bacon

Publications and source records attributed to K Bacon.

26 records · Page 2Linked to original sources
PubMed1975

Coats from Myxococcus xanthus: characterization and synthesis during myxospore differentiation.

An extracellular coat from glycerol-induced myxospores of Myxococcus xanthus has been isolated and characterized. Coats were examined chemically and by using both transmission and scanning electron microscopy. On a dry weight basis, approximately 75% of the coat is polysaccharide composed entirely of galactosamine and glucose. The remainder of the coat is protein (14%), glycine (8%), and organic phosphorus (less than 1%). Coats remained morphologically intact despite boiling in 10 M urea, sodium lauryl sulfate plus beta-mercaptoethanol, or extraction with warm phenol. Coats also resisted digestion with a variety of proteolytic and polysaccharide degrading enzymes. Synthesis of myxospore coat begins approximately 1 h after the addition of glycerol to a culture. One portion of the coat is complete by 5 to 6 h but additional material consisting primarily of glucose is added after 8 h.

Bacterial Proteins↗
PubMed1974

Phospholipid metabolism and membrane synthesis during sporulation in Bacillus megaterium.

In view of previously published reports of localized membrane growth in exponentially growing Bacillus megaterium and in sporulating Bacillus cereus, an attempt was made to describe phospholipid metabolism and the topology of membrane synthesis during sporulation in B. megaterium. The cells were pulsed with radioactive glycerol or acetate at the time of septum formation, and the specific activity of the lipid fraction was measured at various times through the free spore stage. The bulk of the material labeled during septation could not be recovered in the spore. Rather, it was found that the labeled lipid fraction underwent considerable turnover during spore development. Additionally, other experiments revealed that the lipid made before the initiation of sporulation was also subject to extensive turnover. In order to minimize both the confounding effects of lipid turnover and the possible presence of lateral diffusion of labeled lipid in the membrane, autoradiography of cells pulse labeled with radioactive glycerol at the time of septation was performed; a symmetrical grain distribution resulted. Thus, despite previously published suggestions to the contrary, the current experimental techniques could not demonstrate the existence of localized membrane synthesis in B. megaterium during sporulation.

Acetates↗
PubMed1972

Growth, cell division, and fragmentation in a species of Flexibacter.

Flexibacter FS-1, a gram-negative gliding bacterium was grown in liquid culture as long (over 100-mum) filaments. The filaments possessed a triple-track wall which resembled that found in other gram-negative bacteria. Although phase-contrast microscopy indicated that the long filaments were nonseptate, electron microscopy revealed three or four septa along the length of each filament. The septa contained lysozyme-sensitive, electron-opaque material, presumed to be peptidoglycan, sandwiched between cell membranes. The outer triple track wall was not part of the septum. Mesosomes were seen in various areas of the cell and frequently were observed attached to septa in different stages of completion. Studies of the organism in slide culture revealed that individual filaments grew in an exponential fashion and divided in the middle despite the long length and multiseptate condition. When the temperature of a liquid culture growing exponentially with a generation time of 90 minutes was shifted from 30 to 35 C, the filaments fragmented into three or four shorter cells within 120 min. The short cells continued to grow exponentially at 35 C at approximately the same rate as at 30 C. When the culture was shifted back to 30 C, the cells immediately stopped dividing and began to elongate. After a period of 2 to 3 hr, cell division resumed. It is suggested that the shift-up in temperature induced the completion of the cross wall (centripetal growth of the triple-track wall) and cell separation at the sites of previously formed septa, whereas the shift-down in temperature caused a transient inhibition of cross-wall formation but not of growth. Fragmentation was inhibited by sodium azide but took place despite the inhibition of protein synthesis by chloramphenicol or the inhibition of deoxyribonucleic acid synthesis by mitomycin C.

Azides↗
PubMed1970

Ribonucleic acid synthesis during microcyst formation in Myxococcus xanthus: characterization by deoxyribonucleic acid-ribonucleic acid hybridization.

The technique of deoxyribonucleic acid-ribonucleic acid (RNA) hybridization was used to compare the RNA synthesized during vegetative growth and microcyst formation in Myxococcus xanthus. All classes of RNA, including ribosomal RNA, were synthesized during microcyst formation. The results indicate that the ribosomal RNA synthesized during microcyst formation was indistinguishable from that made during vegetative growth. Hybridization competition experiments demonstrated that certain messenger RNA species are synthesized only during vegetative growth, whereas others are synthesized only during microcyst formation. The synthesis of a new species of RNA polymerase does not appear to be responsible for differential transcription during morphogenesis in M. xanthus since the rifampicin sensitivity of transcription was conserved during microcyst formation.

Bacteria↗
PubMed1967

Ribonucleic acid synthesis during morphogenesis in Myxococcus xanthus.

Ribonucleic acid synthesis was measured during the morphogenesis of Myxococcus xanthus. After induction of microcyst formation by the addition of glycerol to an exponential culture, net ribonucleic acid (RNA) synthesis was immediately terminated (measured either chemically or by the accumulation of acid-insoluble radioactivity). Extensive RNA turnover did take place, however, including RNA made both before and after induction. Sucrose gradient centrifugation revealed that ribosomes and ribosomal RNA were synthesized during microcyst formation even though there was no net RNA synthesis. Base analyses of the total RNA of vegetative cells and 120-min microcysts were indistinguishable.

Adenine↗
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