Separation and properties of the cytoplasmic and outer membranes of vegetative cells of Myxococcus xanthus.

We have developed methods for separating the cytoplasmic and outer membranes of vegetative cells of Myxococcus xanthus. The total membrane fraction from ethylenediaminetetraacetic acid-lysozyme-treated cells was resolved into three major fractions by isopycnic density centrifugation. Between 85 and 90% of the succinate dehydrogenase and cyanide-sensitive reduced nicotinamide adenine dinucleotide oxidase activity was found in the first (I) fraction (rho = 1.

A method for establishing stable concentration gradients in agar suitable for studying chemotaxis on a solid surface.

A simple technique has been developed for establishing stable gradients of a substance in agar. The technique involves the creation of a spherically symmetric concentration profile in which concentration varies inversely with the distance from the source and is independent of the diffusion coefficient of the substance. It has been shown that the gradients established with this technique are stable for at least 190 h.

Cytoplasmic nonpolysomal ribonucleoprotein particles in sea urchin embryos and their relationship to protein synthesis.

We have examined the relationship between the newly synthesized mRNA that enters polysomes in sea urchin embryos and the messengerlike RNA that enters the pool of ribosome-free ribonucleoprotein particles (free RNPs or informosomes). Although the RNA in the free RNPs turns over 25% more rapidly than in the polysomes, labeling kinetics indicate that the RNA containing poly(A) [poly(A)(+)RNA] and the RNA not containing poly(A) [poly(A)(-)RNA] within each cytoplasmic compartment have very similar half-lives. The poly(A)(+)RNA from both free RNPs and polysomes binds ribosomes almost equally well in a reticulocyte lysate, and this binding is sensitive to inhibitors of initiation.

Effect of temperature on the growth of Myxococcus xanthus.

The cardinal growth characteristics of Myxococcus xanthus were examined from 14 to 40 degree C, and the examinations indicated that the organism is mesophilic in character. The maximum growth rate (0,3 doublings per h) was between 34 and 36 degree C and the temperature characteristic (micron) is 17,000 cal/mol (71,162 J/mol).

Solubility and diffusion coefficient of adenosine 3':5'-monophosphate.

Several previously unavailable parameters of adenosine 3':5'-monophosphate have been determined. The molar extinction coefficient at pH 7.0 is 1.

Developmentally induced autolysis during fruiting body formation by Myxococcus xanthus.

The developmental events during fruiting body construction by the myxobacterium M. xanthus is an orderly process characterized by several sequential stages: growth leads to aggregation leads to formation of raised, darkened mounds of cells leads to autolysis leads to myxospore induction. The temporal sequence of autolysis followed by myxospore induction is consistent with the interpretation that developmental autolysis provides essential requirements for the surviving cells to induce to myxospores.

Cell density-dependent growth of Myxococcus xanthus on casein.

When Myxococcus xanthus FB was grown on 0.2% casein it exhibited a phenomenon we call cooperative growth. That is, above 104 cells per ml, both strains that were studied exhibited increasing growth rates as a function of increasing cell numbers.

Gene transfer to myxobacterium by Escherichia coli phage P1.

Myxococcus xanthus is a bacterium with an interest for studies of development because it has an organized multicellular phase in its life cycle. Bacteriophage Pl can adsorb to M. xanthus and inject its DNA into this organism despite the wide taxonomic gap separating myxococcus from Escherichia coli, the source of Pl.

Intracellular and extracellular nucleotides and related compounds during the development of Myxococcus xanthus.

Changes in nucleotide pools and extracellular nucleotides during the developmental cycle of the myxobacterium Myxococcus xanthus were determined using a high-pressure liquid chromatography nucleotide analyzer. A general increase in all nucleotide pools occurred during the morphological phase of glycerol conversion of vegetative cells to myxospores. The levels of the nucleoside triphosphate pools remained high as the myxospore matured and throughout subsequent germination.

Fatty acids of Myxococcus xanthus.

Fatty acids were extracted from saponified vegetative cells and myxospores of Myxococcus xanthus and examined as the methyl esters by gas-liquid chromatography. The acids consisted mainly of C(14) to C(17) species. Branched acids predominated, and iso-pentadecanoic acid constituted half or more of the mixture.

Ribonucleic acid and protein synthesis during germination of Myxococcus xanthus myxospores.

Ribonucleic acid (RNA) and protein synthesis during myxospore germination were examined. When RNA synthesis was inhibited more than 90% by either actinomycin D (Act D) or rifampin, germination was prevented. The data were consistent with the interpretation that rifampin did not interfere with protein synthesis in any way other than by inhibition of messenger RNA formation.

Bacteriolytic enzymes produced by Myxococcus xanthus.

The bacteriolytic activities in the culture fluid of Myxococcus xanthus were purified and separated into six active fractions by the use of Bio-Gel CM-2 and Bio-Gel P-60. These fractions were identified as: (i) an amidase, (ii) a glucosaminidase, (iii) a glucosaminidase and an amidase, (iv) a protease with probable amidase activity, (v) another protease with probable amidase activity, and (vi) a peptidase active on both d-alanyl-diaminopimelate and d-alanyl-lysine peptide bonds. On one occasion, another amidase was eluted from Bio-Gel CM.

Stable messenger ribonucleic acid and germination of Myxococcus xanthus microcysts.

We have examined germination, protein synthesis and ribonucleic acid (RNA) synthesis by microcysts of the fruiting myxobacterium Myxococcus xanthus. The morphological aspects of microcyst formation were completed at about 2 hr after induction had begun. In such microcysts, germination, RNA synthesis, and protein synthesis were inhibited by actinomycin D (Act D).

Induction of myxospore formation in Stigmatella aurantiaca (Myxobacterales) by monovalent cations.

Suspension cultures of Stigmatella aurantiaca can be induced to form myxospores by addition of the monovalent cations Li(+), Na(+), NH(4) (+), K(+), or Rb(+).