Calcium reversal of the heat susceptibility and dipicolinate deficiency of spores formed "endotrophically" in water

Endoplasmic Reticulum Interaction Supports Energy Production and Redox Homeostasis in Mitochondria Released from Astrocytes

Mitochondria can be released by astrocytes as part of a help-me signaling process in stroke. In this study, we investigated the molecular mechanisms that underlie mitochondria secretion, redox status, and functional regulation in the extracellular environment. Exposure of rat primary astrocytes to NAD or cADPR elicited an increase in mitochondrial calcium through ryanodine receptor (RyR) in the endoplasmic reticulum (ER). Importantly, CD38 stimulation with NAD accelerated ATP production along with increasing glutathione reductase (GR) and dipicolinic acid (DPA) in intracellular mitochondria. When RyR was blocked by Dantrolene, all effects were clearly diminished. Mitochondrial functional assay showed that these activated mitochondria appeared to be resistant to H2O2 exposure and sustained mitochondrial membrane potential, while inhibition of RyR resulted in disrupted membrane potential under oxidative stress. Finally, a gain- or loss-of-function assay demonstrated that treatment with DPA in control mitochondria preserved GR contents and increased mitochondrial membrane potential, whereas inhibiting GR with carmustine decreased membrane potentials in extracellular mitochondria released from astrocytes. Collectively, these data suggest that ER-mitochondrial interaction mediated by CD38 stimulation may support mitochondrial energy production and redox homeostasis during the mode of mitochondrial transfer from astrocytes.

REVERSIBLE ACTIVATION FOR GERMINATION AND SUBSEQUENT CHANGES IN BACTERIAL SPORES

Lee, W. H. (University of Illinois, Urbana) and Z. John Ordal. Reversible activation for germination and subsequent changes in bacterial spores. J. Bacteriol. 85:207-217. 1963.-It was possible to isolate refractile spores of Bacillus megaterium, from a calcium dipicolinate germination solution, that were activated and would germinate spontaneously in distilled water. Some of the characteristics of the initial phases of bacterial spore germination were determined by studying these unstable activated spores. Activated spores of B. megaterium were resistant to stains and possessed a heat resistance intermediate between that of dormant and of germinated spores. The spontaneous germination of activated spores was inhibited by copper, iron, silver, or mercury salts, saturated o-phenanthroline, or solutions having a low pH value, but not by many common inhibitors. These inhibitions could be partially or completely reversed by the addition of sodium dipicolinate. The activated spores could be deactivated and made similar to dormant spores by treatment with acid. Analyses of the exudates from the variously treated spore suspensions revealed that whatever inhibited the germination of activated spores also inhibited the release of spore material. The composition of the germination exudates was different than that of extracts of dormant spores. Although heavy suspensions of activated spores gradually became swollen and dark when suspended in solutions of o-phenanthroline or at pH 4, the materials released resembled those found in extracts of dormant spores rather than those of normal germination exudates.

Germination properties of spores with low dipicolinic acid content

Keynan, A. (University of Wisconsin, Madison), W. G. Murrell, and H. O. Halvorson. Germination properties of spores with low dipicolinic acid content. J. Bacteriol. 83:395-399. 1962.-When the dipicolinic acid content of spores of Bacillus cereus strain T is reduced from 7.5 to 2 or 3%, the spores germinate spontaneously after heat activation and are sluggish in their response to l-alanine and other germination agents. Only germination initiated by calcium dipicolinic acid is unaffected. l-Alanine-induced germination is stimulated by exogenous dipicolinic acid. These results support the hypothesis that endogenous dipicolinic acid regulates the l-alanine-triggered germination.

Chemical analyses of asporogenic mutants of Bacillus cereus

Lundgren, D. G. (Syracuse University, Syracuse, N.Y.) and J. J. Cooney. Chemical analyses of asporogenic mutants of Bacillus cereus. J. Bacteriol. 83:1287-1293. 1962.-Bacillus cereus ATCC 4342 and three temperature-sensitive asporogenic mutants were compared regarding some basic cellular components and response to metals in a synthetic medium. The mutants sporulate when cultured at 28 C but are asporogenic when cultured at 37 C; the parent sporulates at both temperatures. Results of amino acid analyses of cells harvested at characteristic times during the culture cycle revealed no qualitative differences which could be related to the asporogenic nature of the mutants. All sporulating cultures synthesized dipicolinic acid during sporulation, but asporogenic cultures did not. The patterns of zinc, potassium, sodium, and calcium uptake, but not of iron or manganese uptake, appear to be affected in the asporogenic mutants.

Chemical and morphological studies of bacterial spore formation. IV. The development of spore refractility

From the stage of a completed membranous forespore to that of a fully ripened free spore, synchronously sporulating cells of a variant Bacillus cereus were studied by cytological and chemical methods. Particular attention was paid to the development of the three spore layers—cortex, coat, and exosporium—in relation to the forespore membrane. First, the cortex is laid down between the recently described (5) double layers of the forespore membrane. Then when the cortex is ⅓ fully formed, the spore coat and exosporium are laid down peripheral to the outer membrane layer covering the cortex. As these latter layers appear, the spores, previously dense by dark phase contrast, gradually "whiten" or show an increase in refractive index. With this whitening, calcium uptake commences, closely followed by the synthesis of dipicolinic acid and the process is terminated, an hour later, with the formation of a fully refractile spore. In calcium-deficient media, final refractility is lessened and dipicolinic acid is formed only in amounts proportional to the available calcium. If calcium is withheld during the period of uptake beyond a critical point, sporulating cells lose the ability to assimilate calcium and to form normal amounts of dipicolinic acid. The resulting deficient spores are liberated from the sporangia but are unstable in water suspensions. Unlike ripe spores, they do not react violently to acid hydrolysis and, in thin sections, their cytoplasmic granules continue to stain with lead solutions.

Permeability of bacterial spores. IV. Water content, uptake, and distribution

Black, S. H. (The University of Michigan, Ann Arbor) and Philipp Gerhardt. Permeability of bacterial spores. IV. Water content, uptake, and distribution. J. Bacteriol. 83:960-967. 1962.-Dormant and germinated spores of Bacillus cereus strain terminalis were examined for water properties. Respectively, they exhibited a mean density of 1.28 and 1.11 g/ml, a water content of 64.8 and 73.0%, and a total water uptake of 66.6 and 75.6%, based on spore weight, or 86.0 and 83.9%, based on spore volume. The results confirmed a previous report that internal and external water are in virtually complete equilibrium, but refuted a prevailing hypothesis that heat resistance is attributable to a dry core. A model of spore ultrastructure that evolved from the cumulative results pictures a moist, dense, heteroporous core. A new hypothesis is formulated as an explanation for thermostability in spores and possibly in other instances; it postulates the occurrence of an insolubly gelled core with cross-linking between macromolecules through stable but reversible bonds so as to form a high-polymer matrix with entrapped free water.

PHYSIOLOGY OF THE SPORULATION PROCESS IN CLOSTRIDIUM BOTULINUM. II. MATURATION OF FORESPORES

Day, Lawrence E., (Michigan State University, East Lansing) and Ralph N. Costilow. Physiology of the sporulation process in Clostridium botulinum. II. Maturation of forespores. J. Bacteriol. 88:695-701. 1964.-Clostridium botulinum, strain 62-A, did not sporulate endotrophically, but forespores matured to refractile, heat-resistant spores when replaced in solutions containing l-alanine and l-proline, l-isoleucine and l-proline, or l-alanine and l-arginine. Solutions of l-arginine or l-citrulline would not support the maturation process. Acetate, CO(2), and delta-amino valeric acid were produced during sporulation in a replacement solution of l-alanine and l-proline, indicating the operation of the Stickland reaction. There was no large uptake of either exogenous l-alanine or acetate during this process. Similarly, there was no apparent protein or nucleic acid synthesis, since high levels of chloramphenicol, 8-azaguanine, or mitomycin C failed to inhibit, and no significant amount of P(32) was incorporated into the spore nucleic acids. Dipicolinic acid (DPA) was synthesized during forespore maturation. It is believed that these final steps in sporulation of C. botulinum require only an exogenous source of energy which can be obtained via the Stickland reaction system, and that the synthesis of DPA and other unknown materials relies primarily on endogenous substrates.

RADIOSENSITIVITY OF SEVERAL DEHYDROGENASES AND TRANSAMINASES DURING SPOROGENESIS OF BACILLUS SUBTILIS

Rowley, D. B. (Syracuse University, Syracuse, N.Y.), and H. R. Newcomb. Radiosensitivity of several dehydrogenases and transaminases during sporogenesis of Bacillus subtilis. J. Bacteriol. 87:701-709. 1964.-Cells of Bacillus subtilis grown in a chemically defined medium for 17 hr, subsequently washed, and transferred to a phosphate solution containing CaCl(2) sporulated in a reproducible pattern. The synthesis of dipicolinic acid essentially paralleled the appearance of thermoresistant cells. X-ray resistant cells appeared 2 to 3 hr before the appearance of thermoresistant cells and the formation of dipicolinic acid. Changes in enzyme activity of cells undergoing sporogenesis varied among the enzymes studied. The transaminases exhibited a marked decrease in activity during early sporogenesis, whereas the dehydrogenases exhibited maximal activity. The determination of enzyme radioresistance in extracts of sporulating cells indicated that the resistance of transaminases remained essentially unchanged, whereas the dehydrogenases exhibited a decreased resistance early in sporogenesis. Although both glutamic-pyruvic transaminase and glutamic-oxaloacetic transaminase (GOT) were demonstrated in vegetative cells, only the latter was detected in mature spores. The radioresistance of GOT in vegetative-cell extracts was two to three times greater than in spore extracts.

TRACE METAL REQUIREMENTS FOR SPORULATION OF BACILLUS MEGATERIUM

Kolodziej, Bruno J. (Northwestern University, Evanston, Ill.), and Ralph A. Slepecky. Trace metal requirements for sporulation of Bacillus megaterium. J. Bacteriol. 88:821-830. 1964.-A sucrose-mineral salts medium was purified for the purpose of definitively re-examining the trace metal cations associated with the sporulation of Bacillus megaterium. Two heretofore unknown requirements for copper (0.013 mug/ml of cupric ion) and molybdenum (27.2 mug/ml of molybdate ion) were uncovered. In the purified copper-supplemented medium, sporulation levels of other metals were determined as follows: iron, 0.5 mug/ml of ferrous ion; zinc, 1.1 mug/ml of zinc ion; manganese, 0.037 mug/ml of manganous ion; and calcium, 0.9 mug/ml of calcium ion. The approximate time during which the various metals were required was determined with iron, zinc, calcium, and manganese. A molybdenum substitution for copper, iron, or zinc was noted. The copper requirement was shown for the sporulation of B. cereus var. mycoides and var. albolactis, suggesting that this may be a general requirement for sporulation. The specific functions of metal ions in sporulation are not known, but they probably act as activators of the various enzyme systems necessary for sporulation.

Involvement of calcium and dipicolinic acid in the resistance of Bacillus cereus BIS-59 spores to u.v. and gamma radiations

The role of dipicolinic acid (DPA) in determining the resistance of Bacillus cereus spores to u.v. and gamma radiation was investigated. B. cereus BIS-59 spores containing varying amounts of DPA were prepared by appropriate compositional adjustments in the secondary media. Compared with spores containing 6 per cent DPA (dry weight) those containing 0.8 per cent DPA were far more sensitive to u.v. radiation. Similar u.v. radiation sensitivity was also found in respect of a DPA-less mutant of B. cereus T 6A 1. Pre-treatment of DPA deficient spores (of wild type or mutant B. cereus) with DPA or the presence of DPA during irradiation resulted in increased resistance of these spores to u.v. radiation. In the range 0.2 to 1 per cent DPA content of spores of B. cereus BIS-59, a striking inverse relationship could be discerned between the DPA content and the number of spore photo-products (5-thymidyl, 5,6-dihydrothymine) formed in DNA and spore viability. The resistance of B. cereus spores to gamma radiation did not seem to be influenced by their DPA content.

Regulation of dihydrodipicolinate synthase during growth and sporulation of Bacillus cereus

A four- to sixfold increase in specific activity of dihydrodipicolinic acid synthase was observed during sporulation of Bacillus cereus. The enzyme from cells harvested before and after the increase in specific activity appeared to be very similar as judged by pH optima, heat denaturation kinetics, apparent Michaelis constants, chromatography on diethylaminoethyl-cellulose and Sephadex G-200, and polyacrylamide gel electrophoresis. Studies with various combinations of amino acids and one of the enzyme substrates, pyruvate, failed to give evidence for control of the enzyme by activation, inhibition, repression, induction, or stabilization. Omission of calcium from the sporulation medium had no significant effect on the specific activity pattern of the enzyme as a function of age of culture.

Growth and sporulation characteristics of Bacillus megaterium under different conditions of nutrient limitation

The quantitative nutritional requirements to achieve specific cell densities have been studied for B. megaterium. Growth of batch cultures was separately limited by depletion of glucose, ammonium, sulphate, potassium, phosphate, manganese and magnesium. Maximum population density (E420) for graded concentrations of each limiting nutrient was plotted against nutrient concentration and a linear plot was obtained below a critical concentration. Under conditions of magnesium depletion, two phases of growth occurred separated by a plateau. Proposals are made for the use of these cultures in drug resistance studies. Sporulation occurred in all cultures except those limited by potassium, manganese or magnesium. Spores were produced in magnesium-limited cultures provided that glucose was simultaneously depleted. Spores produced under different conditions of nutrient depletion varied in germination characteristics, heat resistance and spore volume.

Minimal requirements for commitment to sporulation in Bacillus megaterium

Commitment to sporulation was examined by means of both endotrophic sporulation and rejuvenation experiments. In both cases, a point of commitment to the completion of sporulation occurred at stage II. With 2 x 10(8) cells/ml, the process by which commitment occurred required 0.5 mm Mg(2+), 10.0 mm phosphate, and an energy source (minimum of 5.0 mm acetate). For completion of sporulation and formation of normal, heat-resistant refractile spores, 0.3 mm Ca(2+) was required. Except for this Ca(2+) requirement, the completion of sporulation after commitment was independent of the nature of the surrounding medium. Some aspects of the utilization of these required substances were examined.

Effect of carbon source on size and associated properties of Bacillus megaterium spores

The size of the spores produced by Bacillus megaterium ATCC 19213 depended upon the nature of the carbon source present in the defined medium in which they were produced. Homogeneous preparations of small (0.38 mum(3)), nearly spherical spores were produced after batch culture in the presence of 2.8 mm citrate, and large (1.17 mum(3)), oblong spores were produced by replacement culture in the presence of 7.35 mm acetate. Large and small spores had approximately the same deoxyribonucleic acid content, density, and heat resistance. Large spores contained about 2.5 times the dipicolinic acid, glucosamine, ribonucleic acid, Mn(2+), and lipid and about 1.5 times the Mg(2+), Fe(2+), Ca(2+), and dry weight of small spores. Large spores were especially enriched in Zn(2+) (4.5-fold). More protein (1.5-fold) was extracted from small spores with 1 n NaOH than from large spores, possibly indicating a difference in the spore coats, but large spores contained about twice the Kjeldahl nitrogen of small spores. A difference in the coats may account for the fact that, unlike small spores, large spores showed improved germination with increased times and temperature of heat shocking. The possibility of determining the location of some of these substances within the spore by comparing the compositional ratios with estimated volumes of specific spore layers is discussed.

Regulation of dipicolinic acid biosynthesis in sporulating Bacillus cereus. Characterization of enzymic changes and analysis of mutants

Some of the early enzymes in the lysine-biosynthetic pathway also function for dipicolinic acid synthesis in sporulating Bacillus cereus T. 1. The first enzyme, aspartokinase, loses its sensitivity to feedback inhibition by lysing. This change occurs before the time of dipicolinic acid synthesis but at a time when diaminopimelic acid is required for spore cortex formation. 2. A possible regulatory change at a branch point in the pathway was studied by examining the properties of a key enzyme, dihydrodipicolinic acid reductase. No alteration in the feedback sensitivity or sedimentation rate of this enzyme could be detected during sporulation. 3. Two mutants producing heat-sensitive spores were analysed. Both produced spores that contained decreased amounts of dipicolinic acid. Although neither was a lysine auxotroph, they both had greatly decreased activities of certain lysine-biosynthetic enzymes in sporulating cells. 4. Starvation of cells for calcium also results in the production of spores that are heat-sensitive and contain less dipicolinic acid than the control. A decreased content of one of the lysine-biosynthetic enzymes, dihydrodipicolinic acid synthetase, in calcium-starved cells could account for the lower concentration of dipicolinic acid in the spores.

Relationship of dipicolinic acid content in spores of Bacillus cereus T to ultraviolet and gamma radiation resistance

Spores of Bacillus cereus T lacking dipicolinic acid showed a statistically significant reduction in resistance to ultraviolet and gamma radiation as compared with spores with high dipicolinic acid content.

Comparisons of cells, refractile bodies, and spores of Bacillus popilliae

Spores of Bacillus popilliae from infected larvae and refractile bodies produced in a Trypticase-barbiturate medium were similar but distinct from vegetative cells of this organism in protein, nucleic acid, and enzyme composition. The spores and refractile bodies were found to have catalase activity, some of which was heat-resistant. This enzyme was not found in the vegetative cells. The spores contained dipicolinic acid, but the refractile bodies did not. The latter were similar to cells in having considerably higher levels of phosphate extractable with cold trichloroacetic acid and of poly-beta-hydroxybutyrate than had the spores. Electron microscopy demonstrated conclusively that the refractile bodies are distinctly different from either cells or spores of B. popilliae. The possibility that these bodies are formed as a result of an aborted sporulation process is discussed.

Physiology of growth and sporulation in Bacillus cereus. I. Effect of glutamic and other amino acids

Buono, F. (Syracuse University, Syracuse, N.Y.), R. Testa, and D. G. Lundgren. Physiology of growth and sporulation in Bacillus cereus. I. Effect of glutamic and other amino acids. J. Bacteriol. 91:2291-2299. 1966.-Growth and sporulation were studied in Bacillus cereus by use of an active culture technique and a synthetic medium. A high level of glutamic acid (70 mm) was required for optimal growth and glucose oxidation followed by sporulation even though relatively little glutamic acid was consumed (14 mm). Optimal growth occurred with a combination of 14 mm glutamic acid and 56 mm (NH(4))(2)SO(4), aspartic acid, or alanine. Ornithine or arginine at 70 mm could replace glutamic acid in the synthetic medium without affecting the normal growth cycle. Glutamic acid was not replaced by any other amino acid, by (NH(4))(2)SO(4), or by a combination of either alpha-ketoglutarate or pyruvate plus (NH(4))(2)SO(4). Enzyme assays of cell-free extracts prepared from cells harvested at different times were used to study the metabolism of glutamic acid. Glutamic-oxaloacetic and glutamic-pyruvate transaminases were completely activated (or derepressed) during early stages of sporulation (period of 6 to 8 hr). Alanine dehydrogenase responded in a similar manner, but the levels of this enzyme were much higher throughout the culture cycle. Neither glutamic dehydrogenase nor alpha-ketoglutarate dehydrogenase was detected. Sporulation in a replacement salts medium was studied with cells harvested at different times from the synthetic medium. Cultures 2 to 6 hr old were unable to sporulate in the replacement salts medium unless glutamic acid (7.0 mm) was present. By the 6th hr, cells were in the early stages of sporulation, showing spore septa development. Cultures 8 hr old sporulated in the replacement salts medium. Other metabolic intermediates able to replace glutamic acid in the replacement salts medium were alanine, aspartic acid, and glutamine at equimolar concentrations. Also, ammonium ions in combination with pyruvic, oxaloacetic, alpha-ketoglutaric, or fumaric acid replaced glutamic acid. The likely role of these metabolites is discussed.

ENDOGENOUS FACTOR IN SPOROGENESIS IN BACTERIA II

Kerravala, Zarrine J. (University of Illinois, Urbana), V. R. Srinivasan, and H. Orin Halvorson . Endogenous factor in sporogenesis in bacteria. II. Growth and sporulation of Bacillus subtilis . J. Bacteriol. 88: 374–380. 1964.—The presence of an endogenous factor in Bacillus subtilis which could initiate sporogenesis in suspensions of washed vegetative cells was demonstrated. The inability to obtain a culture of vegetative cells, relatively free from spores, by the “active culture” technique necessitated the use of the “continuous culture” method. The investigations on the continuous cultivation of this organism, to obtain a steady-state population of actively growing vegetative cells, resulted in certain observations which gave an insight into the nature of sporogenesis. Growth studies of the organism under these conditions showed that there was a rise in viable cell numbers, until a maximal population was reached. This was maintained at a steady-state level for sometime; on further incubation, there was a reduction in cell numbers, and consequently the steady state could not be maintained any longer. Spore counts showed that the spore fraction of the total population increased on prolonged incubation. The commitment to sporulation appeared to have caused a reduction in the growth rate of the population, which was experimentally demonstrated by a decline in cell numbers. In contrast, when B. cereus strain T. was grown as a continuous culture, it could be maintained as a steady-state population of vegetative cells, for longer periods, like a nonsporeformer (e.g., Escherichia coli ). This difference in behavior could be attributed to the fact that whereas B. subtilis can sporulate in the presence of nutrients, B. cereus strain T. cannot do so until the medium has been depleted of nutrients.

STUDIES OF ASPOROGENIC MUTANTS OF BACILLUS CEREUS: PRELIMINARY INVESTIGATIONS WITH CALCIUM AND ZINC

The physiology of spore formation was studied in Bacillus cereus and a temperature-sensitive asporogenic mutant. The parent organism sporulates when cultured in a minimal medium at either 28 °C or 37 °C while the mutant sporulates only at 28 °C. The blocking of sporulation at 37 °C has been referred to as "abortive" sporulation. Uptake of calcium and zinc was followed during growth and sporulation or "abortive" sporulation. Calcium and dipicolinic acid (DPA) levels in sporogenic cultures increased as the medium calcium was increased. The asporogenic mutant took up less calcium and synthesized little DPA. Heat resistance of spores increased as the calcium and DPA increased. Over 99% of Ca45or Zn65were released from labelled spores when autoclaved to release DPA. Chemical fractionations were made of cells labelled with Zn65and Ca45and harvested at different times during the culture cycle. Smaller percentages of calcium than of zinc were located in the cold trichloroacetic acid soluble fraction. The alcohol-soluble, ether-insoluble fraction of spores contained a greater percentage of calcium than was found in vegetative cells. Cells which had undergone "abortive" sporulation contained the same percentage of calcium in this fraction as homologous vegetative cells.

THE PHYSIOLOGY AND NATURAL RELATIONSHIPS OF THE MOTILE, SPOREFORMING SARCINAE

Eleven strains of Sarcina ureae were compared to members of the genus Sarcina and to three species of Bacillus. Biochemically these 11 strains are very much alike. They appear to be more closely allied to members of the genua Bacillus than to the sarcinae, both on the basis of biochemical patterns and DNA composition. The spores of S. ureae are very similar to spores of the bacilli in their degree of heat resistance, requirements for formation, and composition. Serological differences among the 11 strains of S. ureae were observed, although no cross reactions with the spore forming bacilli or the other sarcinae were found, We propose that S. ureae (Beijerinck) Löhnis be called Sporosarcina ureae (Beijerinck) Kluyver and van Niel and that it be classified as a member of the family Bacillaceae.