Cytological observations on the chromatin bodies of two Bacillus species

Chatterjee, B. R. (Baylor University College of Medicine, Houston, Tex.) and Robert P. Williams. Cytological observations on the chromatin bodies of two Bacillus species. J. Bacteriol. 83:1112-1118. 1962.-The nature of the chromatin bodies in Bacillus anthracis and B. megaterium has been studied intracellularly as well as after isolation from the bacilli. Preparations were examined by phase-contrast microscopy in the living state and by acid-Giemsa and Feulgen staining. In cells from young cultures, chromatin bodies occupy a continuous, long, central area in the bacteria. As the cells mature, the bodies lose their continuity and divide into two halves. In cells grown for 24 hr or longer, the chromatin bodies become more complex, and appear as multiple, spherical, interconnected constellations. Nuclear staining reveals that only the peripheral area, whether in cells from young or older cultures, takes up the stain, leaving a clear, central core. Discrete chromatin bodies are liberated from cells grown for longer periods after disintegration of the bacterial cell wall. These discrete bodies have been isolated from whole bacteria by treating washed, buffered saline suspensions of old cells with high concentrations of lysozyme followed by digestion with purified pancreatic lipase. The isolated chromatin bodies retain the same structure and appearance as inside the cells and show the same staining characteristics. Observations suggest that the chromatin bodies are discrete and circumscribed in nondividing, resting-phase bacteria.

Cinemicrophotographic observations on granule lysis in polymorphonuclear leucocytes during phagocytosis

Phagocytosis of yeast cell walls and of Bacillus megaterium by human, rabbit, and chicken polymorphonuclear leucocytes has been observed by phase contrast microscopy and recorded on motion picture film. In suitably thin preparations intracellular events could be visualized well. Lysis of cytoplasmic granules began early in the course of the ingestion process, rupture occurring only in granules adjacent to the microorganism being engulfed. Formation of a visible vacuole about the ingested particle frequently followed degranulation. Chicken polymorphonuclear leucocytes, with their large phase-dense granules, were particularly suitable subjects for observations on detailed morphologic aspects of granule lysis. Rupture took place rapidly (0.1 second or less); in place of the granule there appeared a clear zone, often with a small phase-dense round structure in its center. Also accompanying granule lysis was an increase in phase density of the adjacent surface of the microorganism. Over the course of the following few seconds the darkening on the organism faded, the dense small body disappeared from view, and the clear zone contracted towards the engulfed particle. The observations are discussed in relation to the hypothesis that fusion takes place between the granule membrane and the invaginated cell membrane overlying the ingested particle, with discharge of granule contents directly into the phagocytic vacuole.

LEAF-NODULE SYMBIOSIS. I. ENDOPHYTE OF PSYCHOTRIA BACTERIOPHILA

Centifanto, Ysolina M. (University of Florida, Gainesville), and Warren S. Silver. Leafnodule symbiosis. I. Endophyte of Psychotria bacteriophila. J. Bacteriol. 88:776-781. 1964.-The leaf-nodule endophyte of Psychotria bacteriophila has been repeatedly isolated in pure culture from germinating seedlings and young leaves on a nitrogen-free mineral agar. Its morphological, serological, and cultural characteristics place it within the Klebsiella-Aerobacter group. The endophyte has been provisionally named Klebsiella rubiacearum. Pure cultures fix N(2) under anaerobic conditions with good efficiency (4.54 mug of N fixed/mg of glucose utilized in 3 days). Nitrogen fixation by pure cultures is intimately related to pyruvate and hydrogen metabolism.

EFFECT OF CATALASE AND CULTURAL CONDITIONS ON GROWTH OF BEGGIATOA

Burton, Sheril D. (Oregon State University, Corvallis), and Richard Y. Morita. Effect of catalase and cultural conditions on growth of Beggiatoa. J. Bacteriol. 88:1755-1761. 1964.-The addition of catalase to culture medium increased the period of viability of Beggiatoa from 1 week to 2 months. Addition of catalase also produced a marked increase in cell yield and enzyme activity. Cultures grown without catalase exhibited an absorption peak characteristic of peroxides. This absorption peak was removed by addition of catalase during or after growth. Oxygen was required for growth, but carbon dioxide was not produced. Malate and acetate stimulated growth at low concentrations. Glucose and thiosulfate were not oxidized, and cytochromes were not detectable by spectrophotometric analysis.

TIME-LAPSE PHOTOMICROGRAPHY OF THE FORMATION OF A FREE SPHERICAL GRANULE IN AN ESCHERICHIA COLI CELL END

Hoffman, Heiner (New York University, New York), and Michael E. Frank. Time-lapse photomicrography of the formation of a free spherical granule in an Escherichia coli cell end. J. Bacteriol. 86:1075-1078. 1963.-Only a single case of the formation of a free spherical granule at an Escherichia coli cell end was found among several thousand cells recorded by time-lapse photomicrography. The spherical end body apparently arose immediately upon or soon after binary fission, at the newly formed cell end. Several minutes elapsed between the appearance of the end body and its full separation, apparently by constriction, from the mother cell. The end body showed no cytological changes during a 51-min period of observation after its separation from the mother cell. A hypothesis concerning the nature of end bodies and the mechanisms underlying their production is presented.

CHROMOSOME VELOCITY DURING MITOSIS AS A FUNCTION OF CHROMOSOME SIZE AND POSITION

Chromosome velocity has been studied in living Melanoplus differentialis spermatocytes by phase contrast cinemicrography. Melanoplus chromosomes (and bivalents) differ in length by as much as 1:3.5. As expected, no size-dependent velocity differences were detected in anaphase, and this is also shown to be true for the less predictable movements during prometaphase congression. The size of the X chromosome can change during observation following x-irradiation, but this is equally without influence on velocity. However, an effect of position on velocity is found in both prometaphase and in anaphase: the chromosomes furthest from the central interpolar axis move 25 per cent faster than more central chromosomes. A simple mechanical model relating frictional resistance and mitotic forces to chromosome velocity is discussed in detail. Calculations from the model suggest that a significant difference in the force acting on a large, as compared with a small chromosome is necessary to account for the observed similarity in velocity. Therefore, it is concluded that the mitotic forces are so organized or regulated that velocity is, within limits, independent of load. The implications of velocity-load independence in relation to the molecular origin of mitotic forces are discussed.

THE ORIGIN OF THE CELLS IN THE EFFERENT LYMPH FROM A SINGLE LYMPH NODE

The popliteal nodes of sheep were perfused continuously for over 100 hours with a solution containing ³H-thymidine. The labelling pattern of the lymphocytes in the efferent lymph from the perfused nodes showed that under normal conditions not more than 4 per cent of these lymphocytes were actually produced in the node. The transitional cells, large lymphocytes and cells of the plasma cell series which appeared in the lymph following antigenic stimulation of the node were all produced in the node.

FURTHER STUDIES ON CELL DIVISION WITHOUT MITOTIC APPARATUS IN SEA URCHIN EGGS

A large quantity of paraffin oil, sucrose solution, or sea water was injected into the eggs of the heart urchin Clypeaster japonicus shortly before the onset of the first cleavage. The injected oil became spherical, pushing the mitotic apparatus aside. The sucrose solution mixed with the protoplasm and caused disintegration of the mitotic apparatus, and the sea water formed a vacuole at the center of the cell. In all these cases, cleavage may take place almost normally in spite of the absence of the mitotic apparatus or its displacement within the cell. In some eggs, furrowing may take place when more than fifty per cent of the endoplasm has been replaced with sea water before onset of cleavage.

SPORULATION IN PROTOPLASTS AND ITS DEPENDENCE ON PRIOR FORESPORE DEVELOPMENT

Fitz-James, Philip C. (University of Western Ontario, London, Ontario, Canada). Sporulation in protoplasts and its dependence on prior forespore development. J. Bacteriol. 87:667-675. 1964.-Phase-contrast and electron microscopy were used to decide whether cells from late growth or sporulating cultures could, where converted into protoplasts, complete the process of sporulation. The cell wall was found essential to the development of the forespore. Incomplete forespores formed a satellite protoplast. Completed forespores were enclosed by the sporangial protoplast, and only these or later forms were able to complete sporulation in protoplasts.