scholarly journals Considérations quantitatives sur des coupes ultraminces de bactéries infectées par un bactériophage

1959 ◽  
Vol 5 (3) ◽  
pp. 469-478 ◽  
Author(s):  
Janine Séchaud ◽  
Antoinette Ryter ◽  
Edouard Kellenberger
Keyword(s):  
Statistical Error ◽  
Relative Number ◽  
Quantitative Relationship ◽  
Bacterial Cells ◽  
Average Volume ◽  
Upper Limits ◽  
Ultrathin Sections ◽  
Different Sources ◽  
Made In ◽  
Number Of Particles

A quantitative relationship has been established between the number of particles, for example bacteriophages, counted in ultrathin sections of bacteria and the total number present in the whole bacterial cells. The factor F relating particles counted per section with the total number of these particles per entire bacterium could be arrived at by two methods, which proved to give results in close agreement. The first involves knowledge of the average volume of a bacterial section in proportion to the average volume of a whole bacterium; if the mean number of appearances of the same particle on consecutive sections is also known, F may then be calculated. The thickness of sections and, therefore, their volume, as well as the average number of times a single particle is sectioned could be learned by examination of serial sections. By counting the relative number of T2 phage particles which had been intersected once or twice, and relating this proportion to the known phage dimensions, the thickness of the sections was determined to be about 400 A. The second measurement of F could be made in a particular case of late phage development where the number of particles per cell was countable or titratable directly in the bacterial lysate, this number being compared with the number seen in sections of the bacteria just before lysis. The different sources of errors are discussed. The statistical error is under 20 per cent, while the systematic errors are higher and cannot yet be indicated precisely. After a very cautious estimation of the upper limits, we can state, however, that the counts made with this method are certainly reliable to well within a factor of two.

Defining Relationship Marketing: A review of Research

2007 ◽  
Vol 3 (2) ◽  
pp. 64-76 ◽  
Author(s):  
C. Madhavaiah ◽  
S. Durga Rao
Keyword(s):  
Content Analysis ◽  
Relationship Marketing ◽  
Customer Loyalty ◽  
Previous Literature ◽  
The Core ◽  
Analysis Methodology ◽  
Different Sources ◽  
Made In

The term “relationship marketing” has become a popular concept among the practitioners of marketing as well as academics during the last several years. It is very beneficial to firms because it can foster customer loyalty and re-patronage behaviour. Apart from its growing popularity among academia and practitioners, still there exists no consensus on the basic “constructs” of relationship marketing. Different authors have different opinions about what should and what should not be at the core of what constitutes “relationship marketing”. In view of this, an attempt is made in this paper to collect and analyse 36 definitions of relationship marketing from different sources of previous literature. Content analysis methodology has been used to identify the underlying “constructs” in each of the 36 definitions. The results suggest that there are seven RM “constructs” which constitute the major conceptualisations of relationship marketing. Out of 36 definitions of relationship marketing, only one definition is judged as being more comprehensive and generally acceptable and a new definition for relationship marketing is presented as an inducement to further research and discussion.

scholarly journals MUTATION OF THE BACILLUS OF RABBIT SEPTICEMIA

1922 ◽  
Vol 35 (4) ◽  
pp. 561-574 ◽  
Author(s):  
Paul H. De Kruif
Keyword(s):  
Room Temperature ◽  
Relative Number ◽  
Pure Line ◽  
Rabbit Serum ◽  
Type D ◽  
Pure Cultures ◽  
High Concentrations ◽  
Distinct Maximum ◽  
Made In

Type G microbes, discovered in pure cultures of the rabbit septicemia bacillus, have been demonstrated to arise from the parent D form by mutation. The D → G mutation takes place in broth cultures of pure-line strains of Microbe D, when these are kept for several days without transplant at 37°C., or at room temperature, or in the ice box. The mutation is greatly inhibited by filtrates from 6 and 24 hour cultures of Microbe D, and to some extent by filtrates from 48 hour cultures. The process of transformation takes place to a very slight extent or not at all in undiluted rabbit serum, but Type G colonies subcultured to this medium do not revert to the parent D form. The D → G change is strongly inhibited in cultures made in simple beef infusion, or in 5 per cent rabbit serum-beef infusion. Peptone would seem to be the constituent of plain broth which favors the process. In high concentrations of peptone, the mutation is rapid and may reach a degree of 90 per cent of the total organisms in 5 to 6 days. A distinct maximum of the relative number of Type G colonies as compared to the parent Type D is observable in plain broth and in some concentrations of peptone, when these are kept at 37°C. for some days without transplant. Subsequent tests show the concentration of Type G microbes to diminish. The change in acid agglutination optimum exhibited by the mutant G forms implies a distinct change in bacterial protoplasm and would seem to be one of the most fundamental mutations so far described.

Electron Microscopic Study of the Graffi Virus in Bone Marrow of Leukemic Mice.

1966 ◽  
Vol 52 (1) ◽  
pp. 35-59 ◽  
Author(s):  
Natale Pennelli ◽  
Luciano Fiore-Donati ◽  
Luigi Chieco-Bianchi ◽  
Giuseppe Tridente
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Electron Microscopic ◽  
Virus Particles ◽  
Negative Stain ◽  
Cytoplasmic Vesicles ◽  
C57bl Mice ◽  
Ultrathin Sections ◽  
Number Of Particles ◽  
Marrow Cells

Bone marrow from C57BL mice with myeloid leukemia induced by Graffi virus has been studied with the electron microscope by ultrathin section and negative stain techniques. Virus particles were usually found in different types of bone marrow cells as well as in extracellular spaces. However, the highest number of particles in various stages of maturation was observed in the cytoplasm of megakaryocytes. Two main types of virus particle were found: the immature Al particle and the mature C particle. They were morphologically indistinguishable from other murine leukemogenic viruses. In partially purified preparations studied by negative staining, some of the particles which were not penetrated by PTA, frequently showed a tail-like structure of variable length. In ultrathin sections, particles were found to originate by budding from the cell membranes. Budding of particles was particularly evident in megakaryocytes and especially within the granules and cytoplasmic vesicles or in connection with the platelet demarcating membranes. The findings of a high number of virus particles in all stages of maturation in megakaryocytes together with a certain degree of megakaryocytosis observed in the bone marrow suggest that this type of cell is possibly one of the main source of production of the virus. A few particles resembling morphologically mycoplasma were detected within the cytoplasm of some immature bone marrow cells.

Sky survey of high-energy cosmic X-rays and spectral information on sources in the Crab nebula, Cygnus, and Scorpius

1968 ◽  
Vol 46 (10) ◽  
pp. S409-S413 ◽  
Author(s):  
Walter H. G. Lewin ◽  
George W. Clark ◽  
William B. Smith
Keyword(s):  
Crab Nebula ◽  
High Energy ◽  
X Rays ◽  
Coma Cluster ◽  
X Ray ◽  
Sky Survey ◽  
Upper Limits ◽  
Intensity Ratios ◽  
The Crab Nebula ◽  
Made In

A complete X-ray survey of the northern sky has been made in the energy range 20–100 keV. Spectra are given for Cyg X-1 and Tau X-1. Intensity ratios (Cyg X-1/Tau X-1) of 0.84 ± 0.10 and 1.30 ± 0.25 were derived in the 20–70 keV range from data obtained on July 19, 1966 and February 13, 1967, respectively. Observations on Sco X-1 and the Coma cluster show upper limits which are quite different from results reported by other groups.

Algicidal activity and gliding motility of Saprospira sp. SS98-5

2003 ◽  
Vol 49 (2) ◽  
pp. 92-100 ◽  
Author(s):  
Gou Furusawa ◽  
Takeshi Yoshikawa ◽  
Akihiro Yasuda ◽  
Taizo Sakata
Keyword(s):  
Cell Walls ◽  
Marine Bacterium ◽  
Sea Water ◽  
Gliding Motility ◽  
Microtubule Assembly ◽  
Algicidal Activity ◽  
Bacterial Cells ◽  
Kagoshima Bay ◽  
Motile Cells ◽  
Ultrathin Sections

A marine bacterium, Saprospira sp. SS98-5, which was isolated from Kagoshima Bay, Japan, was able to kill and lyse the cells of the diatom Chaetoceros ceratosporum. The multicellular filamentous cells of this bacterium captured the diatom cells, formed cell aggregates, and lysed them in an enriched sea water (ESS) liquid medium. Strain SS98-5 also formed plaques on double layer agar plates incorporating diatom cells. The diatom cell walls were partially degraded at the contact sites with the bacteria, the bacteria invaded from there into the diatom cells, and then the diatom cells were completely lysed. The strain possessed gliding motility and grew as spreading colonies on ESS agar plates containing lower concentrations of polypeptone (below 0.1%) while forming nonspreading colonies on ESS agar plates containing 0.5% polypeptone. Electron micrographs of ultrathin sections demonstrated that microtubule-like structures were observable only in gliding motile cells. Both the gliding motility and the microtubule-like structures were diminished by the addition of podophyllotoxin, an inhibitor of microtubule assembly, suggesting that the microtubule-like structures observed in these bacterial cells are related to their gliding motility.Key words: Saprospira sp., Chaetoceros ceratosporum, gliding motility, algicidal activity, microtubule-like structure.

scholarly journals A Fragment from Chronicle of George Synkellos in Slavonic Translation

2020 ◽  
pp. 139-149
Author(s):  
Anna-Maria Totomanova
Keyword(s):  
Historical Narratives ◽  
Linguistic Features ◽  
The World ◽  
Editorial Work ◽  
Draft Version ◽  
History Of ◽  
In The Beginning ◽  
Eastern Traditions ◽  
Different Sources ◽  
Made In

The only fragment from the Chronicle of George Synkellos in Slavic translation is found in a chronographic compilation known in five Russian witnesses of the 15th – 16th cc. A large and coherent excerpt from the Chronography of Julius Africanus that survived in about 100 fragments scattered in Latin, Greek and Eastern traditions became a basis of the compilation. Africanus’ excerpt reveals the Christian history of the world from the Creation to the Resurrection of Christ and occupies about two thirds of the whole text. It is complemented by the end of Synkellos’ Chronicle that stops with Diocletian’s reign and by the beginning of the Chronicle of his follower Theophanes the Confessor, which brings the narrative to the foundation of Constantinople. The missionary pathos of the compilation leaves no doubt and makes us think that it occurred on Byzantine soil in the first half of the 9th c. after the end of the iconoclasm. The Linguistic features of the Slavonic text prove that the translation was made in Bulgaria in the early 10th century during the reign of Simeon the Great (893–927). The paper explores the traces of the editorial work of the compilers, who were supposed to bring into line the two historical narratives that disagree in their historical and chronological concepts and refer to different sources. The problem deserves attention given the fact that in the beginning of the last century V. Istrin erroneously identified the compilation as an abridged and even draft version of the Chronicle of Synkellos.

TEM observation of compacted DNA of Synechococcus elongatus PCC 7942 using DRAQ5 labeling with DAB photooxidation and osmium black

Microscopy ◽  
2020 ◽  
Author(s):  
Ilika Ghosh ◽  
Kimie Atsuzawa ◽  
Aoi Arai ◽  
Ryuzo Ohmukai ◽  
Yasuko Kaneko
Keyword(s):  
Electron Microscopy ◽  
Synechococcus Elongatus ◽  
Bacterial Cells ◽  
Specific Time ◽  
Dark Cycle ◽  
Transmission Electron ◽  
Ultrathin Sections ◽  
Set Up ◽  
Synechococcus Elongatus Pcc 7942 ◽  
Pcc 7942

Abstract To visualize the fine structure of compacted DNA of Synechococcus elongatus PCC 7942, which appears at a specific time in the regular light/dark cycle prior to cell division, ChromEM with some modifications was applied. After staining DNA with DRAQ5, the cells were fixed and irradiated by red laser in the presence of 3,3ʹ-diaminobenzidine and subsequently fixed with OsO4. A system with He–Ne laser (633 nm) was set up for efficient irradiation of the bacterial cells in aqueous solution. The compacted DNA was visualized by transmission electron microscopy, in ultrathin sections as electron dense staining by osmium black.

scholarly journals Bacterial Vivisection: How Fluorescence-Based Imaging Techniques Shed a Light on the Inner Workings of Bacteria

2020 ◽  
Vol 84 (4) ◽  
Author(s):  
Alexander Cambré ◽  
Abram Aertsen
Keyword(s):  
Real Time ◽  
Bacterial Cell ◽  
Cell Biology ◽  
Imaging Techniques ◽  
Time Lapse ◽  
Bacterial Cells ◽  
The Past ◽  
Current State ◽  
Architectural Features ◽  
Made In

SUMMARY The rise in fluorescence-based imaging techniques over the past 3 decades has improved the ability of researchers to scrutinize live cell biology at increased spatial and temporal resolution. In microbiology, these real-time vivisections structurally changed the view on the bacterial cell away from the “watery bag of enzymes” paradigm toward the perspective that these organisms are as complex as their eukaryotic counterparts. Capitalizing on the enormous potential of (time-lapse) fluorescence microscopy and the ever-extending pallet of corresponding probes, initial breakthroughs were made in unraveling the localization of proteins and monitoring real-time gene expression. However, later it became clear that the potential of this technique extends much further, paving the way for a focus-shift from observing single events within bacterial cells or populations to obtaining a more global picture at the intra- and intercellular level. In this review, we outline the current state of the art in fluorescence-based vivisection of bacteria and provide an overview of important case studies to exemplify how to use or combine different strategies to gain detailed information on the cell’s physiology. The manuscript therefore consists of two separate (but interconnected) parts that can be read and consulted individually. The first part focuses on the fluorescent probe pallet and provides a perspective on modern methodologies for microscopy using these tools. The second section of the review takes the reader on a tour through the bacterial cell from cytoplasm to outer shell, describing strategies and methods to highlight architectural features and overall dynamics within cells.

scholarly journals From single bacterial cell imaging towards in vivo single-molecule biochemistry studies

2019 ◽  
Vol 63 (2) ◽  
pp. 187-196 ◽  
Author(s):  
Ulrike Endesfelder
Keyword(s):  
Single Molecule ◽  
Model Systems ◽  
Current Status ◽  
Bacterial Cells ◽  
Molecular Architecture ◽  
Cellular Mechanisms ◽  
Microscopy Techniques ◽  
Made In

Abstract Bacteria as single-cell organisms are important model systems to study cellular mechanisms and functions. In recent years and with the help of advanced fluorescence microscopy techniques, immense progress has been made in characterizing and quantifying the behavior of single bacterial cells on the basis of molecular interactions and assemblies in the complex environment of live cultures. Importantly, single-molecule imaging enables the in vivo determination of the stoichiometry and molecular architecture of subcellular structures, yielding detailed, quantitative, spatiotemporally resolved molecular maps and unraveling dynamic heterogeneities and subpopulations on the subcellular level. Nevertheless, open challenges remain. Here, we review the past and current status of the field, discuss example applications and give insights into future trends.

scholarly journals Radiocarbon Dating at the University of Washington III

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 498-506 ◽  
Author(s):  
A. W. Fairhall ◽  
W. R. Schell ◽  
J. A. Young
Keyword(s):  
Standard Deviation ◽  
Oxalic Acid ◽  
Lower Limit ◽  
Half Life ◽  
Radiocarbon Dating ◽  
Isotope Fractionation ◽  
Statistical Error ◽  
Sample Count ◽  
The University ◽  
Made In

This date list consists of those measurements made since 1962. The counter is one described previously (Fairhall and Schell, 1963). The results are computed using NBS oxalic acid as the standard and 5568 for the half-life of C14. Standard deviations are computed for each measurement, including the statistical error in the sample count and uncertainties in background and standard. In general, each sample is counted at least twice. The quoted error on the date is the standard deviation. A 2σ criterion is used to establish a lower limit to the age of very old samples with no detectable trace of C14. No correction for isotope fractionation has been made in any of the measurements.

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