scholarly journals CHEMICAL STUDIES ON HOST-VIRUS INTERACTIONS

1946 ◽  
Vol 84 (5) ◽  
pp. 511-523 ◽  
Author(s):  
Seymour S. Cohen ◽  
Thomas F. Anderson
Keyword(s):  
Respiratory Rate ◽  
Cytoplasmic Granules ◽  
E Coli ◽  
T4 Bacteriophage ◽  
Chemical Studies ◽  
Host Virus Interactions ◽  
Virus Interactions ◽  
Relationship Of ◽  
The Relationship ◽  
Similar Substance

The addition of active or irradiated T2 bacteriophage and T4 bacteriophage to E. coli B stops bacterial multiplication. The respiratory rate and respiratory quotient of the inhibited bacteria remained at the values observed just before infection. A respiratory rate decrease which occasionally appears can be roughly correlated with change of turbidity of the suspension. An intracellular inhibitor of multiplication appears to be liberated into lysates. A similar substance has been separated from normal E. coli B after sonic disintegration. These bacteriostatic preparations contain cytoplasmic granules with lactic acid dehydrogenase activity. The relationship of these phenomena to the interference effect in this system and others has been considered.

scholarly journals CHEMICAL STUDIES ON HOST-VIRUS INTERACTIONS

1946 ◽  
Vol 84 (5) ◽  
pp. 525-533 ◽  
Author(s):  
Seymour S. Cohen ◽  
Thomas F. Anderson
Keyword(s):  
Synthetic Medium ◽  
Interference Effects ◽  
Oxygen Utilization ◽  
E Coli ◽  
Chemical Studies ◽  
Bacterial Viruses ◽  
Host Virus Interactions ◽  
Virus Interactions

5-methyl tryptophane inhibited the multiplication of E. coli B without apparently affecting the rate of its oxygen utilization or R. Q. in a synthetic medium. E. coli B, under conditions of inhibition in the presence of this compound, was infected with the bacterial viruses T2 or T4. Infected organisms, in the presence of this compound, were unable to reproduce virus, assayable by the plaque method. Indeed, the number of infectious centers disappeared at a logarithmic rate in the presence of 5-methyl tryptophane, although the compound did not reduce the titers of B, T2, or T4, when the bacteria or viruses were exposed separately to the agent. In contrast to the irreversibility of the interference effects induced by viruses, the effects induced by short exposures to 5MT appear to be reversible on removal of the compound.

scholarly journals CHEMICAL STUDIES IN HOST-VIRUS INTERACTIONS

1950 ◽  
Vol 91 (6) ◽  
pp. 607-618 ◽  
Author(s):  
Seymour S. Cohen ◽  
Rachel Arbogast
Keyword(s):  
Nucleic Acid ◽  
Differential Centrifugation ◽  
Host Organism ◽  
Constituent Part ◽  
E Coli ◽  
Virus Activity ◽  
Chemical Studies ◽  
Bacterial Viruses ◽  
Host Virus Interactions ◽  
Virus Interactions

Three mutant pairs of bacterial viruses T2r+ and T2r, T4r+ and T4r, T6r+ and T6r, have been concentrated by differential centrifugation and analyzed. Under conditions of prolonged lysis of organisms grown on broth-agar, the virus concentrates frequently contained phosphorus (P) other than that contained in desoxyribose nucleic acid (DNA). These concentrates reacted with antisera to the host organism, E. coli, specifically precipitating the non-DNA-P but not virus activity or DNA. The amounts of nitrogen precipitated in the virus concentrates by antisera were related to their content of non-DNA-P. These viruses could be purified by differential centrifugation after such treatment to yield preparations apparently free of P other than DNA-P. It has been concluded that there is no satisfactory evidence for the presence of ribose nucleic acid as a constituent part of these viruses.

scholarly journals Exploring the taxonomical and functional profile of As Burgas hot spring focusing on thermostable β-galactosidases

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
María-Eugenia DeCastro ◽  
Michael P. Doane ◽  
Elizabeth Ann Dinsdale ◽  
Esther Rodríguez-Belmonte ◽  
María-Isabel González-Siso
Keyword(s):  
Microbial Community ◽  
Hot Spring ◽  
Functional Characterization ◽  
Tca Cycle ◽  
Maximal Activity ◽  
Sulfur Cycle ◽  
E Coli ◽  
Complex Microbial Community ◽  
Relationship Of ◽  
The Relationship

AbstractIn the present study we investigate the microbial community inhabiting As Burgas geothermal spring, located in Ourense (Galicia, Spain). The approximately 23 Gbp of Illumina sequences generated for each replicate revealed a complex microbial community dominated by Bacteria in which Proteobacteria and Aquificae were the two prevalent phyla. An association between the two most prevalent genera, Thermus and Hydrogenobacter, was suggested by the relationship of their metabolism. The high relative abundance of sequences involved in the Calvin–Benson cycle and the reductive TCA cycle unveils the dominance of an autotrophic population. Important pathways from the nitrogen and sulfur cycle are potentially taking place in As Burgas hot spring. In the assembled reads, two complete ORFs matching GH2 beta-galactosidases were found. To assess their functional characterization, the two ORFs were cloned and overexpressed in E. coli. The pTsbg enzyme had activity towards o-Nitrophenyl-β-d-galactopyranoside (ONPG) and p-Nitrophenyl-β-d-fucopyranoside, with high thermal stability and showing maximal activity at 85 °C and pH 6, nevertheless the enzyme failed to hydrolyze lactose. The other enzyme, Tsbg, was unable to hydrolyze even ONPG or lactose. This finding highlights the challenge of finding novel active enzymes based only on their sequence.

Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

2005 ◽  
Vol 288 (5) ◽  
pp. R1396-R1410 ◽  
Author(s):  
Shaun W. Phillips ◽  
Gerard L. Gebber ◽  
Susan M. Barman
Keyword(s):  
Respiratory Rate ◽  
Sympathetic Nerve ◽  
Artificial Ventilation ◽  
Critical Role ◽  
Lung Inflation ◽  
Chemical Inactivation ◽  
A Value ◽  
Relationship Of ◽  
The Relationship ◽  
Nerve Discharge

We used spectral analysis and event-triggered averaging to determine the effects of chemical inactivation of the medullary lateral tegmental field (LTF) on 1) the relationship of intratracheal pressure (ITP, an index of vagal lung inflation afferent activity) to sympathetic nerve discharge (SND) and phrenic nerve activity (PNA) and 2) central respiratory rate in paralyzed, artificially ventilated dial-urethane-anesthetized cats. ITP-SND coherence value at the frequency of artificial ventilation was significantly ( P < 0.05; n = 18) reduced from 0.73 ± 0.04 (mean ± SE) to 0.24 ± 0.04 after bilateral microinjection of muscimol into the LTF. Central respiratory rate was unexpectedly increased in 12 of these experiments (0.28 ± 0.03 vs. 0.95 ± 0.25 Hz). The ITP-PNA coherence value was variably affected by chemical inactivation of the LTF. It was unchanged when central respiratory rate was also not altered, decreased when respiratory rate was increased above the rate of artificial ventilation, and increased when respiratory rate was raised from a value below the rate of artificial ventilation to the same frequency as the ventilator. Chemical inactivation of the LTF increased central respiratory rate in four of six vagotomized cats but did not significantly affect the PNA-SND coherence value. These data demonstrate that the LTF 1) plays a critical role in mediating the effects of vagal lung inflation afferents on SND but not PNA, 2) helps maintain central respiratory rate in the physiological range, but 3) is not involved in the coupling of central respiratory and sympathetic circuits.

scholarly journals Characterization of the β-lactamase specified by the resistance factor R-1818 in Escherichia coli K12 and other Gram-negative bacteria

1971 ◽  
Vol 123 (4) ◽  
pp. 501-505 ◽  
Author(s):  
J. W. Dale
Keyword(s):  
Escherichia Coli ◽  
Host Species ◽  
Host Bacterium ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
R Factor ◽  
Relationship Of ◽  
The Relationship

1. The amino acid composition of the β-lactamase from E. coli (R-1818) was determined. 2. The R-1818 β-lactamase is inhibited by formaldehyde, hydroxylamine, sodium azide, iodoacetamide, iodine and sodium chloride. 3. The Km values for benzylpenicillin, ampicillin and oxacillin have been determined by using the R-factor enzyme from different host species. The same values were obtained, irrespective of the host bacterium. 4. The molecular weight of the enzyme was found to be 44600, and was the same for all host species. 5. The relationship of R-1818 and R-GN238 β-lactamases is discussed.

scholarly journals Myeloperoxidase Selectively Binds and Selectively Kills Microbes

2010 ◽  
Vol 79 (1) ◽  
pp. 474-485 ◽  
Author(s):  
Robert C. Allen ◽  
Jackson T. Stephens
Keyword(s):  
Streptococcus Pyogenes ◽  
Direct Evidence ◽  
Minimal Bactericidal Concentration ◽  
Viridans Streptococci ◽  
E Coli ◽  
Horse Blood ◽  
Valid Comparison ◽  
Relationship Of ◽  
The Relationship ◽  
Lysed Horse Blood

ABSTRACTMyeloperoxidase (MPO) is reported to selectively bind to bacteria. The present study provides direct evidence of MPO binding selectivity and tests the relationship of selective binding to selective killing. The microbicidal effectiveness of H2O2and of OCl−was compared to that of MPO plus H2O2. Synergistic microbicidal action was investigated by combiningStreptococcus sanguinis, a H2O2-producing microbe showing low MPO binding, with high-MPO-bindingEscherichia coli,Staphylococcus aureus, orPseudomonas aeruginosawithout exogenous H2O2, with and without MPO, and with and without erythrocytes (red blood cells [RBCs]). Selectivity of MPO microbicidal action was conventionally measured as the MPO MIC and minimal bactericidal concentration (MBC) for 82 bacteria includingE. coli,P. aeruginosa,S. aureus,Enterococcus faecalis,Streptococcus pyogenes,Streptococcus agalactiae, and viridans streptococci. Both H2O2and OCl−destroyed RBCs at submicrobicidal concentrations. Nanomolar concentrations of MPO increased H2O2microbicidal action 1,000-fold. Streptococci plus MPO produced potent synergistic microbicidal action against all microbes tested, and RBCs caused only a small decrease in potency without erythrocyte damage. MPO directly killed H2O2-producingS. pyogenesbut was ineffective against non-H2O2-producingE. faecalis. The MPO MICs and MBCs forE. coli,P. aeruginosa, andS. aureuswere significantly lower than those forE. faecalis.The streptococcal studies showed much higher MIC/MBC results, but such testing required lysed horse blood-supplemented medium, thus preventing valid comparison of these results to those for the other microbes.E. faecalisMPO binding is reportedly weak compared to binding ofE. coli,P. aeruginosa, andS. aureusbut strong compared to binding of streptococci. Selective MPO binding results in selective killing.

scholarly journals A comparison of the levels of faecal indicator bacteria in water and human faeces in a rural area of a tropical developing country (Sierra Leone)

1982 ◽  
Vol 89 (1) ◽  
pp. 69-78 ◽  
Author(s):  
R. C. Wright
Keyword(s):  
Sierra Leone ◽  
Water Sources ◽  
Indicator Bacteria ◽  
Rural Settlements ◽  
Faecal Coliforms ◽  
Human Faeces ◽  
E Coli ◽  
Faecal Samples ◽  
Relationship Of ◽  
The Relationship

SUMMARYThe levels of faecal coliforms (FC), indole-positive FC (presumptiveEscherichia coli), faecal streptococci (FS),Streptococcus faecalisandClostridium perfringensin the natural water sources used by 29 rural settlements in Sierra Leone were investigated. Levels of the same indicators in human faeces were also investigated. The incidence ofSalmonellaspp. in both habitats and the temperature, pH and conductivity of water sources were also recorded. All water sources were contaminated with the indicator bacteria, mean numbers of which occurred in the relationship FC > presumptiveE. coli≏ FS ≏C. perfringens>S. faecalis.FC were also predominant in human faeces, the relationship of means being FC ≏ presumptiveE. coli> FS >S. faecalis>C. perfringens.The need for confirmation of FC counts obtained from water sources was indicated by the large number of positive tubes produced in the FC multiple-tube dilution test from some samples which could not be confirmed as presumptiveE. coli. Salmonellaspp. were isolated from 13 water sources and 6% of faecal samples. Mean water temperature was high (26·2 °C), pH low (5·04) and conductivity low (34μS cm−1). PresumptiveE. coliwas considered the most appropriate indicator of faecal pollution of the types of water investigated.

scholarly journals CHEMICAL STUDIES IN HOST-VIRUS INTERACTIONS

1948 ◽  
Vol 87 (4) ◽  
pp. 275-282 ◽  
Author(s):  
Seymour S. Cohen ◽  
Catherine B. Fowler
Keyword(s):  
Virus Production ◽  
Acid Synthesis ◽  
Defined Medium ◽  
Virus Growth ◽  
Chemical Studies ◽  
One Step ◽  
Growth Promoting ◽  
The One ◽  
Host Virus Interactions ◽  
Virus Interactions

Omission of a single constituent from a chemically defined medium approximating the virus growth-promoting properties of broth affects virus production in infected bacteria. This may be estimated by the one-step growth technique and the course of desoxyribose nucleic acid synthesis. Nine amino acids and one purine have been shown to be important by these tests. A combination of all constituents observed to be important by the single supplement and single omission techniques has approximated the virus growth-promoting properties of broth. Certain anomalous results have been commented upon.

scholarly journals CHEMICAL STUDIES ON HOST-VIRUS INTERACTIONS

1947 ◽  
Vol 85 (6) ◽  
pp. 771-784 ◽  
Author(s):  
Seymour S. Cohen ◽  
Catherine B. Fowler
Keyword(s):  
Latent Period ◽  
Virus Multiplication ◽  
Killing Effect ◽  
Chemical Studies ◽  
Host Virus Interactions ◽  
Virus Interactions

The inhibition of virus multiplication by 5-methyl tryptophane can be specifically reversed by tryptophane. The conditions of reversal indicate that 5MT specifically interferes with tryptophane utilization. The tryptophane requirements of virus multiplication appear to exist throughout the latent period and determine the time of lysis and amount of virus liberated. A latent period may be interrupted for 15 minutes or more and be resumed on addition of tryptophane. Extended inhibition with 5MT results in a somewhat variable "killing" effect, the extent of which determines aspects of the reversal of the inhibition by tryptophane. The implications of these phenomena have been discussed.

scholarly journals CHEMICAL STUDIES IN HOST-VIRUS INTERACTIONS

1948 ◽  
Vol 87 (4) ◽  
pp. 259-274 ◽  
Author(s):  
Catherine B. Fowler ◽  
Seymour S. Cohen
Keyword(s):  
Amino Acids ◽  
Burst Size ◽  
Host Cells ◽  
Simple Medium ◽  
Chemical Studies ◽  
One Step ◽  
Nutritional Environment ◽  
The One ◽  
Host Virus Interactions ◽  
Virus Interactions

Using the one-step growth technique the production of the virus T2 in its host, measured by latent period and burst size, was shown to depend on the nutritional environment of the host cell. When E. coli, grown in broth, was transferred to a simple medium, single organic compounds such as some amino acids and nucleosides were found to increase or accelerate the synthesis of virus. An antimetabolite of glutamic acid, an amino acid important for virus synthesis, was shown to be inhibitory. Several naturally occurring amino acids, leucine, serine, and cysteine, inhibited virus synthesis in the simple medium. A chemically defined mixture was found which supported a rate of virus synthesis very nearly comparable to that found for host cells in nutrient broth.

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