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S Ulitzur

Publications and source records attributed to S Ulitzur.

At least 37 records · Page 2Linked to original sources
PubMed1984

Elucidation of the phagocytosis mechanism with the aid of luminous bacteria.

Phagocytosis of the luminous bacterium Vibrio cholerae var. albensis caused a similar decrease both in viable count and in the in-vivo luminescence. These effects of polymorphonuclear neutrophil leukocytes (PMN) were oxygen-dependent processes. Exposure of PMN to oxygen caused a prompt decrease in the luminescence of bacteria that had been ingested in anaerobic conditions. Cell-free supernates from active PMN suspensions caused a decrease in luminescence and as much as 10% of the killing could be attributed to extracellular killing. Similarly, bacteria entrapped on a membrane filter showed a decrease in luminescence upon addition of active PMN, even though they could not be ingested.

Aerobiosis↗
PubMed1984

A new rapid and sensitive bioluminescence assay for antibiotics that inhibit protein synthesis.

A new sensitive, rapid and simple bioluminescence assay for antibiotics inhibiting protein synthesis is described. In this assay the ability of the tested antibiotic to inhibit the de novo synthesis of the enzymes participating in the bacterial luminescence system is determined by means of a dark variant of a luminous bacterium that undergoes prompt induction of the luminescence system with certain DNA-intercalating agents. Upon induction, the in vivo luminescence of the dark variant is increased more than 50-fold within 30 min. Antibiotics that block the de novo synthesis of protein limit the development of luminescence at a level that was found to be a function of the antibiotic concentration. The minimum detectable concentration of antibiotics in the bioluminescence test, after 45-60 min of incubation, was 0.1 microgram/ml for streptomycin, gentamicin, kanamycin, lincomycin and chloramphenicol and 0.3 microgram/ml for neomycin, clindamycin and spectinomycin. The new bioluminescence test has been used to assay these antibiotics in serum.

Anti-Bacterial Agents↗
PubMed1983

The use of luminous bacteria for determination of phagocytosis.

The existing methods for phagocytosis evaluation are inadequate for assessing all the real events occurring during phagocytosis, or for continuously following the kinetics of the process. Our purpose is to establish the use of luminous bacteria as an object for phagocytosis. The bioluminescence test offers an easy and simple method to determine the kinetics of phagocytosis by following the luminescence of the bacteria. The terrestrial luminous bacteria Vibrio cholerae var. albensis are readily phagocytosed by polymorphonuclear (PMN) cells. The correlation coefficient between the decrease in luminescence and the decrease in viable count is 0.999. The rate of decrease in luminescence and the residual level of luminescence after 60 min of phagocytosis are proportional to the rate of increase in phagocytosis induced chemiluminescence, and to its maximal level, respectively. Opsonization requirements are comparable in both tests. Different inhibitors of the phagocytosis process caused similar changes in the rates of the bio- and chemiluminescence (correlation coefficient 0.974), and in the luminescence maximal level (correlation coefficient 0.804). The validity of the bioluminescence assay being proved, it is suggested as an alternative assay for phagocytosis assessment.

Azides↗
PubMed1983

Phagocytosis-induced mutagenesis in bacteria.

Dark mutants of the luminous bacteria Photobacterium fischeri reverted to hereditary stable luminescent forms when incubated with human polymorphonuclear neutrophils (PMN). The maximal mutagenic effect occurred during the first 15 min of phagocytosis, and was dependent on the phagocyte:bacterium ratio as well as on the integrity of the PMN cells. Heat-killed phagocytes or disintegrated phagocytes did not show any mutagenic activity, whereas the supernatant of the phagocytosis reaction exerted mutagenic activity. Scavengers of hydroxyl radical such as mannitol or benzoate and scavengers of singlet oxygen such as beta-carotene, as well as the presence of superoxide dismutase, prevented the mutations. The role of reactive oxygen metabolites in the phagocyte-mediated mutagenic process is discussed.

Anaerobiosis↗
PubMed1983

Determination of serum bactericidal activity with the aid of luminous bacteria.

Nonmarine luminous bacteria belonging to the genus Vibrio cholerae were extremely sensitive to the bactericidal activity of human serum. Luminous bacteria incubated in a medium containing serum showed a decrease in their in vivo luminescence that was directly proportional to the decrease in the viable count and was a function of the serum concentration. Both immunoglobulins and the complement system were required to exert the serum bactericidal activity. Serum lacking immunoglobulins or certain complement components, especially C3, did not affect the luminescence. The bactericidal effect of the serum on luminous bacteria was diminished by the presence of lipopolysaccharide or by pretreatment of the serum with different species of killed bacteria. As found in other systems, the bacteriolytic activity of serum was only augmented by lysozyme, but was not lysozyme dependent; although the luminous bacteria were converted into spheroplasts in serum containing 0.5 M sucrose, their in vivo luminescence was almost not affected. This system could easily distinguish between the C classical pathway and the properdin pathway. Ethylene glycol-bis (beta-aminoethyl ether)-N,N'-tetraacetic acid, which inhibits only the classical complement pathway, did not inhibit the decrease in luminescence as did EDTA. Thus, it was possible to distinguish between deficiencies in complement components participating in both pathways and complement components that were involved only in the classical pathway. This system could also be used as a substitute to the hemolytic system in complement fixation tests.

Animals↗
PubMed1981

Factors affecting the cellular expression of bacterial luciferase.

The in vivo expression of cellular bacterial luciferase has been defined as the luciferase expression quotient, measured as the ratio of the bioluminescence intensity in vivo to the in vitro activity of luciferase in crude cell extracts. The expression is greater in the presence of inhibitors of the electron transport system such as cyanide and N-heptyl-4-hydroxy-quinoline and also at lower oxygen tensions. The higher expression of the cellular luciferase under these conditions is postulated to be due to an increase in the intracellular levels of reduced coenzymes which enhance both the reduction of flavin and the reduction of fatty acid to aldehyde. Both FMNH2 and aldehyde are substrates in the light emitting reaction.

Cyanides↗
PubMed1981

DNA-damaging agents and DNA-synthesis inhibitors induce luminescence in dark variants of luminous bacteria.

The DNA-damaging agents mitomycin C and UV irradiation, as well as the DNA-synthesis inhibitors nalidixic acid, novobiocin and coumermycin, induce the de novo synthesis of luciferase and in vivo luminescence in dark variant cells of the luminous bacteria Photobacterium leiognathi. Mitomycin C and nalidixic acid also cause the induction of luminescence in wild-type cells in the absence of its natural inducer. In spite of the high level of in vivo luminescence of the treated dark-variant cells, none of these agents result in the appearance of genetically luminous revertants. The possibility is discussed that these agents phenotypically induce luminescence through their ability to trigger 'SOS functions', which in turn leads to the transitory inactivation of certain repressors.

Aminocoumarins↗
PubMed1981

Acridine dyes and other DNA-intercalating agents induce the luminescence system of luminous bacteria and their dark variants.

Acridine dyes and other DNA-intercalating agents such as ethidium bromide, theophylline, and caffeine induce luminescence in dark variants (K variants) different luminous species of bacteria, as well as in their wild-type luminous cells, prior to induction. The increase in luminescence appears 10-20 min after addition of these agents and is inhibited by chloramphenicol or rifampicin. Addition of these agents affects the synthesis of both luciferase and aldehyde-synthesizing enzymes. It is hypothesized that these agents, through their intercalation into DNA, cause configurational changes resulting in derepressed transcription of the luminescence operon.

Acridines↗
PubMed1980

A new, sensitive and simple bioluminescence test for mutagenic compounds.

A spontaneous dark variant of the luminous bacterium Photobacterium leiognathi was isolated. The reversion frequency of this variant to genetic-hereditary luminescent cells is greatly increased by nanogram quantities of different base-substitution and frameshift agents. This makes it possible to detect mutagenic compounds at concentrations 100 times lower than that detected by the Ames Test. Curing agents, such as acridine dyes, ethidium bromide and sodium dodecyl sulfate, are also very active in the reversion of this dark variant to the luminous state, but fail to revert it to a genetic-hereditary luminescent type. The nature of the primary mutation in the dark variant, and the potential use of this luminescence system for detecting different classes of carcinogenic chemical, are discussed.

Drug Evaluation, Preclinical↗
PubMed1979

A sensitive bioassay for lipase using bacterial bioluminescence.

A new bioassay for lipase utilizes a dim mutant of luminous bacteria which emit light upon the addition of long chain fatty acids, especially myristic acid. The luminescence response is proportional to the amount of added myristic acid over a 100-fold range, down to 10 nM. Trimyristin was used as a substrate for lipase and the hydrolyzed myristic acid was determined by the response of the luminous bacteria either on a continuous basis in the same reaction mixture or alternatively, when the hydrolytic stage is done separately followed by the independent detecting system. Using these procedures it is possible to assay lipase activity at rate corresponding to a release of as low as 10 pmol myristic acid per min.

Biological Assay↗
PubMed1979

Evidence for tetradecanal as the natural aldehyde in bacterial bioluminescence.

Dim aldehyde mutants of the luminous bacterium Beneckea harveyi emit light with exogenously added long-chain aliphatic aldehyde. In one class of these mutants, luminescence is also stimulated by myristic (tetradecanoic) acid. In such mutants the amount of light obtained by the addition of a small (limiting) amount of either tetradecanal or myristic acid may be increased 60-fold by cyanide and other agents that block respiration. This indicates that the fatty acid product of the luminescent reaction is recycled. The effect, like the stimulation by exogenous fatty acid, exhibits specificity for the 14-carbon compound, suggesting that tetradecanal is the natural aldehyde. In those aldehyde mutants that are not stimulated to emit light by fatty acids, and thus presumably lack the recycling system, the chain-length-specific stimulation by cyanide does not occur.

Aldehydes↗
PubMed1979

Determination of lipopolysaccharide by a bioluminescence technique.

The determination of the lipid A content of bacterial lipopolysaccharide by using a dim mutant of the luminous bacterium Beneckea harveyi is described. The luminous bacteria emitted light upon the addition of an acid hydrolysate of lipopolysaccharide which contained myristic acid, thus making it possible to detect as little as 1 ng of lipopolysaccharide. By converting the 3-OH-myristic acid to myristic acid, it was possible to further increase the detection sensitivity and to establish a basis for a specific and highly sensitive bioassay for the detection of lipopolysaccharide.

Biological Assay↗
PubMed1979

Control of aldehyde synthesis in the luminous bacterium Beneckea harveyi.

Some of the Beneckea harveyi dim aldehyde mutants, all of which emit light upon addition of exogenous long-chain aldehyde, also emit light when myristic acid is added. Analysis of these myristic acid-responsive mutants indicates that they are blocked before fatty acid formation, whereas another class of mutants, which respond only to aldehyde, appear to be defective in the enzyme(s) involved in the conversion of acid to aldehyde. Evidence is presented that this activity, designated myristic acid reductase, is coinduced with luciferase and is involved in the recycling of acid produced in the luciferase reaction, with specificity for the C14 compounds.

Aldehyde Oxidoreductases↗
PubMed1978

A new, fast, and very sensitive bioluminescence assay for phospholipases A and C.

A new, simple, and very sensitive assay for phospholipase A and C is described. The assay is based on the bioluminescence developed by the mutant of the bacterium Beneckea harveyi as a response to myristic acid released from dimyristoyl phosphatidylcholine by either phospholipase A or by a phospholipase C-lipase coupled system. It is possible to assay these enzymes at a rate corresponding to a release of as little as 1 to 2 pmol of myristic acid per minute.

Hydrogen-Ion Concentration↗
PubMed1978

Myristic acid stimulation of bacterial bioluminescence in "aldehyde" mutants.

The involvement of long chain aldehyde in bacterial luminescence was known both from its being required for light emission in the in vitro reaction with pure luciferase and from its ability to stimulate luminescence in vivo in a certain class of dark "aldehyde" mutants. We have found that the luminescence of some (but not all) of such aldehyde mutants is also stimulated by long chain aliphatic fatty acids, with a marked specificity for myristic (tetradecanoic) acid. This stimulation has been demonstrated in aldehyde mutants of two species of luminous bacteria, Beneckea harveyi and Photobacterium fischeri. The responses, both in intensity and yield, are proportional to the amount of added tetradecanoic acid over a 1000-fold range, down to 10 pmol ml-1. Unsaturated long chain fatty acids are potent inhibitors of the tetradecanoic acid stimulation, but they do not effect the in vivo luminescence of wild-type bacteria.

Fatty Acids↗
PubMed1978

Growth, luminescence, respiration, and the ATP pool during autoinduction in Beneckea harveyi.

The bacterial bioluminescence system is unusual because it is self-induced. In the late logarithmic phase of growth, upon the accumulation of an autoinducer, the synthesis of the components of the system is initiated. We were interested in determining what effect this burst of synthesis and activity has on cellular energy metabolism. The ATP pool of the luminous bacterium Beneckea harveyi was found to dip 10- to 20-fold during the luminescence period, while the respiration per unit cell mass (optical density) increased but by much less. The dip in the ATP pool did not occur in four different types of dark mutants, including one that was temperature conditional and another that was conditional upon added cyclic AMP for luminescence. However, it is neither the synthesis nor the activity of luciferase that is responsible for the ATP dip; the dip does not occur in certain dark "aldehyde" mutants which nevertheless synthesize normal levels of luciferase, whereas it does occur at 36 degrees C in a temperature-sensitive luciferase mutant which forms normal levels of inactive luciferase. Results with other aldehyde mutants implicate the pathway involved in the synthesis of the aldehyde factor with the ATP dip.

Adenosine Triphosphate↗
PubMed1977

Control of luciferase synthesis in a newly isolated strain of Photobacterium leiognathi.

In previous studies with luminous bacteria of all different species it has been reported that the synthesis of luciferase is autoinducible: during growth at low cell densities synthesis is effectively repressed while after induction, at higher cell densities, the rate of synthesis of enzyme is up to five times the growth rate. In this paper we report on newly isolated strains of Photobacterium leiognathi which show continued luciferase synthesis irrespective of the cell density. The specific synthesis rate may nevertheless differ from the rate of growth and depends on the luciferase content of the inoculated cells. A ratio of 1 was established for cells having a maximum luciferase content varying to a ratio of about 2 for cells that contained only 1% of the maximum.

Luciferases↗