Transport in bacteriophage P22-infected Salmonella typhimurium.
(57/1572)
There was rapid efflux of L-leucine, L-phenylalanine, and alpha-methyl-D-glucoside after infection of Salmonella typhimurium with the clear plaque mutant C1 of phage P22. The efflux was similar to that observed with cyanide or arsenate treatment except that there was partial recovery in the case of phage infection and almost complete recovery under the condition of lysogeny. There was no efflux after infection with the temperature-sensitive mutant ts16C1 at nonpermissive temperature. Superinfection of superinfection exclusion negative lysogen (sie A minus sie B minus) with C1 led to efflux, whereas the efflux was much less on superinfection of sie A+ Sie B+ lysogen. These results indicate that an effective injection process is enough to cause depression in the cellular transport processes. (+info)
The preparation of 5-cyanouracil and 5-cyano-2'-deoxyuridine from the corresponding 5-iodo derivative and cuprous cyanide.
(58/1572)
5-Cyanouracil has been prepared in high yield from cuprous cyanide and 5-iodouracil. The deoxynucleoside has been similarly prepared form 5-iodo-2'-deoxyuridine and this has enabled these compounds to be labelled with (14-C) cyanide. Attempts have been made to incorporate 5-cyanouracil into Escherichia coli 15T and into Mycoplasma mycoides var. capri DNA under conditions in which several other 5-substituted uracils have been incorporated, but without success. Similarly 5-cyano-2'-deoxyuridine could not be incorporated into the DNA of T3 phage under conditions in which 5-bromo-2'-deoxyuridine is easily incorporated. These results suggest that the criteria for a 5-substituted uracil to be incorporated into DNA in vivo depends on some factor other than the size of the substituent. (+info)
Mating aggregates in Escherichia coli conjugation.
(59/1572)
Mating mixtures of Escherichia coli cells were shown to contain mating aggregates of two to 20 cells each rather than only mating pairs of two cells each. The mating aggregate size distribution shows two broad peaks, at two to four cells and at eight to 13 cells. The quantitative mating aggregate size distribution and the proportion of male cells in mating aggregates are dependent on the input ratio of male to female cells. At an input ratio of one to one, the average mating aggregate contains equal proportions of male and female cells and most of the cells involved in mating are in large aggregates of seven or more cells each. The deoxyribonucleic acid (DNA) transfer efficiency per mating aggregate cell was constant regardless of average aggregate size or of the ratio of male to female cells in the aggregate. Under optimal conditions essentially every male cell or every female cell in a mating aggregate can be involved in DNA transfer. A comparison of light microscopy, sucrose gradient centrifugation, and analysis with a modified Coulter counter indicated that the number of cells in mating aggregates is best equantitated using a modified Coulter counter. (+info)
Specific cyanylation and cleavage at cysteine-104 human hemoglobin alpha-chain. A novel approach to the problem of the alpha-chain tryptic core in the study of haemoglobin variants by "fingerprinting" methods.
(60/1572)
1. A new approach to the analysis, by "fingerprinting", of the tryptic core region of human haemoglobin alpha-chain is described. 2. The alpha-chain is cyanylated at its single cysteine residue (alpha104) and then split, by exposure to mild alkali, at the N-peptide bond of the resulting beta-thiocyanoalanine residue. 3. The two cleavage fragments, alpha1-103 and alpha104-141, are separated by gel filtration, and the fragment alpha104-141, which contains all the residues of the alpha-chain tryptic core, is digested with pepsin. 4. Preparative "fingerprints" of these peptic peptides yield eight major peptides, which provide complete sequence information for the whole region alpha104-141. 5. The utility of the method is demonstrated by repeating the determination of the substitution in haemoglobin Hopkins-2, a known alpha-chain core variant in which histidine-alpha112 (G19) is replaced by an aspartic acid residue. (+info)
Synthesis of alternative membrane-bound redox carriers during aerobic growth of Escherichia coli in the presence of potassium cyanide.
(61/1572)
Aerobic growth of Escherichia coli with an oxidizable substrate as carbon source in the presence of low concentrations of KCN leads to the synthesis and integration into the membrane of menaquinone and cytochromes b558, a1 and d in addition to the redox carriers normally present under aerobic growth conditions, namely ubiquinone and cytochromes b562, b556 and o. The results are discussed with reference to other phenotypic and genotypic modifications to the electron-transport chains of E. coli. (+info)
Differences in coupling of energy to glycine and phenylalanine transport in aerobically grown Escherichia coli.
(62/1572)
Differences exist in the coupling of energy to transport of glycine and phenylalanine in aerobically grown cells of Escherichia coli. Energy derived from respiration, although involved in both uptake systems, is not employed identically as shown by kinetic effects of cyanide and anoxia and by temperature dependencies. Additional evidence for aerobic differences was provided by the effects of azide which greatly decreased initial rates of uptake of glycine but not phenylalanine. The effect on glycine uptake was not due to uncoupling of oxidative phosphorylation or to a decrease in respiration rate. Evidence for anaerobic differences was provided by the addition of either glucose or ferricyanide to cell suspensions containing glycerol, thereby maintaining anoxic uptake of phenylalanine, but not glycine, at the aerobic level. Ferricyanide stimulation required a functional Ca, Mg-adenosine 5'-triphosphatase and involved cell metabolism. Ferricyanide was also found to produce differential stimulation of other amino acid transport systems; tyrosine, tryptophan and leucine uptakes were stimulated whereas those for alanine, proline, threonine, and glutamine were relatively unaffected. (+info)
Inhibition of DNA replication in Escherichia coli by cyanide and carbon monoxide.
(63/1572)
The inhibition of DNA replication in aerobically growing Escherichia coli by cyanide or carbon monoxide occurs within about 20 s at 15 degrees, as previously reported by Cairns and Denhardt (Cairns, J., and Denhardt, D.T. (1968) J. Mol. Biol. 36, 335-342). This rapid inhibition can be explained by the nearly complete depletion of both intracellular ATP and deoxynucleoside triphosphates which occurs during the time that replication stops. There is probably no direct effect of carbon monoxide on any of the enzymes involved in replication because this reagent has no effect on replication rate or ATP level in anaerobic cells. These cells produce ATP by glycolysis. The inhibition of replication by cyanide, a highly reactive compound, appears to be more complex since anaerobically growing cells can still be completely inhibited, although higher concentrations are required than for aerobically growing cells. The sensitivity of anaerobic cells to cyanide is probably due to the ability of this highly reactive compound to react nonspecifically with many proteins and other molecules. (+info)
Fatal methane and cyanide poisoning as a result of handling industrial fish: a case report and review of the literature.
(64/1572)
The potential health hazards of handling industrial fish are well documented. Wet fish in storage consume oxygen and produce poisonous gases as they spoil. In addition to oxygen depletion, various noxious agents have been demonstrated in association with spoilage including carbon dioxide, sulphur dioxide, and ammonia. A fatal case of methane and cyanide poisoning among a group of deep sea trawler men is described. Subsequent independent investigation as a result of this case led to the discovery of cyanides as a further potential noxious agent. This is thus the first case in which cyanide poisoning has been recognised as a potentially fatal complication of handling spoiled fish. The previous literature is reviewed and the implications of the current case are discussed. (+info)