Bacteria typhimurium

A great deal of our current understanding of the structure and function of the outer membrane of Gram-negative bacteria has come from studies with Escherichia coli and Salmonella typhimurium. The permeability barrier function of the outer membrane can... 

Most of the bacterial viruses which have been studied in any detail infect bacteria of the enteric group, such as Escherichia coli and Salmonella typhimurium. However, viruses are known that infect a variety of procaryotes, both eubacteria and archaebacteria. A few bacterial viruses have lipid envelopes but most do not. However,... 

McCann et al. (67) had shown that benzo[a]pyrene was mutagenic for j>. typhimurium only if the bacteria carried the mutation enhancing plasmid pKMIOl whose activity was later shown by Walker (23) to be entirely dependent on bacterial recA and lexA controlled functions. 

In bacteria and yeasts, Li+ has strain-dependent, inhibitory, and morphological effects upon growth. The driving force behind the transport of carbohydrates and amino acids in bacteria is the proton gradient, and in both E. coli [228] and Salmonella typhimurium cells [229], Li+ stimulates the movement of proline into cells via a Li+/proline symport and the transport of melibiose via a cotransport pathway [230]. In both cases, Li+ is replacing Na+ and results in the inhibition of growth. 

Negative results for mutagenicity of d.v-chlordanc and tran.v-chlordanc were reported in various strains of bacteria and in hepatocyte cultures of small mammals. But technical chlordane proved mutagenic to selected strains of Salmonella typhimurium and induced gene conversions in certain strains of the yeast, Saccharomyces cervisiae (IARC 1979 USEPA 1980, 1988 WHO 1984). 

Mutagenic responses were produced in Escherichia coli and certain strains of Salmonella typhimurium bacteria by 2,3,7,8-TCDD, but not by octa-CDD (Vos 1978). Further, chromosomal aberrations were induced in at least one species of higher plant and mammal (Ramel 1978). It must be concluded at this time that 2,3,7,8-TCDD is mutagenic or has mutagenic potential. 

The ammonium/methylammonium transport (Amt) proteins of enteric bacteria are required for fast growth at very low concentrations of the uncharged NH3. Homologues exist in all three domains of life. They are essential at low ammonium (NHj + NH3) concentrations under acidic conditions. The Amt protein of S. typhimurium (AmtB) participates in acquisition of NHj /NH3, but cannot concentrate either NH3 or NHJ. In general, Amt proteins appear to be bidirectional channels for NH3. They are examples of protein facilitators for a gas [93], The majority of Amt proteins contain 11 transmembrane helices with the C-terminus facing the cytoplasm [94],... 

The Ames salmonella-microsome test is a principal sensitive mutagen screening test. Compounds are tested on the mutants of Salmonella typhimurium for reversion from a histidine requirement back to prototrophy. A positive result is seen by the growth of revertant bacteria (which do not require an external histidine source). A microsomal activation system should be included in this assay. The use of five different bacterial test strains are generally required. 

Aizawa, S. I. (1996). Flagellar assembly in Salmonella typhimurium. Mol. Microbiol. 19, 1-5. Alfano, J., and Collmer, A. (1997). The type III (Hrp) secretion pathway of plant pathogenic bacteria trafficking hairpins, Avr proteins, and death./. Bacteriol. 179, 5655-... 

Hydrogenase isoenzymes are also common among the metabolically more versatile bacteria (see Chapter 2). For instance, H2 metabolism and isoenzyme composition in enteric bacteria, including Escherichia coli and Salmonella typhimurium, appear to be differentially regulated under the two modes of anaerobic life, fermentation and anaerobic respiration (Table 3.1). Furthermore, biosynthesis of the individual isoenzymes appears to be controlled at a global level by the quality of the carbon source. 

Jason Kindrachuk is a postdoctoral fellow at the University of British Columbia (UBC) in the laboratory of Professor R. E. W. Hancock. Jason received his Ph.D. from the University of Saskatchewan in 2007 where his research focused on host and pathogen sensory systems. During his study he specially focused on TLR-9 receptor—ligand interactions and the interactions between host defense peptides and the PhoPQ two-component sensory system of Salmonella typhimurium. In 2008 Jason received the Canadian Cystic Fibrosis Foundation Kin Canada Fellowship for his research in the area of alternative therapies for treatment of antibiotic- and multidrug-resistant bacteria. Currently his research is focused on the investigation of structure-activity relationships amongst natural and synthetic host defense peptides from the perspective of associated immunomodulatory activities and as well as vaccine formulation strategies. 

Genotoxic Effects. No studies were located regarding the genotoxicity of 1,2-diphenylhydrazine in humans by any route of exposure. A limited number of assays have been conducted using bacteria, mammalian cell and whole animal systems. As indicated in Table 2-2, 1,2-diphenylhydrazine was mutagenic in Salmonella typhimurium, out not in Escherichia coli, and produced chromosome aberrations and sister chromatid exchanges in Chinese hamster cells. An exogenous metabolic activation system was necessary for expression of the aforementioned effects. In in vivo studies... 

Conversion of 4-aminopyrazolo [3,4-d] pyrimidine (VIII) to its ribonucleotide by mouse tumours and host tissues has been observed [118,119]. Although no evidence of the anabolism of A -methyladenine (111) [120] to the ribonucleotide was obtained in mice with Ehrlich ascites carcinoma [121, 122], it is anabolized by bacteria [123. 124] and the enzyme responsible was partially purified from Salmonella typhimurium [125]. Human epidermoid carcinoma No. 2 cells resistant to 2-fluoroadenine (H.Ep.-2/FA) have lost adenine phosphoribosyl-... 

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