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Resistant Genes (resistant + gene)

Distribution by Scientific Domains

Life Sciences	57%
Chemistry	28%

Selected Abstracts

Construction of self-cloning industrial brewing yeast with high-glutathione and low-diacetyl production

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2008
Zhao-Yue Wang
Summary Self-cloning strains of industrial brewing yeast were constructed, in which one allele of ,-acetohydroxyacid synthase (AHAS) gene (ILV2) was disrupted by integrating Saccharomyces cerevisiae genes, ,-glutamylcysteine synthetase gene (GSH1) and copper resistant gene (CUP1) into the locus of ILV2. The self-cloning strains were selected for their resistance to CuSO4 and identified by PCR amplification. The results of AHAS and glutathione (GSH) assay from fermentation with the self-cloning strains in 500-mL conical flask showed that AHAS activity decreased and GSH content increased compared with that of host yeasts. The results of pilot scale brewing in 5-L fermentation tank also indicated that GSH content in beer fermented with self-cloning strains T5-3 and T31-2 was 1.3 fold and 1.5 fold of that of host QY5 and QY31, respectively; and diacetyl content decreased to 64% and 58% of their hosts, respectively. The self-cloning strains do not contain any heterologous DNA, they may be more acceptable to the public. [source]

A host-vector system for molecular study of the intracellular growth of Mycobacterium tuberculosis in phagocytic cells

MICROBIOLOGY AND IMMUNOLOGY, Issue 10 2009
Mari Nomoto
ABSTRACT The mechanisms by which Mycobacterium tuberculosis survives and persists in phagocytic cells remain poorly understood. To study the question, a convenient and safe host-vector system is indispensable. In this study it has been shown that, in contrast with M. smegmatis strain mc2155 which has been widely used for molecular analysis, M. smegmatis strain J15cs is able to survive even at day 6 post-infection in a murine macrophage cell line, J774. The survivability of J15cs was found to depend on the culture medium used for the bacteria prior to infection. Bacteria precultured on nutrient agar medium showed a high survivability and a characteristic cell wall ultrastructure. A plasmid vector, pYT923hyg, was developed from an Escherichia coli - mycobacterium shuttle vector pYT923 (previously constructed in our laboratory) to obtain three drug resistant genes (amp-, hyg- and km-resistant gene) and cloning sites in the km resistant gene. The vector pYT923hyg exerted no influence on in vitro growth of J15cs and intracellular survival in J774 cells, and was stably retained in J15cs after serial subculturing (three subcultures) in Luria-Bertani broth and at day 5 post-infection into J774 cells. Furthermore, using this system, the possibility of a relationship between some seemingly essential genes of M. tuberculosis and intracellular growth was demonstrated. In this study, M. smegmatis strain J15cs and pYT923hyg were found to be capable of serving as an appropriate host-vector system for molecular study of the intracellular growth of M. tuberculosis in phagocytic cells; this system may be useful as a screening tool for M. tuberculosis genes. [source]

Drug metabolic activity of cultured hepatocytes can synchronize with bile acid concentration in the medium

CELL BIOCHEMISTRY AND FUNCTION, Issue 1 2002
Nobuhiro Sugihara
Abstract The regulation of drug metabolic activity of cultured hepatocytes can be applied to the evaluation of pharmacokinetics, analysis of drug delivery and the bioartificial liver system. It is very difficult to maintain the drug metabolic activity mediated by cytochrome P-450 (CYP) 3A. Recently we found that the CYP3A aminopyrine N-demethylase (AMND) activity of hepatocytes cultured on collagen surface oscillated with culture time. This phenomenon was related to the concentration of bile acid in the culture medium. CYP3A, multidrug resistant gene 2 (MDR2) and heat shock protein 84 (HSP84) mRNA appeared in a manner corresponding to this oscillation. When a large quantity of bile acid was taken up into hepatocytes from the medium, low AMND activity was observed, and these proteins did not appear. When bile acid was secreted and the bile acid concentration inside the hepatocytes was low, high AMND activity was obtained, and these proteins appeared. In order to clarify the mechanism of oscillation between AMND activity and bile acid, 8,,M glycocholic acid was added to the culture medium 15,h before the measurement. No oscillation in AMND activity was observed in the presence of 8,,M glycocholic acid. Bile acid controls the AMND activity in the transcription of hepatocytes. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Antibiotics: Has the magic gone?

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2007
Yogesh Chander
Abstract The emergence of antibiotic resistant bacteria has diminished the efficacy of several antibiotics that were used to treat infectious diseases in humans and animals. In recent years, the problem of antibiotic resistance has become more apparent as increasing numbers of bacteria have acquired resistance to multiple antibiotics. Antibiotics inhibit bacterial growth through a variety of mechanisms including inhibition of cell wall or protein synthesis, interference with DNA (or RNA) replication, and disruption of metabolic pathways or cell membrane. Bacteria develop resistance through genetic mutations or by acquiring resistant genes involved in the production of antibiotic degrading enzymes, overproduction of target molecules, efflux pumps to drain out antibiotics, and/or altered cell wall permeability to survive adverse physiological conditions. Published literature suggests that sub-therapeutic feeding of food animals for growth promotion along with casual use of antibiotics in household products such as soaps and creams is contributing to increased antimicrobial resistance in the environment. If steps are not taken to minimize selective pressure on bacteria, the effectiveness of antibiotics (hailed as ,magic bullets') may be marginalized. Important steps in the judicious use of antibiotics on the farm are: (1) education of farmers on the pitfalls of using antibiotics sub-therapeutically in the production of food animals; (2) development of animal production practices that reduce dependence on antibiotics; and (3) development of manure disposal practices that minimize the spread of residual antibiotics and antibiotic resistant bacteria into the environment. In addition, educating the general public on the use and misuse of antibiotics in daily life is also important if there is to be any significant impact on reducing the environmental spread of antibiotic resistance. Copyright © 2006 Society of Chemical Industry [source]

Characterization of antimicrobial resistance and seasonal prevalence of Escherichia coli O157:H7 recovered from commercial feedlots in Alberta, Canada

LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2010
M. Aslam
Abstract Aims:, To characterize antimicrobial resistance (AMR) and determine the seasonal prevalence of Escherichia coli O157:H7 isolated from commercial feedlots. Methods and Results:,Escherichia coli O157:H7 were isolated from faecal and oral samples collected at monthly intervals from three commercial feedlots over a 12-month period. A total of 240 isolates were characterized using pulsed-field gel electrophoresis (PFGE) technique. A subset of 205 isolates was analysed for AMR using Sensititre system and AMR genes (tet, sul and str) by PCR. Seven PFGE clusters (,90% Dice similarity) were identified, and two clusters common to all three feedlots were recovered year-round. The majority of isolates (60%) were susceptible to all antimicrobials and were closely related (P < 0.001), whereas isolates with unique AMR patterns were not related. The prevalences of AMR from feedlots A, B and C were 69%, 1% and 38%, respectively. Resistance to tetracycline (69%) and sulfisoxazole (68%) was more prevalent in feedlot A than other two feedlots. The presence of strA and strB genes was linked in the majority of isolates, and tet(A) and tet(B), and sul1 and sul2 genes were present individually. Escherichia coli O157:H7 were genetically diverse during summer and fall, and strains from winter and spring months were more closely related. Conclusions:, Antimicrobial resistance was more common in E. coli O157:H7 obtained from two of the three commercial feedlots, and the phenotypic expression of resistance was correlated with the presence of resistant genes. A highly diverse E. coli O157:H7 population was found during summer and fall seasons. Significance and Impact of the Study:, Information would help understanding the dynamics of AMR in E. coli O157:H7 from commercial feedlots. [source]

A host-vector system for molecular study of the intracellular growth of Mycobacterium tuberculosis in phagocytic cells

The emergence and implications of metallo-,-lactamases in Gram-negative bacteria

CLINICAL MICROBIOLOGY AND INFECTION, Issue 2005
T. R. Walsh
Abstract The increase in Gram-negative broad-spectrum antibiotic resistance is worrisome, particularly as there are few, if any, ,,pipeline'' antimicrobial agents possessing suitable activity against Pseudomonas spp. or Acinetobacter spp. The increase in resistance will be further enhanced by the acquisition of metallo-,-lactamase (MBL) genes that can potentially confer broad-spectrum ,-lactam resistance. These genes encode enzymes that can hydrolyse all classes of ,-lactams and the activity of which cannot be neutralised by ,-lactamase inhibitors. MBL genes are often associated with aminoglycoside resistant genes and thus bacteria that possess MBL genes are often co-resistant to aminoglycosides, further compromising therapeutic regimes. Both types of genes can be found as gene cassettes carried by integrons that in turn are embedded within transposons providing a highly ambulatory genetic element. The dissemination of MBL genes is typified by the spread of blaVIM-2, believed to originate from a Portuguese patient in 1995, and is now present in over 20 counties. The increase in international travel is likely to be a contributory factor for the ascendancy of mobile MBL genes as much as the mobility among individual bacteria. Fitness, acquisition and host dependency are key areas that need to be addressed to enhance our understanding of how antibiotic resistance spreads. There is also a pressing need for new, and hopefully novel, compounds active against pan-resistant Gram-negative bacteria , a growing problem that needs to be addressed by both government and industry. [source]