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Although the spread of plasmid-mediated antibiotic-resistant bacteria is a public health concern, food contamination with plasmid-mediated antibiotic-resistant Escherichia coli in Vietnam has not been well investigated. This study aimed to describe the prevalence of colistin-resistant, carbapenem-resistant, and endemic blaCTX-M in extended-spectrum β-lactamase (ESBL) producing E. coli isolates. Colistin and carbapenem-resistant ESBL-producing E. coli were isolated from chickens in Vietnam and Japan. Colistin-resistant and AmpC/ESBL-producing E. coli (52% and 93%, respectively) were detected in chickens from Vietnam, in comparison to 52.7%, AmpC/ESBL-producing E. coli found in chicken from Japan. Carbapenem-resistant E. coli has not been isolated in Vietnam and Japan. Genotyping revealed that colistin-resistant E. coli harboured mcr-1, and most of the AmpC/ESBL-related genes were blaCTX-M-55 and blaCTX-M-65 together with blaTEM in Vietnamese chickens and blaCMY-2 in Japanese chickens. Multi-drug resistance analysis showed that ESBL-producing E. coli isolates had greater resistance to quinolones, streptomycin, and chloramphenicol than colistin-resistant E. coli isolates from Vietnam, suggesting the selection of multiple antibiotic resistance genes in ESBL-producing E. coli. In conclusion, colistin-resistant E. coli was detected in approximately half of the chicken samples, the majority of which harboured mcr-1. The high prevalence of ESBL-producing E. coli has remained constant in the last 5 years. The predominant blaCTX-M in ESBL-producing E. coli was blaCTX-M-55 or blaCTX-M-65, with the coexistence of blaTEM in Vietnam. These results can be implemented in monitoring systems to overcome the development of antimicrobial resistance. [ABSTRACT FROM AUTHOR]

This study was conducted to examine total phenolic contents of Sorghum bicolor (L.) Moench shoot extracts in different cultivars andunder different extraction methods by HPLC analysis. In the first experiment, five cultivars of sorghum (Milyang-1ho, Milyang-5ho, Donganme, Hwanggumchal and Nampungchal) were extracted by soaking in distilled water for 24h at room temperature and boiling for 2 h, followed by filtering and evaporating. For the second experiment, focus was given to a known allelochemical, the phenolic compound 4-hydroxybenzoic acid. Hwanggumchal, the cultivar with the highest 4-hydroxybenzoic acid content from the first experiment, was chosen for optimizing phenolic compound extraction under different conditions such as solvent (distilled water or ethanol), temperature (4o, 25o and 40°C), and time (24, 48 and 72 h). An HPLC system was used to quantitatively determine total phenolic contents of extracts. Results showed that, between the five cultivars, Donganme had the highest total phenolic compounds (402.6 mg/l), while Hwanggumchal had the highest amount of 4-hydroxybenzoic acid (96.0 mg/l). In the second experiment, the highest amount of total phenolic compounds was obtained when the sorghum samples were extracted in ethanol by soaking for 72 h at 40°C, while the lowest amount was obtained by soaking 72 h at 4oC in distilled water. The study and application of the allelopathy phenomenon in weed control is essential for the protection of the environment. If adopted successfully, it could lead to significant accomplishments for sustainable agriculture. [ABSTRACT FROM AUTHOR]

To investigate the dissemination of ESBL/pAmpC-producing E. coli within the food distribution system of Ho Chi Minh City (HCMC), Vietnam, the prevalence of ESBL/pAmpC-producing E. coli strains in chicken meat, pork, beef, and fish/shrimp samples obtained from slaughterhouses, a wholesale market, and supermarkets was examined. Among the total of 330 collected food samples, ESBL/pAmpC-producing E. coli was detected in 150 samples (45.5%). The highest prevalence of these isolates was in chicken meat (76/82, 92.7%), followed by pork (32/92, 34.8%), beef (18/74, 34.3%), and fish/shrimp (24/82, 29.3%). A total of 342 strains of ESBL/pAmpC-producing E. coli were isolated from 150 positive food samples. The most prevalent genes responsible for ESBL or pAmpC activity belonged to the CTX-M-9 (110/342, 31.2%), CTX-M-1 (102/342, 29.8%), and CIT (118/342, 34.5%) groups. To our knowledge, this is the first report of the high occurrence of pAmpC (37.1%) in animal-based food in Vietnam. Among the 342 total ESBL/pAmpC-producing E. coli isolates, 276 (80.7%) were resistant to at least 6 antibiotic agents. Notably, high percentages of resistance to ciprofloxacin and fosfomycin were found in isolates from chicken (80.5% and 50.8%, resp.). These findings demonstrate that animal-based food products in HCMC represent a major reservoir of ESBL/pAmpC-producing E. coli. [ABSTRACT FROM AUTHOR]

The agricultural industry has tried to develop effective herbicides, especially biological herbicides, with less impact on our agricultural environment. Recently, allelopathy has emerged as a potential alternative to chemical herbicides for weed management. Allelopathy is defined as "any direct or indirect, harmful or beneficial effects of one plant on another through the production of chemical compounds that are released into the environment." Sorghum bicolor (L.) Moench, a species that originates from Africa and is widely cultivated in both tropical and sub-tropical regions, is considered as a rich source of allelochemicals with biological weed control ability. Chemical constituents of sorghum include tannins, phenolic acids, anthocyanins, phytosterols and policosanols. Investigations on underground parts of sorghum indicate that sorgoleone is in charge of the weed control activity, while phenolic compounds play a vital role in its herbicidal activity on aerial parts of weeds. This review aims at providing up-to-date and comprehensive information about allelopathy in sorghum and further application of sorghum extract in weed control. [ABSTRACT FROM AUTHOR]

For many applications it would be desirable to be able to control the activity of proteins by using an external signal. In the present study, we have explored the possibility of modulating the activity of a restriction enzyme with light. By cross-linking two suitably located cysteine residues with a bifunctional azobenzene derivative, which can adopt a cisor trans-configuration when illuminated by UV or blue light, respectively, enzymatic activity can be controlled in a reversible manner. To determine which residues when crosslinked show the largest "photoswitch effect," i.e., difference in activity when illuminated with UV vs. blue light, >30 variants of a single-chain version of the restriction endonuclease Pvull were produced, modified with azobenzene, and tested for DNA cleavage activity. In general, introducing single cross-links in the enzyme leads to only small effects, whereas with multiple cross-links and additional mutations larger effects are observed. Some of the modified variants, which carry the cross-links close to the catalytic center, can be modulated in their DNA cleavage activity by a factor of up to 16 by illumination with UV (azobenzene in cis) and blue light (azobenzene in trans), respectively. The change in activity is achieved in seconds, is fully reversible, and, in the case analyzed, is due to a change in Vmax rather than Km. [ABSTRACT FROM AUTHOR]

Plasmid-mediated antibiotic-resistant bacteria's transmission is fatal and a major threat to public health. This study aimed to clarify the presence of plasmid-mediated quinolone resistance（PMQR）genes in extended-spectrum β-lactamase（ESBL）-producing or/and mcr-harbouring colistin（COL）-resistant Escherichia coli（ESBL-COL-EC）isolates from Vietnamese and Japanese chicken meat. Resistance towards ciprofloxacin（CIP）was examined in 308 ESBL-COL-EC isolates; CIP-resistant ESBL-COL-EC isolates were examined for the PMQR gene. Approximately, 71.1% and 38.1% of ESBL-COL-EC and ESBLproducing E. coli isolates from Vietnamese and Japanese chicken meat were CIP-resistant, respectively. Multiplex PCR led PMQR detection showed that 35.2% of CIP-resistant ESBL-COL-EC isolates from Vietnamese food contained PMQR gene, whereas CIP-resistant ESBL-COL-EC isolates from Japanese chicken meat did not. Conjugation assays showed that the transmission of qnrS gene carried by E. coli to Salmonella. In conclusion, ESBL-COL-EC isolates from Vietnamese food are associated with a high frequency of fluoroquinolone resistance and a high distribution of the qnrS gene.

We developed a metal ion chelate-assisted ligation for SNP detection by microarray. An oligonucleotide probe was separated into two 9-10-mers bearing iminodiacetic residues at the gap point. Duplex formation with the DNA target was possible only if nickel ions were added, but a nucleotide substitution opposite the gap point prevented duplex formation. Here we demonstrate the application of this approach for SNP detection (A1298C) within the 5,10-methylenetetrahydrofolate reductase gene on a microarray.