scholarly journals Studies on transfer ribonucleic acids and related compounds. XXXVIII. A rapid method for the synthesis of ribooligonucleotides by using 3',5'-unsubstituted nucleosides. Synthesis of a hexanucleotide containing anticodon triplet of E. coli tRNAfMet.

1981 ◽  
Vol 29 (3) ◽  
pp. 759-765 ◽  
Author(s):  
EIKO OHTSUKA ◽  
TOSHIAKI WAKABAYASHI ◽  
MORIO IKEHARA
1978 ◽  
Vol 26 (10) ◽  
pp. 2998-3006 ◽  
Author(s):  
EIKO OHTSUKA ◽  
EIKO NAKAGAWA ◽  
TOSHIKI TANAKA ◽  
ALEXANDERF. MARKHAM ◽  
MORIO IKEHARA

2020 ◽  
Author(s):  
Hanh Vu ◽  
Cornelia Appiah-Kwarteng ◽  
Kaori Tanaka ◽  
Ryuji Kawahara ◽  
Diep Thi Khong ◽  
...  

Abstract Background: The dissemination of colistin-resistant bacteria carrying the colistin-resistant mobile gene, mcr-1 threatens medical care worldwide. In particular, contamination of food with colistin-resistant bacteria accelerates the community dissemination of colistin-resistant bacteria. Therefore, monitoring of colistin-resistant bacteria in food is important for controlling resistant bacteria. Unfortunately, the conventional culture methods for detecting colistin-resistant bacteria are not practical for monitoring food saftey. Therefore, development of a simple and rapid method to detect food contamination with colistin-resistant bacteria is desirable as an effective means for preventing the dissemination of resistant bacteria, particularly colistin-resistant bacteria.Findings: We developed a simple and rapid method for detecting Escherichia coli harboring the mcr-1 colistin resistance gene using a high-speed real-time polymerase chain reaction (PCR). The entire procedure, from sample processing to finals results, was performed within one hour. The practical utility of this method was verified by analyzing 27 retail meat samples for the presence of colistin-resistant bacteria. The results of the developed method were in agreement with the results of culturing colistin-resistant E. coli from the meat samples, demonstrating its efficacy and usefulness.Conclusions: A simple and rapid real-time PCR-based screening method was developed for detecting E. coli harboring mcr-1 in food samples. The practical utility of the procedure was confirmed using retail meat samples, indicating its potential as a convenient and rapid method to detect bacterial contamination of food items, especially in developing communities.


2018 ◽  
Vol 38 (3) ◽  
Author(s):  
Thomas D. Niehaus ◽  
Mona Elbadawi-Sidhu ◽  
Lili Huang ◽  
Laurence Prunetti ◽  
Jesse F. Gregory ◽  
...  

NAD(P)H-hydrate epimerase (EC 5.1.99.6) is known to help repair NAD(P)H hydrates (NAD(P)HX), which are damage products existing as R and S epimers. The S epimer is reconverted to NAD(P)H by a dehydratase; the epimerase facilitates epimer interconversion. Epimerase deficiency in humans causes a lethal disorder attributed to NADHX accumulation. However, bioinformatic evidence suggest caution about this attribution by predicting that the epimerase has a second function connected to vitamin B6 (pyridoxal 5′-phosphate and related compounds). Specifically, (i) the epimerase is fused to a B6 salvage enzyme in plants, (ii) epimerase genes cluster on the chromosome with B6-related genes in bacteria, and (iii) epimerase and B6-related genes are coexpressed in yeast and Arabidopsis. The predicted second function was explored in Escherichia coli, whose epimerase and dehydratase are fused and encoded by yjeF. The putative NAD(P)HX epimerase active site has a conserved lysine residue (K192 in E. coli YjeF). Changing this residue to alanine cut in vitro epimerase activity by ≥95% but did not affect dehydratase activity. Mutant cells carrying the K192A mutation had essentially normal NAD(P)HX dehydratase activity and NAD(P)HX levels, showing that the mutation had little impact on NAD(P)HX repair in vivo. However, these cells showed metabolome changes, particularly in amino acids, which exceeded those in cells lacking the entire yjeF gene. The K192A mutant cells also had reduced levels of ‘free’ (i.e. weakly bound or unbound) pyridoxal 5'-phosphate. These results provide circumstantial evidence that the epimerase has a metabolic function beyond NAD(P)HX repair and that this function involves vitamin B6.


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