The nick-directed DNA repair efficiency of a set of M13mp18-derived heteroduplexes containing 8-, 12-, 16-, 22-, 27-, 45-, and 429-nucleotide loops was determined by in vitro assay. Unpaired nucleotides of each heteroduplex reside within overlapping recognition sites for two restriction endonucleases, permitting independent evaluation of repair occurring on either DNA strand. Our results show that a strand break located either 3 or 5 to the loop is sufficient to direct heterology repair to the nicked strand in Escherichia coli extracts. Strandspecific repair by this system requires Mg 2؉ and the four dNTPs and is equally efficient on insertions and deletions. This activity is distinct from the MutHLS mismatch repair pathway. Strand specificity and repair efficiency are largely independent of the GATC methylation state of the DNA and presence of the products of mismatch repair genes mutH, mutL, and mutS. This study provides evidence for a loop repair pathway in E. coli that is distinct from conventional mismatch repair.DNA mispairs can occur within the DNA helix as a consequence of DNA biosynthetic errors or as a result of recombinational strand transfer between nonidentical sequences (1-4). Such pairing errors may take the form of base-base mismatches or loops, in which one strand contains one or more unpaired nucleotides. Strand-specific correction of base-base and loop mismatches produced during DNA biosynthesis plays an important role in mutation avoidance (2, 5, 6), and mismatch repair within the recombination heteroduplex has been implicated in gene conversion (3,4,7,8).Base-base mispairs are subject to strand-specific correction by the mismatch repair system of both prokaryotes and eukaryotes (5, 6, 9, 10), but action of this system on loop mispairs is limited to fairly small heterologies. The Escherichia coli mismatch repair pathway will correct loops up to about 7 unpaired nucleotides, but larger heterologies are poorly processed by this system (11)(12)(13)(14). A similar specificity is characteristic of the human mismatch repair system, which can correct loops up to about 10 unpaired nucleotides (15-17).There is evidence that eukaryotes can rectify large unpaired heterologies by a pathway distinct from the mismatch repair system. Available evidence suggests that specificities of the eukaryotic mismatch repair and large loop repair systems partially overlap. When transformed into Saccharomyces cerevisiae, plasmids harboring 8-or 12-base heterologies undergo loop correction (18), and repair is partially reduced but not eliminated by inactivation in the mismatch repair gene PMS1 (19). 21) found that heteroduplexes containing loops of 16, 27, and 216 bases were repaired both in vivo and in vitro by mismatch repair-deficient yeast strains.Transformation of monkey cells with heteroduplex DNAs containing unpaired single-stranded loops has indicated that mammalian cells can rectify such structures (22)(23)(24)(25). In vitro experiments have also indicated that human cells possess a system distinct from the mism...

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In the post-pandemic era, two issues including the currency competition between BTC and the US dollar and the competition between the commodity and monetary medium functions of BTC are critical. By applying the Markov switching model, the cyclical nature of the numbers of additional confirmed COVID-19 cases and deaths are verified on daily basis. So, these two factors are assumed to follow the Ornstein–Uhlenbeck process. Then, we estimate parameters to establish the structural characteristics of post-pandemic era and the start of post-pandemic era. In order to clarify these two issues, we use vector autoregression for testing the related macrocosmic and financial variables and BTC. Systematic evidences are provided regarding the relationships among BTC, related macrocosmic, related financial variables, related COVID-19 variables. Our findings provide a useful insight into currency competition and commodity competition on the basis of the impulse response of BTC to US dollar fluctuation and the impulse response of BTC to expected inflation and volatility in the post-pandemic era. These findings indicate increased currency competition between Bitcoin and the US dollar in the post-pandemic era. Therefore, currency competition should be more valued than Commodity Competition in the post-pandemic era. This provides a useful guideline for Bitcoin’s management.

Wang C-H (2023), Why does excessively exquisite packaging hinder consumers to buy circular products? a perspective of signaling theory.