Precipitates on Beach Electrical Ground of Optical-cable-type Ocean-bottom Seismometer and Tsunami Meter System off the Sanriku Coast

We found precipitates on the beach electrical ground (negative electrode) of the optical-cable-type ocean-bottom seismometer and tsunami meter system off the Sanriku coast (Sanriku system). These precipitates formed from 2014 to 2018. The DC voltage that feeds the Sanriku system began to increase and fluctuate in June 2017. This fluctuation suggests instability in the Sanriku system. To investigate the relationship between the precipitate growth and supply voltage fluctuation, we sampled and analyzed the precipitates in September 2018. The main components of the precipitates were calcium carbonate (CaCO3) and dolomite (CaMg(CO3)2), which are abundant in seawater. The metallic positive ions in seawater were drawn to the negative electrode, precipitating on the beach electrical ground and increasing its electrical resistance. This change in electrical resistance caused the observed DC voltage fluctuation. The beach electrical ground should be regularly cleaned to maintain the stability of the Sanriku system.＜論説

Autofluorescent bodies in the toxic dinoflagellate Alexandrium tamarense: A potential indicator of the physiological condition of the species

Autofluorescent bodies were examined in cultured and natural cells of Alexandrium tamarense (Lebour) Balech collected from Ofunato Bay, Japan. Three different autofluorescent bodies (pale blue, light blue, and white) and the autofluoresced chloroplast were observed under ultraviolet light excitation. We suggest that the pale-blue and light-blue bodies represent a novel type in dinoflagellates based on their fluorescent properties. We also found that cells with pale-blue and light-blue bodies appeared predominantly in the early and middle to late exponential phases, respectively. A similar pattern was observed in natural populations during a 2-year field survey. Cells with pale-blue bodies were dominant almost one week before the bloom, whereas those with light-blue bodies were mostly apparent during the blooming stage. These results indicate that the observation of autofluorescent bodies could be useful as a physiological indicator for predicting natural population blooms of A. tamarense in Ofunato Bay

High frequency of extended-spectrum beta-lactamase-producing Enterobacteriaceae carriers at a Japanese long-term care hospital

Introduction: Long-term care hospitals (LTCHs) are at a high risk for the inflow and spread of antimicrobial resistance (AMR) pathogens. However, owing to limited laboratory resources, little is known about the extent to which AMR organisms are endemic. Methods: We performed active surveillance for carbapenem-resistant Enterobacteriaceae (CRE) and extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) in newly admitted patients at Marugame Medical Center, a nearly 200-bedded LTCH located in Kagawa, Japan. From August to December 2021, we tested stool samples from patients wearing diapers and confirmed the genetic variants using specific PCR assays. We also collected clinical variables and compared them between AMR carriers and non-carriers. Results: Stool samples were collected from 75 patients, with a median age of 84 years. CRE strain was not detected, but 37 strains of ESBL-E were isolated from 32 patients (42.7%). During the study period, 4.9% of in-hospital patients (37 per 756 patients) were identified to be ESBL-E carriers in the routine microbiological processing, suggesting that active surveillance detected approximately 9-fold more ESBL-E carriers. The bla(CTM-M-9) group was the most common (38.5%), followed by the bla(TEM) (26.9%). The clinical backgrounds of the ESBL-E non-carriers and carriers were not significantly different. Conclusion: Our active screening demonstrated that nearly half of the patients hospitalized or transferred to a Japanese LTCH were colonized with ESBL-E. We highlight the enforcement of universal basic infection prevention techniques at LTCHs where patients carrying AMR pathogens gather

Inhibition of DNA Methylation at the <i>MLH1</i> Promoter Region Using Pyrrole–Imidazole Polyamide

Aberrant DNA methylation causes major epigenetic changes and has been implicated in cancer following the inactivation of tumor suppressor genes by hypermethylation of promoter CpG islands. Although methylated DNA regions can be randomly demethylated by 5-azacytidine and 5-aza-2′-deoxycytidine, site-specific inhibition of DNA methylation, for example, in the promoter region of a specific gene, has yet to be technically achieved. Hairpin pyrrole (Py)–imidazole (Im) polyamides are small molecules that can be designed to recognize and bind to particular DNA sequences. In this study, we synthesized the hairpin polyamide MLH1_–16 (Py-Im-β-Im-Im-Py-γ-Im-Py-β-Im-Py-Py) to target a CpG site 16 bp upstream of the transcription start site of the human <i>MLH1</i> gene. <i>MLH1</i> is known to be frequently silenced by promoter hypermethylation, causing microsatellite instability and a hypermutation phenotype in cancer. We show that MLH1_–16 binds to the target site and that CpG methylation around the binding site is selectively inhibited in vitro. MLH1_non, which does not have a recognition site in the <i>MLH1</i> promoter, neither binds to the sequence nor inhibits DNA methylation in the region. When MLH1_–16 was used to treat RKO human colorectal cancer cells in a remethylating system involving the <i>MLH1</i> promoter under hypoxic conditions (1% O₂), methylation of the <i>MLH1</i> promoter was inhibited in the region surrounding the compound binding site. Silencing of the <i>MLH1</i> expression was also inhibited. Promoter methylation and silencing of <i>MLH1</i> were not inhibited when MLH1_non was added. These results indicate that Py–Im polyamides can act as sequence-specific antagonists of CpG methylation in living cells