DNA methylation is an epigenetic mechanism for gene expression modulation and can be used as a predictor of future disease risks. A prospective birth cohort study was performed to clarify the effects of neurotoxicants on child development, namely, the Tohoku Study of Child Development, in Japan. This study aimed to evaluate the association of prenatal exposure to five toxic metals—arsenic, cadmium, mercury, lead (Pb), antimony (Sb), and polychlorinated biphenyls (PCBs, N = 166)—with global DNA methylation in umbilical cord blood DNA. DNA methylation markers, 5-methyl-2′-deoxycytidine (mC) and 5-hydroxymethyl-2′-deoxycytidine (hmC), were determined using liquid chromatography-tandem mass spectrometry. The mC content in cord blood DNA was positively correlated with Pb and Sb levels (r = 0.435 and 0.288, respectively) but not with cord blood PCBs. We also observed significant positive correlations among Pb levels, maternal age, and hmC content (r = 0.155 and 0.243, respectively). The multiple regression analysis among the potential predictors demonstrated consistent positive associations between Pb and Sb levels and mC and hmC content. Our results suggest that global DNA methylation is a promising biomarker for prenatal exposure to Pb and Sb.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariant BA.5 emerged as of February 2022 and replaced the earlier Omicron subvariants BA.1 and BA.2. COVID-19 genomic surveillance should be continued as new variants seem to subsequently appear, including post-BA.5 subvariants. A rapid assay is needed to differentiate between the currently dominant BA.5 variant and other variants. This study successfully developed a high-resolution melting (HRM)-based assay for BA.4/5-characteristic spike mutation F486V detection and demonstrated that our assay could discriminate between BA.1, BA.2, and BA.5 subvariants in clinical specimens. The mutational spectra at two regions (G446/L452 and F486) for the variant-selective HRM analysis was the focus of our assay. The mutational spectra used as the basis to identify each Omicron subvariant were as follows: BA.1 (G446S/L452/F486), BA.2 (G446/L452/F486), and BA.4/5 (G446/L452R/F486V). Upon mutation-coding RNA fragment analysis, the wild-type fragments melting curves were distinct from those of the mutant fragments. Based on the analysis of 120 clinical samples (40 each of subvariants BA.1, BA.2, and BA.5), this method’s sensitivity and specificity were determined to be more than 95% and 100%, respectively. These results clearly demonstrate that this HRM-based assay is a simple screening method for monitoring Omicron subvariant evolution.

DNA methylation is an epigenetic mechanism for gene expression modulation and can be used as a predictor of future disease risks. A prospective birth cohort study was performed to clarify the effects of neurotoxicants on child development, namely, the Tohoku Study of Child Development, in Japan. This study aimed to evaluate the association of prenatal exposure to five toxic metals—arsenic, cadmium, mercury, lead (Pb), antimony (Sb), and polychlorinated biphenyls (PCBs, N = 166)—with global DNA methylation in umbilical cord blood DNA. DNA methylation markers, 5-methyl-2’-deoxycytidine (mC) and 5-hydroxymethyl-2’-deoxycytidine (hmC), were determined using liquid chromatography-tandem mass spectrometry. The mC content in cord blood DNA was positively correlated with Pb and Sb levels (r = 0.442 and 0.288, respectively) but not with cord blood PCBs. We also observed significant positive correlations among Pb levels, maternal age, and hmC content (r = 0.159 and 0.243, respectively). The multiple regression analysis among the potential predictors demonstrated consistent positive associations between Pb and Sb levels and mC and hmC content. Our results suggest that global DNA methylation is a promising biomarker for prenatal exposure to Pb and Sb.

Bstract: Didecyldimethylammonium chloride (DDAC) is a widely used quaternary ammonium disinfectant, but its effects on intestinal physiology following chronic oral exposure remain poorly understood. Here, we investigated the impact of chronic dietary DDAC exposure on intestinal function, gut microbial composition, and microbiota-related metabolites in mice. After 12 weeks of exposure, DDAC induced distinct intestinal phenotypes depending on exposure level. Exposure to 32.5 ppm DDAC increased intestinal permeability and was associated with reduced ileal mucus content and decreased expression of barrier-related genes in both the ileum and colon, whereas exposure to 130 ppm DDAC induced colon shortening, colonic mucus depletion, and histological remodeling. Notably, several intestinal alterations were observed at estimated exposure levels below the reported no-observed-adverse-effect level, highlighting intestinal endpoints as potentially sensitive measures of chronic DDAC exposure that warrant further investigation. Cecal microbiota analysis revealed substantial shifts in microbial community structure despite minimal effects on alpha diversity. Multivariable association analysis identified DDAC-responsive microbial features associated with host intestinal phenotypes after adjustment for DDAC treatment group. Among these, a Lactobacillus -associated amplicon sequence variant (ASV) was positively associated with colon length, whereas a Duncaniella -associated ASV was inversely associated with colonic histological score. Collectively, these findings demonstrate that chronic oral DDAC exposure induces region-specific intestinal dysfunction accompanied by microbial community remodeling. These results identify intestinal endpoints that may be sensitive to chronic DDAC exposure and suggest that microbiota remodeling may accompany the observed intestinal effects.

The xerophilic fungal genus Wallemia is an important cause of fungal contamination in bread manufacturing environments, but its detection by conventional culture-based methods is often difficult because of slow growth and competitive overgrowth by other fungi. Here, we report the development of a genus-specific TaqMan real-time polymerase chain reaction assay targeting the internal transcribed spacer (ITS) region for rapid detection of Wallemia. Primer and probe sequences were designed based on comparative ITS analysis of all nine recognized Wallemia species and non-target fungi commonly encountered in bakery environments. The probe-binding region was fully conserved among all Wallemia ITS reference sequences evaluated. Analytical specificity was confirmed using synthetic DNA fragments representing predicted amplicon groups, with amplification observed exclusively in Wallemia. The assay demonstrated excellent linearity over 10²–10⁶ copies per reaction (R² = 0.9988), with an amplification efficiency of 102.7%. Analytical sensitivity evaluation yielded an estimated LOD95 of 9.46 copies per reaction. Application to environmental swab samples from an operational bakery production line enabled culture-independent detection of Wallemia, including in samples in which culture-based identification was obscured by fungal overgrowth. This assay provides a rapid and specific molecular tool for culture-independent monitoring of Wallemia contamination and may support improved hygienic control in bakery manufacturing environments.