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The diversity of pigmentation in the skin, hair, and eyes of humans has been largely attributed to the diversity of p H in melanosomes with acidic p H being proposed to suppress melanin production. Tyrosinase has an optimum p H of 7.4 and its activity is suppressed greatly at lower p H values. The first step of eumelanogenesis is the oxidation of tyrosine to dopachrome ( DC) via dopaquinone. However, how eumelanogenesis is controlled by p H beyond this stage is not known. In this study, we examined the effects of p H (5.3-7.3) on the conversion of DC to 5,6-dihydroxyindole ( DHI) and 5,6-dihydroxyindole-2-carboxylic acid ( DHICA) and the subsequent oxidation of DHI and DHICA to form eumelanin. The effects of Cu2+ ions on those reactions were also compared. The results indicate that an acidic p H greatly suppresses the late stages of eumelanogenesis and that Cu2+ ions accelerate the conversion of DC to DHICA and its subsequent oxidation. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 nucleic acid detection tests enable rapid virus detection; however, it is challenging to identify genotypes to comprehend the local epidemiology and infection routes in real-time qRT-PCR. At the end of June 2022, our hospital experienced an in-hospital cluster of COVID-19. When examined using the GeneXpert ® System, the cycle threshold (Ct) value of the N2 region of the nucleocapsid gene of SARS-CoV-2 was approximately 10 cycles higher than that of the envelope gene. Sanger sequencing revealed a G29179T mutation in the primer and probe binding sites. A review of past test results revealed differences in Ct values in 21 of 345 SARS-CoV-2-positive patients, of which 17 cases were cluster-related and 4 were not. Including these 21 cases, 36 cases in total were selected for whole-genome sequencing (WGS). The viral genomes in the cluster-related cases were identified as BA.2.10, and those in the non-cluster cases were closely related and classified as being downstream of BA.2.10 and other lineages. Although WGS can provide comprehensive information, its use is limited in various laboratory settings. A measurement platform reporting and comparing Ct values of different target genes can improve test accuracy, enhance our understanding of infection spread, and be applied to the quality control of reagents.