Reverse pH-dependent fluorescence protein visualizes pattern of interfacial proton dynamics during hydrogen evolution reaction

Abstract Reverse pH-dependent fluorescent protein, including dKeima, is a type of fluorescent protein in which the chromophore protonation state depends inversely on external pH. The dependence is maintained even when immobilized at the metal-solution interface. But, interestingly, its responses to the hydrogen evolution reaction (HER) at the interface are not reversed: HER rises the pH of the solution around the cathode, but, highly active HER induces chromophore deprotonation regardless of the reverse pH dependence, reflecting an interface-specific deprotonation effect by HER. Here, we exploit this phenomenon to perform scanning-less, real-time visualization of interfacial proton dynamics during HER at a wide field of view. By using dKeima, the HER-driven deprotonation effect was well discriminated from the solution pH effect. In the electrodes of composite structures with a catalyst, dKeima visualized keen dependence of the proton depletion pattern on the electrode configuration. In addition, propagations of optical signals were observed, which seemingly reflect long-range proton hopping confined to the metal-solution interface. Thus, reverse pH-dependent fluorescent proteins provide a unique tool for spatiotemporal analysis of interfacial proton dynamics, which is expected to contribute to a better understanding of the HER process and ultimately to the safe and efficient production of molecular hydrogen

Dogs and humans share a common susceptibility gene SRBD1 for glaucoma risk.

Glaucoma is a degenerative optic neuropathy that is associated with elevated intraocular pressure. Primary open angle glaucoma is the most common type of glaucoma in canines, and its highest incidence among dog breeds has been reported in Shiba-Inus, followed by Shih-Tzus. These breeds are known to have an abnormal iridocorneal angle and dysplastic prectinate ligament. However, the hereditary and genetic backgrounds of these dogs have not yet been clarified. In this study, we investigated the association between polymorphisms of the glaucoma candidate genes, SRBD1, ELOVL5, and ADAMTS10, and glaucoma in Shiba-Inus and Shih-Tzus. We analyzed 11 polymorphisms in these three genes using direct DNA sequencing. Three SRBD1 SNPs, rs8655283, rs22018514 and rs22018513 were significantly associated with glaucoma in Shiba-Inus, while rs22018513, a synonymous SNP in exon 4, showed the strongest association (P = 0.00039, OR = 3.03). Conditional analysis revealed that rs22018513 could account for most of the association of these SNPs with glaucoma in Shiba-Inus. In Shih-Tzus, only rs9172407 in the SRBD1 intron 1 was significantly associated with glaucoma (P = 0.0014, OR = 5.25). There were no significant associations between the ELOVL5 or ADAMTS10 polymorphisms and glaucoma in Shiba-Inus and Shih-Tzus. The results showed that SRBD1 polymorphisms play an important role in glaucoma pathology in both Shiba-Inus and Shih-Tzus. SRBD1 polymorphisms have also been associated with normal- and high-tension glaucomas in humans. Therefore, SRBD1 may be a common susceptibility gene for glaucoma in humans and dogs. We anticipate that the nucleotide sequencing data from this study can be used in genetic testing to determine for the first time, the genetic status and susceptibility of glaucoma in dogs, with high precision. Moreover, canine glaucoma resulting from SRBD1 polymorphisms could be a useful animal model to study human glaucoma