In zebrafish, Rhcg1 was found in apical membranes of skin ionocytes [H⁺-ATPase-rich (HR) cells], which are similar to α-type intercalated cells in mammalian collecting ducts. However, the cellular distribution and role of Rhbg in zebrafish larvae have not been well investigated. In addition, HR cells were hypothesized to excrete ammonia against concentration gradients. In this study, we attempted to compare the roles of Rhbg and Rhcg1 in ammonia excretion by larval skin and compare the capability of skin cells to excrete ammonia against concentration gradients. Using in situ hybridization and immunohistochemistry, Rhbg was localized to both apical and basolateral membranes of skin keratinocytes. A scanning ion-selective electrode technique (SIET) was applied to measure the NH₄⁺ flux at the apical surface of keratinocytes and HR cells. Knockdown of Rhbg with morpholino oligonucleotides suppressed ammonia excretion by keratinocytes and induced compensatory ammonia excretion by HR cells. To compare the capability of cells to excrete ammonia against gradients, NH₄⁺ flux of cells was determined in larvae exposed to serial concentrations of external NH₄⁺. Results showed that HR cells excreted NH₄⁺ against higher NH₄⁺ concentration than did keratinocytes. Knockdown of the expression of either Rhcg1 or H⁺ -ATPase in HR cells suppressed the capability of HR cells.

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contributed equally to this article.

Reactions of divalent metal salts with 4,4-oxybis(N-(pyridine-4-yl)-benzamide), L, and naphthalene-1,4-dicarboxylic acid (1,4-H2NDC) in various solvents gave [Zn(L)(1,4-NDC)·H2O]n, 1, [Cd(L)(1,4-NDC)(H2O)·MeOH]n, 2, and [Co(L)(1,4-NDC)(H2O)0.5·MeOH]n, 3, which have been structurally characterized. Complexes 1–3 show eight-fold interpenetrating frameworks with the dia topology, which exhibit porosities substantiated by CO2 adsorption, whereas 1 and 2 manifest stability in aqueous environments and show high selectivity toward sensing of mesitylene molecules and Fe3+ ions with low detection limits and good reusability up to five cycles.

Diabetic kidney disease (DKD) is the leading cause of morbidity and mortality in patients with diabetes mellitus (DM) and the most common variant of end-stage renal disease (ESRD) globally. The economic burden of ESRD treatment with dialysis is substantial. The incidence and prevalence of ESRD in Taiwan remain the highest worldwide. Therefore, identifying genetic factors affecting kidney function would have valuable clinical implications. We performed microarray experiments and identified that ubiquitin protein ligase E3C (UBE3C) is differentially expressed in two DKD patient groups with extreme (low and high) urine protein-to-creatinine ratios. A follow-up genotyping study was performed in a larger group to investigate any specific variants of UBE3C associated with DKD. A total of 263 patients were included in the study, comprising 172 patients with DKD and 91 control subjects (patients with DM without chronic kidney disease (CKD)). Two UBE3C variants (rs3802129(AA) and rs7807(CC)) were determined to be associated with reduced kidney function. The haplotype analysis revealed that rs3802129/rs3815217 (block 1) with A/G haplotype and rs8101/rs7807 (block 2) with T/C haplotype were associated with higher risks of CKD phenotypes. These findings suggest a clinical role of UBE3C variants in DKD risk.