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Tooth enamel is the most highly mineralized tissue in vertebrates. Enamel crystal formation and elongation should be well controlled to achieve an exceptional hardness and a compact microstructure. Enamel matrix calcification occurs with several matrix proteins, such as amelogenin, enamelin, and ameloblastin. Among them, amelogenin is the most abundant enamel matrix protein, and multiple isoforms resulting from extensive but wellconserved alternative splicing and postsecretional processing have been identified. In this report, we recruited a family with a unique enamel defect and identified a silent mutation in exon 4 of the AMELX gene. We show that the mutation caused the inclusion of exon 4, which is almost always skipped, in the mRNA transcript. We further show, by generating and characterizing a transgenic animal model, that the alteration of the ratio and quantity of the developmentally conserved alternative splicing repertoire of AMELX caused defects in enamel matrix mineralization.

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Amorphous Zn 2 SnO 4 (am-ZTO) films with extreme surface uniformity, high electron mobility, and fewer charge traps were successfully developed by controlling the concentrations of 2methoxyethanol solutions containing the 2:1 stoichiometric ratio of Zn to Sn. For the first time, we demonstrate that solution-processed am-ZTO thin films are highly efficient as an electron-selective layer (ESL) for mixed perovskite solar cells (PSCs). When am-ZTO ESLs were combined with bandgap-tuned FAMAPbI 3 perovskites, a champion efficiency of 20.02% was achieved. In addition, devices based on am-ZTO showed a statistical reproducibility of 18.38 ± 0.61% compared to 15.85 ± 1.02% of the TiO 2 -based counterparts. This high efficiency is achieved by the significant increase in both the short-circuit current and opencircuit voltage owing to improved charge transport/extraction and recombination. Moreover, am-ZTO ESL-based devices show improved stability and reduced hysteresis, which is a promising result for future PSC research.

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Apoptosis plays important roles in various stages of organogenesis. In this study, we hypothesized that apoptosis would play an important role in tooth morphogenesis. We examined the role of apoptosis in early tooth development by using a caspase inhibitor, z-VAD-fmk, concomitant with in vitro organ culture and tooth germ transplantation into the kidney capsule. Inhibition of apoptosis at the early cap stage did not disrupt the cell proliferation level when compared with controls. However, the macroscopic morphology of mice molar teeth exhibited dramatic alterations after the inhibition of apoptosis. Crown height was reduced, and mesiodistal diameter was increased in a concentration-dependent manner with z-VAD-fmk treatment. Overall, apoptosis in the enamel knot would be necessary for the proper formation of molar teeth, including appropriate shape and size.

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