“…Conversely, in Danio rerio (i.e., zebrafish) the expression pattern of the orthologous protein changes during development, being ubiquitous immediately after fertilization and becoming more and more restricted and limited to the tectum, the gill arches, and the developing ear at 48 h and 120 h post-fertilization [29]. Interestingly, in human, hearing loss is frequently associated with PNPT1 mutations, with or without other neurological symptoms depending on the mutations, and PNPT1 knock-out in inner ear hair cells causes hearing loss in mice [10,15,29]. PNPases are members of the PDX family of exoribonucleases [30] and in all organisms share a similar domain structure, consisting of two RNase PH like domains (RPH1 and RPH2), separated by an all-α-helical domain (AAHD), and followed by the KH and S1 RNA binding domains [31].…”