Background: Prestin (SLC26A5) is responsible for acute sensitivity and frequency selectivity in the vertebrate auditory system. Limited knowledge of prestin is from experiments using site-directed mutagenesis or domain-swapping techniques after the amino acid residues were identified by comparing the sequence of prestin to those of its paralogs and orthologs. Frog prestin is the only representative in amphibian lineage and the studies of it were quite rare with only one species identified. Results: Here we report a new coding sequence of SLC26A5 for a frog species, Rana catesbeiana (the American bullfrog). In our study, the SLC26A5 gene of Rana has been mapped, sequenced and cloned successively using RNA-Seq. We measured the nonlinear capacitance (NLC) of prestin both in the hair cells of Rana’s inner ear and HEK293T cells transfected with this new coding gene. HEK293T cells expressing Rana prestin showed electrophysiological features similar to that of hair cells from its inner ear. Comparative studies of zebrafish, chick, Rana and an ancient frog species showed that chick and zebrafish prestin lacked NLC. Ancient frog’s prestin was functionally different from Rana. Conclusions: We mapped and sequenced the SLC26A5 of the Rana catesbeiana from its inner ear cDNA using RNA-Seq. The Rana SLC26A5 cDNA was 2292 bp long, encoding a polypeptide of 763 amino acid residues, with 40% identity to mammals. This new coding gene could encode a functionally active protein conferring NLC to both frog HCs and the mammalian cell line. While comparing to its orthologs, the amphibian prestin has been evolutionarily changing its function and becomes more advanced than avian and teleost prestin.

The prestin-based active process in the mammalian outer hair cells (OHCs) is believed to play a crucial role in auditory signal amplification in the cochlea. Prestin belongs to an anion transporter family (SLC26A). It is densely expressed in the OHC lateral plasma membrane and functions as a voltage-dependent motor protein. Analog genes can be found in the genome of nonmammalian species, but their functions in hearing are poorly understood. In the present study, we used the gerbil prestin sequence as a template and identified an analog gene in the bullfrog genome. We expressed the gene in a stable cell line (HEK293T) and performed patch-clamp recording. We found that these cells exhibited prominent nonlinear capacitance (NLC), a widely accepted assay for prestin functioning as a motor protein. Upon close examination, the key parameters of this NLC are comparable to that conferred by the gerbil prestin, and nontransfected cells failed to display NLC. Lastly, we performed patch-clamp recording in HCs of all three hearing organs in bullfrog. HCs in both the sacculus and the amphibian papilla exhibited a capacitance profile that is similar to NLC while HCs in the basilar papilla showed no sign of NLC. Whether or not this NLC-like capacitance change is involved in auditory signal amplification certainly requires further examination; our results represent the first and necessary step in revealing possible roles of prestin in the active hearing processes found in many nonmammalian species.

Introduction: Fractures in the pyriform buttress area adversely affect facial appearance and nasal airway patency. Nasal airway function has received less attention than aesthetic problems in the literature. This retrospective study classified the different fracture types in this area and determined their impact on nasal airway function. Mathods: Three-dimensional computed tomography images of patients with fractures in the pyriform buttress area were analyzed to identify the exact fracture pattern. The nasal airway functions were evaluated and compared between patients with different fracture patterns using acoustic rhinometry, rhinomanometry, and the nasal obstruction symptom evaluation scale. Results: Overall, 47 patients, including 16 with type I fractures (high fracture line; group I), 16 with type II fractures (intermediate fracture line; group II), and 15 with type III fractures (low fracture line; group III), were included in the study. The mean minimal cross-sectional area (MCA), total nasal inspiratory resistance (Tri) and total nasal expiratory resistance (Tre) of group I were 0.51 ± 0.06 cm², 1.67 ± 0.11 kPa L⁻¹ s⁻¹, and 1.66 ± 0.12 kPa L⁻¹ s⁻¹, respectively; those of group II were 0.48 ± 0.07 cm², 1.89 ± 0.15 kPa L⁻¹ s⁻¹, and 1.88 ± 0.14 kPa L⁻¹ s⁻¹, respectively; and those of group III were 0.36 ± 0.04 cm², 1.94 ± 0.21 kPa L⁻¹ s⁻¹, and 2.01 ± 0.34 kPa L⁻¹ s⁻¹, respectively. The nasal obstruction symptom evaluation (NOSE) scale scores for groups I, II, and III were 7.188, 9.813, and 13.27, respectively. Conclusion: Therefore, the severity of the nasal airway obstruction depends on the displacement of the fractured bones in patients with fractures in the pyriform buttress area. The most profound nasal obstruction occurs in patients with the lowest fracture line.

Background Prestin (SLC26A5) is responsible for acute sensitivity and frequency selectivity in the vertebrate auditory system. Due to lacking of the 3D structure, most of the mechanism of prestin is from experiments using site-directed mutagenesis or domain-swapping techniques after the amino acid residues were identified by comparing the sequence of prestin to those of its paralogs and orthologs. Frog prestin is the only representative in amphibian lineage. The knowledge of frog SLC26A5 is quite limited with only one species has been identified. Results Here we report a new coding sequence of SLC26A5 for a frog species, the American bullfrog (Rana catesbeiana). In our study, the SLC26A5 gene of bullfrog has been mapped, sequenced and cloned successively using RNA-SEq. The comparative study revealed an alignment with nearly 40% identity among bullfrogs and mammalian species. The predicted 3D protein structure showed that the frog prestin possessed a transmembrane domain (TM) and a STAS domain similar to the mammalian prestin. The function of prestin crucially relies on its integration into the cell membrane. Such localization was observed when a prestin-EGFP fusion protein was expressed in HEK293T cells. We measured the nonlinear capacitance (NLC) of prestin both in the hair cells of frog’s inner ear and HEK293T cells transfected with this new coding gene. We observed that HEK293T cells expressing frog prestin showed electrophysiological features similar to that of hair cells from the amphibian’s inner ear. Conclusions We mapped and sequenced the SLC26A5 of the American bullfrog from its inner ear cDNA using RNA-SEq. The frog SLC26A5 cDNA was 2,292 bp long, encoding a polypeptide of 763 amino acid residues, with 40% identity to mammals. After isolating the prestin gene of the frog, we generated a stable cell line transfected with this new coding gene and found it possessing similar electrophysiological features as the hair cells from the frog’s auditory organ. Our experiment demonstrated that the new coding gene could encode a functionally active protein conferring NLC to both frog HCs and the mammalian cell line.