Transcriptome Analyses Provide Insights into the Auditory Function in Trachemys scripta elegans

SIMPLE SUMMARY: Auditory function is an important sensory ability that contributes to the survival and reproduction of vertebrates. Studies have shown that turtles can hear and that sex-related differences exist in the auditory function of Trachemys scripta elegans. However, the associated gene expression characteristics are unknown. Therefore, we performed comparative transcriptomics to identify hub genes related to hearing organs involved in development and signal transduction. Six differentially expressed genes in the GABAergic synapse pathway were identified to explain the differences in hearing sensitivity. These results offer new insights into the genetic mechanisms underlying hearing characteristics and auditory adaptation in turtles. ABSTRACT: An auditory ability is essential for communication in vertebrates, and considerable attention has been paid to auditory sensitivity in mammals, birds, and frogs. Turtles were thought to be deaf for a long time; however, recent studies have confirmed the presence of an auditory ability in Trachemys scripta elegans as well as sex-related differences in hearing sensitivity. Earlier studies mainly focused on the morphological and physiological functions of the hearing organ in turtles; thus, the gene expression patterns remain unclear. In this study, 36 transcriptomes from six tissues (inner ear, tympanic membrane, brain, eye, lung, and muscle) were sequenced to explore the gene expression patterns of the hearing system in T. scripta elegans. A weighted gene co-expression network analysis revealed that hub genes related to the inner ear and tympanic membrane are involved in development and signal transduction. Moreover, we identified six differently expressed genes (GABRA1, GABRG2, GABBR2, GNAO1, SLC38A1, and SLC12A5) related to the GABAergic synapse pathway as candidate genes to explain the differences in sexually dimorphic hearing sensitivity. Collectively, this study provides a critical foundation for genetic research on auditory functions in turtles.