Induction of Hibernation and Changes in Physiological and Metabolic Indices in .

() is a commonly cultivated turtle species with a habit of hibernation. To study the changes in histone expression and methylation of during hibernation induction, a model was established by artificial induction. Physiological and metabolic indices were measured, and the expression and localization of histone (, , , , and ) and methylation-related genes (, , , , , and ) were measured by quantitative PCR, immunohistochemistry, and Western blot analysis. The results indicated that the metabolism, antioxidation index, and relative expression of histone methyltransferase were significantly decreased ( < 0.05), whereas the activity and expression of histone demethyltransferase were significantly increased ( < 0.05). Although our results showed significant changes in physiological and gene expression after hibernation induction, we could not confirm that entered deep hibernation. Therefore, for the state after cooling-induced hibernation, cold torpor might be a more accurate description. The results indicate that the can enter cold torpor through artificial induction, and the expression of histones may promote gene transcription. Unlike histones expressed under normal conditions, histone methylation may activate gene transcription during hibernation induction. Western blot analysis revealed that the and proteins were differentially expressed in the testis at different months ( < 0.05), which may perform a role in regulating gene transcription. The immunohistochemical localization of and in spermatogonia and spermatozoa suggests that and may perform a role in mitosis and meiosis. In conclusion, this study is the first to report changes in histone-related genes in reptiles, which provides insight for further studies on the physiological metabolism and histone methylation regulation of during the hibernation induction and hibernation period.