<b>Genome-wide identification and expression analysi</b><b>s</b><b>of the aquaporin gene family in the Qinghai Toad-Headed Agama (</b><b><i>Phrynocephalus vlangalii</i></b><b>) and responses to acute cold stress</b>

Phrynocephalus vlangaliiis a unique oviparous lizard species in China. Previous field observations have revealed that <i>P. vlangalii</i>can enter a completely frozen state during non-hibernation seasons when triggered by sudden temperature drops, and recover normal physiological activity upon warming. The tolerance to acute cold stress is exceptionally rare among reptiles, and the underlying molecular physiological mechanisms remain unclear. Aquaporins (AQPs) are a family of transmembrane proteins, which play essential roles in maintaining water balance, regulating cellular functions, and supporting energy metabolism. Studies on freeze-tolerant frogs and insects have demonstrated that AQPs may play a significant role in whole-body water redistribution during low-temperature. We hypothesize that the remarkable tolerance to acute cold stress in P. vlangalii critically depends on the coordinated action of its AQP family members at the molecular level.Nevertheless, the regulation of water transport in <i>P. vlangalii</i>remains poorly understood, and the roles of different AQPs under varying temperature conditions are still unclear. This study aims to characterize the AQP gene family in P. vlangaliiand analyze their tissue-specific expression patterns. By elucidating how AQPs regulate internal water balance, this research will uncover the molecular mechanisms of water metabolism underpinning extreme climate adaptation, providing insights for conserving this and other plateau species.