Comparative Analysis of the Daily Liver Metabolomics of Asian Particolored Bat.

Mammals rely on an intricate network of circadian clocks to regulate daily metabolic and physiological processes throughout the body. The liver, as a key peripheral organ, plays a crucial role in coordinating circadian rhythms and metabolic regulation. Bats, the only mammals capable of true flight, present unique nocturnal behaviors, which have garnered significant research interest. However, the daily metabolic fluctuations in bat liver and the underlying mechanisms of circadian regulation remain largely unexplored. To elucidate the metabolic foundations and rhythmic patterns in bat liver, a comparative LC-MS analysis was conducted to characterize the type, composition, and abundance of metabolites in the liver of Asian particolored bats at four distinct time points throughout a single day. This analysis identified a total of 7211 metabolites, with approximately 2.0% exhibiting significant rhythmicity, though with varying rhythmic patterns. Integrating these findings with RNA-Seq data revealed that differentially expressed genes and differentially accumulated metabolites were significantly enriched in two key pathways: the protein digestion and absorption pathway and the glutathione metabolism pathway. Notably, our results suggest that L-glutamate and L-tryptophan may play pivotal roles in the metabolic regulation of hepatic circadian rhythms, as indicated by metabolomics analysis. This study provides a systematic examination of the cyclic variations in metabolites within the bat liver, uncovering the physiological and biochemical processes involved and thereby enhancing our understanding of the molecular mechanisms governing circadian rhythms in bats.