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

## TL;DR

This study explores daily liver metabolite changes in Asian particolored bats to understand how their circadian rhythms regulate metabolism.

## Contribution

The study provides the first systematic analysis of circadian liver metabolite rhythms in bats, identifying key metabolic pathways and potential regulatory metabolites.

## Key findings

- Approximately 2.0% of identified metabolites showed significant rhythmicity with varying patterns.
- L-glutamate and L-tryptophan are suggested to play pivotal roles in regulating hepatic circadian rhythms.
- Protein digestion, absorption, and glutathione metabolism pathways were significantly enriched in circadian regulation.

## Abstract

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.

This study elucidated the composition of liver metabolites and clarified the rhythmic patterns of critical metabolites and associated physiological processes in the bat liver. The circadian‐regulated metabolic patterns in bats may have significant implications for their energy strategies and survival. Antioxidant‐related physiological processes are activated both before and after bats' energy‐intensive flight behavior, preparing and protecting the body from oxidative stress.