Excessive heavy metals enrichment disturbs the liver function through gut microbe in great Himalayan leaf-nosed bat (Hipposideros armiger)
Heavy metals residue in the natural ecosystem had become one global environmental problem that was eager to solve. Due to the non-biodegradability, organism could deposit excessive heavy metals elements into tissues. Existing literature proposed that prolonged heavy metals enrichment had comprehensive toxicity to multi-organs of vertebrates. However, little research focus on the molecular mechanism for the hepatotoxicity of heavy metal enrichment to Chiroptera. In the present study, ten Hipposideros armiger individuals from Yingde City (YD, relatively pollution-free) and Chunwan City (CW, excessive heavy metals emission) were dissected while environment samples were also obtained. To corroborate the toxicity mechanism of heavy metals to bats liver, multi-omics, pathology and molecular biology methods were performed. Our results showed that more Cd and Pb elements were significantly enriched in bats liver and food sources in the CW group. In addition, prolonged heavy metals accumulation disturbed the hepatic transcription profiling associated with solute carriers family, ribosome pathway, ATP usage and heat shock proteins. Excessive heavy metals enrichment also altered the relative abundance of typical gut microbe taxa to inhibit the tight-junction protein expression. We also found that the levels of superoxide dismutase, glutathione peroxidase and glutathione were decreased while ROS density and malondialdehyde content were elevated after excessive heavy metals enrichment. Besides, hepatic fat accumulation and inflammation injury were also observed under the excessive heavy metals enrichment while the metabolism biomarkers contents were decreased. Therefore, prolonged heavy metals enrichment would induce a series of hepatotoxicity by disturbing the microbes-gut-liver axis and hepatic transcription modes, which could decrease the overall metabolism level in bats. Our study provided protection strategy for biodiversity conservation and raised public attention to environment pollution. Overall design: Two caves located in the Guangdong Province were selected in the present experiment. One is located in Yingde City (YD) ,  the other is located in Chunwan City (CW).Hipposideros armiger were caught using mist-nets at midnight.Only five male adult individuals in each cave were euthanized by inhaling ethyl ether and removed the liver tissue quickly.