Objective : To investigate the differences in gut microbiota and metabolites between urban and rural middle school students and explore their significance in gut homeostasis , so as to establish a healthy lifestyle and diet for children. Methods : Fecal samples were collected from middle school students in Hefei ( n = 14) and Jixi county ( n = 18 , Southern Anhui) , aged 13. 0 - 13. 5 years. Stool samples were sequenced by 16S ribosomal DNA (LC⁃MS) , followed by bioinformatic analysis. Results : Lachnoclostridium and Anaerostipes were dominant in the urban students that had been reported to be associated with colorectal cancer, atherosclerosis , depression and other disorders. In the village children , Ruminococcaceae UCG⁃002 , Barnesiella and Eubacterium dominated. An increased proportion of these microbes were related to metabolism of bile acids , short⁃chain fatty acids , lipid and carbohydrate decomposition , and play an important role in maintaining immune balance and physiological function. Additionally , significant differences in gut metabolites of the two groups were noted , mainly in arachidonic acid metabolism , platelet activation , serotonin metabolism , vitamin absorption , primary bile acid metabolism and other pathways. Conclusion Adolescent students of urban and mountainous areas differ in gut microbiota and metabo⁃ lites. Rural children have a healthy bacterial flora and metabolites in guts due to a reasonable lifestyle and diet in comparison with the city children.

Objective: To investigate the effects of hepatobiliary metabolie dysfunction on gut microbiota in rats with intrahepatic cholestasis of pregnancy (ICP). Methods: Forty Sprauge-Dawley(SD) rats at 10 days of gestation were randomly divided into two groups,25 for ICP induction and 15 as control. Estradiol benzoate, combined with progesterone, was given to the rats by intraperitoneal injjection from 10 to 14 days after gestation. Hepatic impairment indicators of total bilirubin(TBIL), alanine aminotransferase (ALT), aspartate aminotransferase (AST),-glutamyl transferase ( GGT), alkaline phosphatase(AL.P), and total bile acids (TBA) in sera of the animals were detected in each group to verify the model construction. Simultaneously, the liver tissues were subjected to pathology examination and fresh faeces samples were collected for 16S rDNA sequencing to explore the gut microbiota profiles. Results: The serum levels of TBIL,ALT,AST,GGT,ALP and TBA in ICP group were significantly elevated compared with the control (P<0. 05 );the ICP rats presented obvious characteristics of hepatobiliary disorders, showing prominent steatosis, necrosis of hepatocytes and infiltration of inflammatory cells, with formation of bile thrombus in some animals. The abundance of Eubacterium, Bacteroides, Parabacteroides distasonis and Bacteroides uniformis remarkably decreased wereas Prevotela and Fusobacterium significantly increased in ICP rats when compared with the control (P<0.05). Conclusion The hepatic injuries and bile acid metabolic disorders occurred in ICP rats,which resulted in dysbiosis of gut microbiota.