7–8-week C57BL/6 male mice (specific pathogen-free grade) were purchased from Jackson Laboratories (Bar Harbor, ME). Mice were maintained at the University of North Carolina animal facility in static microisolator cages with Bed-O-Cob (The Andersons Inc., Maumee, OH) combination bedding under standard environmental conditions (22°C, 40–70% humidity, and a 12:12-h light: dark cycle). Mice were monitored for 1 week at the animal facility without any treatment. Pelleted rodent diet and sterilized tap water were provided to the mice ad libitum. Sodium arsenite was obtained from Fisher Scientific and exposed to mice by drinking water. Three groups of mice were set: Control group (n=15), and arsenic-dosing group (1 ppm; n=6–8). After 3-month exposure, fecal samples will be collected for microbiota analysis. Then, mice were euthanatized, and heart blood and liver samples were collected as previously described.2 (link) All samples were then stored at −80 °C until use. The experimental protocol was approved by the University of North Carolina Animal Care Committee and mice were treated humanely.