Laboratory Mouse (image) Instituto Gulbenkian de Ciencia Caption This shows bacteria carrying different mutations compete for fixation in the gut of the laboratory mouse. Credit Roberto Keller (IGC). Usage Restrictions Image credits should be given. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.