Project Summary The Harvard Digestive Disease Center (HDDC) is a community of scientists focused on understanding the cellular, immune, and microbial biology of mucosal surfaces lining the alimentary tract: this is the Center’s Theme. We aim to elucidate the integrated cell and molecular biology of the epithelial, immune, neuronal, mesenchymal, and microbial cell types that comprise the complex ecosystem of the gut. The overarching mission of the HDDC is to foster better clinical, translational, and basic science in fields related to the digestive diseases by: Connecting People, Creating Opportunity, Providing Critical Technologies, and Extending Resources. Here, we apply for Supplemental Funds to purchase new equipment for each of our 3 Scientific Cores Scientific Core B - Microscopy and Histopathology Core: Funds to purchase a Abberior Stedycon STED nanoscope are requested. This technology is not available on the Harvard longwood Campus and will enable super-resolution microscopy with a resolution down to 30 mm Scientific Core C - Epithelial Cell and Mucosal Immunology Core: Funds for a 10X Genomics Chromium Controller are requested. This will further enable the Core to provide the new services in single cell mRNA sequencing outlined in our competitively renewed award 2021. Scientific Core D - Gnotobiotic Mice, Microbiology, Metagenomics, and Metabolism Core: Funds for two companion instruments are requested. These two purchases will enable simultaneous non-invasive measurement of 13CO2, C18O2, CO2, and H2O in unrestrained freely moving germ-free, gnotobiotic mice, or microbially colonized mice. This would be another resource of Core D uniquely needed by investigators The duration of the parent P30 grant supporting this request will extend for the next 5 years - we were just competitively renewed for another 5-year cycle starting December 1, 2020.