Project Summary/Abstract This proposal represents a request from a group of 15 NIH-funded investigators with overlapping imaging needs for funding to acquire a Nikon AX Laser Scanning Confocal Microscope (LSM) to facilitate the visualization and quantification of the three-dimensional spatial organization of fixed cells and tissues as well as living specimens, with the latter including the need to monitor time-dependent changes. The system will be housed in the Washington University Center for Cellular Imaging (WUCCI), an institution-wide shared technology resource based at the School of Medicine. The current laser scanning confocal microscopes in the WUCCI are already heavily subscribed by different user groups with different needs (upright configuration for model system imaging and Airyscan capabilities for sub-diffraction limited imaging) and additional workhorse confocal capacity is needed to facilitate the work of the Major and Minor user projects described herein. The Nikon AX confocal microscope platform is configured with (i) a Nikon Ti2 inverted motorized microscope frame, (ii) 405 nm, 488 nm, 561 nm, and 640 nm excitation lasers, (iii) high-sensitivity filter-based and spectral detectors, (iv) a variety of dry and immersion-based objective lenses and (v) a stage-top incubation system to facilitate the physiological imaging of living specimens. Fifteen investigators from nine different units at the School of Medicine will make use of this imaging platform to enable a wide-range of basic and translational research studies aimed at understanding the mechanisms of viral and bacterial pathogenesis, the dynamics of cell migration, mitochondrial dysfunction, metabolic homeostasis, diabetes, circadian physiology and neurodegenerative disease. While the instrument has been configured to meet the specific needs of the major user group, we thoroughly expect it to impact many other research programs. The expertise and institutional support for this instrument are exceptional. Dr. James Fitzpatrick, the Scientific Director of WUCCI, and Dr. David Piston, the Chair of Cell Biology & Physiology and head of the WUCCI Advisory Board, are both world-renowned experts in cellular microscopy and their combined leadership brings over 40 years of experience in providing cost-efficient training and support for high quality quantitative cellular imaging to a wide range of NIH-funded users. In support of this S10 grant application, the institution will also commit $100,000 ($20,000 per year for five years) to ensure the long-term success of this instrument.