The Digital Imaging Core (Core A) comprises valuable and modem tools, which are to be made available as routine services to program participants. A major goal of Core A is to provide uniform services to enable Program investigators to validate transduced cardiac cells and tissues. Validation includes assessing level of gene expression, cell-to-cell variability in expression, and structural or functional consequences to transduced cells of the altered gene expression. Services include 3-dimensional cell and tissue digital imaging with multi-color fluorescence microscopy for both living and fixed samples. Since the last review, Core A has evolved to include access to a multi-photon and a multi-spectral confocal microscope fitted for live-cell imaging, and an intra-vital confocal system for live animal imaging. Many components of this Program involve analysis of gene expression in cells and tissues, and as such this Core will be widely utilized. Based upon high resolution imaging techniques, including a DeltaVision deconvolution microscope system and UNIX workstations, these services include quantitative image analysis, time-lapse microscopy and volume 3-dimensional renderings of cells and tissues. Through Core A image analysis is greatly enhanced through interactions with the VisLab at the San Diego Supercomputer Center, with use of NPACI Scalable Visualization Tools. These tools allow for real-time exploration of the special locations of 3 or 4 cellular components in 3-D. These services have been crucial for individual lab projects and intra-programmatic research projects in this new program. In this service, animal tissues following transgene expression can be analyzed at several levels, including gross pathology and 3- dimensional tissue imaging with immunofluorescence staining. The service will be able to provide imaging analysis of various aspects of the targeted tissues, including specific cell type identification of transgene expression, tissue inflammatory responses, resultant tissue organization, and any changes in cellular gene expression or sarcomeric structural organization. Cells transduced in culture can be imaged as live cells revealing temporal relationships or as fixed samples, stained with immunofluorescent reagents for subsequent 3- dimensional structural analysis. As research goals and efforts within our Program address the molecular and cellular functions of endogenous and transduced genes, this resource promises to provide cost-effective support for these cellular, tissue and animal-based studies.