ABSTRACT This is a diversity supplement for Ph.D. candidate Jared Rafael Camillo to provide him guided career development while working on his dissertation project, which is related to an NIH MERIT award to Sanford I. Bernstein entitled Genetics and Molecular Biology of Striated Muscle Myosin. We will study two cardiac myosin heavy chain isoforms that are expressed in Drosophila cardiomyocytes, in order to compare ATPase, motility and structural properties. The latter will be determined using cryo-electron microscopy, which will allow visualization of interactions with actin. As the two isoforms differentially affect muscle function when expressed in indirect flight and jump muscles, we hypothesize that our studies will yield insights into cardiac myosin structure/function relationships. We will then use CRISPR to introduce dilated cardiomyopathy (DCM) mutations into each of the cardiac isoforms. We will assess the effects of the mutations on ATPase, motility and molecular structure. We will then examine flight and jump muscle structure of mutant muscle via transmission electron microscopy and function via flight and jump assays. The Swank lab (RPI) will measure impacts on force, velocity, work, power generation, and identify steps of the myosin cross-bridge cycle that are altered. This integrative analysis will test the hypothesis that DCM mutations yield reduced contractility. Overall, we will gain insights into how the biochemical and structural properties of two cardiac myosin isoforms yield different functional properties in muscle and how dilated cardiomyopathy mutations affect myosin and muscle structure and function.