THE MAJOR OUTCOMES OF OUR STUDY WILL BE A DETAILED UNDERSTANDING OF GENETIC INNOVATIONS THAT UNDERLIE THE TRANSITION TO PHOTOTROPHY AN UNDERSTANDING OF HOW BIOTIC INTERACTIONS MAY SUPPORT PLASTID AND HOST HEALTH THE GENERATION OF A GEM MODEL FOR PAULINELLA THAT PROVIDES A VALUABLE COMMUNITY RESOURCE TO DRIVE FUTURE SCIENCE AND FUNCTIONAL DATA FOR NOVEL GENES IMPORTANT FOR FITNESS WHEN THE CELLS EXPERIENCE STRESS RESULTING FROM HIGH LIGHT OR NUTRIENT DEPRIVATION. THESE GOALS FIT IN WELL WITH THE SCOPE OF THE NASA C.5 EXOBIOLOGY PROGRAM THAT AIMS TO UNDERSTAND THE ORIGIN EVOLUTION DISTRIBUTION AND FUTURE OF LIFE IN THE UNIVERSE. IN PARTICULAR OUR WORK ADDRESSES THE RESEARCH EMPHASIS EVOLUTION OF ADVANCED LIFE BECAUSE IT DIRECTLY EXAMINES PROCESSES ASSOCIATED WITH ENDOSYMBIOSIS. THE PROPOSED RESEARCH IS ALSO INTEGRAL TO THE EMPHASIS EARLY EVOLUTION OF LIFE AND THE BIOSPHERE BECAUSE IT INVESTIGATES THE DEVELOPMENT OF KEY BIOLOGICAL PROCESSES (PHOTOSYNTHESIS) AND THEIR ENVIRONMENTAL IMPACT.