MICROBIAL CELLS EXPOSED TO THE HUMAN SPACEFLIGHT ENVIRONMENT ARE OBSERVED TO RESPOND DIFFERENTLY TO SIMILARLY-TREATED GROUND CONTROLS A PHENOMENON DUBBED THE SPACEFLIGHT SYNDROME . OVER THE PAST 4 DECADES A NUMBER OF EXPERIMENTS HAVE BEEN CONDUCTED INSIDE VARIOUS VEHICLES (E.G. SHUTTLE MIR ISS) TO UNDERSTAND HOW MICROBES SENSE AND RESPOND TO STRESSES OF HUMAN SPACEFLIGHT INCLUDING BUT NOT LIMITED TO MICROGRAVITY AND IONIZING RADIATION. IN EARLY STUDIES VARIOUS PHENOTYPIC OUTPUTS WERE MEASURED SUCH AS: GROWTH RATE AND YIELD; VIRULENCE; BIOFILM FORMATION AND ARCHITECTURE; AND RESISTANCE TO ANTIBIOTICS OR ABIOTIC STRESSES. WITH THE ADVENT OF THE GENOMICS AND POST-GENOMICS REVOLUTIONS IN BIOLOGY THERE HAVE BEEN INITIAL EFFORTS TO UNDERSTAND MORE FUNDAMENTAL MOLECULAR ASPECTS OF THE SPACEFLIGHT SYNDROME BY PERFORMING GLOBAL-SCALE "-OMICS" ANALYSES OF THE TRANSCRIPTOME PROTEOME METABOLOME ETC. OF MICROBES EXPOSED TO SPACEFLIGHT. SUCH STUDIES HAVE YIELDED VALUABLE INSIGHTS INTO THE MOLECULAR RESPONSES OF CERTAIN INDIVIDUAL MICROBES TO THE SPACEFLIGHT ENVIRONMENT; FURTHERMORE DATASETS FROM THESE EXPERIMENTS HAVE BEEN DEPOSITED INTO A COMMON PUBLICLY AVAILABLE DATABASE THE GENELAB DATA SYSTEM (GDS). WE PROPOSE TO USE THE DATA IN THE GDS AS A STARTING POINT TO EXPLORE COMMONALITIES AND DIFFERENCES IN THE RESPONSES TO SPACEFLIGHT OF VARIOUS DIFFERENT MICROBES WITH AN EYE TOWARDS UNCOVERING POSSIBLE COMMON FUNDAMENTAL MECHANISMS. WORKING HYPOTHESIS: EXPOSURE TO THE HUMAN SPACEFLIGHT ENVIRONMENT ALTERS THE PHYSICOCHEMICAL ENVIRONMENT IMMEDIATELY SURROUNDING BACTERIAL CELLS AND WITHIN THE CELLS THEMSELVES (MAINLY DUE TO MICROGRAVITY EFFECTS AND IONIZING RADIATION). CELLS SENSE THE ALTERED CONDITIONS AND RESPOND USING THE SYSTEMS THEY POSSESS--WHICH EVOLVED ON EARTH NOT IN SPACE. A LARGE PROPORTION OF MICROBIAL PHYSIOLOGICAL RESPONSES ARE REGULATED AT THE LEVEL OF TRANSCRIPTION THUS THE TRANSCRIPTOME IS A LOGICAL PLACE TO SEARCH FOR COMMON FUNDAMENTAL MECHANISMS. OBJECTIVES: IN ORDER TO ADDRESS THIS HYPOTHESIS WE PROPOSE THE FOLLOWING SPECIFIC AIMS: 1. MINE THE GDS BACTERIAL TRANSCRIPTOME DATABASE AND REPROCESS THE DATA IN A FASHION THAT WILL ALLOW CROSS-ORGANISM COMPARISONS. 2. SEARCH THE SPACEFLIGHT LITERATURE TO IDENTIFY ADDITIONAL RELEVANT DATASETS THAT MAY HAVE ESCAPED INCLUSION IN THE GDS. DEPOSIT THESE ADDITIONAL DATASETS IN THE GDS. ACCESS AND REFORMAT THE ADDITIONAL DATA AS IN SPECIFIC AIM 1. 3. PERFORM BIOINFORMATICS ANALYSES TO IDENTIFY PATHWAYS AND REGULONS SIGNIFICANTLY ACTIVATED OR REPRESSED BY EXPOSURE TO SPACEFLIGHT VS. GROUND CONTROLS IN INDIVIDUAL ORGANISMS. 4. COMPARE TRANSCRIPTOMES OF THE SAME ORGANISM GROWN IN SIMULATED MICROGRAVITY (CLINOSTATS) VS. ACTUAL SPACEFLIGHT CONDITIONS. 5. PERFORM COMPARISONS ACROSS SPECIES GENERA FAMILIES AND HIGHER TAXONOMIC GROUPINGS TO FIND SIMILARITIES AND DIFFERENCES IN SPACEFLIGHT RESPONSES. 6. DEVELOP SPECIFIC HYPOTHESES FROM THE COMPARISONS IN SPECIFIC AIM 5 AND PERFORM WET-LAB EXPERIMENTS TO TEST THESE HYPOTHESES IN GROUND-BASED SYSTEMS AND IN FUTURE SPACEFLIGHT MISSIONS. EXPECTED SIGNIFICANCE: MICROBES ARE UBIQUITOUS IN SPACE VEHICLES AS WELL AS ON AND WITHIN HUMANS THEMSELVES. BECAUSE MICROBES PLAY SUCH IMPORTANT AND ESSENTIAL ROLES IN THE HEALTH AND WELL-BEING OF ASTRONAUTS AND THEIR LIFE-SUPPORT SYSTEMS IT IS IMPERATIVE TO UNDERSTAND THEIR RESPONSES TO THE HUMAN SPACEFLIGHT ENVIRONMENT. THE ANALYSES PROPOSED HERE WILL ATTEMPT TO SYSTEMATICALLY IDENTIFY COMMON MOLECULAR MECHANISMS USED BY A WIDE RANGE OF BACTERIA TO COPE WITH THE STRESSES ENCOUNTERED IN HUMAN SPACEFLIGHT A PRIMARY GOAL OF BOTH THE GENELAB ENDEAVOR AND THE BROADER MISSION OF THE NASA SPACE BIOLOGY PROGRAM. IN ADDITION THE PIPELINES AND PROTOCOLS DEVELOPED IN THIS STUDY WILL HAVE APPLICATIONS BEYOND GENELAB AND IN PRINCIPLE CAN BE APPLIED TO COMPARISON OF THE TRANSCRIPTOMIC RESPONSES OF ANY COLLECTION OF MICROBES TO ANY GIVEN TYPE OF STRESS.