PROJECT SUMMARY Numerous studies in recent years have demonstrated that paternal experiences (e.g. smoking, nutrition, stress) prior to having children can influence the health, development, and behavior of the following generations. Existing studies exploring prefertilization paternal effects have been conducted in mammalian model systems, where it is difficult to isolate direct paternal influences on offspring from postfertilization maternal-offspring interactions. This project develops a new model for understanding the effects of stressors across generations: threespined sticklebacks (Gasterosteus aculeatus). Because sticklebacks have external fertilization, maternal influences can be teased apart from paternal influences. The applicant (Jennifer Hellmann) and her mentor (Dr. Alison Bell) will assess the influence of prefertilization paternal stress on embryonic development (Aim 1). They will also evaluate if the effects of paternal stress are transmitted across multiple generations by assessing if grandpaternal experiences can influence grandoffspring behavior and development (Aim 2). Finally, they will use embryonic manipulations to determine if sperm RNA is a mechanism underlying the epigenetic inheritance of paternal experiences (Aim 3). The project has relevance for human health because paternal stress in humans has multigenerational consequences, but there is a lack of understanding regarding the molecular mechanisms by which epigenetic modifications can be transmitted from one generation to the next. Further, predation risk in non- human animals is an ecologically relevant stressor that mirrors situations precipitating trauma (e.g. PTSD) in humans. This proposal will provide excellent training opportunities for the applicant (Jennifer Hellmann), whose long-term research interests center around understanding factors that promote individual variation in behavior and phenotype, including understanding the molecular mechanisms regulating phenotypic differences among individuals. The skills gained during her PhD work (behavioral, genetic, physiological) will provide a base from which to expand her research questions and Dr. Alison?s Bell laboratory group will provide an excellent avenue to gain the genomic research skills needed to address her long-term research interests. Further, this fellowship will provide mentoring opportunities, publications, and training that will better prepare the applicant for attaining a tenure-track faculty position at a research institution.