The overall objective of this project is to investigate molecular mechanisms that enable a select group of fishes, including tilapia, to live in a wide range of salinity, including seawater and fresh water. These fishes are called euryhaline and, unlike most fishes, they possess adaptive mechanisms that allow them to tolerate extreme salinity stress and to actively counteract such stress. Using tilapia as a model this project aims to determine the molecular signaling pathways that control salinity adaptation in euryhaline fishes. Proteomics methods (2D electrophoresis, mass spectrometry, bioinformatics), tissue microarray/ laser scanning cytometry analysis, co-immunoprecipitation, and recombinant DNA methodology will be used to address three specific aims: 1. Investigation of the mechanisms by which OSTF1 and 14 3-3 signaling proteins control salinity adaptation; 2. Identification of the signal (plasma cortisol, plasma osmolality, medium salinity) that triggers adaptations mediated by OSTF1 and 14-3-3 during salinity stress; 3. Determination of full-length coding sequence and in-depth characterization of 15 novel salinity-induced tilapia genes recently identified in the PI's laboratory. The overall significance of this work lies in its inherent potential for unraveling major mechanisms of cellular signal transduction that control salinity adaptation and environmental stress tolerance in euryhaline fishes. Knowledge about these mechanisms is critical for understanding why some fish species tolerate environmental stress very well whereas other species are vulnerable to even minor environmental change. The advancement of scientific knowledge by the study of environmental regulation of cell and organismal function has the benefit of providing the tools for predicting, monitoring, and counteracting negative effects of environmental stress on organisms. Thus, the results of this project should have broad applicability to the general cell biology of stress and environmental adaptation. Tilapia are ideal for the proposed studies because this species is important for aquaculture in the US and worldwide. Moreover, tilapia are important from an ecological perspective as they are an invasive species in the US because of their high environmental stress tolerance and adaptability. Important broader impacts of this project also pertain to in-depth training of a postdoctoral researcher and students, including underrepresented minority students. Furthermore, a variety of research, educational, and outreach activities will be supported by this project.
