Ion-transport mechanisms in adaptation to extreme salinities

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This project studies how the only two animal species that flourish in inland salt lakes, like the Great Salt Lake, sense and respond to harsh changes in environmental salt content. Brine fly larvae and brine shrimp must maintain a much lower salt content than their environment, which is an energetically costly process. However, the cellular mechanisms by which they achieve this unique feat are poorly understood. The work in this project will deduce how these two organisms adapt cellular mechanisms to retain water and expel salt within environments that strongly favor the opposite. The ability to compare and contrast the mechanisms utilized by these substantially different species to combat this environmental stress will provide critical insights into their adaptation. This collaborative study links research and teaching at Texas Tech University Health Sciences Center and Illinois State University and will immerse graduate and undergraduate students in a rigorous and interdisciplinary educational setting, providing 1) a project-research-based course and 2) continuing laboratory research opportunities for undergraduates, thus creating a pathway to recruit undergraduate students into biological research. in addition to their standard training in research methods. The graduate students involved in the research efforts will also be provided with unique training on how to teach (within a course) and to become a mentor (within the laboratory). Thus, this project accomplishes a multilevel training experience that reinforces scientific skills at both the undergraduate and graduate levels, while providing training to graduate students as future mentors and faculty members. The results from this project will be disseminated by peer-reviewed publications, invited lectures, and presentations at scientific meetings.The ion-transport mechanisms that allow brine shrimp and brine fly larvae adaptation to extreme salinities remain largely unknown. This project utilizes novel integration of bioinformatics, biochemistry, and electrophysiology, to identify such ion- transporters, study their functional properties, and uncover their role and cooperation to allow these animals to thrive in an environment where all other animals die. Several hypotheses organized in three independent research aims will be tested: 1) Identify the ion transporters required for brine shrimp survival in high salinity 2) Identify the ion-transporters required for brine fly survival in high salinity 3) Elucidate the molecular mechanisms of amino acid substitutions linked to salinity adaptation. For aims 1 & 2, target ion-transport proteins will be identified in each organism by transcriptomics, and their functional role evaluated by pharmacological survival assays and siRNA methods and by expression of the identified transporters in heterologous expression systems. An essential player in the adaptation of all osmoregulating animals is the Na,K-ATPase. Most animals that adapt to both ends of the extreme salinity spectrum present radical structural modifications in regions that are critical for the interaction of the transported ions with this protein. To test if and how these modifications may provide an adaptive advantage to the extreme salinity-adapting animals that carry them, the third aim of this project specifically evaluates the stoichiometry and functional properties of Na,K-ATPases with the same structural specialties as those observed in adapting animals. Graduate and undergraduate student trainees will be supported at both institutions. Both PIs have outstanding track records involving undergraduate and graduate students in scientific discovery while authoring articles in high-impact journals.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.