Collaborative Research: Costs and Advantages of a Novel Sodium Channel Mutation in Copepods

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Toxic algal blooms pose a threat to fisheries and public health. A key issue for understanding the effects of toxic algae on aquatic ecosystems is how grazers evolve adaptations to algal toxins. Adaptation of copepods (the most abundant multicellular animals in the sea) to microalgae that produce potent neurotoxins (called saxitoxins, STX) has been previously demonstrated. STX blocks sodium (Na+) channels and interrupts nerve transmission signals. A novel mutation that is located in the inner portion of the Na+ channel, and leads to persistent electrical currents when the channel is inactivated (i.e., a leaky channel), has been identified. Leaky channels result in unintended nerve transmission signals and cell hypersensitivity; hence, they are considered to be very costly to individuals. However, it is hypothesized that in the presence of STX, the leaky channel mutation is advantageous because STX blockage of leaky channels reduces the likelihood of unintended nerve transmission signals and cell hypersensitivity. This project represents an interdisciplinary collaboration between labs at University of Connecticut and the University of Florida with expertise in molecular techniques, neurobiology, and zooplankton ecology and evolution. Expected results are: 1) Development of genetic markers for specifically detecting wild and mutant Na+ channels in individual copepods, 2) Neurophysiological characterization of the functional properties of the mutant Na+ channel and its responses to STX, 3) Quantification of the costs and benefits to individuals bearing the mutation responsible for the leaky Na+ channel. This research can potentially lead to the demonstration of a new molecular mechanism of neurotoxin adaptation, and inform a variety of fields of research from neurobiology to ecology and evolution. The broader impacts of this research are: 1) New key information for predicting whether grazers can control toxic blooms and toxin transfer to fish and shellfish. 2) Collaboration with professional educators to translate results from this study and the toxin adaptation literature into prepared curricular materials that meet national science standards. The material will be made widely available via a website and workshops presented at conference meetings of scientists and secondary educators. 3) Presentations in lecture series aimed at lay audiences. 4) Training of undergraduate and graduate students in an interdisciplinary environment.