Identifying the Genetic Basis of Magnetic Sensory Perception Cells of Fish

Fish can sense geomagnetic field information, but determining which receptor cells are involved in this sensory system has eluded scientific understanding.  One idea is that magnetic crystals of magnetite contained inside receptor cells interact with geomagnetic fields and convert that information into cellular signals.  We studied the genetic underpinnings of magnetite crystal formation in fish by characterizing the full complement of genes expressed in magnetic and non-magnetic olfactory epithelial cells of Chinook salmon (Oncorhynchus tshawytscha).  Through bioinformatics analyses, we identified approximately 1000 genes differentially expressed in the magnetic cell type.  Many of these candidate genes are similar to ones associated with magnetite crystal formation in prokaryotes.  Thus, we are testing the hypothesis that a sub-set of our candidate genes represents a “magnetosome gene island” transferred from prokaryotes to eukaryotes through an ancient lateral gene transfer event.  Our research is foundational for developing gene-based techniques to interrogate cells for response to magnetic treatments and, if responsive, their magnetic sensitivity thresholds.  Study findings are relevant for determining under which conditions wave energy devices might impact magnetic signal processing, and understanding how magnetic sense, genetic programming, and memory may modulate migratory distributions.