Identifying the Genetic Basis of Magnetite-Based Candidate Magnetoreceptors of Salmonids

Highly magnetic receptor cells of trout that contain biogenic crystals of magnetite are hypothesized to transduce geomagnetic information into neural signals utilized by fish as orientation cues during migration.  However, because these cells are extremely difficult to find and study, whether these cells are capable of magnetic signal transduction is not yet confirmed.  Moreover, virtually nothing is known about the genetic underpinnings of magnetite crystal formation in eukaryotes.  Here, from Chinook salmon olfactory epithelium tissue, magnetic and non-magnetic cell mRNA transcripts were isolated and sequenced using RNA-Seq. Approximately 500 genes were differentially expressed in the magnetic-cell sample, with annotation of the full olfactory rosette transcriptome in-progress.  The genes most plausibly involved in magnetic sensory transduction are being developed into fluorescent probes and tested for hybridization to target cells.  If successful, a probe can then be used for rapid and efficient cell location to conduct in situ tests of response to magnetic field treatments.  Findings have relevance to resolving if salmon and other marine organisms imprint on magnetic fields and contributing to our understanding of how magnetic sense, genetic programming, and memory are involved in migratory distributions.