Meeting Abstract
Despite the prevalence of a magnetic sense among diverse taxa, little evidence exists for both the magnetoreceptor and the molecular mechanism responsible. There are currently two hypotheses: 1) light-dependent electron transfer in photoreceptive proteins and 2) interactions of magnetic particles (e.g., magnetite) with cells. In rainbow trout (Oncorhynchus mykiss), the availability of a genome sequence and a variety of behavioral and physiological evidence supporting the presence of magnetite-based magnetoreception make it an excellent model for molecular studies. In this study, we investigated the effects of a magnetic pulse on gene expression in the brain and retina of rainbow trout using next-generation sequencing. In the brain, we found that the magnetic pulse altered the expression of genes associated with iron-ion transport, such as the iron-sequestering protein frim, in addition to genes associated with the development and repair of photoreceptive structures (e.g. crggm3, purp, prl, gcip, crabp1 and pax6). In contrast with the brain, gene expression both between and within the left and right retinae were unaffected by the magnetic pulse, thus suggesting a magnetoreceptor or mechanism located elsewhere. Taken together, our results demonstrated possible roles of iron-binding and trafficking proteins and non-visual encephalic photoreceptors in magnetoreception, and the potential for inadvertent effects of a magnetic pulse on processes unrelated to a magnetic sense. This study is the first to use genomic approaches to characterize magnetite-based magnetoreception in trout and contributes to our understanding of the molecular mechanisms of this enigmatic sense.
