Cryptochrome 2 mediates directional magnetoreception in insects
In this study, by combining behavioral and genetic approaches, we provide the first unambiguous evidence to our knowledge of a Cry-dependent sensitivity to the direction of GMF in two cockroach species.
The ability to perceive geomagnetic fields (GMFs) represents a fascinating biological phenomenon. Studies on transgenic flies have provided evidence that photosensitive Cryptochromes (Cry) are involved in the response to magnetic fields (MFs), albeit of unnatural intensities. However, Cry-dependent responses to natural MF intensities and to the direction of the MF vector have not been demonstrated previously in any organism. Birds, monarch butterflies, and many other species perceive the direction of geomagnetic field (GMF) lines, but the involvement of Cry has not been rigorously proven using genetic tools. In this study, by combining behavioral and genetic approaches, we provide the first unambiguous evidence to our knowledge of a Cry-dependent sensitivity to the direction of GMF in two cockroach species. The response was lost upon covering the eyes, demonstrating that the signal is perceived in the eye region. Immunohistochemical staining detected Cry2 in the hemispherical layer of laminal glia cells underneath the retina. Together, these findings identified the eye-localized Cry2 as an indispensable component and a likely photoreceptor of the directional magnetic compass.
Bazalova O., Kvicalova M., Valkova T., Slaby P., Bartos P., Netusil R., Tomanova K., Braeunig P., Lee H.-J., Sauman I., Damulewicz M., Provazník J., Pokorny R., Dolezel D., Vacha M. (2016) Cryptochrome 2 mediates directional magnetoreception in cockroaches. Proc. Natl. Acad. Sci. USA, doi:10.1073/pnas.1518622113
PubMed: PMCID: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4760799/