title: Observation of magnetic field effects on transient fluorescence spectra of cryptochrome 1 from homing pigeons.
abstract: Cryptochromes are suggested to be involved in the bird magnetoreception based on the radical pair mechanism (RPM), a well established theory of weak magnetic field effects on chemical reactions. Two members of cryptochrome/photolyase family were found to respond to magnetic field, however, no direct responses of bird cryptochrome to magnetic field as weak as the Earth's magnetic field have been obtained so far. In this study, we used transient fluorescence spectroscopy to characterize the weak magnetic field effects of bird cryptochromes. To do this, we cloned the cryptochrome 1 gene (clCRY1) from the retina of homing pigeons (Columba livia), expressed it in insect Sf9 cells and analyzed the transient fluorescence of purified clCRY1 by application of 45-300 μT magnetic fields. The flavin adenine dinucleotide (FADox ) and glucose oxidase (GOD) in PBS buffer were set as controls which could be excited by light to generate radicals, but would not be sensitive to magnetic field. We observed that the transient fluorescence spectra of clCRY1 were sensitive to the applied magnetic field at room temperature. Our result provides a new proof of the cryptochrome-based model of avian magnetoreception in vitro.
authors.affiliation: Department of Chemistry and Biology, National University of Defense Technology, Changsha, China.
authors.forename: Xian-li
authors.initials: XL
authors.lastname: Du
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Wei-song
authors.initials: WS
authors.lastname: Pan
authors.forename: Qi-jun
authors.initials: QJ
authors.lastname: Liu
authors.forename: Xiao-jie
authors.initials: XJ
authors.lastname: Wang
authors.forename: Wen-jian
authors.initials: WJ
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins / Q000737:chemistry* / Q000235:genetics; D003001:Cloning, Molecular; D010856:Columbidae; D056931:Cryptochromes / Q000737:chemistry* / Q000235:genetics; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D005453:Fluorescence; D015870:Gene Expression; D005949:Glucose Oxidase / Q000737:chemistry; D006702:Homing Behavior / Q000502:physiology; D060526:Magnetic Fields; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012160:Retina / Q000737:chemistry; D016415:Sequence Alignment; D061987:Sf9 Cells; D013050:Spectrometry, Fluorescence; D018411:Spodoptera
chemical_list: D030161:Avian Proteins; D056931:Cryptochromes; D011994:Recombinant Proteins; D005182:Flavin-Adenine Dinucleotide; D005949:Glucose Oxidase