Millitesla magnetic field effects on the photocycle of an animal cryptochrome

Abstract

Millitesla magnetic field effects on the photocycle of an animal cryptochrome Sheppard DM, Li J, Henbest KB, Neil SR, Maeda K, Storey J, Schleicher E, Biskup T, Rodriguez R, Weber S, Hore PJ, Timmel CR, Mackenzie SR. Millitesla magnetic field effects on the photocycle of an animal cryptochrome. Sci Rep. 2017 Feb 8;7:42228. doi: 10.1038/srep42228. Abstract Drosophila have been used as model organisms to explore both the biophysical mechanisms of animal magnetoreception and the possibility that weak, low-frequency anthropogenic electromagnetic fields may have biological consequences. In both cases, the presumed receptor is cryptochrome, a protein thought to be responsible for magnetic compass sensing in migratory birds and a variety of magnetic behavioural responses in insects. Here, we demonstrate that photo-induced electron transfer reactions in Drosophila melanogaster cryptochrome are indeed influenced by magnetic fields of a few millitesla. The form of the protein containing flavin and tryptophan radicals shows kinetics that differ markedly from those of closely related members of the cryptochrome-photolyase family. These differences and the magnetic sensitivity of Drosophila cryptochrome are interpreted in terms of the radical pair mechanism and a photocycle involving the recently discovered fourth tryptophan electron donor. Open access paper: ncbi.nlm.nih.gov

AI evidence extraction

Main findings

Photo-induced electron transfer reactions in Drosophila melanogaster cryptochrome were influenced by magnetic fields of a few millitesla. The flavin/tryptophan radical-containing form showed kinetics that differed markedly from closely related cryptochrome-photolyase family members, and the magnetic sensitivity was interpreted in terms of a radical pair mechanism and a photocycle involving a fourth tryptophan electron donor.

Outcomes measured

• Photo-induced electron transfer reactions in Drosophila melanogaster cryptochrome
• Photocycle/kinetics of flavin and tryptophan radical-containing form of cryptochrome
• Magnetic field sensitivity consistent with radical pair mechanism and involvement of a fourth tryptophan electron donor

Limitations

• Frequency of the magnetic field exposure is not specified in the abstract.
• Exposure duration and detailed dosimetry are not provided in the abstract.
• Study context appears to be mechanistic/biophysical; implications for organism-level health outcomes are not assessed in the abstract.

{
    "study_type": "in_vitro",
    "exposure": {
        "band": null,
        "source": "laboratory magnetic field exposure",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Photo-induced electron transfer reactions in Drosophila melanogaster cryptochrome",
        "Photocycle/kinetics of flavin and tryptophan radical-containing form of cryptochrome",
        "Magnetic field sensitivity consistent with radical pair mechanism and involvement of a fourth tryptophan electron donor"
    ],
    "main_findings": "Photo-induced electron transfer reactions in Drosophila melanogaster cryptochrome were influenced by magnetic fields of a few millitesla. The flavin/tryptophan radical-containing form showed kinetics that differed markedly from closely related cryptochrome-photolyase family members, and the magnetic sensitivity was interpreted in terms of a radical pair mechanism and a photocycle involving a fourth tryptophan electron donor.",
    "effect_direction": "mixed",
    "limitations": [
        "Frequency of the magnetic field exposure is not specified in the abstract.",
        "Exposure duration and detailed dosimetry are not provided in the abstract.",
        "Study context appears to be mechanistic/biophysical; implications for organism-level health outcomes are not assessed in the abstract."
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "cryptochrome",
        "Drosophila melanogaster",
        "magnetic field",
        "millitesla",
        "photocycle",
        "electron transfer",
        "radical pair mechanism",
        "tryptophan radicals",
        "magnetoreception"
    ],
    "suggested_hubs": []
}

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