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L‘un des “sixièmes” sens les plus remarquables du règne animal est la magnétoréception, la capacité à détecter les champs magnétiques, mais son fonctionnement exact reste un mystère. Récemment, des chercheurs japonais ont peut-être trouvé un élément essentiel de l’énigme, en réalisant les premières observations de cellules vivantes et non altérées réagissant à des champs magnétiques.

Guru Med | 9 Jan 2021

"On sait que de nombreux animaux se déplacent en détectant le champ magnétique terrestre, notamment les oiseaux, les chauves-souris, les rats-taupes, les anguilles, les baleines… et, selon certaines études, peut-être même les humains. Cependant, le mécanisme exact en jeu chez les vertébrés n’est pas bien compris. Une hypothèse suggère que c’est le résultat d’une relation symbiotique entre les animaux et les bactéries qui détectent le champ magnétique."

"... Dans les cellules vivantes des animaux disposant d’une magnétoréception, on pense que des protéines appelées cryptochromes seraient les molécules qui subissent ce mécanisme de paires radicales. Et à présent, des chercheurs de l’université de Tokyo ont observé pour la première fois des cryptochromes réagissant aux champs magnétiques."

(...)

• L’étude publiée dans The Proceedings of the National Academy of Sciences : Cellular autofluorescence is magnetic field sensitive et présentée sur le site de l’Université de Tokyo : Magnets dim natural glow of human cells, may shed light on how animals migrate.

[Image] A short burst of blue light shines on a specific area (blue circle) of a single HeLa (human cervical cancer) cell and then the light that the cell emits back is measured (center). The cellular autofluorescence occurs only in the area that was irradiated with blue light (center, right). © Ikeya and Woodward, CC BY, originally published in PNAS DOI: 10.1073/pnas.2018043118

Lignes haute tension, téléphones portables, Wi-Fi… Ces ondes agiraient sur le cryptochrome, une protéine au cœur d’un mécanisme pouvant engendrer la production de toxines.

Publié le 16.10.2018 • Mis à jour le 17.10.2018 (accès limité)

• Low-intensity electromagnetic fields induce human cryptochrome to modulate intracellular reactive oxygen species, 02.10.2018 https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2006229

Results

"... We used the fruitfly Drosophila melanogaster, which display a natural behavioral avoidance response to static magnetic fields [16]. Adult flies were placed on square petri plates to lay eggs for 24 hours and were subsequently removed. The ensuing hatched larva migrated freely over the plate for several days before choosing a location to attach to and form sessile pupa for metamorphosis. These pupae were located randomly around the perimeter of the plate, with preference for the corners (Fig 1).

We tested magnetic sensitivity, with a coil generating continuous PEMF at 10 Hz, with peak amplitude of 1.8 mT at the level of the larvae (S1 and S2 Figs), placed underneath one of the 4 corners of the petri plate (see Materials and methods). Fly larvae grown under these conditions avoided the corner of the petri plate above the PEMF device (Fig 1A) compared to the other corners. Both Canton S (WTS) and Oregon (WTO) wild-type fly strains showed this avoidance response (Fig 1A and 1B) in blue light (which activates Drosophila cryptochrome; Fig 1B) but not in red light (which does not activate Drosophila cryptochrome; S3 Fig).

As a control, a 1.0 mm mu-metal plate, which blocks static or low-frequency magnetic fields, was inserted between the magnetic coil and the petri plate containing the fly larvae. In these conditions, larvae did not show the avoidance response (S3 Fig). As a further control, we tested a coil in which the wire had been wound in an antiparallel fashion in order to cancel the magnetic field without altering the current in any way (see Materials and methods); this was also ineffective in causing an avoidance response. We next observed that fly mutants deficient in cryptochrome (cryb and cry02; [27]) did not avoid the PEMF, confirming a role for cryptochrome in this response.

Finally, we tested transgenic fruitflies expressing the human cryptochrome-1 (HsCry1) protein in Drosophila cryptochrome-deficient strains as described previously [16, 27]). HsCry1 expression indeed restored the behavioral avoidance response to PEMF in flies lacking their endogenous cryptochrome (Fig 1B). These results indicate that PEMF can be detected by insects through the action of either Drosophila (DmCry) or human (HsCry1) cryptochrome, consistent with the response to static magnetic fields in this organism [16]."