Sunday, November 04, 2007

Special blue light.

We all know what migration is but, how it happens, is only being progressed in small steps. The latest addition to knowledge has appeared this week in the on-line Public Library of Science. Today’s theory is based on the cryptochrome. A cryptochrome is a blue-light sensitive molecule (birds migrate better in blue light apparently) that, when hit by a blue-photon, changes form, with part of it being passed, in one direction, to an adjoining flavin protein. This creates an instability which can be reversed by an electrical shift in the opposing direction. The rate at which this reverse shift occurs can be modulated by a surrounding magnetic field so, if it happens slowly enough a bird can calibrate the signal received against the Earth’s magnetic field and, hey presto, work out where it is. German researchers have discovered that the signal generated lasts a 1000 times longer than is necessary for the bird to interpret the signal received so, they argue, it has more than enough time to calculate where it is in respect of the Earth’s magnetic field.

The image shown is from an unrelated article but is a composite image of the magnetic ‘fields’ of the Earth.


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