A certain protein could possibly be the key to understanding navigation in birds

April 4, 2018 by Bob Yirka, Phys.org report
Credit: CC0 Public Domain

A team of researchers at Lund University has found evidence that suggests a certain protein plays a prominent role in bird navigation. They have published their findings in Journal of the Royal Society Interface.

Birds that are able to migrate great distances obviously have some form of system—they stop at the same places and have very clear destinations in mind. But how do they do it? In recent years, some in the field believed it had to do with iron-rich cells in their beaks serving as mini-compasses, but this theory has had some problems, such as how the translate beak sensations to directional signals. In this new effort, the suggest it is not the cells in the beak that are responsible, but a type of protein that exists in their eyes. The researchers came to this conclusion by studying the brains, muscles and eyes of . More specifically, they studied Cry1, Cry2 and Cry4, proteins associated with the . The researchers found that Cry1 and Cry2 levels tend to rise and fall throughout each day, but Cry4 remains constant, suggesting it has another purpose.

The researchers chose to study these particular proteins because they are made of a type of molecule that sometimes has an odd number of electrons, leaving some unpaired, and thus sensitive to a magnetic field. They also found that Cry4 tends to exist in clusters in a part of the bird retina that tends to get a lot of light and which is sensitive to blue light—this is important because prior studies have shown that birds are only able to navigate when blue light is available. Taken together, the evidence suggests that the protein plays a strong role in navigation.

The study does not prove that the Cry4 is the key to bird navigation, but it makes a strong case for it. Earlier this month, a Danish and German team of researchers studying robins found that Cry4 levels also remain constant each day, but rise during the migratory season.

Explore further: Migratory birds eye-localized magnetoreception for navigation

More information: Atticus Pinzon-Rodriguez et al. Expression patterns of cryptochrome genes in avian retina suggest involvement of Cry4 in light-dependent magnetoreception, Journal of The Royal Society Interface (2018). DOI: 10.1098/rsif.2018.0058

The light-dependent magnetic compass of birds provides orientation information about the spatial alignment of the geomagnetic field. It is proposed to be located in the avian retina, and be mediated by a light-induced, biochemical radical-pair mechanism involving cryptochromes as putative receptor molecules. At the same time, cryptochromes are known for their role in the negative feedback loop in the circadian clock. We measured gene expression of Cry1, Cry2 and Cry4 in the retina, muscle and brain of zebra finches over the circadian day to assess whether they showed any circadian rhythmicity. We hypothesized that retinal cryptochromes involved in magnetoreception should be expressed at a constant level over the circadian day, because birds use a light-dependent magnetic compass for orientation not only during migration, but also for spatial orientation tasks in their daily life. Cryptochromes serving in circadian tasks, on the other hand, are expected to be expressed in a rhythmic (circadian) pattern. Cry1 and Cry2 displayed a daily variation in the retina as expected for circadian clock genes, while Cry4 expressed at constant levels over time. We conclude that Cry4 is the most likely candidate magnetoreceptor of the light-dependent magnetic compass in birds.

Related Stories

News about the light-dependent magnetic compass of birds

June 6, 2016

Birds have a light-dependent compass in their eyes. This compass gives them information about the direction of the Earth's magnetic field. Prof. Roswitha Wiltschko's research group at Goethe University Frankfurt, together ...

Even non-migratory birds use a magnetic compass

May 18, 2017

Not only migratory birds use a built-in magnetic compass to navigate correctly. A new study from Lund University in Sweden shows that non-migratory birds also are able to use a built-in compass to orient themselves using ...

Birds 'See' Earth's Magnetic Field

November 16, 2009

When birds migrate over long distances -- sometimes thousands of miles -- they usually end up in exactly the same place year after year. Such accurate feats of navigation, accomplished by millions of birds every year, have ...

More light shed on how pigeons navigate

April 27, 2012

(Phys.org) -- Pigeons are renowned for their ability to find their way home from a release point hundreds of miles away, but scientists have never fully understood how they are able to achieve the feat. Now a new study has ...

Recommended for you

How quinoa plants shed excess salt and thrive in saline soils

September 21, 2018

Barely heard of a couple of years ago, quinoa today is common on European supermarket shelves. The hardy plant thrives even in saline soils. Researchers from the University of Würzburg have now determined how the plant gets ...

Basking sharks can jump as high and as fast as great whites

September 20, 2018

A collaborative team of marine biologists has discovered that basking sharks, hundreds of which are found off the shores of Ireland, Cornwall, the Isle of Man and Scotland, can jump as fast and as high out of the water as ...

Decoding the structure of an RNA-based CRISPR system

September 20, 2018

Over the past several years, CRISPR-Cas9 has moved beyond the lab bench and into the public zeitgeist. This gene-editing tool CRISPR-Cas9 holds promise for correcting defects inside individual cells and potentially healing ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Apr 04, 2018
Remove 1 Gene AFTER 1 Gene in "Definitely Migratory" Birds (That Migrate 1000s of Miles only) during their Embryonic Development while they are still within their Egg. See Lack of Which will make the feature Disappear. Focus upon it Carefully.
Then Add Back that Gene to its Babies later on and See what they do ! If they do get back that habit, DON'T ADD TO HUMANS....EXCEPT To Those that Prohibit them unnecessarily !

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.