Dog-like carnivores and some primate species may have a magnetic compass similar to that of birds.
Cryptochromes are light-sensitive molecules that exist in bacteria, plants and animals. In animals, they are involved in the control of the body’s circadian rhythms.
In birds, cryptochromes are also involved in the light-dependent magnetic orientation response based on the Earth’s magnetic field: cryptochrome 1a is located in photoreceptors in birds’ eyes and is activated by the magnetic field.
Now researchers from the Max Planck Institute for Brain Research in Frankfurt have also detected cryptochrome 1 in photoreceptors in several mammalian species. Therefore, it is possible that these animals also have a magnetic sense that is linked to their visual system.
The perception of the Earth’s magnetic field is used by many animal species for orientation and navigation. A magnetic sense is found in some insects, fish, reptiles, birds and mammals, whereas humans do not appear to be able to perceive the Earth’s magnetic field.
The magnetic sense in migratory birds has been studied in considerable detail: unlike a boy scout’s compass, which shows the compass direction, a bird’s compass recognizes the inclination of the magnetic field lines relative to the Earth’s surface. Surprisingly, this inclination compass in birds is linked to the visual system as the magnetic field activates the light-sensitive molecule cryptochrome 1a in the retina of the bird’s eye. Cryptochrome 1a is located in the blue- to UV-sensitive cone photoreceptors and only reacts to the magnetic field if it is simultaneously excited by light.
Together with colleagues from the Ludwig-Maximilians-University Munich, the Goethe University Frankfurt, and the Universities of Duisburg-Essen and Göttingen, Christine Nießner and Leo Peichl from the Max Planck Institute for Brain Research in Frankfurt investigated the presence of cryptochrome 1 in the retinas of 90 species of mammal.
Mammalian cryptochrome 1 is the equivalent of bird cryptochrome 1a. With the help of antibodies against the light-activated form of the molecule, the scientists found cryptochrome 1 only in a few species from the carnivore and primate groups. As is the case in birds, it is found in the blue-sensitive cones in these animals.
The molecule is present in dog-like carnivores such as dogs, wolves, bears, foxes and badgers, but is not found in cat-like carnivores such as cats, lions and tigers. Among the primates, cryptochrome 1 is found in the orang-utan, for example. In all tested species of the other 16 mammalian orders, the researchers found no active cryptochrome 1 in the cone cells of the retina. .
The active cryptochrome 1 is found in the light-sensitive outer segments of the cone cells. It is therefore unlikely that it controls the animals’ circadian rhythms from there, as this control occurs in the cell nucleus which is located a considerable distance away. It is also unlikely that cryptochrome 1 acts as an additional visual pigment for colour perception. The researchers thus suspect that some mammals may use the cryptochrome 1 to perceive the Earth’s magnetic field. In evolutionary terms, the blue cones in mammals correspond to the blue- to UV-sensitive cones in birds. It is therefore entirely possible that the cryptochrome 1 in mammals has a comparable function.
Observations of foxes, dogs and even humans actually indicate that they can perceive the Earth’s magnetic field. For example, foxes are more successful at catching mice when they pounce on them in a north-east direction. “Nevertheless, we were very surprised to find active cryptochrome 1 in the cone cells of only two mammalian groups, as species whose cones do not contain active cryptochrome 1, for example some rodents and bats, also react to the magnetic field,” says Christine Nießner.
One possible explanation for this is that animals can also perceive the magnetic field in a different way: for example, with the help of magnetite, microscopic ferrous particles in cells. A magnetite-based magnetic sense functions like a pocket compass and does not require any light. Mole rats, which live in lightless tunnel systems, orient using this kind of compass. Birds also have an additional orientation mechanism based on magnetite, which they use to determine their position.
Many fundamental questions remain open in the research on the magnetic sense. Future studies will have to reveal whether the cryptochrome 1 in the blue cones is also part of a magnetic sense in mammals or whether it fulfils other tasks in the retina.
Original publication (Open Access):
Christine Nießner, Susanne Denzau, Erich Pascal Malkemper, Julia Christina Gross, Hynek Burda, Michael Winklhofer, Leo Peichl (2016) Cryptochrome 1 in Retinal Cone Photoreceptors Suggests a Novel Functional Role in Mammals. Scientific Reports 6, 21848; doi: 10.1038/srep21848.
Dr. Christine Nießner
Max Planck Institute for Brain Research, Frankfurt/M.
Telephone: +49 69 96769-239
Prof. Dr. Leo Peichl
Max Planck Institute for Brain Research, Frankfurt/M.
Telephone: +49 69 96769-348
Dr. Arjan Vink | Max-Planck-Institut für Hirnforschung
Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University
How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy