What Can The Magnetic Compass of Birds Teach Us About Our Own Biology?

The Magnetic Compass of Birds

Interestingly, birds achieve magnetic orientation not by sensing polarity, but by following the axial routes of magnetic field lines. While various theories initially attempted to explain this capability, it is now understood that birds orient their flight using cryptochromes located in photoreceptor neurons. These cryptochromes facilitate the detection of magnetic fields when exposed to blue light, generating a radical pair. The correlation of these pairs, either parallel or antiparallel, is influenced by magnetic fields. Retinal neurons, which are light-sensitive, play a crucial role in this process.

According to Professor Pinzon-Rodriguez, the use of local radio technology disrupts the Earth’s magnetic field, complicating migratory flights for birds.

"Birds completely lost their magnetic orientation in the presence of radio waves, at levels a thousandth of the safe limit"

One study found that birds could not navigate effectively in areas with high electromagnetic field (EMF) pollution. However, when placed in huts grounded to attenuate surrounding EMFs, the birds regained their orientation abilities, losing this capability once the grounding was removed.

In a separate study on Robins, the birds completely lost their magnetic orientation in the presence of radio waves at levels a thousandth of the safe limit set by the World Health Organization (WHO). Research biologist Henrik Mouritsen commented, “The effects of these weak electromagnetic fields are remarkable: They disrupt the functioning of an entire sensory system in a healthy higher vertebrate.” The research, spanning seven years and corroborated through double-blind studies by successive generations of graduate students, strongly supports these findings.

Blue light regulates numerous cellular responses across bacteria, plants, and animals, including photoreactivation, plant development, and circadian photoentrainment. These activities are mediated by a family of highly conserved flavoproteins known as the photolyase/cryptochrome family. Photolyase binds to UV-induced DNA photoproducts and repairs them in a process called photoreactivation, where blue light initiates cyclic electron transfer to restore DNA integrity. Cryptochrome, sharing significant sequence identity with photolyase, acts as the primary circadian photoreceptor and a component of the molecular clock in animals, including mammals, and regulates growth and development in plants.

Biological rhythms control many metabolic and physiological processes, with a natural cycle of approximately 24 hours, commonly referred to as the circadian rhythm. Almost all behaviors and physiological activities, including those in bacteria, fungi, plants, fruit flies, fish, mice, and humans, follow this 24-hour cycle. In mammals, the suprachiasmatic nucleus (SCN) in the brain functions as the master clock, sensing light signals and transmitting them to peripheral clock systems in tissues such as the liver, muscle, and skin. This process initiates transcription factors that drive tissue-specific gene expression. 

What Do CRYs Teach us About Human Diseases like Cancer?

Circadian components interact with metabolic enzymes and oncogenic factors derived from the tumor microenvironment to construct a complex network, which may account for circadian desynchrony and metabolic dysrhythmia in cancer cells. Elements such as REV-ERBα and cryptochromes (CRYs) might play differential or even opposing roles in various types of cancer. As most of these family members function as transcription factors, they may be recruited to different transcriptional activator or repressor complexes in specific cancer cell scenarios, thereby influencing distinct transcriptional programs and downstream signaling pathways.

Clearly, our circadian rythms can be upset in a similar manner as the magnetic compass of birds, by disorienting the crytochomes ability to provide circadian balance. In future articles we will examine the role of EMFs in human health, and the complicated health effects these kinds of radiation have on all organisms. 

References

1. University of Oldenburg. "'Electrosmog' disrupts orientation in migratory birds, scientists show." ScienceDaily, 8 May 2014. <www.sciencedaily.com/releases/2014/05/140508163644.htm>.

2. Engels, S., Schneider, N.L., Lefeldt, N. et al. "Anthropogenic electromagnetic noise disrupts magnetic compass orientation in a migratory bird." Nature 509, 353-356 (2014). https://doi.org/10.1038/nature13290.

3. Thompson, C.L., & Sancar, A. (2002). "Photolyase/cryptochrome blue-light photoreceptors use photon energy to repair DNA and reset the circadian clock." Oncogene, 21(58), 9043-9056. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10310980/.