New research on magnetite in salmon noses sheds light on understanding of sensory mechanisms enabling magnetic perception across the lifespan – ScienceDaily
It is widely believed that animals such as salmon, butterflies and birds have an innate magnetic sense, allowing them to use the Earth’s magnetic field for navigation to places such as feeding and breeding grounds. .
But scientists have struggled to determine exactly how the sensory mechanism underlying magnetic perception actually works.
In an article published this week in the Proceedings of the National Academy of Sciences, an international team of researchers, including scientists from Oregon State University, presents a new theory. Magnetite crystals that form inside specialized receptor cells of salmon and other animals may have roots in ancient genetic systems that were developed by bacteria and passed on to animals long ago through evolutionary genetics.
The theory is based on new evidence from nanoscopic magnetic materials found in salmon nose cells. The main author of the article is Renee Bellinger, who began research as a doctoral student at Oregon State, completing her doctorate. in Fisheries Science in 2014.
“Cells that contain magnetic material are very rare,” said Bellinger, who now works as a research geneticist at the US Geological Survey and is affiliated with the University of Hawaii, Hilo. “We were unable to definitively prove that magnetite was the underlying key to magnetic perception in animals, but our study found that associated genes were an important tool in finding new evidence for potential function. magnetic sensors. “
“Finding magnetic receptors is like trying to find a needle in a haystack. This work paves the way for a truly brilliant ‘needle’ glow so that we can more easily find and understand receptor cells, ”Bellinger said.
The findings have the potential to be widely applied, from improving salmon management to a better understanding of how they use the ocean to targeted medical treatments based on magnetism, said co-author Michael Banks, professor. of Fisheries Genomics, Conservation and Behavior at Oregon State.
“Salmon lead a hard and fast life, going out into the ocean to specific areas to feed, then returning to their original spawning grounds where they die. They don’t have the ability to teach their offspring where to go, but the offspring always know where to go, ”Banks said. “If we can understand how animals such as salmon smell and orient themselves, there are many potential applications to help preserve the species, but also for human applications such as medicine or other technology. ‘orientation.”
Bellinger’s work builds on research conducted more than 20 years ago by Michael Walker of the University of Auckland in New Zealand, who initially traced magnetic detection to the tissues of the nose of trout.
“He reduced it to magnetite in the scent rosette,” Bellinger said. “We expected to see strings of crystals in the noses of salmon, the same way magnetite-producing bacteria grow strings of crystals and use them as a compass needle. But it turns out that the individual crystals are organized in compact clusters, like little eggs. The setup was different from the original hypothesis.
The form in which magnetite appears, as tiny crystals inside specialized receptor cells, represents biomineralization, or the process by which living organisms produce minerals. The similarity between magnetite crystals from bacteria and fish suggests they share a common evolutionary genetic history, Bellinger said.
The mechanism for the development of magnets was first developed by bacteria over two billion years ago and then passed on to animals. Today, these tools for perceiving magnetism continue to be present in a wide range of animal species, said Banks, who is affiliated with OSU’s Department of Fisheries, Wildlife and Conservation Sciences. at OSU’s College of Agricultural Sciences and at the Oregon Coastal Marine Experiment Station at OSU’s Hatfield Marine Science Center.
The process of sharing them through animal life may have been similar to the evolution of mitochondria, which control how animals release energy. Mitochondria originate from bacteria and were then transferred to other organisms, he said.
Understanding the evolutionary history of magnetite is a step towards more precisely identifying the underlying process, the researchers said. Banks, Bellinger and their colleagues would then like to test their new understanding and associated markers to deepen the mystery of why and how some life forms have well-tuned tools for long and precise migration strategies.
The co-authors of the article are Jiandong Wei of the University of Shanghai in China; Uwe Hartmann from the University of Saarland in Germany; Hervé Cadiou from the Institute of Cellular and Integrative Neurosciences in France; and Michael Winklhofer from the University of Oldenburg in Germany.
Bellinger’s work was supported in part by a Mamie Markham Research Prize; Several scholarships of up to $ 10,000 are available to support the research of Hatfield Marine Science Center graduate students each year. These funds enabled Bellinger to travel to France to conduct primary research for the project.