The sensory mechanisms that enable magnetic perception in life

But scientists have struggled to determine exactly how the underlying sensory mechanism of magnetosensing works
.

In a paper published this week in the Proceedings of the National Academy of Sciences, an international research team of scientists from Oregon State University outlines a new theory
.

The magnetite crystals that form inside special receptor cells in salmon and other animals may be related to ancient genetic systems that were developed from bacteria and passed on to animals through evolutionary genetics long ago

The theory is based on new evidence of nanomagnetic materials found in salmon nose cells
.

The paper's lead author is Renee Bellinger, who began the research as a PhD student at Oregon State and completed her PhD in Fisheries Science in 2014

"Cells that contain magnetic material are very rare," said Bellinger, now a research geneticist with the U.
S.
Geological Survey at the University of Hawaii at Hilo
.

"We couldn't definitively prove that magnetite is a potential key to magnetic perception in animals, but our study uncovered the genes involved, which is an important tool for uncovering new evidence of how potential magnetic sensors work

"Finding magnetoreceptors is like looking for a needle in a haystack
.

This work paves the way for making 'needles' glow really bright so we can more easily find and understand receptor cells," Bellinger said

The findings have potential for a wide range of applications, from improving salmon management, to better understanding how they use the ocean, to magnetism-based targeted medicine, says Michael Banks, professor of fisheries genomics, conservation and behavior at OSU ( Michael Banks) said
.

"Salmon live a hard and fast life, foraging in specific areas of the ocean and then returning to their original spawning grounds, where they die
.

They don't have a chance to teach their offspring where to go, but the offspring still somehow know where to go.

Bellinger's work builds on research more than 20 years ago by Michael Walker of the University of Auckland in New Zealand, who initially tracked magnetic induction in trout nose tissue
.

"He narrowed it down to magnetite in an olfactory wreath," Bellinger said
.

"We wanted to see chains of crystals in salmon's noses, just as magnet-producing bacteria grow chains of crystals and use them as a compass.

Magnetite occurs as tiny crystals inside specialized receptor cells and represents biomineralization, or the process by which an organism produces minerals
.

The similarities between the magnetite crystals of bacteria and fish suggest that they share a common evolutionary genetic history, Bellinger said

The mechanism for developing magnets was developed by bacteria more than 2 billion years ago and then passed on to animals
.

Today, these tools for detecting magnetism continue to exist in a wide range of animal species, said Banks, who is affiliated with the Division of Fisheries, Wildlife and Conservation Sciences in OSU's College of Agricultural Sciences and the OSU Hatfield Marine Science Center.

The process of sharing them throughout an animal's life cycle may be similar to the evolution of mitochondria, which control how animals release energy
.
Mitochondria originated in bacteria and then moved into other organisms, he said
.

Understanding the evolutionary history of magnetite is a step toward further identifying its underlying processes, the researchers said
.
Banks, Bellinger and colleagues next want to test their new understanding and associated markers to further explain why and how some life forms have good tools for long-term and precise migration strategies
.

Co-authors of the paper are Jiandong Wei of Shanghai University in China; Uwe Hartmann of Saarland University in Germany; Herve Cadiou of the French Institute for Cellular and Integrative Neurosciences; and Michael Winkerhoff of the University of Oldenburg in Germany
.

Bellinger's research is supported in part by the Mamie Markham Research Award; several fellowships of up to $10,000 each year at the Hatfield Marine Science Center support graduate student research
.
The funds allowed Bellinger to travel to France to conduct preliminary research for the project
.

Journal Reference :

1. M.
   Renee Bellinger, Jiandong Wei, Uwe Hartmann, Hervé Cadiou, Michael Winklhofer, Michael A.
   Banks.
   Conservation of magnetite biomineralization genes in all domains of life and implications for magnetic sensing .
   Proceedings of the National Academy of Sciences , 2022; 119 (3): e2108655119 DOI: 10.
   1073/pnas.
   2108655119