They call him Magneto.
“It’s a nickname my colleagues gave me,” said Illinois State Biology Professor Andres Vidal-Gadea, who studies how animals detect the Earth’s magnetic field.
Now his colleagues can call him something else: the world leader in understanding the key to how animals migrate.
Laboratories around the globe have been racing to be the first to find the
receptor in the brain that helps animals use the planet’s magnetic field to navigate.
A research team that Vidal-Gadea led while a postdoctoral student at the University of Texas at Austin discovered the sensor in tiny worms called C. elegans. The research, published last summer in the scientific journal eLife, places Vidal-Gadea on the frontier of neuroethology—or the study of how animal behavior is linked to the nervous system.
“The selective force of magnetic fields have long been recognized and appreciated for their role in migration. But the search for how the magnetic fields are detected by organisms has remained a mystery,” said Russell Fernald, the Benjamin Scott Crocker Professor of Biology at Stanford University, who was the reviewing editor of eLife. “The work by Vidal-Gadea et al. now provides the first example of a mechanism that answers the question.”
Animals and magnetism
Researchers have known for years that animals such as geese and sea turtles use the Earth’s magnetic field in migration. “When you think of a bird flying over thousands of miles of sky, or a sea turtle in an ocean where everything is blue, there are no landmarks,” Vidal-Gadea said. “Animals use the magnetic field when traveling over vast distances.”
What researches have not understood—until now—is how the brain receives and interprets the magnetic field. “We have known that many animals have a set of magnetic beads that act like the needle of a compass, but what we did not know is how the brain senses it. We did not know what the magnetic receptor looked like,” Vidal-Gadea said.
Finding exactly where the magnetic beads lie in a gigantic migrating whale or tracking the same birds that fly 5,000 miles is generally not conducive to a lab environment. Instead, Vidal-Gadea concentrated on C. elegans. The worms, which reach only 1 millimeter in length, possess an antenna-like structure that allows them to navigate through the soil. “There are a lot of critters in the soil that use magnetic fields to do vertical migrations,” he said. “Now we have a better idea how they do it.”
These worms possess only 302 neurons, making them ideal for research. The team found the sensor in a neuron that had been well studied. “This same neuron detects carbon dioxide and soil temperature for the worms, so it makes sense that it is also the magnetic receptor in what amounts to a depth receptor,” said Vidal-Gadea. When the temperature of the soil rises, the worms tend to migrate down to cooler soil, toward the roots of plants, where the C. elegans’ main food source, bacteria, tends to grow.
Getting to molecular level
In Vidal-Gadea’s lab, students have continued to run tests to understand the sensors on a molecular level, with the hopes of helping researchers across the globe understand magnetic detection. Using fluorescent dyes, his team tags the very proteins that convert the forces of the magnetic field into information the neurons use.
Another experiment is exploring how the magnetic field properties can impact the sensors. Standing in front of a large, wooden crate lined with shining copper wires, Vidal-Gadea asked, “Do you remember in science class in school when you would wrap a wire around a bolt and make a magnet? This is a lot like that, just bigger.”
Inside the box sat a case where lab students placed a small petri dish holding around 100 C. elegans. The case looks oddly familiar—gray and red blocks stacked on top of each other. “It’s made of Legos,” Vidal-Gadea said with a smile. “We needed something not made of metal.” Standing firmly on guard in front of the case is a tiny Lego figure of the X-Men character Magneto, in a nod to Vidal-Gadea’s nickname.
Vidal-Gadea explained how the surrounding wires allow those in the lab to manipulate the magnetism within the box. “We can simulate almost no magnetic field at all, and see how that affects the worms.” The C. elegans worms only take three days to go from egg to adulthood, so the experiment can bring quick results.
With the crate experiment, Vidal-Gadea hopes to discover what happens when worms are born with no magnetic field at all. He believes what may happen would be similar to animals, like humans, that have little need for using the magnetic field. They generally don’t develop the sensors that detect it. “So much around us generates a magnetic field, and we interact with that. If we could see it, it would look like a Van Gogh painting with fields swirling like Starry Night,” said Vidal-Gadea. “Humans are a bit blind to it. Maybe our ancestors needed the sensor, but today we don’t need to migrate 5,000 miles, or use it to search for food.”
Vidal-Gadea has been studying magnetic detection since his undergraduate days at the University of Victoria in British Columbia, Canada. Though his work and acclaim have taken him to the University of Texas, Louisiana State University, and Southampton University in England, it was at Illinois State that Vidal-Gadea decided to continue his groundbreaking research.
“The people here are incredible—the faculty, the chance to work with students, it all appealed to me,” said Vidal-Gadea. “The neurobiologists here are making advances that complement the work my lab is doing. It all fits together nicely.”
Vidal-Gadea said there is much to learn about how animals interact with the magnetic field, and that is what makes the topic so exciting. “We didn’t understand how many aspects of gravity were necessary to human functions until we sent astronauts into space and noted how a lack of gravity impacted us,” he said. “It may be the same with magnetic fields. We may have just scratched the surface, and it will be fun to see where we can go next.”
Rachel Hatch can be reached at rkhatch@IllinoisState.edu.