Magnetic Crystals, Guides for Animals, Found in Humans
PASADENA, Calif., May 11 — An intriguing claim that human brain cells possess crystals of a highly magnetic mineral known as magnetite was described today by Dr. Joseph Kirschvink, a professor at the California Institute of Technology.
Other scientists are likely to withhold belief until Dr. Kirschvink's finding has been confirmed in independent laboratories. His article describing his work was rejected by three leading research journals: Nature, Science and The New England Journal of Medicine.
Dr. Kirschvink says it has been accepted, however, by another journal, The Proceedings of the National Academy of Sciences, and will appear in a future issue. Dr. Kirschvink elaborated on his results today at a news conference at Caltech.
That magnetite, one of the hardest metals on earth, is synthesized by the human brain "is sure to astound most scientists," Dr. Kirschvink said, but what it is doing there is a "total mystery." It might be a vestige from evolution and serve no purpose, he said. Or it could play a role in biology, explaining why electromagnetic fields have been associated with brain cancer and leukemia and why certain odd blips, called spin echoes, show up on magnetic resonance images of the brain.
Dr. Kirschvink is at present a lonely voice because of the rarity of his research field. He has built what he says is the only laboratory in the world dedicated to finding biomagnetic materials in animal tissue. It is a tiny clean room, shielded from the earth's magnetic field by six tons of transformer steel, in the basement of the geology building at Caltech. It houses one of the world's most powerful superconducting magnetometers, an instrument for measuring the faintest magnetic moments in rocks -- or animals.
In this laboratory, Dr. Kirschvink has already measured and extracted microscopic magnetic crystals from bacteria, salmon and tuna. He could not get financing to try the same in homing pigeons, turtles, monarch butterflies, shrimps, barnacles, bats and rodents.
The National Institutes of Health and other agencies that finance research have balked at supporting the work, he said, "because they can't understand what a geologist is doing fooling around with human brain tissue."
To be rejected by financing agencies and leading journals is the common fate of scientists with profound but radically new insights, as well as of those who are merely wrong. It is too early to tell which category Dr. Kirschvink's work falls into. But within the small group of perhaps a dozen researchers worldwide who study biomagnetism, he is highly regarded. Opinions on Researcher
"Joe is the only person who has tried to carefully isolate these materials," said Richard Frankel, a leading expert on magnetic bacteria who is a physics professor at California Polytechnic State University in San Luis Obispo. "If something is in low concentrations in tissue, you have to be ultra careful about contamination. He goes the extra mile."
Kenneth H. Nealson, an expert on biomineralization who is a professor of biology at the University of Wisconsin in Milwaukee, said: "Joe is a young, ambitious, very good person at Caltech who is at the top of his field. But whenever you put out a new hypothesis, you step on important toes. This makes it hard to get funding when money is tight."
Dr. Mitchell Sogin of the Woods Hole Marine Biological Laboratory, a leading authority on molecular evolution, about which Dr. Kirschvink has published several papers, said, "I've never heard of the guy."
Lynn Margulis, a leading authority on the evolution of life who is a professor of botany at the University of Massachusetts at Amherst, said: "Kirschvink is a very clever researcher who tends to be in too much of hurry, and therefore requires other scientists to follow up on his pioneering work." Origin of Concept
Dr. Kirschvink's interest in biomagnetism began 20 years ago when he was an undergraduate at Caltech with a double major in biology and geology. In geology class, he was taught that magnetite is formed by geologic processes. One day his adviser, a biologist, handed him a primitive mollusk whose teeth contained large amounts of biologically formed magnetite. "The entire tongue plate will stick to an ordinary hand magnet," Dr. Kirschvink said. "It was the most fascinating thing I'd ever seen."
Soon afterward scientists stumbled on a family of bacteria that contain magnetosomes -- chains of biological bar magnets wrapped in a membrane. The bacteria use the earth's magnetic field to move up and down in the mud, searching for the right level of oxygen, Dr. Kirschvink said. Bacteria in the Northern Hemisphere are north-seeking. In the Southern Hemisphere, they are south-seeking. At the Equator, both kinds exist.
The young student was hooked. Animals have specialized cells for taste, smell, touch, vision and hearing, Dr. Kirschvink said. "I couldn't help wondering, do some also have a magnetic sensory system?" he said.
Functional Neuroscience: Sensory, Motor and Cognitive Systems
Intra-subject replication of brain magnetic activity during the processing of speech sounds [An article from: Cognitive Brain Research]
Functional Neuroscience: Sensory, Motor and Cognitive Systems
Intra-subject replication of brain magnetic activity during the processing of speech sounds [An article from: Cognitive Brain Research]
In the early 1980's, "researchers began throwing their favorite pets into magnetic detectors to see if they had magnetic properties," Dr. Kirschvink said, but the experiments were usually contaminated by magnetically charged dust. People could not prove that the extremely faint magnetic signals they were measuring came from their animals, he said.
After completing a Ph.D. in geology at Princeton University in 1981, Dr. Kirschvink returned to Caltech as an assistant professor and built his special laboratory for studying biomagnetism.
He developed the hypothesis that whales navigate using a magnetic sensory system, following the dips, angles and intensity of geomagnetic fields on the ocean floor as roadmaps. Whales beach themselves at geomagnetic anomalies, he asserted, where fields shift or drop off suddenly.
He and his wife trained honeybees to exit a maze following a north or south compass, then reversed the magnetic orientation in the bees' magnetite crystals with a strong magnetic field. Afterward, the bees flew in the opposite directions to those they had been trained to fly.
But it was a health controversy that drove his research toward exploration of the human brain. Epidemiological studies over the last decade have suggested a possible but inconclusive link between diseases like brain cancer and childhood leukemia and electromagnetic fields from power lines and certain household appliances.
Physicists rejected the idea that weak electromagnetic fields might induce any biological effect, saying the fields would slip and slide around cells like syrup poured on a balloon. Studies of Human Brains
Dr. Kirschvink supposed this might not be the case if by any chance humans possessed substances capable of responding to magnetic fields. He obtained fresh brain tissue from seven corpses and dissected clumps of cells using Teflon-coated instruments.
Some samples were frozen and put in the magnetometer, which found unmistakable evidence of a ferromagnetic mineral -- compounds that interact strongly with magnetic fields. None of the body's iron, which is bound up in biological molecules, is ferromagnetic, Dr. Kirschvink said.
Other samples were dissolved and put into special test tubes fitted with magnets. After a week, magnetite crystals stuck to the glass.
Magnetite, in minuscule amounts, was found all over the brain, said Dr. Kirschvink and his co-authors, his wife, Atsuko Kobayashi-Kirschvink, and Dr. Barbara J. Woodford of the University of Southern California. Most regions of the brain had five million magnetite crystals per gram of tissue. The tough membrane that covers the brain had 100 million crystals per gram. Each human brain on average contains seven billion particles of magnetite, weighing a total of one-millionth of an ounce.
Half of the brain tissue samples came from patients with Alzheimer's disease and half did not; Dr. Kirschvink believes these circumstances had no effect on his findings.
Magnetite interacts over a million times more strongly with external magnetic fields than any other biological material, Dr. Kirschvink said, including the iron in red blood cells. If only one cell in a million contains magnetite, he said, magnetic fields could exert an effect on the tissue.
For instance, if the magnetite were coupled to channels that let substances pass through cell membranes and the crystals began to oscillate during exposure to an external magnetic field, Dr. Kirschvink said, one could imagine all sorts of biological effects, including the promotion of cancer.
"It's very interesting work," said Dr. Charles Rafferty, who is in charge of studying health effects of magnetic fields at the Electric Power Research Institute in Menlo Park, Calif. "It does provide a possible link for biological effects."
The presence of magnetite in the human brain might also account for the unexplained blips seen on MRI scans.
It is tempting to invoke magnetite crystals to explain many other mysteries of the human brain, Dr. Kirschvink said. First of all, do people with a good sense of direction possess a magnetic sensory system? It could even be asked if people who claim to have extrasensory perception or the ability to find water with a divining rod have a better than average magnetic sense.
But every carefully controlled experiment designed to prove that such abilities exist has failed dismally, Dr. Kirschvink said. There is not a shred of evidence so far that these microscopic magnets mediate any sensory capability in humans, he said. His work, if confirmed, is likely to stimulate a new round of research into these old questions.
Meanwhile, Dr. Kirschvink is exploring an older question -- the origin of the eukaryotes. This is the name given to all cells that have visible nuclei, and includes those of all higher forms of life on earth from fungi to humans.
Dr. Kirschvink believes the first eukaryotic cell may have been a bacterium that had evolved the trick of storing iron in the form of magnetite crystals. When the earth developed its magnetic field about 2.8 billion years ago, the magnetite-storing bacteria were able to exploit their sensitivity to it, using the field to move up and down in the mud to find the right oxygen gradient. The magnetic bacteria were large enough to engulf and permanently incorporate the other, once free-living bacteria that now serve as the chloroplasts and mitochondria of eukaryotic cells. They also probably possessed some kind of internal skeleton to hold the magnetite crystals, just as eukaryotes have internal scaffolding to support the mitochondria and other organelles.
The fossil record indicates that the magnetic bacteria lived for at least 400 million years before the first eukaryotic cells, Dr. Kirschvink said, making them suitable candidates as precursors.
Dr. Kirschvink has published this idea in several geological journals, but these are not much read by biologists. Experts in evolution are not unanimously enthusiastic about his hypothesis.
"It's a just-so story," Dr. Frankel said. There's no evidence that magnetic bacteria can swallow other bacteria, he said. "It's not one of Joe's finer pieces of work." Dr. Margulis says the idea makes sense in principle but is weak is detail.
The identity of the first eukaryotic cell is hotly contested, said Dr. Sogin of Woods Hole. "It would have to be something very special," he said. "There is no consensus on what it was."
"My ideas can be tested," Dr. Kirschvink said. If the biochemical pathway for making magnetite is the same in bacteria, bees, birds and humans, he said, it will prove an evolutionary link. If the proteins that envelop magnetosomes are the same as those that make scaffolding in animal cells and if magnetic bacteria older than 2.8 billion years cannot be found in the fossil record, the link would be stronger.
"If I'm right," Dr. Kirschvink said, "higher life will not evolve on planets without a steady geomagnetic field."
With so many ideas to test, it is a good thing Dr. Kirschvink is relatively young. He works closely with his wife, an engineer who shares his passion for biomagnetism. When their two sons were born, the couple looked for distinctive Japanese names. The eldest is called Jiseki, which means magnet stone, and the youngest Koseki, or mineral stone.
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