1998-1999 indexDistributed March 24, 1999
Powerful magnetic field forces living cells to change
Brown University researchers have found that a strong, steady magnetic field can alter the way cells divide in a developing frog. Their work may end the decades-old debate among scientists over whether a magnetic field can affect an organism. The research was published in the Proceedings of the National Academy of Sciences.
PROVIDENCE, R.I. -- Talk about animal magnetism. Brown University researchers have found that a strong steady magnetic field can alter the way cells divide in a developing frog.
"There has been considerable disagreement as to whether magnetic field effects exist," said James Valles, an associate professor of physics. "This one was obvious."
The researchers discovered that the second cleavages of dividing cells in frog embryos, which are normally vertical, could be re-oriented to a horizontal plane by applying a horizontal magnetic field. Third cleavages, normally horizontal, flipped to a vertical plane when a vertical magnetic field was introduced. The more powerful the field, the higher the number of re-oriented cleavages among the embryos. The frog embryos, each the thickness of a paper clip, are made up of large cells, up to 100 times the size of human tissue cells.
"We don't know if the effect is particular to these large cells or if the effect is applicable to all cells," said Kimberly Mowry, assistant professor of molecular biology, cell biology and biochemistry. Smaller cells, for example, may lack internal structures that are large enough to be flipped by a magnetic field, she said.
Writing in the Proceedings of the National Academy of Sciences, the researchers suggest that the magnetic field forced cellular protein ropes, called microtubules, to orient parallel to it, re-orienting the cleavages. A microtubule is a cellular structure, part of what is called the mitotic spindle apparatus, which normally determines cleavage direction.
The microtubules re-orient in a similar way as a compass needle turns along magnetic north. Unlike the iron in a compass needle, the Earth's weak magnetic field is insufficient to cause the microtubules to realign. The materials composing the microtubules and the rest of the frog eggs respond very weakly to magnetic fields. This weak response is probably at the root of disagreements among scientists about whether steady magnetic fields affect living things, the researchers said. Their study shows that a huge magnetic field, more than 100,000 times as strong as Earth's, will affect the eggs.
The Brown researchers hope to learn how the strong field affects the eggs, and how large a magnetic field impacts biological processes. The researchers said it is vital that they understand the exact impact on plants and animals examined in a powerful magnetic field. The knowledge is important for developing magnetic field manipulation as a tool for dissecting biological processes, such as cell division, and for establishing general guidelines on how a fundamental field of physics interacts with life.
The magnetic field was created inside a large bagel-shaped solenoid - a cylindrical coil of tightly wound insulated wire through which a powerful electric current flowed. The solenoid was about 20 inches tall and 30 inches in diameter, with a 2-inch center hole.
The study's lead author is James M. Denegre, a post-doctoral researcher in molecular biology, cell biology and biochemistry.######