Brown University News Bureau

The Brown University News Bureau

1996-1997 index

Distributed May 8, 1997
Contact: Scott Turner

Floating frog embryos

Scientists use magnetic field as alternative to space-based zero gravity

Use of a magnetic field to levitate living specimens suggests a ground-based alternative to sending astronauts into space for expensive zero-gravity experiments.

PROVIDENCE, R.I. -- Peter Pan, make room for frog eggs.

Brown University scientists have used a magnetic field to levitate embryos of a small frog. The maneuver suggests an Earth-based alternative to expensive space missions for observing how living plants and animals develop in a low-gravity environment.

The Brown scientists think that use of a technique called magnetic field gradient levitation (MFGL) could allow researchers on Earth to perform experiments in simulated low gravity at a fraction of the cost of doing the work in a space shuttle. However, the scientists are unsure of the exact impact on plants and animals examined under the MFGL technique. In the study, the magnetic field caused changes in the early development of almost half of the frog embryos.

Editors: Color illustrations are available at the News Bureau's website.

The study has been accepted for publication in the Biophysical Journal. The scientists first described their findings at the March 1996 annual meeting of the American Physical Society. Their study marked the first account of living creatures levitated in a magnetic field. Last April, researchers in the Netherlands reported use of a magnetic field to levitate a frog, grasshoppers, fish and plants.

The Brown scientists created the magnetic field inside a large bagel-shaped solenoid - a cylindrical coil of tightly wound insulated wire through which a powerful electric current flows. The solenoid was about 20 inches tall and 30 inches in diameter, with a 2-inch diameter center hole. Up to 100 embryos - each the thickness of paper clip metal - were placed one-by-one in a drop of pure water levitated in a magnetic field created by 5 megawatts of electricity.

The procedure worked because the water, proteins and lipids inside the embryos created a weak magnetic field that repelled them slightly from the powerful field inside the solenoid. The result was a force that levitated the embryo-laden drop inside the solenoid for several minutes until the current was cut.

The technique reduced both the body forces and the gravity-induced stresses on the frog embryos by a factor of 10, which simulated a near-weightless environment. No other ground-based technique has produced a similar reduction in forces and stresses.

"The magnetic field actually picked up every single molecule in the embryos, mimicking the type of cell-by-cell levitation of astronauts that occurs in the weightless conditions of space," said study director James M. Valles, an associate professor of physics. "Because the embryos contain the same materials, such as water and proteins, that comprise most biological systems, we think this form of levitation can reduce gravitational stresses in a wide range of plants and animals."

"This could even be a way for scientists to perform a range of preliminary experiments relative to zero gravity to decide which ones would be more important for including in a space shuttle mission," said James M. Denegre, a post-doctoral researcher in the Department of Molecular Biology, Cell Biology and Biochemistry. "For example, several types of plants or body-tissue cultures would fit nicely in the solenoid."

Valles and Kimberly Mowry are co-leaders of the research. Mowry is an assistant professor in the Department of Molecular Biology, Cell Biology and Biochemistry.