Seeing the invisible field: genetic engineering gives yeast the gift of magnetic sight

Written by Rose Eveleth, Contributing Editor

Right now, there are magnetic fields sweeping all around you. You cannot see them, or feel them, but they are there, moving in and out of everything around you. Some bacteria use metal inside their bodies to act as a magnet to detect these fields. Others, like birds, turtles and fish use the earth's magnetism to migrate. But most organisms simply move through the world without ever sensing a thing.

Now, a group of scientists at Harvard Medical School, have figured out a way to give the gift of magnetism to new organisms – in this case, yeast. “The yeast were magnetized by adding genes to increase their ability to sequester iron and by mutating other genes to increase their magnetic properties by altering their metabolism," said Dr. Pamela Silver in a press release.

This is a two-part process. First, the scientists added a gene that helped the yeast produce a protein called ferritin – which sequesters iron inside the cells. Normally ferratin’s job is to keep that iron away from the rest of the cell, since iron is toxic in high quantities. The second step was to mutate the gene that helps the cell move that sequestered iron into cellular storage containers called vacuoles. So when they put the yeast into a medium with lots of iron, what they had was a yeast cell that sequestered that iron, but didn’t move it anywhere. That iron then made those cells magnetic.

But the researchers also wanted to know if they could make the yeast magnetic in other ways. The next thing they tried was to fiddle with the genes that effected iron reactions inside the cell – something called “redox balance.” Redox, short for reduction, oxidation, is a term for the number of electrons that are floating around in the cell. Fewer electrons means that the iron in the cell is more likely to stick around in clumps.

When the researchers screened about 60 genes for what might affect magnetism, the one they found was involved in this redox process - keeping the number of electrons balanced. When they deleted that gene, the cells lost their magnetism. When they multiplied it into many copies, the cells got more magnetic.

What all this means is that magnetism, that elusive sense that so many animals lack, could potentially be induced through some simple genetic engineering. Making cells magnetic could have uses for therapy and bioengineering. “In bioprocessing, the ability to separate a specific population of cells using magnets; using magnetism to organize cells in tissue engineering; and using magnetism as an input for therapeutic cells and to track cells by MRI," would all be useful, said Dr. Silver.

If you could see magnetic fields, they would look something like this. (Movie by NASA's Space Sciences Laboratory)

Harvard also has a video of the authors talking about their work.

Photo via Newton Henry Black/Wikimedia Commons

This post was originally published on Smartplanet.com

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