Magnetic Microbes Pave Way for New Machine Interfaces
CREDIT: kaibara87, via Flickr
Using genetic engineering techniques, scientists have created "magnetic microbes," which researchers say could lead to novel ways to control cells through magnetic fields and allow organisms to interact with machines.
Magnetic fields are everywhere, including emanating from the Earth, but few organisms can sense them.
"Magnetism in nature is a unique and mysterious biological function that very few living systems exploit," said researcher Pamela Silver, a synthetic biologist at the Wyss Institute for Biologically Inspired Engineering at Harvard University and Harvard Medical School.
The internal compasses that guide birds, turtles, fish and butterflies along migratory routes rely on magnetic sensitivity. How all these organisms gain their magnetism remains one of biology's unsolved mysteries. Scientists say human nerve cells also may also contain magnetically sensitive particles — iron deposits are seen in neurodegenerative disorders such as Alzheimer's.
Silver and her colleagues use synthetic biology to produce organisms that do things they normally can't. For instance, they have manipulated bacteria to generate fuel. Now they have successfully conferred magnetic sensitivity to an organism that is not naturally magnetized: yeast.
"While magnetic yeast may not sound like a serious scientific breakthrough, it's actually a highly significant first step toward harnessing this natural phenomenon and applying it to all sorts of important practical purposes," Silver said.
The microscopic fungi that comprise yeast are readily amenable to genetic manipulation and commonly used in lab experiments. In this case, scientists removed the gene for an iron transporter protein that normally moves excess iron to cellular storage containers known as vacuoles. The researchers also gave some of the microbes the gene for human ferritin, a protein that forms a shell around iron to prevent it from damaging the cell.
When these modified fungi were fed iron-rich diets, microbes with just the iron transporter deleted became magnetically sensitive, and those with both the iron transporter deleted and the ferritin added became strongly so. The key was allowing iron to accumulate and concentrate.
"Certain crystallized forms of iron are magnetic, and by knocking out the processes sequestering iron in vacuoles, we keep them in an environment that is compatible for iron crystals to form," Silver explained.
The ability to magnetize organisms could have a variety of medical, industrial and research applications. For instance, magnetism could be used to organize cells for building new tissues and organs as implants. New therapies might be created in which cells grow or heal in response to a magnetic field. Moreover, magnetic resonance imaging (MRI) could be used to track implanted magnetic stem cells to see if they reach their intended targets. In addition, magnets could be used to isolate desirable or undesirable cells from biological fluids.
"Personally, I'm interested in being able to interface living things with machines, and this is a perfect example — magnetic fields could allow you to interface biological systems with non-living ones," Silver said.
Further experiments identified the genes that triggered the formation of iron-containing particles and subsequent magnetization of the cells. A better understanding of how magnetization is regulated might shed light on what magnetic particles are doing in diseases like Alzheimer's.
"We did it to understand magnetism in nature, and just frankly because it's cool," Silver added. "There should be a place in science and engineering just to do things because they're cool."
Silver and her colleague Keiji Nishida detailed their findings online Feb. 28 in the journal PLoS Biology.