Interview over bioelektriciteit met professor aan Oxford University
- 04 oktober 2012
British Scientist Driven To Find 'Spark Of Life'
Beluister het interview hier.
npr.org - One night in 1984, British scientist Frances Ashcroft was studying electricity in the body and discovered the protein that causes neonatal diabetes. She says she felt so "over the moon" that she couldn't sleep.
By the next morning, she says, she thought it was a mistake.
But luckily, that feeling was wrong, and Ashcroft's revelation led to a medical breakthrough decades later, which now enables people born with diabetes to take pills instead of injecting insulin.
"I don't think people realize the excitement of being a true discoverer," Ashcroft tells Fresh Air's Terry Gross. "There are no new places to discover on this Earth, but there are many, many new ideas to discover — new things to find out about the way the world works."
Ashcroft says she grew up wanting to be a farmer's wife but later became fascinated with studying electrical impulses in the body. Her new book The Spark of Life details how electricity drives everything we think, feel or do through ion channels that are found in the membranes of each of our cells.
"Your ability to hear me now is because there are cells in your ears that are converting sound waves into an electrical signal, which is what the brain can interpret as sound," Ashcroft says.
Ashcroft is a professor at Oxford University and the winner of the L'oreal-UNESCO Award for Women in Science. She is now working on trying to see a particular protein at atomic resolution and on understanding why people become overweight.
On discovering the protein that causes neonatal diabetes
"Diabetes happens when you have too high a blood sugar concentration, and that usually happens because you don't have enough of the hormone insulin, which is the only hormone which can lower your blood sugar concentration after a meal. So every time you eat a Mars bar or Hershey bar, what happens is your blood sugar level will go up, insulin will be released from the pancreas, and that will cause the blood sugar to be lowered.
"This doesn't happen in diabetes. And what I was interested in understanding is how the rise in blood sugar causes insulin to be released in the pancreas. And it turns out — this is what I discovered late one night — that this is down to a whole complex series of events.
"But one of the crucial events, the little bit in the jigsaw puzzle that I discovered, is a protein that acts like a tiny hole in the cell membrane. And when this little pore is open, ions can go through it, so they carry, in this case, an electric current. And when the pore is shut, the ions can't go through, and the movement of the ions triggers a series of events that influences whether insulin is secreted or not. So, very simply put, when the pore is open, insulin is not released. And when the pore is shut, insulin is released. And glucose, or the rise in blood sugar, stimulates insulin secretion by closing these tiny pores. And what we found, together with a wonderful colleague of mine, Professor Andrew Hattersley, is that mutations, genetic defects in the gene that makes this tiny pore, cause it to always be open, so of course no insulin is ever released."
On the difference between electricity in wires and electricity in bodies
"Bioelectricity is similar but not identical to the stuff that's in sockets. Both are electrical currents, and, in both cases, the electrical current is nothing more than a flow of charged particles. But the stuff in our houses is carried by electrons whereas the stuff in our bodies is carried by ions — salt such as sodium chloride, common salt, in other words, the stuff you put on your meat. The second thing is that the speed is very different. So electricity in wires is carried at the speed of light, which is around 186,000 miles a second, whereas that in our bodies is very, very much slower."
On how electricity drives the way our bodies and bats sense heat
"Whenever you feel something that's burning hot — this is detected by this particular ion channel. It's sensitive to heat. And it fires off a signal that goes up your nerve cells. And it's exactly the same ion channels that are stimulated by chili peppers. So the reason that chili peppers taste so hot is that they stimulate the same ion channel, and the brain interprets them both as the same thing. And interestingly, they have been modified in vampire bats to detect the body heat of their prey. So that's how they can pick up the fact that your big toe is sticking out of a mosquito net, so they can come and suck your blood."
On how she became a scientist
"Well, I wanted to be a farmer's wife because I wanted a pony, and that was the only way that I thought I could ever get one. I think it's very interesting that I was educated to believe that I would not be the farmer but only a wife.
"However, I became very interested in natural history. I fell into a green lane one day — that's an old lane which has never been tarmac-ed over but was still used as a lane — and it was full of the most exquisite wild orchids in Britain. So I fell in love with them and I became a naturalist. I used to trek around the fields looking at plants and animals.
"And then when I went to university — I went to read natural sciences at Cambridge — and there was a choice of doing many different things. And somehow or other, ecology and nature conservation, which is what I thought I'd work in afterward, wasn't as exciting, wasn't as stimulating as the pure sciences and, in this case, biophysics ... because you can ask questions that are so well-defined that you can actually get an answer. You can do that now in the fields that I didn't take, but at the time, you couldn't."
On how science and scientists work
"Scientists are just like novelists in a way. We're all trying to tell a good story that explains how the world works, and we're interested in understanding how it works in exactly the same way that perhaps the early philosophers were. But we have much better tools with which to dissect it and understand it today. And the thing about science is it's always based on the facts. So if facts change and you discover new ones, or many more new facts don't fit the old ones, then you have to change the story. That's how major scientific revolutions happen, as, for example, when people suddenly realized that the Earth goes around the sun. So science is indeed a theory. But I really like what the very famous American physicist [Richard] Feynman said. He said, 'Science is imagination in a straitjacket.' We are constrained by all the things which we already know, so you can't simply conjure a story out of the air. It has to explain all the current facts and the new ones that have just been discovered. And it has to make predictions that can then be tested to see whether in fact that story continues to hold when we know even more information."