Tuesday, September 11, 2007

Farandolae

"Mitochondria are tiny little organisms living in our cells. That gives you an idea of how tiny they are, doesn't it?"

"Enough."

"A human being is a whole world to a mitochondrion, just the way our planet is to us. But we're much more dependent on our mitochondria thn the earth is on us. The earth could get along perfectly well without people, bu if anything happened to our mitochondria, we'd die."
- A Wind in the Door by Madeleine L'Engle (1973)
I'm a bit sad that my first "back from vacation" post is in memory of Madeleine L'Engle, who died last Thursday at the age of 88. A Wrinkle in Time, a wonderful mixture of science fiction and fantasy, was one of the favorite books of my girlhood.

In the sequel, A Wind in the Door, L'Engle introduced legions of elementary school students to mitochondria. And not just the fact that mitochondria are important organelles inside our cells, but the idea that our mitochondria are derived from symbiotic prokaryotes. This was a cutting edge (and controversial) idea when A Wind in the Door was published in 1973, the endosymbiotic theory of mitochondrial origins having been proposed by Lynn Margulis just six years earlier.
"Your parents are scientists, aren't they?" She did not wait for an answer. "Let's see what you have to tell us."

Charles Wallace ("You should have known better!" Meg scolded him that night) stood and said, "What I'm interested in right now are the farandolae and the mitochondria."

"What was that, Charles? The mighty what"

"Mitochondria. They and the farandolae come from the prokaryocytes ---"

"The what?"

"Well, billions of years ago they probably swam into what eventually became our eukaryotic cells and they've just stayed there. They have their own DNA and RNA, which means they're quite separate from us. They have a symbiotic relationship with us, and the amazing thing is that we're completely dependent on them for our oxygen."

"Now, Charles, suppose you stop making silly things up, and the next time I call on you, don't try to show off. Now, George, you tell the class something . . . "
Now, the science isn't quite right: mitochondria don't produce oxygen. They do use oxygen, though, to generate ATP, which the cell then uses as a source of chemical energy. Mitochondria are essential to our utilization of oxygen as an energy source. L'Engle may have confused mitochondria with chloroplasts, which are found only in plants. Chloroplasts also are thought to have originated endosymbiotically and they do produce oxygen as a byproduct of the conversion of carbon dioxide and water to glucose during photosynthesis.

And that brings us to the farandolae, which are microscopic life forms inside mitochondria. Just as mitochondria are necessary for our cells, farandolae are essential for our mitochondria. They are, of course, entirely fictional and that's where the story slides into fantasy. Unlike our mitochondria, which are derived from ancient prokaryotes, the farandolae are living organisms that have names and can communicate, in a fashion.

Despite - or because of - L'Engle's imaginative take on cell biology, many kids were inspired to study science. The story inspired blogger the dubious biologist's PhD work:
Ms. L’Engle is the one of the deities of my childhood pantheon, right after and essentially tied with Ray Bradbury. I pretty much wore out the library copy of A Wrinkle in Time. Her Time Trilogy was the first book set I ever bought with my own money. I learned about tesseracts and mitochondria from Ms. L’Engle. I even quoted from A Wind in the Door in my Ph.D. dissertation.

I was fascinated by what she called the “farandolae”, living beings within the mitochondria that were born and grew as freely mobile slyph (as I envisioned them) organisms but then had to mature and root themselves in order for the mitochondria to survive. When I saw my first micrograph of the inner mitochondrial membrane, I was mesmerized by the small bumps that would eventually be identified as the FoF1 ATPase or ATP synthase. The key to making the energy of life in the powerhouse of the cell! In the back of my mind, I’ve always thought of them as farandolae.
The power of science fiction - even when the "science" is largely fictional - to stimulate kids' interest in science is one of the reasons I think science fiction books should be included in every elementary and high school reading list.

Thanks for the farandolae Ms. L'Engle!

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