Lesbian Necrophiliac Bdelloid Rotifers (and the Scientists who Love Them): Part 2

by Jennifer Frazer on May 5, 2009

So what is a bdelloid rotifer anyway? As you can see from the photomicrographs in the previous post, they are not going to be trying out for the Flyers anytime soon. Rotifers are among the simplest, smallest animals. In less than half a millimeter they pack in about a thousand cells, including a primitive nervous system (we’re talking like 15 cells here. “Rotifer-brained”: for times when “bird-brained” just doesn’t cut it), digestive system, and foot with — incredibly — toes.

Let’s put it this way: rotifers are multicellular animals that are smaller than some ciliated protists (protists include this blog’s titular amoebae and other high school biology favorites like Paramecium). They’re called bdelloid because they inch along like a leech — yes, bdelloid apparently means leech-like, as in, “Attack of the Giant Bdelloids.” Just doesn’t quite have the same ring to it as this.

They’re called rotifers (Latin: wheel-bearers) because they have a crown of little beating hairs called cilia surrounding their head that they use to suck in food — suspended organic particles, protists, or other small animals. Even more impressively, some rotifers have a toothed organ inside their mouth called the mastax that they use to grind food, and which they can actually sometimes evert to snare dinner.

An artist's interpretation of mastax eversion by a bdelloid rotifer. Any resemblance to Ridley Scott films is purely coincidental. Original image by rkitko, available under a Creative Commons Atribution license. Click image for link.

Rotifers have resurrectional powers rarely matched on Earth. After the typically fatal DNA- and membrane-shredding treatment incurred by drying up, they can somehow, once wetted, mend hundreds of DNA breaks and simply swim off. Even more jaw-droppingly, they can apparently use those same powers to withstand searing doses of radiation:

A comparison: in the most resistant arthropod[ed. note: arthropods include animals with jointed exoskeletons like insects and crustaceans] known, a 200 Gy dose produces more than 99% sterility; in bdelloids, a 560 Gy dose causing approximately 500 double-strand breaks per genome reduces fecundity by only 20%. The researchers point out that resistance to ionizing radiation may be an accidental by-product of resistance to desiccation. Both factors cause double-strand DNA breakage.

Forget balls of steel. This is DNA of steel. Why are we thinking of sending humans to Mars? Clearly, we should be sending bdelloid rotifers, who can thrive in the radiation-soaked environment of space, attack the Martians, and do it all backwards, in a high heel, and without breaking a chromosome.

In any case, you may be wondering where the lesbian necrophilia comes in. I’ll let the scientist at Harvard who studies these things  — Matthew Meselson — speak for himself.

It’s likely, he says, that during recovery from dessication, bdelloids pick up genes from members of their own species, too—dead members, that is, whose genes spill out of ruptured cell membranes. That process would provide the kind of genetic reshuffling that other animals achieve through sexual reproduction.

“It may be their form of sex,” Meselson says. “But their partner is essentially dead. So you’d have to call it necrophilia. Actually, since they’re all females, lesbian necrophilia.”

Kudos to you, sir, for being a scientist and not speaking like a grant application. If more scientists spoke this way, we might have less of a problem with people not giving a d— about science.

Much additional bio geek goodness can be found over at Small Things Considered.

(Additional source: Purves, Orians and Heller. Life: The Science of Biology. 4th ed.)

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A Protist’s Worst Nightmare
March 12, 2011 at 8:44 am

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Boyce Rensberger May 5, 2009 at 9:29 pm

Congratulations on a fascinating blog! I’ll be looking in again.

I want to echo your praise of Matt Meselson. In an earlier life he helped investigate something called yellow rain in Vietnam. This was in the time of the American war on Vietnam, and the local people were complaining about toxic yellow stuff raining down from the sky and making them sick. Yellow rain seemed very much like other nasty things the Americans were spraying over the countryside. The Nixon administration took up the issue, verified that the yellow material did indeed contain three potent toxins, but they blamed it on the Soviet Union, said the Soviets were supplying it to Communist sympathizers in Southeast Asia.

Meselson went to investigate and, honest scientist that he was, his group discovered and reported that yellow rain was actually bee droppings. Seems the local bees sometimes would swarm in great numbers and, from an altitude where they couldn’t easily be seen from the ground, defecate in unison.

Oh, and Jennifer, you’ll be pleased to know that the toxins in yellow rain are mycotoxins, the products of your beloved fungi.

Jennifer Frazer May 6, 2009 at 6:29 pm

Thanks, Boyce! Good story too. If you ever read this, Prof. Meselson, we salute you!

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