I am going to blow your mind.
There’s a luminescent bacteria named Vibrio harveyi. It doesn’t glow when it’s off on its own, but they do so collectively when a bunch of them get together. Which makes sense, since one cell glowing all by itself is just wasting energy — its light is too weak to be seen — and it takes a certain number to be useful.
They’d have to communicate to do that, and they have to use that ability to figure out when there’s a quorum. And that’s precisely what they do, using a pair of communications systems based on released enzymes. One communicates only with other V. harveyi cells, while the other communicates with any cells.
As it turns out, it’s not just V. harveyi doing this: many bacteria do. It’s suicide for a single Vibrio cholerae bacterium to start manufacturing the toxic proteins that cause cholera — the host’s immune system would destroy it. In fact, it takes about a million V. cholerae to overpower a healthy immune system. So it waits for a quorum, communicating by the same pair of channels used by V. harveyi.
Now that we know how bacteria communicate, we can learn how to prevent them from communicating. If V. cholerae can be prevented from recognizing a quorum, it can’t infect people with cholera. Ditto for tuberculosis, leprosy, syphilis, pneumonia, plague, and any other bacterial illness you can think of.
But let’s go back to that second communication channel, the one that allows all bacteria to talk to each other. This is amazing. It was surely the first universal language. One can imagine what they must talk about. I’ll bet some bacteria bluff, claiming to have a quorum when they don’t really, in order to get dibs on alveoli or a particularly choice intestinal fold. Maybe some other bacteria claims to be a tougher bacteria than it really is, just to keep from ending up as prey.
As you know, one division that can be made between life forms is single-cell versus multi-cellular. Advanced multi-cellular organisms, such as mammals, have many different cell types that are grouped together for common purposes. Some cells join up to become, say, the liver. Others colonize an area to create bone. Each functions as its own group, though there is, of course, coordination between the groups.
The bobtail squid, found in the Pacific Ocean, glows in the dark. Or, more accurately, it uses V. fischeri (a close relative of V. harveyi) to glow in the dark. The nocturnal squid filters V. fischeri out of the sea water and stores it in a chamber in its body, feeding it amino acids and oxygen. The brightness of the light can be adjusted by the squid in order to eliminate its shadow from the ocean’s bottom, to avoid tipping of prey.
Here’s the part where I blow your mind.
What’s the difference between a human and colonies of different types of group-based bacteria like V. harveyi? Isn’t my stomach just a grouping of subgroups of single-celled organisms that digest my food for me, manufacture acid, and form the tissue of the organ itself? Isn’t my eye just light-collecting cells arranged in a way that benefits both me and the whole of them, and communicates with the cells that make up my visual cortex? Am I not, in short, nothing that couldn’t be accomplished by 180lbs of bacteria? (Hold your jokes, please.)
Mind? Blown.
You have the right of it, of course. Multicelluar life is just a subset of single-celled life, not something radically different. That’s evolution at work: nested subgroups rather than something changing into something different.
Ever read “Parasite Rex” by Carl Zimmer? There’s a blow-yer-mind on nearly every page.
For instance, consider the differing interests of an embryo, the mother, and the father. The embryo wants all the nutrients it can get, even at the risk of harming the mother. Same goes for the father: if the embryo carrying half his genes benefits at the expense of the mother, well, that’s good for him. The mother though: her genes benefit from her being able to have many babies, not to be drained to death by this one. And so we have the set-up for a great fight. And what do we find? That exact fight going on: the mothers body trying to fight back the embryo’s demands, and the embryo secreting signals to supress the mother’s immune system and allow it to take more and more from the mother even as her body resists.
Waldo, a friend lent me a book, which I have since given back to him, and unfortunately, I am not certain of the title. “The Universal Mind” rings a bell, but I cannot find it on Amazon.com. (There is another book by that title but it’s a different one.) Anyway, the author traces the evolution of species from bacteria mulitcellular organisms to mammals to humans with a focus on communication and social organization. Bacteria, as you point out, are far more complex and sophisticated than we humans give them credit for being. It’s a shame the author did not know about Vibrio harveyi — it would have fit his argument perfectly.
Yes, my mind is blown.
But I still do not feel guilty about exterminating whole colonies of them when I clean my kitchen.
Furthermore, the number of cells in your body that are genetically you are vastly outnumbered by parasitical and symbiotic bacterial cells. You are a minority in your own body.
The New Yorker has a fascinating article about that a couple of months ago, focusing specifically on the enzyme-based battle for supremacy between mother and fetus that can leave one or both dead. I read it with my jaw hanging wide open. I’d always learned of a nurturing, entirely one-way relationship. On the contrary, fetuses are constantly considering whether they’re developed enough to kill their mother and still survive.
Ah, here’s the article. It completely changed my understanding of pregnancy and, in fact, human reproduction. It turns out that unborn babies can be Machiavellian little critters. It’s very much worth reading.
Nah, it all just part of an intelligent design.
(ducks)
Here’s where the distinction gets even fuzzier, Waldo: biomats. Vibrios can form complex structures on the seafloor as part of their lifecycle (other parts of which involve a free-floating form and a zooplankton-munching form). These “biomats” (these aren’t your father’s biofilms) have cells that lose their ability to reproduce and apparently exist only to feed the breeder cells. Remind you of somatic vs. sex cells? These biomats contain tubes, sheets, and strands that are reminiscent in both form and function of mammal tissues. Some scientists even think that these are the “adult form” of bacteria, and that the free-floating types are mere seeds.
But biomat organization can get even more complex than mammal organization, because some of these biomats are collaborations between unrelated species of bacteria. Mammals only have that to a limited extent with beneficial bacteria and other symbiotes.
Mind definitely blown. My reading list just got three books longer – thanks!
Ah, but here’s the rub:
Unlike the mass of bacteria, YOU were made in the image of God. Chew on that for a while.
Is God full of bacteria too?
Hmmm…. was someone listening to NPR too the other day?
How remarkable that you know what God looks like. So God’s a tall white guy? Does he have a penis and a belly button? Or would they not do him much good?
You bet — that’s where I first heard about this.
Here’s a reprint of a National Geographic piece describing how the human body is really a giant ecosystem for microbes.
As far pregnancy and cell communication go, you might remember this NPR piece from the beginning of the year.
Wow, grs, that National Geographic piece is remarkable, particularly this bit:
On that note, I’m — no kidding — going to take a shower.
I do remember a great sci-fi short story once where the cells of some guy’s body develop consciousness and take over. Or maybe it was nanorobots egging the cells on. They are pretty shocked when they realize they are being controlled by this other being, and that there are worlds beyond it. Then they make a break for freedom….ick.
Fascinating New Yorker artice, Waldo. Victoria suffered from preeclampsia w/Brianna. Now I know to push her OB/GYN to look for soluable FLT during routine testing and to see about obtaining supplemental VEGF and P1GF. Also the oral sex part doesn’t sound like it would hurt either ;)
Chris — When I was doubly-pregnant with Waldo and Jack, I read somewhere (in some hippie-dippie natural childbirth book) that the secret of avoiding preeclampsia was to eat enough protein. So I would count up my grams of protein every day, and eat a few eggs in the evening if my tally was low. So, protein and fistfuls of vitamins: that’s what Waldo and Jack are made of. I have no idea if there’s any truth to the protein theory, but it couldn’t hurt to get adequate protein (especially when gestating twins).
Pneumococcus is even worse. Rather than just making you glow in the dark, when they sense there’s enough of them, they mug you! See:
http://microbiologybytes.wordpress.com/2006/09/18/pneumococcus-the-quorum-sensing-killer/