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Kamikaze bacteria illustrate evolution of co-operation
by Nature
http://www.nature.com/news/2008/080820/full/news.2008.1056.html
Kamikaze bacteria illustrate evolution of co-operation
Suicidal Salmonella sacrifice themselves to allow their clones to get a foothold in the gut.
James Morgan
Bacteria can commit suicide to help their brethren establish more damaging infections — and scientists think that they can explain how this behaviour evolved.
The phenomenon, called self-destructive cooperation, can help bacteria such as Salmonella typhimurium and Clostridium difficile to establish a stronghold in the gut.
By studying mice infected with S. typhimurium, researchers from Switzerland and Canada have now demonstrated how this 'kamikaze' behaviour arose.
The team, led by Martin Ackermann of ETH Zurich in Switzerland, studied how S. typhimurium expresses the Type III secretion systems virulence factors (TTSS-1) that inflame the gut. This eradicates intestinal microflora that would otherwise compete for resources — but also kills most of the S. typhimurium cells in the vicinity. After this assault, the way is clear for remaining S. typhimurium to take advantage and further colonise the gut.
But in the middle of the gut cavity, or lumen, only about 15% of the S. typhimurium population actually expresses TTSS-1. In contrast, in the tissue of the gut wall, almost all bacteria express TTSS-1. As more bacteria invade the tissue, gut inflammation increases and kills off the invaders (especially those within the tissue) - along with the other competing gut flora.
"We thought it was a very strange phenomenon," says team member Wolf-Dietrich Hardt, also at ETH Zurich. "The bacteria in the gut lumen are genetically identical, but some of them are prepared to sacrifice themselves for the greater good. You could compare this act to Kamikaze fighter pilots of the Japanese army."
Kamikaze genes
This self-destructive cooperation relies on the genes controlling this suicidal behaviour not always being expressed. This 'phenotypic noise' means that only a fraction express TTSS-1, allowing the kamikaze genes to persist in the population. If every cell expressed the genes, they would all commit suicide, benefiting none of the population.
The team concluded that acts of self-destructive cooperation can arise, providing that the level of "public good" — in this case, the inflammation of the gut — is high enough. Crucially, cooperative individuals must also benefit from other cooperative acts more often than individuals who are not cooperating, a situation the scientists call 'assortment'.
In the case of gut bacteria, assortment can arise if the minimum number of pathogens required to infect a host is relatively small — as few as 100 cells, in cases such as Escherichia coli.
Change of strategy
The findings, published in Nature1, chime well with long-established theories on the evolution of altruism and co-operation.
If a gene for sibling altruism is always expressed, it will tend to disappear, because those members of a clutch or litter who possess it may sacrifice themselves for those who do not. However, if the gene is present but not always expressed, it can persist, because some of its carriers may survive to pass it on to subsequent generations.
The research could also aid the design of more potent strategies against pathogenic bacteria. The Salmonella bacterium causes one of the most common bacterial infections in western countries, and is highly dangerous among the elderly and frail. "There is no doubt that a vaccine for Salmonella in humans is needed," says Hardt. "And many strains infecting livestock are becoming resistant to antibiotics.
"But based on our results, I would suggest that the usual strategy of targeting the vaccine against a virulence factor might not be the best strategy, if only a small fraction of the bacteria express it."
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Posted: Friday, August 22, 2008 | PermalinkComments 1 - 50 of 152 | | View Alternate Comment Thread
Reload Comments | Back to Top | Page Numbers2. Comment #234939 by Ex~ on August 22, 2008 at 9:23 am
A prime example of the most important discovery in evolution since Darwin:It's not survival of the fittest ANIMALS, it's survival of the fittest GENES.
Other Comments by Ex~
3. Comment #234944 by jhm on August 22, 2008 at 9:34 am
Instead of "if the gene is present but not always expressed, it can persist," I would say, "the gene will only persist if it is not always expressed.." Other Comments by jhm
4. Comment #234947 by kkelly on August 22, 2008 at 9:42 am
1, gene expression is continually regulated, so yes it's possible to get all to express that gene. In this case, the environment of the gut tissue coinhabited with other species of competing bacteria turns the expression on. Other Comments by kkelly
5. Comment #234948 by Steve Zara on August 22, 2008 at 9:48 am
Comment #234947 by kkellyI would like to apologise to you. Your first posts were a bit shocking, but you have moderated your style to suit this site, and I may have overreacted to some of your posts.
Other Comments by Steve Zara
7. Comment #234974 by Ishruul on August 22, 2008 at 10:16 am
After reading this article I can only understand more what Islam is: Kamikaze bacteria.
It's all there, wow, it was so obvious! :)
Other Comments by Ishruul
8. Comment #235097 by DamnDirtyApe on August 22, 2008 at 12:19 pm
'First wave, operation buggy shield! go go go!' Other Comments by DamnDirtyApe
9. Comment #235154 by Lucas on August 22, 2008 at 1:30 pm
Ishruul - My thought exactly. Okay, so bear with me on a bit of stretch: if genes can propagate themselves by having the organisms sacrifice some of themselves in order for the rest of the organisms to succeed, could memes work the same way? If so, might this mean that the phenomenon of religious extremism is a way for the larger meme (or, memeplex, whatever) to survive? I'm thinking of the "healers" in recent articles here. If Michael Guglielmucci "takes one for the team," does that strengthen the chances of survival for less offensive versions of his religion? And maybe the same with suicide bombers and "moderate" Islam?
Other Comments by Lucas
10. Comment #235187 by ridelo on August 22, 2008 at 2:13 pm
Lucas: I've heard (on YouTube?) some extremist imam saying that if believers started to kill off infidels (as most as possible) in suicide attacks then in the long run Islam would prevail. Same logic.Other Comments by ridelo
11. Comment #235207 by mandydax on August 22, 2008 at 2:35 pm
@2 Ex~That's exactly what I was thinking. It's brilliant.
Other Comments by mandydax
12. Comment #235412 by Richard Dawkins on August 23, 2008 at 2:27 am
Wait a minute. Isn't there something odd about the entire logic of this paper? It uses a game-theoretic type of reasoning, which would be appropriate if the bactera were not genetically identical. Since they are genetically identical, the case is analogous to the liver cells, muscle cells, skin cells etc (call them somatic cells) of an animal such as a human 'sacrificing' themselves for the good of the germ line cells (those destined to make sperms or eggs). These somatic cells are genetically identical, yet they have different phenotypes (liver cells are different from muscle cells, etc). You can call that phenotypic noise if you want, although it would sound odd. But the point is that nobody would think of using game theory to compute the optimum ratio of somatic to germ line cells.What we have here is good old gene selection. In a clone of genetically identical cells, genes that cause an an optimum proportion of cells to sacrifice themselves survive better than genes that cause a sub-optimal proportion of cells (for example zero) to sacrifice themselves. Computing relative benefits to the sacrificing and the non-sacrificing cells is inappropriate, because they are all genetically identical anyway.
This seems very clear to me, and I am baffled as to why the paper was written in this way (I have looked at the original paper in Nature).
Richard
Other Comments by Richard Dawkins
13. Comment #235477 by Laurie Fraser on August 23, 2008 at 5:57 am
It is ironic that the titles of some of your books actually befit yourself! Selfish Gene - and it is you that is selfish
Blind Watchmaker - and it is definately you that is blind
and The God Delusion and no doubt it is you that is deluded!
Top marks for debating skills, Joe.
Other Comments by Laurie Fraser
14. Comment #235482 by Thor'Ungal on August 23, 2008 at 6:03 am
Kin selection, Like ants. It would be more interesting to find an article about mutually cooperative bacteria that were not related. It might shed some light on the Eukaryote revolution.Ah sorry off topic.
Other Comments by Thor'Ungal
15. Comment #235493 by Thor'Ungal on August 23, 2008 at 6:23 am
What was that...what is with religious people and capitals. Joe, Richard has said no. How many Biologists are there out there that would take up said challenge. In this kind of debate wouldn't it be better dealt with by correspondence. Surely the sheer scope of the subject (especially when dealing with "irreducible complexity") requires some time in front of peer reviewed papers to answer properly. Why exactly do some people think that science is best discussed in a debate format anyway.
Try Ken Miller or someone, keep Atheism out of the argument (or is that really what you wanted to discuss).
Other Comments by Thor'Ungal
16. Comment #235525 by Laurie Fraser on August 23, 2008 at 7:15 am
JOE YOU BEING SHOUTING AT SUCH LEVEL BIG CAN YOU SEE NOT THAT THIS GIVE EVERYONE SHIT NO DOUBT AND PLEASE USE PUNCTUATION AT APPROPRIATE TIME OTHERWISE WE ALL AT DAWKIN SITE THINK YOU ARE JUST BIG GALAH NOTHING LESS OR BRAINDEAD FUCKTARD.Irritating, isn't it Joe?
Other Comments by Laurie Fraser
17. Comment #235526 by Faithhead on August 23, 2008 at 7:15 am
Comment #235475 by Joe Morreale on August 23, 2008 at 5:51 am
Is it possible for mods to move these comments to somewhere more appropriate? (The Good, The Bad, The Ugly) It has got nothing to do with the article and they are just preaching.
Regards
Lorcan
Other Comments by Faithhead
18. Comment #235532 by Roger Stanyard on August 23, 2008 at 7:26 am
Message to Joe Morreale,
So which jail can we contact Adnan Oktar in so he can convert us with his obious high levels of personal integrity compared to Richard Dawkins?
Presumably he hasn't asked to share the same cell with Kent Hovind.
(Shakes head at the utter banality of a person pushing a convicted criminal as a paragon of virtue.)
Other Comments by Roger Stanyard
19. Comment #235533 by Roger Stanyard on August 23, 2008 at 7:29 am
Joe Morreale appears to be so stupid that he doesn't appear to realise that Adnan Oktar is in jail for a long period and therefore Richard can't debate with him. Other Comments by Roger Stanyard
20. Comment #235534 by Brian English on August 23, 2008 at 7:35 am
Joe, what evidence or arguments do you present for the existence of god? The Quran or Bible rely on the existence of a god so are useless. We cannot adduce that there is a designer of the world without knowing everything about each organism and how it came to be. There are many uncaused things so we cannot assume the universe was caused. So, what evidence or arguments do you have to convince us that there is a god? Other Comments by Brian English
21. Comment #235539 by Steve Zara on August 23, 2008 at 7:44 am
Comment #235538 by Joe MorrealeYou surely know the ideological importance of evolution
Please explain.
lies and deceptive scenario of religion and science not being compatable
What predictive power has religion? What testable ideas does it put forward?
Other Comments by Steve Zara
22. Comment #235540 by Thor'Ungal on August 23, 2008 at 7:44 am
Joe, are you a parody or a troll by chance. It's a little hard to take you conspiracy theory ranting on face value and you don't seem to have much in the way of comment history.I fear that if peered reviewed studies aren't enough for you then neither side will have anything to go on. Both sides will simply say that the evidence on the other side is lies and conspiracies. Either that or you side will degrade into saying evolution is the work of the devil and lies to promote atheism.
Ooh do we have a link for him to go to so he can express his ideas elsewhere to get torn apart by people in the know? There's got to be a Harun Yahya thread somewhere.
Isn't he still in jail??
http://www.reuters.com/article/artsNews/idUSL0992091620080509?sp=true
edit: Man I'm too slow at this, several comments just in the time it took to write this.
Other Comments by Thor'Ungal
23. Comment #235541 by Brian English on August 23, 2008 at 7:45 am
Joe, I see you've taken the path of the ignorant guy who'd like to consider himself knowledgeable but can't be bothered studying. You've become a believer in a conspiracy. I really think you should stop talking to us and go study for a while, you don't even know that you don't know.... Other Comments by Brian English
24. Comment #235542 by Hellene on August 23, 2008 at 7:50 am
JOE MORRALLEI have picture of TRANSITIONAL SPECIES. It DESTROYS THE LIE OF CREATIONISM once and for all. Hanum Yia Yia and all FALSE CREATIONISTS will all tremble WITH FEAR at this image.
CLICK HERE
Other Comments by Hellene
25. Comment #235547 by Brian English on August 23, 2008 at 8:04 am
Totally off topic. But an Aussie diver has just one the gold medal against the local favorites. Normally I detest the olympics, but this guy is a bit of a gay icon and so should pull the wind from the sails of the bigots. I can't wait to see how the TV stations try to celebrate his gold while trying to tip toe around his partner. I hope they have the guts to show both guys as a normal couple and not pretend something else or ignore it. It would be a step up for Australia from the 'can we still get more medals than Great Britain' shite that's been going on.....
Other Comments by Brian English
26. Comment #235550 by Peacebeuponme on August 23, 2008 at 8:09 am
Joe MorrealeNo joking can avoid the fact that Dawkins like the true coward that he is cannot bring any or ONE SINGLE GENUINE TRANSITIONAL FOSSIL to the table and this is why he avoids the public debate.Every single fossil ever found is a transitional fossil between an earlier form and a later form.
Other Comments by Peacebeuponme
27. Comment #235551 by Steve Zara on August 23, 2008 at 8:09 am
Comment #235548 by Joe MorrealeNo joking can avoid the fact that Dawkins like the true coward that he is cannot bring any or ONE SINGLE GENUINE TRANSITIONAL FOSSIL to the table and this is why he avoids the public debate.
What are your criteria for a transitional fossil being genuine?
Other Comments by Steve Zara
28. Comment #235552 by Brian English on August 23, 2008 at 8:10 am
UNLESS HE ACCEPTS THE CHALLENGE WE CAN CONCLUDE THAT HE KNOWS THE GAME IS UP
UNLESS HE ACCEPTS THAT TODAY IS CHRISTMAS DAY THEN WE CAN CONCLUDE THAT HE KNOWS IT'S NEW YEAR'S DAY.
Great logic. Joe, you seriously can't be that stupid.
Other Comments by Brian English
29. Comment #235553 by Peacebeuponme on August 23, 2008 at 8:11 am
Brian EnglishJoe, you seriously can't be that stupid.He follows a rapist and worships a child rapist.
He surely can.
Other Comments by Peacebeuponme
30. Comment #235555 by Brian English on August 23, 2008 at 8:14 am
He follows a rapist and worships a child rapist.
He surely can.
you're probably right. I like to give people a chance to amend their ways when they've fucked up. But to amend one's way one has to admit that one has fucked up. And good old Joe doesn't even understand the rules of the game he's playing, so he's not likely to realize that he's fucked them up. Sigh..
Other Comments by Brian English
31. Comment #235556 by Hellene on August 23, 2008 at 8:14 am
JOE MORRALIOnly Hanum Yia Yia is cornered like an animal. IN JAIL!!!
NOTHING TO DEBATE> You HAVE SEEN TRANSITIONAL SPECIES. It has FISH HOOK. SO IS REAL!!!!!
CREATIONISTS DESTROYED!!!! ALL YOUR BASE ARE BELONG TO US!!!!
Other Comments by Hellene
32. Comment #235558 by Steve Zara on August 23, 2008 at 8:15 am
Comment #235554 by Joe MorrealeIf you think that your games will cut any ice me you are deluded.
What game?
You said that Dawkins would not bring a single genuine transitional fossil to the table.
If you use the term "genuine transitional fossil", you presumably must have some idea what it means. I am asking you what you understand by that term.
How can that be a difficult question? How can you ask Dawkins to bring something to the table if you are not prepared to explain what he should bring?
Other Comments by Steve Zara
33. Comment #235559 by Brian English on August 23, 2008 at 8:16 am
If god exists, he would give a clear messageJoe doesn't give any message
therefore, if god exists he'd hate Joe.
Other Comments by Brian English
34. Comment #235560 by Brian English on August 23, 2008 at 8:19 am
If you use the term "genuine transitional fossil", you presumably must have some idea what it means. I am asking you what you understand by that term.by that term Joe understands anything that can be said to not agree with science, specifically evolutionary theory. Anything else you need to be cleared up?
Other Comments by Brian English
35. Comment #235561 by decius on August 23, 2008 at 8:20 am
Don't feed the troll. Other Comments by decius
36. Comment #235562 by Brian English on August 23, 2008 at 8:21 am
Sorry decius, but he seemed so forlorn and lonely. Other Comments by Brian English
37. Comment #235563 by Steve Zara on August 23, 2008 at 8:23 am
Comment #235560 by Brian EnglishThis reminds me of discussions with txpiper, in which he claims that the fossil record shows that crocodiles have not changed, so Darwin was wrong. A creationist using the fossil record...
Other Comments by Steve Zara
38. Comment #235564 by Steve Zara on August 23, 2008 at 8:25 am
Comment #235561 by deciusBut it's fun! I am dying to learn what a creationist like Joe considers to be a "transitional fossil".
Other Comments by Steve Zara
39. Comment #235565 by Hellene on August 23, 2008 at 8:26 am
deciusSorry, I couldn't help myself. The shiny fish hook mesmerized me.
Hows the sea animation coming along?
Other Comments by Hellene
40. Comment #235567 by Roger Stanyard on August 23, 2008 at 8:28 am
Joe Morreale: Oh, I forgot, How silly of me. Evolution is just part of a giant international conspiracy organised by the Freemasons just for the fun of it. I'll have to ring up the New World Order and find out more.
Do you have a contact name and telephone number at the New World Order? Do they have a branch office in my local high street. Is it anywhere near Boots the Chemist?
Roger Stanyard, British Centre for Science Education
Other Comments by Roger Stanyard
41. Comment #235568 by Peacebeuponme on August 23, 2008 at 8:29 am
SteveBut it's fun! I am dying to learn what a creationist like Joe considers to be a "transitional fossil".I wonder what will happen when you show him one.
My guess will be that, if you show him fossil A, being transtional between form X and form Y, he will demand to see fossil B as a transitional between A and Y. And so on.
The point will not be conceded.
Other Comments by Peacebeuponme
42. Comment #235569 by Steve Zara on August 23, 2008 at 8:30 am
Joe-What fossil are you asking Dawkins to bring to the table? What would it look like?
Other Comments by Steve Zara
43. Comment #235575 by Peacebeuponme on August 23, 2008 at 8:37 am
reptile/bird creatures, which had acquired some avian traits in addition to the reptilian traits they already possessed.~Ummm well, I learned about Archaeopteryx in junior school.
Other Comments by Peacebeuponme
44. Comment #235576 by Steve Zara on August 23, 2008 at 8:37 am
Comment #235568 by PeacebeuponmeThe point will not be conceded.
I am taking Joe at his word, and seeing where it leads. He asked Dawkins to provide evidence. That implies he knows what evidence he is asking Dawkins to provide. At least I hope so, otherwise Joe is being just a bit naughty.
Other Comments by Steve Zara
45. Comment #235578 by Steve Zara on August 23, 2008 at 8:39 am
Comment #235577 by Joe MorrealeJoe. Don't be a tease. If you are going to criticise someone for not providing acceptable transitional fossils, you are going to have to say what is acceptable.
I am waiting...
If richard believes he has a case what is he worried about?
I can't speak for Richard, but if it were me, I would be worried about a boring waste of time.
Other Comments by Steve Zara
46. Comment #235579 by Hellene on August 23, 2008 at 8:39 am
Fish Hook JoeCould you just provide us with links instead of cut and paste?
That way we don't waste time determining the source.
Joe my friend, for the record you have been brainwashed by an Islamic cult.
Consider it.
While I may poke fun at you, I truly wish you no harm.
Long life and good health to you.
An Hellene
Other Comments by Hellene
47. Comment #235581 by J Mac on August 23, 2008 at 8:41 am
Live fossils huh? That'd be interesting. Perhaps the first thing you should do is buy a dictionary. Bu bye troll. Other Comments by J Mac
48. Comment #235582 by Peacebeuponme on August 23, 2008 at 8:43 am
Adnan has a lot of concrete evidence via his atlasesMy dad has lots of similar evidence in his fishing jacket.
Other Comments by Peacebeuponme
49. Comment #235583 by Steve Zara on August 23, 2008 at 8:45 am
Joe-Why don't you answer my simple question?
You set up the challenge for transitional fossils. You have to say what the conditions are.
Other Comments by Steve Zara
50. Comment #235588 by J Mac on August 23, 2008 at 8:48 am
RD is kind enough not to enter a battle of wits with against an unarmed man. Other Comments by J Mac
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1. Comment #234935 by JFHalsey on August 22, 2008 at 9:16 am
Question--is there a way for them to cause all the bacteria to express the TTSS-1 gene, and therefor all kill themselves off? Or can genes only be switched on/off at "birth"?Other Comments by JFHalsey