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[IMG]http://img269.imageshack.us/img269/3112/embryonicfinvspaw.jpg[/IMG]
[I]Image: Left: A zebra-fish–embryo fin. Right: The paw of an embryonic mouse.
Jing Zhang[/I]
Two genes found only in fish may be a key piece in the puzzling evolution of limbs.
The genes’ removal from zebra-fish embryos resulted in the loss of actinotrichia — a basic fin component — and made their proto-fins resemble appendages seen in ancient fossils of the first four-legged creatures.
“The loss of actinotrichia may have contributed to the evolutionary transition from fin to limb,” wrote researchers led by University of Ottawa biologists Jing Zhang and Marie-Andrée Akimenko in a study published June 23 in [I]Nature[/I].
During early embryonic development, fins and limbs look strikingly alike. In fish, however, some cells form a pattern of fine fibers. These are the actinotrichia, which form the scaffold on which fin rays are assembled.
In their study, Zhang and Akimenko noticed that two genes, actinodin 1 and 2, are especially active during zebra-fish fin development. These proved to code for previously unknown proteins that mix with collagen to form actinotrichia.
Subsequent searches of animal-genome databases found the actinodin genes in other bony fishes (including whale sharks, living fossils little changed in the 400 million years since the Devonian, before limbs evolved) but not in mammals, birds or amphibians.
When the researchers knocked actinodin genes out of zebra-fish embryos, actinotrichia didn’t form in the resulting fishes’ pectoral fins. Their tails, however, were unaffected. That fits with the evolutionary narrative suggested by fossils of the earliest known four-limbed creatures, which kept their fishy tails even as legs started to form.
Similar general patterns of gene expression are also found in embryonic chickens and mice with extra toes, a condition known as polydactyly.
“This is also in agreement with the fossil record, which indicates that the earliest primitive aquatic tetrapods of the late Devonian were polydactylous,” wrote the researchers.
[URL]http://www.wired.com/wiredscience/2010/06/evolution-of-limbs/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+wired%2Findex+%28Wired%3A+Index+3+%28Top+Stories+2%29%29&utm_content=Google+Feedfetcher[/URL]
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Pretty neat discovery.
:science:
Sounds pretty fishy.
:downs:
Awesome, now I know which gene to thank for my limbs and digits!
Rate me hearts if you like actinodin 1 & 2.
Cool. Now all we need to do is reverse evolve to make fish people!
I wonder how many creationists will go out on a limb and say that this discovery is very fishy.
They should do some looking at the mudskipper, that thing practically lives out of water.
[img]http://img197.imageshack.us/img197/6721/mudskipper.jpg[/img]
[QUOTE=wonkadonk;22943235]I wonder how many creationists will go out on a limb and say that this discovery is very fishy.[/QUOTE]
Jesus Christ, that was bad.
You gotta' be squiddin me.
[QUOTE=Billiam;22943280]Jesus Christ, that was bad.[/QUOTE]
I'm actually ashamed of that pun :frown:
[QUOTE=wonkadonk;22943235]I wonder how many creationists will go out on a limb and say that this discovery is very fishy.[/QUOTE]
Well you've made absoloute cod of that 'aven't you?
[QUOTE=DireAvenger;22943436]Well you've made absoloute cod of that 'aven't you?[/QUOTE]
I don't get it
Also on topic:
Is this related to the fact some whales can randomly grow tiny, useless legs?
[QUOTE=wonkadonk;22943478]I don't get it[/QUOTE]
Stop being so koi.
[QUOTE=wonkadonk;22943478]I don't get it
Also on topic:
Is this related to the fact some whales can randomly grow tiny, useless legs?[/QUOTE]
Fun Fact: Whales have hip bones.
[IMG]http://img824.imageshack.us/img824/2391/humpbackwhaleskeleton.jpg[/IMG]
Whales went from giant rat-like land animals to sea animals, and are mammals, so they never had the actinodin 1 and 2 genes that disappeared to helped fish climb out of the water. Instead they were more like, "Fuck you guys, were going back to the water." and eventually lost all their hair, and their arms and legs turned into a fins and fluke, along with becoming more stream lined and all the other neat evolutionary traits whales posses.
[IMG]http://img340.imageshack.us/img340/4101/18evowch03.jpg[/IMG]
[QUOTE=wonkadonk;22943478]I don't get it[/QUOTE]
Cod is a kind of fish.
Also off topic:
Your avatar looks like a man that is jerking off 2 penises.
Their citation for the article is wrong, it's not in no. 7301 of [i]Nature[/i], so far it's just in advanced online publication. I was going to post scans of the article, but I can't if it's not in the current issue. If anyone wants I could post the PDF.
Still a really cool discovery, another good piece of the puzzle, and not just a what, but a how. Knock-out hybrids are really awesome.
I really wouldn't trout it.
Saw this on PubMed
[url]http://www.ncbi.nlm.nih.gov/pubmed/20574421[/url]
[QUOTE=Perfumly;22944115]I really wouldn't trout it.[/QUOTE]
I'm sorry man but that was just carp.
I simply cannot believe we evolved from fish by mere 'chance'.
Incoming Shitstorm.
[QUOTE=stewe231;22944873]I simply cannot believe we evolved from fish by mere 'chance'.
Incoming Shitstorm.[/QUOTE]
Look up Natural Selection, broski.
[QUOTE=Aries;22944777]I'm sorry man but that was just carp.[/QUOTE]
Holy [I]Mackerel[/I] you're dumb.
I swear to cod that was the worst pun i ever heard.
[QUOTE=stewe231;22944873]I simply cannot believe we evolved from fish by mere 'chance'.
Incoming Shitstorm.[/QUOTE]
Genetic drift, natural selection, biotic interactions of competition and predation, abiotic interactions such as environment becoming less favourable as well as resource partitioning.
In other words, go read about evolution, we evolved by chance because all the unfavourable mutations died out and the ones that survived proliferated and further changed, and the unfavourable of those died and so on and so forth.
[url]http://en.wikipedia.org/wiki/Tiktaalik[/url]
[IMG]http://i305.photobucket.com/albums/nn205/abracadabravoila/Tiktaalik_450x300.jpg[/IMG]
Y'all bitches don't know 'bout my Tiktaalik.
Can't believe that in this day and age, only like 20% of Americans think evolution is true...
:eng99:
[QUOTE=OvB;22943639]Evolution of whales from land animals back to sea animals[/QUOTE]
That's awesome. I learnt something today.
[QUOTE=SuperLoz;22947589]Can't believe that in this day and age, only like 20% of Americans think evolution is true...
:eng99:[/QUOTE]
and in sweden only 23% believe in god.
:sweden:
[QUOTE=Hoffa1337;22947956]and in sweden only 23% believe in god.
:sweden:[/QUOTE]
Brb moving to Sweden.
Actually, I suppose things are fine here in England - We have Charles Darwin on our money, and God is never mentioned. Yay, secularity!
[QUOTE=bravehat;22945883]Genetic drift, natural selection, biotic interactions of competition and predation, abiotic interactions such as environment becoming less favourable as well as resource partitioning.
In other words, go read about evolution, we evolved by chance because all the unfavourable mutations died out and the ones that survived proliferated and further changed, and the unfavourable of those died and so on and so forth.[/QUOTE]
I think it's more Causality than casuality then.
Calling it 'chance' takes away some of its beauty.
[QUOTE=Eudoxia;22949643]I think it's more Causality than casuality then.
Calling it 'chance' takes away some of its beauty.[/QUOTE]
In my opinion the fact that it is chance makes it more beautiful, that one tiny genetic change thousands of years ago completely changes what we would have been is amazing.
And either way it is chance.
I guess.
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