The planarian has come up several time here on/. and I thought that some people might like a quick intro these guys.
The flatworm used in this study is the planarian S. mediterranea, a free living (i.e. non-parasitic) flatworm. They have a distinct head and tail. They have non-lensed eyes capable of detecting the direction and strength of light allowing them to move away from it. Finally, they have a bi-lobed cephalic ganglia (rudimentary brain) and a rudimentary CNS. A similar species of planarians (dorotocephala) is frequently seen in high school science class.
There are 2 varieties of this species - one reproduces asexually while the other reproduces sexually. Both varieties are capable of complete regeneration (i.e. a full worm from almost any fragment) when cut. In both cases, the only dividing cells in the worms are stem cells called neoblasts.
Fun Fact: Thomas Hunt Morgan did many of the initial experiments on planarians.
----- Standard disclaimer: I work in a lab that uses these animal.
Additionally, Bill and Melinda Gates are the second most-generous philanthropists in America (as of 2007 by Bloomberg ratings). He has been successfully married for 17 years and has 3 children. He is an honorary Knight.
Jobs has an illegitimate child that he caused to be raised on welfare when he denied (then later acknowledged) paternity. He allowed his personal feelings to influence his business decisions when he banned all books from a publisher from Apple stores because the publisher had published an unauthorized biography of him. While his wife is now focused on non-profit and charity work, he is not noted to sit on any of the boards she serves on.
I make no claim about their companies, but their lives outside their jobs are as different as night and day.
They did blood tests to monitor hormones and no increase in appetite inducing hormones was seen. Additionally participants didn't report being hungrier. This would imply that the brain is not actually signalling for higher caloric intake. However they comment that they did not check for satiation signals or stress-reward signals.
They suggest that the 'mental stress' caused by playing the games is the cause. This stress should be the same regardless of the type of game played. They have seen similar increases in other studies with mentally strenuous activities such as arithmetic.
Right now it has the pleasure of being the place for the young and the cool. In another 5 or 10 years when all your parents are on Facebook, teenagers will find a new 'cool' online hangout. No teen wants to hangout with their parent and so it will change as it really beings bridging the generational gaps.
Its just like real life - 50 years ago it was 'Soda Fountains', 30 years ago it was Bowling alleys, 15 years ago it was the Arcade, 5 years ago it was Myspace, and now it's Facebook.
This is a truly novel approach, but what kind of sophisticated aqua-terrorists are we genuinely preparing to encounter?
This is not a novel approach. Both the US and Russian governments have been training and using marine mammals (wikipedia) as well as other animals (wikipedia) to help with military tasks. Dolphins and sea lines have been in training and use in the Gulf Wars. Perhaps the funniest example of military animals is the dogs that the failed Russian anti-tank dogs (wikipeida) that due to their training attacked Russian instead of enemy tanks. Its worth noting that this was again unsuccessfully attempted by Iraqi insurgents in 2005.
While you are mostly correct about this, even in planarians, head regeneration requires a suite of genes. By cutting the animal, those genes are activated and then the RNAi is used to alter their expression patterns. It is not as simple as one gene makes the whole head. Its that this gene is one of several including the Wnt/beta-catenin genes that work in concert to properly pattern the head.
To get the multiple head phenotype, the animal must be cut and in its 'regeneration' expression profile - not its homeostasis expression patterns. Nou-darke causes ectopic (extra) brain formation (in a different species of planarians) and brain region extension (in both species) even in non-regenerating planarians, which is not how this gene (Smed-prep) works.
Note that S. mediterranea has two strains, a sexual (cross-fertilizing hermaphrodites) and an asexual strain (that reproduces by fissioning). This means that the animals maintain adult stem cells that can regenerate an entire planarian (and are the only dividing cells in the animal). This gene is not expressed in those stem cells, but it certainly interacts with them in the development of the ectopic heads.
Disclaimer: I work in a S. mediterranea research lab
Re:And for further reading
on
How To Grow a Head
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· Score: 4, Insightful
This is very true. Just look at Nobel [Wikipedia]. When designed nitroglycerin, he was trying to make a safer explosive for miners. Instead he made a tool of war and was horrified by it. It was not his morality nor his invention that was flawed. It was the people who used it.
I would think by now that our society had moved past the base point of science is evil and technology is amoral. That cell phone in your pocket could be used to make a bomb threat or call an ambulance for the guy having a heart attack.
As for this research, it is quite a ways off from any useful/practical applications. But people hope that when it does come to fruition, it will be for things first like severe brain damage cause by an accident, a blood clot or other damage. And while yes, planarians have a cephalic ganglia (brain) and a complex nervous system for being a simple invertebrate, it is vastly less complex than even a mouse brain. As a case in point, their "eyes" are a photoreceptor not a lens, so while they can see and react to light, they do not have the capability to distinguish shapes.
Disclaimer: I work in a research lab that uses S. mediterranea, the flatworm used in this paper.
Slashdot Mirror
The planarian has come up several time here on /. and I thought that some people might like a quick intro these guys.
The flatworm used in this study is the planarian S. mediterranea, a free living (i.e. non-parasitic) flatworm. They have a distinct head and tail. They have non-lensed eyes capable of detecting the direction and strength of light allowing them to move away from it. Finally, they have a bi-lobed cephalic ganglia (rudimentary brain) and a rudimentary CNS. A similar species of planarians (dorotocephala) is frequently seen in high school science class.
There are 2 varieties of this species - one reproduces asexually while the other reproduces sexually. Both varieties are capable of complete regeneration (i.e. a full worm from almost any fragment) when cut. In both cases, the only dividing cells in the worms are stem cells called neoblasts.
Fun Fact: Thomas Hunt Morgan did many of the initial experiments on planarians.
-----
Standard disclaimer: I work in a lab that uses these animal.
Additionally, Bill and Melinda Gates are the second most-generous philanthropists in America (as of 2007 by Bloomberg ratings). He has been successfully married for 17 years and has 3 children. He is an honorary Knight. Jobs has an illegitimate child that he caused to be raised on welfare when he denied (then later acknowledged) paternity. He allowed his personal feelings to influence his business decisions when he banned all books from a publisher from Apple stores because the publisher had published an unauthorized biography of him. While his wife is now focused on non-profit and charity work, he is not noted to sit on any of the boards she serves on. I make no claim about their companies, but their lives outside their jobs are as different as night and day.
They did blood tests to monitor hormones and no increase in appetite inducing hormones was seen. Additionally participants didn't report being hungrier. This would imply that the brain is not actually signalling for higher caloric intake. However they comment that they did not check for satiation signals or stress-reward signals. They suggest that the 'mental stress' caused by playing the games is the cause. This stress should be the same regardless of the type of game played. They have seen similar increases in other studies with mentally strenuous activities such as arithmetic.
Obligatory "Our Germans are better than their Germans." (From The Right Stuff)
Right now it has the pleasure of being the place for the young and the cool. In another 5 or 10 years when all your parents are on Facebook, teenagers will find a new 'cool' online hangout. No teen wants to hangout with their parent and so it will change as it really beings bridging the generational gaps. Its just like real life - 50 years ago it was 'Soda Fountains', 30 years ago it was Bowling alleys, 15 years ago it was the Arcade, 5 years ago it was Myspace, and now it's Facebook.
This is a truly novel approach, but what kind of sophisticated aqua-terrorists are we genuinely preparing to encounter?
This is not a novel approach.
Both the US and Russian governments have been training and using marine mammals (wikipedia) as well as other animals (wikipedia) to help with military tasks. Dolphins and sea lines have been in training and use in the Gulf Wars. Perhaps the funniest example of military animals is the dogs that the failed Russian anti-tank dogs (wikipeida) that due to their training attacked Russian instead of enemy tanks. Its worth noting that this was again unsuccessfully attempted by Iraqi insurgents in 2005.
While you are mostly correct about this, even in planarians, head regeneration requires a suite of genes. By cutting the animal, those genes are activated and then the RNAi is used to alter their expression patterns. It is not as simple as one gene makes the whole head. Its that this gene is one of several including the Wnt/beta-catenin genes that work in concert to properly pattern the head.
To get the multiple head phenotype, the animal must be cut and in its 'regeneration' expression profile - not its homeostasis expression patterns. Nou-darke causes ectopic (extra) brain formation (in a different species of planarians) and brain region extension (in both species) even in non-regenerating planarians, which is not how this gene (Smed-prep) works.
Note that S. mediterranea has two strains, a sexual (cross-fertilizing hermaphrodites) and an asexual strain (that reproduces by fissioning). This means that the animals maintain adult stem cells that can regenerate an entire planarian (and are the only dividing cells in the animal). This gene is not expressed in those stem cells, but it certainly interacts with them in the development of the ectopic heads.
Disclaimer: I work in a S. mediterranea research lab
This is very true. Just look at Nobel [Wikipedia]. When designed nitroglycerin, he was trying to make a safer explosive for miners. Instead he made a tool of war and was horrified by it. It was not his morality nor his invention that was flawed. It was the people who used it. I would think by now that our society had moved past the base point of science is evil and technology is amoral. That cell phone in your pocket could be used to make a bomb threat or call an ambulance for the guy having a heart attack. As for this research, it is quite a ways off from any useful/practical applications. But people hope that when it does come to fruition, it will be for things first like severe brain damage cause by an accident, a blood clot or other damage. And while yes, planarians have a cephalic ganglia (brain) and a complex nervous system for being a simple invertebrate, it is vastly less complex than even a mouse brain. As a case in point, their "eyes" are a photoreceptor not a lens, so while they can see and react to light, they do not have the capability to distinguish shapes. Disclaimer: I work in a research lab that uses S. mediterranea, the flatworm used in this paper.