Scientists identify seventh and eighth bases of DNA (article)

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[h1]Scientists identify seventh and eighth bases of DNA[/h1]





For decades, scientists have known that DNA consists of four basic units -- adenine, guanine, thymine and cytosine. Those four bases have been taught in science textbooks and have formed the basis of the growing knowledge regarding how genes code for life. Yet in recent history, scientists have expanded that list from four to six.



Now, with a finding published online in the July 21, 2011, issue of the journalScience, researchers from the UNC School of Medicine have discovered the seventh and eighth bases of DNA.

These last two bases – called 5-formylcytosine and 5 carboxylcytosine – are actually versions of cytosine that have been modified by Tet proteins, molecular entities thought to play a role in DNA demethylation and stem cell reprogramming.

Thus, the discovery could advance stem cell research by giving a glimpse into the DNA changes – such as the removal of chemical groups through demethylation – that could reprogram adult cells to make them act like stem cells.

"Before we can grasp the magnitude of this discovery, we have to figure out the function of these new bases," said senior study author Yi Zhang, Ph.D., Kenan Distinguished Professor of biochemistry and biophysics at UNC and an Investigator of the Howard Hughes Medical Institute. "Because these bases represent an intermediate state in the demethylation process, they could be important for cell fate reprogramming and cancer, both of which involve DNA demethylation."

Much is known about the "fifth base," 5-methylcytosine, which arises when a chemical tag or methyl group is tacked onto a cytosine. This methylation is associated with gene silencing, as it causes the DNA's double helix to fold even tighter upon itself.

Last year, Zhang's group reported that Tet proteins can convert 5 methylC (the fifth base) to 5 hydroxymethylC (the sixth base) in the first of a four step reaction leading back to bare-boned cytosine. But try as they might, the researchers could not continue the reaction on to the seventh and eighth bases, called 5 formylC and 5 carboxyC.

The problem, they eventually found, was not that Tet wasn't taking that second and third step, it was that their experimental assay wasn't sensitive enough to detect it. Once they realized the limitations of the assay, they redesigned it and were in fact able to detect the two newest bases of DNA. The researchers then examined embryonic stem cells as well as mouse organs and found that both bases can be detected in genomic DNA.

The finding could have important implications for stem cell research, as it could provide researchers with new tools to erase previous methylation patterns to reprogram adult cells.

It could also inform cancer research, as it could give scientists the opportunity to reactivate tumor suppressor genes that had been silenced by DNA methylation.

Provided by University of North Carolina

http://www.physorg.com/news/2011-07-scientists-seventh-eighth-bases-dna.html

 

[rexanglorum]

This is NT, one more step towards a cure for cancer that is expressed in more than a paragraph will probably get a few views and a maybe a "tl;dr."

This looks interesting and the consensus I have heard from the medical-scientific community is that curing cancer will require DNA level alterations.

 

[thorrocksjs]

Very interesting im trying to grasp its meaning but i think this is a tad bit out of my league.I wonder if they can figure out how to reprogram cells could they possibly reverse things like heart disease and arthritis.Im praying for some major break through in heart disease for before its too late.

 

[based mod]

i have a degree in biology and this went over my head. i thought there were only 4 bases for DNA (A, T, C, G)?

 

[Sir San Diego]

Reprogramming adult cells? And to think, they are only scratching the surface of possibilities.

 

[curt2121]

See, this isn't news to those of us in science. We've known for a while now that transitional states had to exist for certain processes. Plus this stuff was actually done a while back, it just takes a lot of time to get it all worked up to publishing. I remember a guest lecturer from that lab talking about it during my undergrad time a couple years ago. This isn't an issue of "there are other stable forms of bases sitting in our DNA besides the classic ACGT we have known about. This is that there are variations on bases in reactions that result in intermediate forms along the way and the better we understand them, the better we get how they work. Like the "fifth", anyone hwo has taken college chemistry/bio should know the process/reaction steps to methylate cytosine. And the 6th, 5-hydroxymethylcytosine has been known about for decades. Its function was initially guessed using bioinformatics and then later was shown to be true. SO the take home message is nothing has miraculously changed overnight. This isn't some magical step towards cancer or anything that headlines like to overblow. All this is doing is saying "yes, we had guessed these forms exist, now we know for sure they do" Which don't get me wrong, that's definitely important. But no reason for anyone here to care

 

[jj jumpman 23]

intresting read but 

 

[atlien seeko]

Originally Posted by curt2121

See, this isn't news to those of us in science. We've known for a while now that transitional states had to exist for certain processes. Plus this stuff was actually done a while back, it just takes a lot of time to get it all worked up to publishing. I remember a guest lecturer from that lab talking about it during my undergrad time a couple years ago. This isn't an issue of "there are other stable forms of bases sitting in our DNA besides the classic ACGT we have known about. This is that there are variations on bases in reactions that result in intermediate forms along the way and the better we understand them, the better we get how they work. Like the "fifth", anyone hwo has taken college chemistry/bio should know the process/reaction steps to methylate cytosine. And the 6th, 5-hydroxymethylcytosine has been known about for decades. Its function was initially guessed using bioinformatics and then later was shown to be true. SO the take home message is nothing has miraculously changed overnight. This isn't some magical step towards cancer or anything that headlines like to overblow. All this is doing is saying "yes, we had guessed these forms exist, now we know for sure they do" Which don't get me wrong, that's definitely important. But no reason for anyone here to care

I know, right.

 

[noskey]

Good thing I already took biology 

 

[ground king]

one discovery leads to another... is it ever gonna end??

 

[AZwildcats]

These new bases are just intermediate states of cytosine. I knew about methylated cytosine but did not know it was considered a completely different base from cytosine. Interesting stuff

 

[Renaldo Balkman]

this is major news that will go over the heads of 99.99999% of the population... this could lead to MAJOR advances in medicine (which could be good or bad by the way)

 

[curt2121]

Originally Posted by rayray3thousand

this is major news that will go over the heads of 99.99999% of the population... this could lead to MAJOR advances in medicine (which could be good or bad by the way)

 

[mf doomer]

I always figure published material like; reprogramming cells, identifying new cells for this cause, will release once another saving solution is outdated.

 

[biokickz]

Originally Posted by AZwildcats

These new bases are just intermediate states of cytosine. I knew about methylated cytosine but did not know it was considered a completely different base from cytosine. Interesting stuff

This..

If it's an intermediate state, why is it considered a new base? I would think a base would have to be in a "stable"/permanent form..

 

[sevit86]

Originally Posted by Brolic Scholar

Reprogramming adult cells? And to think, they are only scratching the surface of possibilities.

just as a decade ago, they couldn't fathom how far we have come in 2011, imagine how far technology
will advance in 2021

 

[dajoka004]

Originally Posted by Rexanglorum

This is NT, one more step towards a cure for cancer that is expressed in more than a paragraph will probably get a few views and a maybe a "tl;dr."

This looks interesting and the consensus I have heard from the medical-scientific community is that curing cancer will require DNA level alterations.

A cure for cancer is impossible. Yes, I said it.

 

[scshift]

Originally Posted by sevit86

Originally Posted by Brolic Scholar

Reprogramming adult cells? And to think, they are only scratching the surface of possibilities.

just as a decade ago, they couldn't fathom how far we have come in 2011, imagine how far technology
will advance in 2021

Maybe they can make people taller, stronger, faster and smarter

 

[resist]

can anyone break this down for someone who doesn't know what they're talkin about

 

[based mod]

Originally Posted by DaJoka004

Originally Posted by Rexanglorum

This is NT, one more step towards a cure for cancer that is expressed in more than a paragraph will probably get a few views and a maybe a "tl;dr."

This looks interesting and the consensus I have heard from the medical-scientific community is that curing cancer will require DNA level alterations.

A cure for cancer is impossible. Yes, I said it.

false.
is there a cure-all method of curing cancer?  no.  

but different cancers have different qualities that have to be approached in different ways to get rid of them.  trust that biotech/pharma companies are busting their butts to develop these meds.