In biological labs, the term junk DNA is commonly used to describe portion of the genome which have no described function. When I first moved my blog to Scienceblogs, I wrote a little summary of a great theory advanced by William Martin and Eugene V. Koonin on the origin of the eukaryotic nucleus. (Basically the nucleus developed to separate RNA processing from RNA translation, due to the multiplication of introns which made the process of RNA processing that much more complicated.) Well the ID-ots jumped on my little blog entry and accused me of knowing nothing because I called introns "junk DNA". At the time I thought that the whole thing was ludicrous. These ID guys clearly are not involved in the scientific process, let alone talk to people who do primary research (like me!) In cell biology/biochemistry/molecular biology circles "junk DNA" is just shorthand for portion of the genome which have no described function. To pounce on that term is playing "Gotcha". Well I was reading Sandwalk where Larry Moran has an entry on "junk DNA" and the orgin of that term (a 1972 paper by Susumu Ohno.) The post was initiated by a SciAm article that describes this term as unfortunate because:
Although very catchy, the term "junk DNA" repelled mainstream researchers from studying noncoding genetic material for many years. After all, who would like to dig through genomic garbage?
Hmmm.
There are two comments I'd like to make here ...
FIRST. I always though that Sydney Brenner (one of the smartest guys in science) coined the term "junk DNA". So I dug a bit and here is what I came up with ... this quote of his:
I said it was 'junk' DNA, not 'trash'. Everyone knows that you throw away trash. But junk we keep in the attic until there may be some need for it.
In anycase it is possible that Brenner said this after 1972 ... (anyone know when/where that quote comes from?) ... but I wanted to share it with you because it's a real gem and explains perfectly how most scientists I know use the term.
SECOND. I take issue with "the term 'junk DNA' repelled mainstream researchers". Science is very pragmatic. Most good biomedical biologists study biological functions ... apoptosis, the cell cycle, the cytoskeleton, differentiation ... studying a gene, a random stretch of DNA, or a protein in isolation is always usually a bad choice. In addition before the sequencing revolution, how could we have analyzed the whole genome? It was a big effort to find your gene of interest, people couldn't willy nilly study random bits of DNA with no ascribed function. Look, scientists don't have a crystal ball. You can't look for something when you don't know what you are looking for. Plus we have to justify to the NIH, the ACS, the NSF etc... that what we do is important. Randomly going through junk without some hypothesis, especially in the days before the whole genome was sequenced, is the equivalent to committing scientific suicide. Sure some people did do it, and I'm glad that they did. More are doing it now, and that makes sense, they have all these genomes sequenced and many more bioinformatic tools at their disposal, but the idea that we wasted time not going through the junk in the past is clearly a brainless statement.
ADENDUM. Googling "Junk DNA origins of term" I got this crazy creationist wiki site. Now I understood why the ID-ots reacted to my post by criticizing the term "junk DNA". They don't know lab lingo. All they know are talking points that they get from some wiki site or blog. Do they even read primary literature? Do they talk to experimentalists? Man ... to all you ID folk, go talk to people in wet labs or do some experiments yourself. Sites, like the one I described here, just demonstrate that you are nothing but an ideological movement and not some intellectual enterprise.
UPDATE: Martin Hafner sent me a ref to Brenner's discussion on junk (it's in the transcript of a symposia). This may or may not be the first refference that Brenner makes to "junk DNA". He talks about it during the lecture, and during a Q&A where he makes an arguement that is similar to the quote above (was that a misquote?). Here it is:

ref:
S. Brenner
The human genome: the nature of the enterprise (in: Human Genetic Information: Science, Law and Ethics - No. 149: Science, Law and Ethics - Symposium Proceedings (CIBA Foundation Symposia) John Wiley and Sons Ltd 1990

Alex Palazzo is an Assistant Professor in the Department of Biochemistry at The University of Toronto.



Comments
... "studying a gene, or a protein in isolation is always a bad choice." - ap
Never say always.
Posted by: Anonymous Coward | February 12, 2007 11:37 PM
Yeah, I still completely disagree with that statement. It's never wrong to have some focus in your work. If one protein is a gateway to a field, then study that one protein.
Posted by: U | February 13, 2007 12:21 AM
When you search 'Intelligent Design' on Crationwiki you will find:
(emphasis mine)Seems as if all the efforts of the DI to hide the nature of ID did not help. All the money for nothing.
Posted by: sparc | February 13, 2007 2:02 AM
Posted by: sparc | February 13, 2007 2:59 AM
AC & U,
Yes OK I softened the statement. And of course if you are a structure biologist you have no choice but to work on a particular enzyme. But I still contend that if you are a cell biologist, developmental biologist, neurobiologist, microbiologist ... the best work is done by those who study processes.
Posted by: apalazzo | February 13, 2007 8:28 AM
couldn't agree more with your last comment Alex... sure the focus maybe one gene, one protein... but it is the context that should be the focus, even for structural biologists, they should adhere to some sensibilities and choose subjects of current scientific interest rather than the easiest protein to crystalise/purify etc... More crossover of skills/appreciation for structure-function and system biology approaches wouldn't go amiss!
Posted by: Kirklain | February 13, 2007 11:41 AM
Why the attack on structural biologists? No one these days works on only one protein, just one at a time. Cell biologists do the same thing. Most of the papers I see from cell biologists talk about a new role for a protein or a new function. Science is about taking a complex system and understanding the details which is what we all do.
I guess a vast majority of the "junk DNA" is of viral origin. Makes sense that we haven't evolved to get rid of it all yet as it must be constantly replenished.
Posted by: BTM | February 13, 2007 1:59 PM
In his 2002 Nobel Lecture NATURE'S GIFT TO SCIENCE Sidney Brenners said that he had the idea of distinguishing junk from garbage in the 80's:
Hwa A Lim's book GENETICALLY YOURS - Bioinforming, Biopharming, and Biofarming (World Scientific Publishing, online available here: http://www.worldscibooks.com/lifesci/etextbook/4950/4950_chap1_4.pdf ) presents this Brenner statement:
and gives the following reference "Decoding the Book of Life", NOVA, WGBH Educational Foundation, October 31, 1989. WGBH seems to be a radio program. Thus, he developed his idea during the mid 80's.
Posted by: sparc | February 13, 2007 2:20 PM
"Evolution is only a theory!" "Theres no such thing as junk DNA! Everything is DESIGNED!"
Commmon, since when have Creationists cared how words like 'theory' and 'junk DNA' are used in the real world? But I think youre on to something, here-- Im in the process of demolishing a UD article on mobile elements, and theyre all in a tizzy about 'junk DNA' too. Maybe ID Creationists have retreated from flagella and immune systems to the murky waters of unexplored DNA.
Posted by: ERV | February 13, 2007 3:18 PM
I don’t know about the rest of you, but I’ve always found the term “junk DNA” to be appropriate. If you look up the word ‘junk’ for instance in the dictionary, you find:
So while “junk” even in the colloquial sense can refer to something useless, it does not necessarily have to be useless. Pretty much everyone here has a junk drawer or an area where you have a pile of junk, perhaps the attic or garage or both. You don’t save this stuff because it’s worthless garbage, do you? The reason you save this ‘junk’ at all is precisely because it may have some use down the road that you can’t envision at the moment. And it did have a use at some point but is no longer used for the original purpose, perhaps because it’s broken, which is how it found itself in your junk pile in the first place. This is analogous to pseudogenes, which are similar to functional genes by have a mutation that makes them ‘broken’ but are still hanging around and may (or may not) eventually be found useful for some other purpose.
Finding a use for a piece of “junk DNA” no more validates the claim that it’s all really not junk, any more than does using that empty film container to hold thumbtacks mean the rest of the stuff in the drawer is no longer really junk.
Posted by: Dave S. | February 13, 2007 3:20 PM
Brenner (and you) make a good point regarding the difference between junk and trash DNA. However, it is not striking for most non-native English speakers (like myself), who could well be the wealth of science today. And usual translations like the French "ADN poubelle" draw on the "trash" rather than "junk" side of the original phrase. So, the situation might be more ambiguous than you describe, if not intentionally!
Posted by: Enro | March 10, 2007 8:07 AM
This was a very useful post. I encourage the discouragement of creationist nonsense.
Check out this creationist webpage: http://drdino.com
Posted by: Adrian Clement | March 25, 2007 6:43 PM