JR Minkel at the Scientific American blog has responded to the post on Evolgen about his earlier story regarding “junk DNA” (did you catch all that?). At the end of the post, he asks:
Scientists and scientist bloggers: Again, do you care [if journalists call it junk DNA]? If so, what term would you propose instead, or how would you make the distinction between functional and nonfunctional noncoding DNA clear to a popular audience?
Yes, I care, and here are my suggestions. If you mean the general category without any speculation either way about function, then it is simply and accurately “noncoding DNA”. If it has a function, then you specify what that function is: “regulatory DNA” or “structural DNA” or what have you. If the type of sequence is known, then you can use that as well or instead: “transposable elements” or “mobile DNA” or “pseudogenes” or “introns”. Maybe readers won’t know what those terms mean. This is a good opportunity to inform them.
What is missing is a term to describe a given collection of noncoding DNA for which there is thought to be some function, but for which that function and/or the type of sequence is unknown. This would reside somewhere between “junk DNA” (in the vernacular sense) and “functional DNA” (to which specific names can be applied). I therefore suggest the neologism “junctional DNA” to encompass this category. Note that Petsko (2003) suggested “funk DNA” to represent “functionally unknown DNA”, but I think “junctional DNA” is a little less, uh, funky.
Let me be even more specific. The proposed term “junctional DNA” derives from a dual etymology: 1) a simple portmanteau of “junk” and “functional”; 2) an indication that the sequences so described reside at the crossroads between DNA with no evident function and that with a clear function.
Two terms in one day — “the onion test” and “junctional DNA” — how ’bout that.
Incidentally, my annoyance with such reports has less to do with the terminology than with the fact that the highly conserved sequences in question make up about 5% of the total genome. To jump from this to imply that all noncoding DNA is recognized as functional is inappropriate and misleading. I also wish they would cite the source papers they reference; some of us would like to look up the primary material when we see a summary in a news story.
Update: Other bloggers (RPM of Evolgen in personal correspondence, Sandwalk) seem to think this term is not needed. I point out that this post was given in direct response to Minkel’s appeal for a term that would “make the distinction between functional and nonfunctional noncoding DNA clear to a popular audience”. In light of the fact that a journalist sees the need for such a term, and that it was coined in response to that need, I think ‘junctional DNA’ could be a useful term.