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 â€œjunkâ€ and â€œfunctionalâ€; 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.