On "genomenclature": a comprehensive (and respectful) taxonomy for pseudogenes and other "junk DNA".

Genomic nomenclature has not kept pace with the levels and depth of analyzing and understanding genomic structure, function, and evolution. We wish to propose a general terminology that might aid the integrated study of evolution and molecular biology. Here we designate as a "nuon" any stretch of nucleic acid sequence that may be identifiable by any criterion. We show how such a general term will facilitate contemplation of the structural and functional contributions of such elements to the genome in its past, current, or future state. We focus in this paper on pseudogenes and dispersed repetitive elements, since their current names reflect the prevalent view that they constitute dispensable genomic noise (trash), rather than a vast repertoire of sequences with the capacity to shape an organism during evolution. This potential to contribute sequences for future use is reflected in the suggested terms "potonuons" or "potogenes." If such a potonuon has been coopted into a variant or novel function, an evolutionary process termed "exaptation," we employ the term "xaptonuon." If a potonuon remains without function (nonaptive nuon), it is a "nonaptation" and we term it "naptonuon." A number of examples for potonuons and xaptonuons are given.