Problems and paradigms
The relationship between non-protein-coding DNA and eukaryotic complexity
Version of Record online: 12 FEB 2007
Copyright ©2007 Wiley Periodicals, Inc.
Volume 29, Issue 3, pages 288–299, March 2007
How to Cite
Taft, R. J., Pheasant, M. and Mattick, J. S. (2007), The relationship between non-protein-coding DNA and eukaryotic complexity. Bioessays, 29: 288–299. doi: 10.1002/bies.20544
- Issue online: 12 FEB 2007
- Version of Record online: 12 FEB 2007
- Australian Research Council
- United States National Science Foundation Graduate Research Fellowship
There are two intriguing paradoxes in molecular biology—the inconsistent relationship between organismal complexity and (1) cellular DNA content and (2) the number of protein-coding genes—referred to as the C-value and G-value paradoxes, respectively. The C-value paradox may be largely explained by varying ploidy. The G-value paradox is more problematic, as the extent of protein coding sequence remains relatively static over a wide range of developmental complexity. We show by analysis of sequenced genomes that the relative amount of non-protein-coding sequence increases consistently with complexity. We also show that the distribution of introns in complex organisms is non-random. Genes composed of large amounts of intronic sequence are significantly overrepresented amongst genes that are highly expressed in the nervous system, and amongst genes downregulated in embryonic stem cells and cancers. We suggest that the informational paradox in complex organisms may be explained by the expansion of cis-acting regulatory elements and genes specifying trans-acting non-protein-coding RNAs. BioEssays 29: 288–299, 2007. © 2007 Wiley Periodicals, Inc.