There is now compelling evidence that the complexity of higher organisms
correlates with the relative amount of non-coding RNA rather than the
number of protein-coding genes. Previously dismissed as "junk DNA", it
is the non-coding regions of the genome that are responsible for
regulation, facilitating complex temporal and spatial gene expression
through the combinatorial effect of numerous mechanisms and interactions
working together to fine-tune gene expression. The major regions
involved in regulation of a particular gene are the 5' and 3'
untranslated regions and introns. In addition, pervasive transcription
of complex genomes produces a variety of non-coding transcripts that
interact with these regions and contribute to regulation. This book
discusses recent insights into the regulatory roles of the untranslated
gene regions and non-coding RNAs in the control of complex gene
expression, as well as the implications of this in terms of organism
complexity and evolution.