Genomes were forged by massive bombardments with retroelements and retrosequences.
Retroposition is an efficient route to move coding regions around the genome 'in search' of novel regulatory elements and to shotgun regulatory elements into the genome 'in search' of new target genes. The templates for such retrogenes are mRNAs, and for regulatory retronuons (nuon = any definable nucleic acid sequence) usually small non-mRNAs (snmRNAs). An example in support of the 'master gene' model for SINEs (short interspersed repetitive elements) is provided with neuronal BC1 RNA. Furthermore, an alternative explanation of LINE (long interspersed repetitive elements) involvement in the generation of SINEs is given. I will also argue that the status of transposable elements with respect to the host resembles more symbiosis than parasitiasis and that host defense is often lenient as if even to 'tolerate or support' retronuons. Finally the paradox of evolution's lack of foresight and the future exaptive use of retronuons is being dealt with by referring to W.F. Doolittle's 'Hierarchical Approaches to Genome Evolution'.
Brosius
J
J
Institute of Experimental Pathology/Molecular Neurobiology, ZMBE, University of Münster, Germany. RNA.world@uni-muenster.de
D000818:Animals; D019470:Biolistics; D014644:Genetic Variation; D016678:Genome; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics; D012194:RNA-Directed DNA Polymerase; D018626:Retroelements; D013698:Templates, Genetic
D012333:RNA, Messenger; D018626:Retroelements; D012194:RNA-Directed DNA Polymerase