However, our molecular analysis showed evidence for a secondary duplication of the locus in swsn-5 (ok622 ) homozygotes.
For instance, could redundancy resulting from polyploidy destabilize the incipient differentiation of the two paralogs, NRPD2/E2-a and NRPD2/E2-b, or could the occasional loss of primary duplication be compensated for by secondary duplications resulting from polyploidy?
Then in a second phase, portions of these primary duplication blocks are copied and reinserted into the genome at disparate loci forming secondary duplication blocks.
A number of studies suggested that secondary duplications may have occurred recently among existing duplications, and these recent duplications tend to share more duplicons in common [ 24].
Moreover, the domain composition of those proteins – and especially the apparition of the p85-binding domain in class IA – supports the conjecture of a first duplication leading to the separation of the two subclasses before secondary duplications in subclass IA.
SDs are generally found in the genome as mosaic forms of duplicated sequences which are generated by a two-step process: first, multiple duplicated sequences are aggregated at specific genomic regions, and then, these primary duplications undergo multiple secondary duplications.
In the second step, these primary duplications undergo multiple secondary duplications.
For example, whereas krc mutants show polydactyly associated with duplication of the first digit, our mutants show preaxial digit duplication characterized by mirror symmetric duplication of a secondary limb anterior-posterior axis.
Thus, our work lowers the likelihood of the previous proposal that "domain duplication followed by exchange of a secondary structure element can be a source of such a knot in the protein structure" being correct.
