Origin and Evolution
The mir-2 family originated before the last common ancestor of protostomes, and has been ever since linked to mir-71. The evolution of mir-2 is characterized by successive expansions by duplication events. Since most paralogous microRNAs conserve their function, it has been suggested that mir-2 evolution is dominated by a birth-and-death dynamics driven by random drift.
One mir-2 microRNA in Drosophila, dme-miR-2a-2, is two nucleotides offset with respect to the canonical products of other mir-2 precursors. This is likely to affect the function of that particular microRNA. This functional shift is associated to a change in the genomic distribution of mir-2 sequences in Drosophila. The functional diversification of microRNAs may require breaking the genomic linkage between paralogs, probably to avoid the co-regulation of multiple products by the same regulatory sequences.
In the human parasite Schistosoma mansoni the whole mir-71/mir-2 cluster has been duplicated, and one of the copies is in the sexual chromosome.
Read more about this topic: Mir-2 Micro RNA Precursor
Famous quotes containing the words origin and/or evolution:
“In the woods in a winter afternoon one will see as readily the origin of the stained glass window, with which Gothic cathedrals are adorned, in the colors of the western sky seen through the bare and crossing branches of the forest.”
—Ralph Waldo Emerson (1803–1882)
“The more specific idea of evolution now reached is—a change from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, accompanying the dissipation of motion and integration of matter.”
—Herbert Spencer (1820–1903)