Abstract:
MicroRNAs (miRNA) are ~21 nucleotide-long gene regulators whose
action may be via translational repression or protein degradation. Segmental
duplications have been found to be one of the driving forces in acquiring new
genes. Both microRNA and segmental duplication have been speculated to have
played a significant role in evolution, particularly in the divergence of human
(Homo sapiens) from the chimpanzee (Pan troglodytes). The goal of the study is to
determine the distribution of miRNAs in humans and in chimpanzees, and propose
hypotheses on its significance to the occurrence of segmental duplications.
Sequences acquired from miRBASE were subjected to BL AT to identify miRNAs
located in regions of segmental duplication (SD regions) and BLAST to determine
which of these miRNA are also located in non-SD regions. ClustalW was utilized
to determine which human and chimp miRNAs were homologous. BLAST was
then used to determine whether the non-homologous human miRNA are
homologous to any other part of the chimpanzee genome. It was found that all 695
human miRNAs are found exclusively in SD regions, and that 67 are de novo
miRNAs. Thirteen were found to be homologs of chimpanzee miRNA, and 11
were possibly derived from non-miRNA regions in chimp — of these, 6 were
found to be located in SD regions of the chimpanzee genome. This demonstrates
that the evolution of miRNA occurs within regions of segmental duplication. It is
suggested that miRNA duplicates provide raw genetic material, which allows more
exposure to mutations that could necessitate diversification, and possibly
evolution, through sub- and neofunctionalization.
