Title:
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The genomic distribution of Human Endogenous Retroviruses (HERV-K) and the evolution of the primates
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Using my catalogue of HERV-K structure and integration site polymorphisms, PCR-based assays were developed for HERV-K loci and used to screen geographically diverse human DNA samples. The results indicate that the diversity of such elements is higher in African than non-African populations with 90.12 % to 99.37 % of genetic variation being within a population. Furthermore, the findings are consistent with African origin of contemporary humans which was followed by a complex process of interbreeding and population movement. Investigation of the biological contribution of HERV sequences in serving as nucleation points for chromosomal rearrangement demonstrated that such events have been extremely rare during primate genome evolution and may have been overestimated in previous studies. Analysis of HERV-K coding regions and subfamily phylogeny indicated that they have been subject to both purifying selection and extension sequence exchange throughout their expansion. Analysis of sequence variation at synonymous and non-synonymous sites in parsimony reconstructed sequences indicates that constraints on sequence variation have reduced over time, suggesting a decline in the likelihood of HERV functionality. Whilst the role of HERVs in primate evolution is yet to be fully understood, the comprehensive catalogue obtained in this study, the identification of novel proviral sequences and further elucidation of recombinant events provide the foundations for future functional and phylogenetic investigations of human and primate evolution and speciation.
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