Some aspects of the karyotype are highly conserved in certain mammalian groups, while in other groups the karyotype can undergo extensive repatterning in a short period of time. While it is clear that chromosomal mutation represents a reorganization of the genetic material, the molecular basis and effects of such change are largely a matter of speculation. The suggestion has frequently been made that mobile genetic elements play a role in chromosomal rearrangement. This proposal investigates the role of repetitive sequences in karyotypic repatterning by studying the relationship between hypervariable repetitive sequences and karyotypic plasticity in different mammalian groups. Three mammalain groups will be investigated: cetaceans, which are karyotypically conservative; deer mice, which have undergone karyotypic orthoselection for pericentric inversions and heterochromatic additions; and equids, which have shown an extremely rapid and varied repatterning of the karyotype. Hypervariable DNA will be isolated from one species from each group by phylogenetic screening, and approach for identifying rapidly diverging repetitive sequences. The correlation between the amount and nature of hypervariable DNA and the karyotypic stability of each group will be investigated. Because the equids are so karyotypically unstable, the most derived equid genome will be further investigated. Repetitive elements from this group will be more extensively characterized. Equid DNA will be factionated by density gradient centrifugation, and these fractions will be used to determine whether repetitive families from the Hartmann's mountain zebra are non-randomly distributed in the genome. A clear perception of genome organization may be central to understanding development and the regulation of gene expression.
| Erickson, Issac K; Cantrell, Michael A; Scott, LuAnn et al. (2011) Retrofitting the genome: L1 extinction follows endogenous retroviral expansion in a group of muroid rodents. J Virol 85:12315-23 |
