The human genome contains several classes of repeat segments including common repeats, interspersed repeats and tandem repeats (usually called satellites) which, in total, cover more than 60% of the genome sequence. Since their discovery, a number of mechanisms have been proposed to explain the generation and propagation of genome repeats. For example, it is generally accepted that tandem repeats are a result of subsequent unequal crossover events. These events have been observed to occur in the course of meiosis during which a misalignment between sister chromatids followed by a crossover may result in the duplication (as well as a deletion in the sister chromatid) of a basic repeat element. In this talk we challenge the long standing belief that unequal crossovers provide the single mechanism for the evolution of alpha satellite DNA, the primary satellite sequence that cover the centromeric regions of all human chromosomes. We develop algorithmic methods to collect, evaluate and analyze the sequence information from select regions of human centromeric DNA and provide mathematical evidence suggesting an independent inter-chromosomal mechanism complementing the unequal crossover in the evolution of the alpha satellite sequence.

DATE: September 25, 2002, Wednesday @ 16:40
PLACE: EA-409