Patterns of intra- and interarray sequence variation in alpha satellite from the human X chromosome: evidence for short-range homogenization of tandemly repeated DNA sequences.


Journal Article

A number of processes, such as sequence conversion, unequal crossingover, and molecular drive, have been postulated to explain the homogenization of tandemly repeated DNA families. To investigate the nature and extent of such processes in the alpha satellite family of centromeric DNA, we determined the nucleotide sequence of approximately 700 bp from each of 40 representative alpha satellite repeats from six sources of human X chromosomes, obtaining a total of approximately 28 kb of sequence data. Sequence divergence among the repeats examined was low, with an average pairwise difference of approximately 1%. Pairwise comparisons of all repeats indicate that the degree of similarity for those repeats in physical proximity (within approximately 15 kb) of each other is significantly greater than that for randomly located repeats, from either the same or different X chromosomes, suggesting that the mechanisms predicted to homogenize these arrays are effectively short-range in action. Analysis of individual patterns of sequence variation allows the assignment of haplotypes for five high-copy-number diagnostic positions and reveals distinct positions of equilibrium and disequilibrium within the repeat. These analyses address hypotheses about the origin of the observed patterns of variation throughout alpha satellite evolution.

Full Text

Cited Authors

  • Durfy, SJ; Willard, HF

Published Date

  • November 1989

Published In

Volume / Issue

  • 5 / 4

Start / End Page

  • 810 - 821

PubMed ID

  • 2591964

Pubmed Central ID

  • 2591964

Electronic International Standard Serial Number (EISSN)

  • 1089-8646

International Standard Serial Number (ISSN)

  • 0888-7543

Digital Object Identifier (DOI)

  • 10.1016/0888-7543(89)90123-7


  • eng