title: The mutation rates of di-, tri- and tetranucleotide repeats in Drosophila melanogaster.
abstract: In a recent study, we reported that the combined average mutation rate of 10 di-, 6 tri-, and 8 tetranucleotide repeats in Drosophila melanogaster was 6.3 x 10(-6) mutations per locus per generation, a rate substantially below that of microsatellite repeat units in mammals studied to date (range = 10(-2)-10(-5) per locus per generation). To obtain a more precise estimate of mutation rate for dinucleotide repeat motifs alone, we assayed 39 new dinucleotide repeat microsatellite loci in the mutation accumulation lines from our earlier study. Our estimate of mutation rate for a total of 49 dinucleotide repeats is 9.3 x 10(-6) per locus per generation, only slightly higher than the estimate from our earlier study. We also estimated the relative difference in microsatellite mutation rate among di-, tri-, and tetranucleotide repeats in the genome of D. melanogaster using a method based on population variation, and we found that tri- and tetranucleotide repeats mutate at rates 6.4 and 8.4 times slower than that of dinucleotide repeats, respectively. The slower mutation rates of tri- and tetranucleotide repeats appear to be associated with a relatively short repeat unit length of these repeat motifs in the genome of D. melanogaster. A positive correlation between repeat unit length and allelic variation suggests that mutation rate increases as the repeat unit lengths of microsatellites increase.
authors.affiliation: Section of Genetics and Development, Cornell University, Ithaca, New York 14853, USA. mds25@cornell.edu
authors.forename: M D
authors.initials: MD
authors.lastname: Schug
authors.forename: C M
authors.initials: CM
authors.lastname: Hutter
authors.forename: K A
authors.initials: KA
authors.lastname: Wetterstrand
authors.forename: M S
authors.initials: MS
authors.lastname: Gaudette
authors.forename: T F
authors.initials: TF
authors.lastname: Mackay
authors.forename: C F
authors.initials: CF
authors.lastname: Aquadro
mesh_terms: D000349:Africa; D000483:Alleles; D000818:Animals; D018900:Dinucleotide Repeats; D004331:Drosophila melanogaster / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D015723:Gene Library; D005819:Genetic Markers; D006579:Heterozygote; D018895:Microsatellite Repeats; D008957:Models, Genetic; D009154:Mutation; D016133:Polymerase Chain Reaction; D012044:Regression Analysis; D013995:Time; D018911:Trinucleotide Repeats; D014481:United States
chemical_list: D005819:Genetic Markers