title: The spread of sequence variants in Rattus satellite DNAs.
abstract: The genus Rattus has two related families of satellite DNA: Satellite I consists of tandem arrays of a 370 base pair repeat unit which is a dimer of two 185 base pair portions (a, b) which are about 60% homologous. Satellite I' consists of tandem arrays of a 185 base pair repeat unit (a') which is about 85% homologous to a and 60% homologous to b. R. norvegicus contains only satellite I but R. rattus contains both satellites I and I'. We examined certain aspects of satellite DNA evolution by comparing the spacing at which variant repeat units of each satellite have spread among non-variant repeat units in these two species. With but one exception, in R. rattus, 15 different variant repeat units have spread among non-variant repeat units of satellite I, with a spacing equal to the length of the (a,b) dimer. Similarly, fourteen different variant repeat units of the monomeric satellite I' have mixed among non-variant repeat units with a spacing equal to the length of the (a') monomer. These results suggest that a mechanism involving homologous interaction among satellite sequences could account for the spread of variant family members. We also found that a sequence variant present in certain portions of the dimeric repeat unit of satellite I is more efficiently amplified (or less efficiently corrected) than variants occurring in other regions. This was not true for the monomeric repeat unit of satellite I'.
mesh_terms: D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D005075:Biological Evolution; D004262:DNA Restriction Enzymes; D004276:DNA, Satellite / Q000235:genetics*; D014644:Genetic Variation; D008970:Molecular Weight; D009115:Muridae / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D051381:Rats / Q000235:genetics*; D013045:Species Specificity
chemical_list: D004276:DNA, Satellite; D004262:DNA Restriction Enzymes