Superinstability (TCT/TCC)n of microsatellite DNA in parthenogenetic lizards Darevskia unisexualis (family Lacertidae)

Using multilocus DNA fingerprinting, we have examined variability of (TCT)n microsatellite and M13 minisatellite DNA repeats in populations, families, and tissues of Caucasian parthenogenetic rock lizards Darevskia unisexualis (Lacertidae). It has been shown for the first time that population and family DNA samples of D. unisexualis (75 samples in total) have individually specific DNA fingerprinting patterns of (TCT)n fragments. Analysis of inheritance of (TCT)n microsatellites in 46 first-generation progeny in 17 parthenogenetic D. unisexualis families revealed their extremely high instability. Mutant TCT fingerprint phenotypes were found in virtually each animal of the progeny. Moreover, varying fragments in the progeny and their original variants in the mothers were shown to simultaneously contain (TCT)n and (TCC)n polypyrimidine clusters. At the same time, no variability of (TCT)n fragments has been detected in the tissues and organs of mature parthenogenetic lizards and in the analogous tissues of the two-week-old progeny of this year. This suggests the absence of somatic mosaicism and methylation of the corresponding loci in the samples. Along with the hyperinstability of (TCT/TCC)n polypyrimidine clusters, we have shown that the population and family DNA fingerprinting patterns of M13 minisatellites were invariable and monomorphic in the same DNA samples of D. unisexualis. Our results indicate that mutations at loci containing polypyrimidine microsatellites significantly contribute to the total genomic variability of parthenogenetic lizards D. unisexualis.