Instability of (GATA) n microsatellite loci in the parthenogenetic Caucasian rock lizard Darevskia unisexualis (Lacertidae)

Abstract

Mini- and microsatellites, comprising tandemly repeated short nucleotide sequences, are abundant dispersed repetitive elements that are ubiquitous in eukaryotic genomes. In humans and other bisexual species hypervariable mini- and microsatellite loci provide highly informative systems for monitoring of germline and somatic instability. However, little is known about the mechanisms by which these loci mutate in species that lack effective genetic recombination. Here, multilocus DNA fingerprinting was used to study M13 minisatellite and (GATA)n microsatellite instability in the parthenogenetic Caucasian rock lizard Darevskia unisexualis (Lacertidae). DNA fingerprinting of 25 parthenogenetic families, from six isolated populations in Armenia (comprising a total of 84 siblings), using the oligonucleotide (GATA)4 as a hybridization probe, revealed mutant fingerprinting phenotypes in 13 siblings that differed from their mothers in several restriction DNA fragments. In three families (8 siblings), the mutations were present in the germline. Moreover, the mutant fingerprint phenotypes detected in siblings were also present in population DNA samples. No intrafamily variations in DNA fingerprint patterns were observed with the M13 minisatellite probe. Estimates of the mutation rate for (GATA)n microsatellite loci in D. unisexualis showed that it was as high as that seen in some bisexual species, reaching 15% per sibling or 0.95% per microsatellite band. Furthermore, in one case, a somatic (GATA)n microsatellite mutation was observed in an adult lizard. These findings directly demonstrate that mutations in (GATA)n microsatellite loci comprise an important source of genetic variation in parthenogenetic populations of D. unisexualis.

Molecular characterization of allelic variants of (GATA)n microsatellite loci in parthenogenetic lizards Darevskia unisexualis (Lacertidae)

“…The most variable were found to be (GATA) n -, (TCC) n -, and (TCT) n -containing loci in D. unisexualis Ryskov et al, 2000Ryskov et al, , 2003. Moreover, DNA fingerprinting of the parthenogenetic families of D. unisexualis directly demonstrated that mutations, detected as RFLPs in unstable (GATA) n -containing loci, made a significant contribution to the overall genomic diversity of parthenogenetic populations (Tokarskaya et al, 2004). Cloning and sequencing microsatellite-containing loci may be the most unambiguous way of analysing their allelic variability.…”

“…Although they exist as unisexual lineages, parthenogenetic lizards are characterized by a certain degree of clonal diversity resulting from mutations, multiple hybridization events, and some level of recombination, which occur during continued clonal reproduction and the evolution of the species (Murphy et al, 2000;Fu et al, 2000a). We have demonstrated intrafamily restriction fragment length polymorphisms (RFLPs) in parthenogenetic families of D. unisexualis, probably arising from germline and somatic mutations, at loci detectable with a (GATA) 4 microsatellite probe (Tokarskaya et al, 2004).…”

Genetic Variation and De Novo Mutations in the Parthenogenetic Caucasian Rock Lizard Darevskia unisexualis

“…The most straightforward and conclusive way to assess the mutational contribution to genetic variation is the direct detection of mutational events from pedigree genotyping [21]. Multilocus DNA fingerprinting with various microsatellite probes detected intrafamily variability of fingerprint patterns in D. unisexualis and D. armeniaca lizards [22], 23. These results imply that unstable loci may exist intheir genomes, but the real nature of such loci and supposed mutations remains obscure.…”

The gynogenetic form of fish from the genus Cobitis (Cobitidae) in a region of its geographic range is monoclonal: DNA fingerprinting data

“…We obtained similar results when parthenogenetic populations of four lizard species of the genus Darevskia were studied ( D. dahli , D. armeniaca , D. rostombekovi , and D. unisexualis ), though these species were heterogeneous with respect to microsatellite loci [11]. Mutations in both germ and somatic cells proved to determine largely the microsatellite variability of these reptilians [12].…”