Sex chromosomes are an ideal system to study processes connected with suppressed recombination. We found evidence of microsatellite expansion, on the relatively young Y chromosome of the dioecious plant sorrel (Rumex acetosa, XY1Y2 system), but no such expansion on the more ancient Y chromosomes of liverwort (Marchantia polymorpha) and human. The most expanding motifs were AC and AAC, which also showed periodicity of array length, indicating the importance of beginnings and ends of arrays. Our data indicate that abundance of microsatellites in genomes depends on the inherent expansion potential of specific motifs, which could be related to their stability and ability to adopt unusual DNA conformations. We also found that the abundance of microsatellites is higher in the neighborhood of transposable elements (TEs) suggesting that microsatellites are probably targets for TE insertions. This evidence suggests that microsatellite expansion is an early event shaping the Y chromosome where this process is not opposed by recombination, while accumulation of TEs and chromosome shrinkage predominate later.

• MeSH
• A-DNA genetika   MeSH
• chromozomy rostlin genetika   MeSH
• duplikace genu MeSH
• hybridizace in situ fluorescenční MeSH
• lidé MeSH
• lidský chromozom Y genetika   MeSH
• Marchantia genetika   MeSH
• metafáze genetika   MeSH
• mikrosatelitní repetice genetika   MeSH
• modely genetické MeSH
• molekulární evoluce * MeSH
• periodicita MeSH
• Rumex genetika   MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• transpozibilní elementy DNA genetika   MeSH
• Z-DNA genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• A-DNA MeSH
• transpozibilní elementy DNA MeSH
• Z-DNA MeSH

We performed PCR of many DNA fragments of 6-32 nucleotides in length. Some of the fragments expanded into kilobase lengths even in the absence of the complementary strand. The dramatic expansion was observed for (CA)8, (TG)8, (CA)4, (CA)6, (CA)12, (TG)4, (TG)6, (TG)12, (TC)10, (GA)10 and other single strands. Similar expansions were exhibited by related trinucleotide repeats (TTG)5, (CAA)5, (TGG)5, and (CCA)5 as well. However even small perturbations of the strict repetitive nature of the DNA primary structure substantially reduced the expansions. The expansion products had properties characteristic for normal Watson-Crick duplexes. Hence either the Taq polymerase and/or other components of the PCR buffer promote homoduplex formation of the nonselfcomplementary fragments, which is necessary to prime the synthesis of the complementary DNA strand, or the Taq polymerase is able to copy the single-stranded DNA template without any priming effect. The present observations have implications for the evolution of genomic DNA, microsatellite length polymorphism as well as the pathological expansions of trinucleotide repeats in the human genome.

• MeSH
• dinukleotidové repetice genetika   MeSH
• expanze repetic DNA genetika   MeSH
• hybridizace nukleových kyselin MeSH
• jednovláknová DNA chemie   genetika   MeSH
• lidé MeSH
• mutageneze genetika   MeSH
• párování bází MeSH
• polymerázová řetězová reakce * MeSH
• sekvence nukleotidů MeSH
• teplota MeSH
• trinukleotidové repetice genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• jednovláknová DNA MeSH