The study by Christian Schlötterer and Diethard Tautz investigates the slippage synthesis of simple sequence DNA in vitro, aiming to understand how these sequences arise in vivo. They demonstrate that various repetitive di- and trinucleotide motifs can be synthesized from short primers and a polymerase, with the synthesis rate depending on a sequence-specific slippage rate but being independent of fragment length. This suggests that only the ends of the DNA fragments are involved in determining the slippage rate, indicating that slippage is a short-range effect. The authors also show that slippage synthesis occurs on a fixed template where only one strand is free to move, resembling chromosome replication in vivo. They propose that slippage during replication is likely the cause of the observed length polymorphism of simple sequence stretches between individuals of a population. The study uses different DNA polymerases to explore their effects on slippage synthesis, finding that T7 DNA polymerase behaves differently, suggesting that the polymerase's characteristics influence the synthesis process. Overall, the results support the idea that slippage reactions produce unpaired free ends that can be filled by a DNA polymerase, contributing to the formation and elongation of simple sequence stretches.The study by Christian Schlötterer and Diethard Tautz investigates the slippage synthesis of simple sequence DNA in vitro, aiming to understand how these sequences arise in vivo. They demonstrate that various repetitive di- and trinucleotide motifs can be synthesized from short primers and a polymerase, with the synthesis rate depending on a sequence-specific slippage rate but being independent of fragment length. This suggests that only the ends of the DNA fragments are involved in determining the slippage rate, indicating that slippage is a short-range effect. The authors also show that slippage synthesis occurs on a fixed template where only one strand is free to move, resembling chromosome replication in vivo. They propose that slippage during replication is likely the cause of the observed length polymorphism of simple sequence stretches between individuals of a population. The study uses different DNA polymerases to explore their effects on slippage synthesis, finding that T7 DNA polymerase behaves differently, suggesting that the polymerase's characteristics influence the synthesis process. Overall, the results support the idea that slippage reactions produce unpaired free ends that can be filled by a DNA polymerase, contributing to the formation and elongation of simple sequence stretches.