Telomere replication and fusion in eukaryotes.

The requirement for special mechanisms to replicate the ends of linear DNA has resulted in a new model of telomere replication that includes fused telomeres as intermediates. The model suggests a mechanism for Robertsonian fusions and fissions and predicts the formation of dicentric chromosomes during certain types of cellular dysfunction. One possible molecular mechanism for covalently joining the ends of DNA before replication and reforming the ends afterwards is presented. Molecular and cytological evidence is cited in support of the model. The model assigns a role to membrane binding and clustering of telomeres in higher eukaryotes and explains the paired chromosome chains observed during fungal mitosis.