Beginning or end? Telomere structure, genetics and biology.

The word telomere derives from the Greek word telos meaning 'end', roughly translating as 'the thing at the end' when the end is that of a chromosome. Telomeres belie their apparent simplicity of structure by being involved in a wide range of diverse biological phenomena. Much of our understanding of telomere behaviour comes from studies in lower eukaryotes such as ciliates and yeast, the subject of many recent reviews. Here we concentrate on the mammalian telomere, recent progress in its study, and how recent evidence for an involvement of telomeres in the regulation of gene expression and DNA replication in yeast points to new aspects of mammalian telomere function yet to be explored.