1 A History of Telomere Biology

Abstract

An image from early in the history of modern cytogenetics encapsulates the central elements of telomere biology. It is a meticulously rendered drawing made of a microscopic image in a 1910 paper by Theodor Boveri (Fig. 1) (Gall 1996), in which he followed up on his original observation in the late 1800s that soon after fertilization in the roundworm Ascaris, as cell division commences, the chromosomes fragment. This of course does not happen in cells destined to become germ-line cells, but only in a specific subset of the earliest blastomeres. Cytogenetic studies starting in the 1930s, primarily by McClintock and Muller, showed that if a chromosome breaks, the broken end usually becomes unstable. However, McClintock showed that soon after fertilization, in specific cell types, a broken end can heal in a genetically determined process. The implication of Boveri’s image is that the fragmented Ascaris chromosomes have healed their ends, because they persist throughout the life of the animal.

The events so vividly captured in Boveri’s micrograph now have many of their molecular underpinnings known, at least in part. The modern studies of telomere DNA structure that started in the 1970s identified the DNA that confers stability—by binding proteins—to a newly created chromosomal end. The discovery of telomerase in the 1980s demonstrated the enzymatic mechanism by which such DNA can be acquired, and is maintained, at chromosomal termini. This chapter outlines the history of these advances in telomere and telomerase biology research up to the early 1990s. By then,...