11 Cytology of Telomeres

Abstract

Cytological observation of telomere behavior has a long history relative to our understanding of the molecular organization of chromosomes. Evidence accumulated in the late 19th century suggested that in a given organism the number and appearance of chromosomes was a consistent feature of each nucleus. To understand the function of these structures, investigators worked to describe chromosome movements, their global organization within the nucleus, and their associations with each other. Chromosome ends (telomeres) and spindle attachment points (kinetochores) were among the earliest recognized features, and their behavior has been the focus of many studies for more than a century. More recent evidence, discussed in various chapters in this volume, has shown that telomeres are specialized sequences that have roles in protecting chromosomes from fusion and degradation and can also affect genetic activity. These discoveries have spurred new interest in understanding telomere spatial organization and dynamics.

There are significant differences between the conclusions about telomere organization drawn from observations of somatic versus meiotic cells. This is at least in part because some of the processes governing telomere behavior are probably specific to meiosis. Because of these differences, in this review we treat observations from somatic and meiotic nuclei separately.

TELOMERE ORGANIZATION IN SOMATIC CELL NUCLEI
Cytological Techniques for Probing Telomere Organization
For more than a century, investigators have attempted to elucidate elements of order governing the interphase nucleus. Direct observation of interphase organization is difficult because of the decondensed nature of the chromosomes, which renders them indistinguishable in typical microscopic preparations...