The centromere is required to ensure the equal distribution of replica
ted chromosomes to daughter nuclei. Centromeres are frequently associa
ted with heterochromatin, an enigmatic nuclear component that causes t
he epigenetic transcriptional repression of nearby marker genes (posit
ion-effect variegation of silencing). The process of chromosome segreg
ation by movement along microtubules to spindle poles is highly conser
ved, yet the putative cis-acting centromeric DNA sequences bear little
or no similarity across species. Recently, studies in several systems
have revealed that the centromere itself might be epigenetically regu
lated and that the higher-order structure of the underlying heterochro
matin contributes to centromere function and kinetochore assembly.