Histone Gene Expression: Hybrid Cells and Organisms Establish Complex Controls

Abstract

Publisher Summary Complexes of histones with DNA dictate the fundamental structure of chromatin in eukaryotic cells. As visualized by electron microscopy, this structure is monilifom (such as, beads on a string) and consists of a self-associating histone complex around which DNA is wrapped. The histone complexes may package DNA in a manner that is protective yet permissive of both replication and transcription. Alternatively, the association of the histone complexes with DNA may be so precise as to control the transcription of specific genes. Whether one chooses to view the biological role of histones as nearer one or the other of these views, it appears that the DNA of eukaryotic cells is packaged and that histones are indispensible for the packaging process. The genome structure and function are related. There is an evolutionary conservation of a specific number of chromosomes with certain characteristic morphological features in a given species. The addition or deletion of chromosomes, or the unbalanced translocation of parts of chromosomes, often results in specific pathological states.