The genetic analysis of D. melanogaster heterochromatin

Classical, or constitutive (Brown, 1966), heterochromatin is a nearly ubiquitous aspect of higher eukaryotic chromosome structure and its genetic significance has been debated since its first description (Heitz, 1928, 1929). This review describes genetic studies on the heterochromatin of Drosophila and the perspectives they provide on the possible biological role(s) of constitutive heterochromatin. In addition to documenting the existence of gene loci within heterochromatin, these studies provide evidence for long-range interactions within the nucleus and involving heterochromatin. These interactions may reflect more general properties of chromatin related to the three-dimensional structure of the interphase nucleus and its effects on gene expression.