| Institution: | (1) Institute of Cytology and Genetics, Siberian Division of Russian Academy of Sciences, Lavrentyev Ave., 10, 630090 Novosibirsk, Russia;(2) Department of Zoology, University of Geneva, Quai E. Ansermet, CH-1211 Geneva, Switzerland;(3) Department of Cytology and Genetics, Novosibirsk State University, Pirogov Str. 2, 630090 Novosibirsk, Russia |
| Abstract: | The morphological characteristics of intercalary heterochromatin (IH) are compared with those of other types of silenced chromatin in the Drosophila melanogaster genome: pericentric heterochromatin (PH) and regions subject to position effect variegation (PEV). We conclude that IH regions in polytene chromosomes are binding sites of silencing complexes such as PcG complexes and of SuUR protein. Binding of these proteins results in the appearance of condensed chromatin and late replication of DNA, which in turn may result in DNA underreplication. IH and PH as well as regions subject to PEV have in common the condensed chromatin appearance, the localization of specific proteins, late replication, underreplication in polytene chromosomes, and ectopic pairing. |
