Intercalary heterochromatin in Drosophila melanogaster polytene chromosomes and the problem of genetic silencing.
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.
Institute of Cytology and Genetics, Siberian Division of Russian Academy of Sciences, Lavrentyev Ave., 10, 630090, Novosibirsk, Russia. zhimulev@bionet.nsc.ru
Igor F
IF
Zhimulev
Elena S
ES
Belyaeva
Igor V
IV
Makunin
Vincenzo
V
Pirrotta
Valery F
VF
Semeshin
Artyom A
AA
Alekseyenko
Stepan N
SN
Belyakin
Elena I
EI
Volkova
Dmitry E
DE
Koryakov
Evgeniya N
EN
Andreyeva
Olga V
OV
Demakova
Irina V
IV
Kotlikova
Tatyana D
TD
Kolesnikova
Lidiya V
LV
Boldyreva
Roman A
RA
Nanayev
D000818:Animals; D002874:Chromosome Mapping; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics*; D020868:Gene Silencing; D006570:Heterochromatin / Q000235:genetics*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006570:Heterochromatin; C464850:SuUR protein, Drosophila