A dicentric chromosome of Drosophila melanogaster showing alternate centromere inactivation.
Dicentric chromosomes are rarely found, because they interfere with normal cell division causing chromosome instability. By in situ hybridization of region-specific heterochromatic yeast artificial chromosomes we have found that the artificially generated C(1)A chromosome of Drosophila melanogaster has two potential centromeres: one carries all the sequences of the centromere of the Y chromosome and the other carries only a part of the Y centromeric region that is rich in telomere-related sequences. Immunostaining with anti-Bub1 (a kinetochore-specific marker) shows that, in spite of the differences in sequence, both centromeres can be active although as a rule only one at a time. In a small fraction of the chromosomes centromere inactivation is incomplete, giving rise to true dicentric chromosomes. The centromere inactivation is clonally inherited, providing a new example of epigenetic chromosome imprinting and the possibility of genetically dissecting this process. The involvement of telomere-related sequences in centromere function is discussed.
Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain.
M
M
Agudo
J P
JP
Abad
I
I
Molina
A
A
Losada
P
P
Ripoll
A
A
Villasante
D000818:Animals; D002503:Centromere / Q000235:genetics*; D018244:Chromosomes, Artificial, Yeast / Q000235:genetics; D020732:Cytogenetic Analysis; D004331:Drosophila melanogaster / Q000235:genetics*; D005455:Fluorescent Antibody Technique; D018392:Genomic Imprinting; D006570:Heterochromatin / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D016615:Telomere / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics*
D006570:Heterochromatin; D011494:Protein Kinases; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases