[Repetitious DNA in the genome of Drosophila lummei Hackman and its role in replication and chromosome behavior in mitosis].
The toromere previously found by other workers in the distal end of the sixth chromosome (microchromosome) of D. lummei was studied using differential staining of D. lummei giant chromosomes. The toromere which was first described as a quinacrine-bright structure appears as a C-positive body. Quantitative cytofluorometric analysis showed a significant increase in toromeric DNA under low temperature conditions. In situ hybridization of 125I nick-translated D. virilis sDNA (all three satellites were included in the sample) with polytene chromosomes of D. lummei larvae cultured at 12 degrees C revealed no label incorporation into the toromere region. However in situ hybridization of [3H]RNA complementary to highly repetitious DNA of D. lummei and D. virilis (C0t = 10(-1)--10(-2)) with polytene chromosomes of the larvae cultured at 12 degrees coupled with banding studies enable us to conclude that the toromere probably contains AT-rich repeated DNA. Well-developed toromere in the sixth chromosome of D. lummei was also demonstrated at normal temperature (25 degrees) in interspecific hybrids. The role of the toromere structure in the mitotic behaviour of microchromosomes and their replication pattern is discussed.
D000818:Animals; D002871:Chromosome Banding; D002875:Chromosomes / Q000502:physiology*; D004247:DNA / Q000235:genetics*; D004276:DNA, Satellite / Q000235:genetics; D004330:Drosophila / Q000235:genetics*; D008938:Mitosis; D009693:Nucleic Acid Hybridization; D012091:Repetitive Sequences, Nucleic Acid
D004276:DNA, Satellite; D004247:DNA
Povtoriaiushchaiasia fraktsiia DNK v genome Drosophila lummei Hackman, vliiaiushchaia na replikatsiiu i povedenie khromosom v mitoze.