| Citation |
Moshkin, Y.M., Belyakin, S.N., Rubtsov, N.B., Kokoza, E.B., Alekseyenko, A.A., Volkova, E.I., Belyaeva, E.S., Makunin, I.V., Spierer, P., Zhimulev, I.F. (2002). Microdissection and sequence analysis of pericentric heterochromatin from the Drosophila melanogaster mutant Suppressor of
Underreplication. Chromosoma 111(2): 114--125. |
| PubMed Abstract |
In the Suppressor of Underreplication( SuUR) mutant strain of Drosophila melanogaster, the heterochromatin of polytene chromosomes
is not underreplicated and, as a consequence, a number of beta-heterochromatic regions acquire a banded structure. The chromocenter
does not form in these polytene chromosomes, and heterochromatic regions, normally part of the chromocenter, become accessible
to cytological analysis. We generated four genomic DNA libraries from specific heterochromatic regions by microdissection
of polytene chromosomes. In situ hybridization of individual libraries onto SuUR polytene chromosomes shows that repetitive
DNA sequences spread into the neighboring euchromatic regions. This observation allows the localization of eu-heterochromatin
transition zones on polytene chromosomes. We find that genomic scaffolds from the eu-heterochromatin transition zones are
enriched in repetitive DNA sequences homologous to those flanking the suppressor of forked gene [ su(f) repeat]. We isolated
and sequenced about 300 clones from the heterochromatic DNA libraries obtained. Most of the clones contain repetitive DNA
sequences; however, some of the clones have unique DNA sequences shared with parts of unmapped genomic scaffolds. Hybridization
of these clones onto SuUR polytene chromosomes allowed us to assign the cytological localizations of the corresponding genomic
scaffolds within heterochromatin. Our results demonstrate that the SuUR mutant renders possible the mapping of heterochromatic
scaffolds on polytene chromosomes.
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