Observations On the Induction of Position Effect Variegation of Euchromatic Genes in Drosophila-Melanogaster

Pokholkova, GV, Makunin, IV, Belyaeva, ES and Zhimulev, IF (1993) Observations On the Induction of Position Effect Variegation of Euchromatic Genes in Drosophila-Melanogaster. Genetics, 134 1: 231-242.

Author Pokholkova, GV
Makunin, IV
Belyaeva, ES
Zhimulev, IF
Title Observations On the Induction of Position Effect Variegation of Euchromatic Genes in Drosophila-Melanogaster
Journal name Genetics   Check publisher's open access policy
ISSN 0016-6731
Publication date 1993-05-01
Year available 1993
Sub-type Article (original research)
Open Access Status Not yet assessed
Volume 134
Issue 1
Start page 231
End page 242
Total pages 12
Place of publication BALTIMORE
Publisher GENETICS
Language eng
Abstract In the T(1;2)dor(var7) translocation, the IA-2B7-8 segment of the X chromosome is brought to the vicinity of 2R-chromosome heterochromatin resulting in position effect variegation of dor, BR-C and more distal genes, as well as compaction of chromatin in this segment. By irradiation of T(1;2)dor(var7), nine reversions (rev) to a normal phenotype were recovered. In two cases (rev27, rev226), the 1A-2B7-8 section is relocated to the 19A region of the X chromosome, forming free duplications (1A-2B7--8/19A-20F-X-het). Modifiers of position effect do not change the normal expression of the BR-C and dor genes in these duplications. In five reversions (rev3, rev40, rev60, rev167, rev175), free duplications have formed from the 1A-2B7-8 fragment and X chromosome heterochromatin. In these rearrangements, modifiers of position effect (low temperature, removal of Y and 2R-chromosome heterochromatin and a genetic enhancer (E-var(3)201) induce position-effect again. Two reversions (rev45 and rev110) are associated with additional inversions in the original dor(var7) chromosomes. The inversions relocate part of the heterochromatin adjacent to the IA-2B7-8 section into new positions. In T(1;2)dor(rev45), position-effect is seen in the 2B7-8-7A element as compaction spreading from 2B7-8 proximally in some cases as far as the 5D region. Thus, in rev45 the pattern of euchromatin compaction is reciprocal to that of the initial dor(var7) strain. Apparently, it is due to the same variegation-evoking center near the 2R centromere in both cases. In all nine revertants, weakening or complete disappearance of the position-effect is observed despite retention of the 20- kb heterochromatic segment adjacent to the IA-2B7-8 region. Thus, a 20-kb heterochromatic sequence does not inactivate euchromatin joined to it.
Keyword Cytogenetic Analysis
Chromosomal Protein
Molecular Aspects
X-Chromosome
Heterochromatin
Region
Sequences
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: ResearcherID Downloads - Archived
 
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