Reference Report

Reference
Citation	Pokholkova, G.V., Makunin, I.V., Belyaeva, E.S., Zhimulev, I.F. (1993). Observations on the induction of position effect variegation of euchromatic genes in Drosophila melanogaster. Genetics 134(1): 231--242. (Export to RIS)
FlyBase ID	FBrf0058586
Publication Type	Research paper
PubMed ID	8514132
PubMed Abstract	In the T(1;2)dorvar7 translocation, the 1A-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)dorvar7, 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 dorvar7 chromosomes. The inversions relocate part of the heterochromatin adjacent to the 1A-2B7-8 section into new positions. In T(1;2)dorrev45, 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 dorvar7 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 1A-2B7-8 region. Thus, a 20-kb heterochromatic sequence does not inactivate euchromatin joined to it.
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Language of Publication	English
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Publication Type	Journal
Abbreviation	Genetics
Title	Genetics
Publication Year	1916-
ISBN/ISSN	0016-6731
Data from Reference
Aberrations (30)
	Df(1)16-3-22 Df(1)B57 Df(1)GA22 Df(1)mal3 Df(1)Q54 Df(1)Q539 Df(1)R8A Df(1)St472 Df(1)sta Df(2R)M41A10 Dp(1;Y)y²67g19.1 Dp(1;Y)y²67g24.2 T(1;2)dor^rev3 T(1;2)dor^rev27 T(1;2)dor^rev40 T(1;2)dor^rev45 T(1;2)dor^rev60 T(1;2)dor^rev110 T(1;2)dor^rev167 T(1;2)dor^rev175 T(1;2)dor^rev226 T(1;2)dor^var7 Tp(1;3)sta Ts(1Lt;1Rt)dor^rev3 Ts(1Lt;1Rt)dor^rev27 Ts(1Lt;1Rt)dor^rev40 Ts(1Lt;1Rt)dor^rev60 Ts(1Lt;1Rt)dor^rev167 Ts(1Lt;1Rt)dor^rev175 Ts(1Lt;1Rt)dor^rev226
Alleles (2)
	br^npr-6 E(var)3-201¹
Genes (8)
	br dor E(var)3-201 l(1)2Ac l(1)2Ad l(1)2Ae sta su(f)