scholarly journals Exact breakpoints of In(1)wm4 rearrangement

2021 ◽  
Author(s):  
Alexander A. Solodovnikov ◽  
Sergey A. Lavrov
Keyword(s):  
Position Effect ◽  
Position Effect Variegation ◽  
Nanopore Sequencing ◽  
Effect Variegation ◽  
Exact Position ◽  
Breakpoint Position

In(1)wm4 was known for decades as a classic example of position effect variegation-causing rearrangement and was mentioned in hundreds of publications. Nevertheless, the euchromatin breakpoint position of the rearrangement was not precisely localized. We performed nanopore sequencing of DNA from In(1)wm4 homozygous flies and determined the exact position of euchromatic (chrX:2767875) and heterochromatic breakpoints of the rearrangement.

scholarly journals Mutational Analysis of a Histone Deacetylase in Drosophila melanogaster: Missense Mutations Suppress Gene Silencing Associated With Position Effect Variegation

Genetics ◽  
2000 ◽  
Vol 154 (2) ◽  
pp. 657-668 ◽  
Author(s):  
Randy Mottus ◽  
Richard E Sobel ◽  
Thomas A Grigliatti
Keyword(s):  
Drosophila Melanogaster ◽  
Histone Deacetylase ◽  
Transcriptional Activity ◽  
Mutational Analysis ◽  
Position Effect ◽  
Transcriptional Regulator ◽  
Position Effect Variegation ◽  
Missense Mutations ◽  
Effect Variegation ◽  
New Mutations

Abstract For many years it has been noted that there is a correlation between acetylation of histones and an increase in transcriptional activity. One prediction, based on this correlation, is that hypomorphic or null mutations in histone deacetylase genes should lead to increased levels of histone acetylation and result in increased levels of transcription. It was therefore surprising when it was reported, in both yeast and fruit flies, that mutations that reduced or eliminated a histone deacetylase resulted in transcriptional silencing of genes subject to telomeric and heterochromatic position effect variegation (PEV). Here we report the first mutational analysis of a histone deacetylase in a multicellular eukaryote by examining six new mutations in HDAC1 of Drosophila melanogaster. We observed a suite of phenotypes accompanying the mutations consistent with the notion that HDAC1 acts as a global transcriptional regulator. However, in contrast to recent findings, here we report that specific missense mutations in the structural gene of HDAC1 suppress the silencing of genes subject to PEV. We propose that the missense mutations reported here are acting as antimorphic mutations that “poison” the deacetylase complex and propose a model that accounts for the various phenotypes associated with lesions in the deacetylase locus.

pitkinD, a Novel Gain-of-Function Enhancer of Position-Effect Variegation, Affects Chromatin Regulation During Oogenesis and Early Embryogenesis in Drosophila

Genetics ◽  
2001 ◽  
Vol 157 (3) ◽  
pp. 1227-1244 ◽  
Author(s):  
Steffi Kuhfittig ◽  
János Szabad ◽  
Gunnar Schotta ◽  
Jan Hoffmann ◽  
Endre Máthé ◽  
...  
Keyword(s):  
Germ Line ◽  
Position Effect ◽  
Early Embryogenesis ◽  
Position Effect Variegation ◽  
Chromatin Regulation ◽  
Gain Of Function ◽  
Position Effects ◽  
Dominant Female ◽  
Effect Variegation ◽  
Female Germ Line

Abstract The vast majority of the >100 modifier genes of position-effect variegation (PEV) in Drosophila have been identified genetically as haplo-insufficient loci. Here, we describe pitkinDominant (ptnD), a gain-of-function enhancer mutation of PEV. Its exceptionally strong enhancer effect is evident as elevated spreading of heterochromatin-induced gene silencing along euchromatic regions in variegating rearrangements. The ptnD mutation causes ectopic binding of the SU(VAR)3-9 heterochromatin protein at many euchromatic sites and, unlike other modifiers of PEV, it also affects stable position effects. Specifically, it induces silencing of white+ transgenes inserted at a wide variety of euchromatic sites. ptnD is associated with dominant female sterility. +/+ embryos produced by ptnD/+ females mated with wild-type males die at the end of embryogenesis, whereas the ptnD/+ sibling embryos arrest development at cleavage cycle 1-3, due to a combined effect of maternally provided mutant product and an early zygotic lethal effect of ptnD. This is the earliest zygotic effect of a mutation so far reported in Drosophila. Germ-line mosaics show that ptn+ function is required for normal development in the female germ line. These results, together with effects on PEV and white+ transgenes, are consistent with the hypothesis that the ptn gene plays an important role in chromatin regulation during development of the female germ line and in early embryogenesis.

scholarly journals Recombinogenic Effects of Suppressors of Position-Effect Variegation in Drosophila

Genetics ◽  
2002 ◽  
Vol 160 (2) ◽  
pp. 609-621
Author(s):  
Thomas Westphal ◽  
Gunter Reuter
Keyword(s):  
Chromatin Structure ◽  
Position Effect ◽  
Heterochromatic Region ◽  
Crossing Over ◽  
Position Effect Variegation ◽  
Chromosome 2 ◽  
Additive Effects ◽  
Suppressor Mutations ◽  
Effect Variegation ◽  
Meiotic Nondisjunction

Abstract Compact chromatin structure, induction of gene silencing in position-effect variegation (PEV), and crossing-over suppression are typical features of heterochromatin. To identify genes affecting crossing-over suppression by heterochromatin we tested PEV suppressor mutations for their effects on crossing over in pericentromeric regions of Drosophila autosomes. From the 46 mutations (28 loci) studied, 16 Su(var) mutations of the nine genes Su(var)2-1, Su(var)2-2, Su(var)2-5, Su(var)2-10, Su(var)2-14, Su(var) 2-15, Su(var)3-3, Su(var)3-7, and Su(var)3-9 significantly increase in heterozygotes or by additive effects in double and triple heterozygotes crossing over in the ri-pp region of chromosome 3. Su(var)2-201 and Su(var) 2-1401 display the strongest recombinogenic effects and were also shown to enhance recombination within the light-rolled heterochromatic region of chromosome 2. The dominant recombinogenic effects of Su(var) mutations are most pronounced in proximal euchromatin and are accompanied with significant reduction of meiotic nondisjunction. Our data suggest that crossing-over suppression by heterochromatin is controlled at chromatin structure as well as illustrate the possible effects of heterochromatin on total crossing-over frequencies in the genome.

Enhancer of Polycomb Is a Suppressor of Position-Effect Variegation in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 148 (1) ◽  
pp. 211-220
Author(s):  
Donald A R Sinclair ◽  
Nigel J Clegg ◽  
Jennifer Antonchuk ◽  
Thomas A Milne ◽  
Kryn Stankunas ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Position Effect ◽  
Polycomb Group ◽  
P Element ◽  
Homeotic Gene ◽  
Position Effect Variegation ◽  
Negative Regulators ◽  
Recombination Mapping ◽  
Effect Variegation ◽  
Homeotic Gene Expression

Abstract Polycomb group (PcG) genes of Drosophila are negative regulators of homeotic gene expression required for maintenance of determination. Sequence similarity between Polycomb and Su(var)205 led to the suggestion that PcG genes and modifiers of position-effect variegation (PEV) might function analogously in the establishment of chromatin structure. If PcG proteins participate directly in the same process that leads to PEV, PcG mutations should suppress PEV. We show that mutations in E(Pc), an unusual member of the PcG, suppress PEV of four variegating rearrangements: In(l)wm4, BSV, T(2;3)SbV, and In(2R)bwVDe2. Using reversion of a P element insertion, deficiency mapping, and recombination mapping as criteria, homeotic effects and suppression of PEV associated with E(Pc) co-map. Asx is an enhancer of PEV, whereas nine other PcG loci do not affect PEV. These results support the conclusion that there are fewer similarities between PcG genes and modifiers of PEV than previously supposed. However, E(Pc) appears to be an important link between the two groups. We discuss why Asx might act as an enhancer of PEV.

scholarly journals Competition Between Different Variegating Rearrangements for Limited Heterochromatic Factors in Drosophila melanogaster

Genetics ◽  
1997 ◽  
Vol 145 (4) ◽  
pp. 945-959
Author(s):  
Vett K Lloyd ◽  
Donald A Sinclair ◽  
Thomas A Grigliatti
Keyword(s):  
Drosophila Melanogaster ◽  
Chromosome Rearrangement ◽  
Position Effect ◽  
Position Effect Variegation ◽  
Euchromatic Region ◽  
Single Chromosome ◽  
Mosaic Expression ◽  
Effect Variegation ◽  
Protein Components

Position effect variegation (PEV) results from the juxtaposition of a euchromatic gene to heterochromatin. In its new position the gene is inactivated in some cells and not in others. This mosaic expression is consistent with variability in the spread of heterochromatin from cell to cell. As many components of heterochromatin are likely to be produced in limited amounts, the spread of heterochromatin into a normally euchromatic region should be accompanied by a concomitant loss or redistribution of the protein components from other heterochromatic regions. We have shown that this is the case by simultaneously monitoring variegation of a euchromatic and a heterochromatic gene associated with a single chromosome rearrangement. Secondly, if several heterochromatic regions of the genome share limited components of heterochromatin, then some variegating rearrangements should compete for these components. We have examined this hypothesis by testing flies with combinations of two or more different variegating rearrangements. Of the nine combinations of pairs of variegating rearrangements we studied, seven showed nonreciprocal interactions. These results imply that many components of heterochromatin are both shared and present in limited amounts and that they can transfer between chromosomal sites. Consequently, even nonvariegation portions of the genome will be disrupted by re-allocation of heterochromatic proteins associated with PEV. These results have implications for models of PEV.

scholarly journals Interactions Among Dosage-Dependent Trans-Acting Modifiers of Gene Expression and Position-Effect Variegation in Drosophila

Genetics ◽  
1998 ◽  
Vol 150 (1) ◽  
pp. 251-263 ◽  
Author(s):  
Utpal Bhadra ◽  
Manika Pal Bhadra ◽  
James A Birchler
Keyword(s):  
Gene Expression ◽  
Quantitative Traits ◽  
Position Effect ◽  
Position Effect Variegation ◽  
Developmental Transitions ◽  
Eye Color ◽  
Dosage Effects ◽  
Effect Variegation ◽  
Hierarchical Manner ◽  
Color Gene

Abstract We have investigated the effect of dosage-dependent trans-acting regulators of the white eye color gene in combinations to understand their interaction properties. The consequences of the interactions will aid in an understanding of aneuploid syndromes, position-effect variegation (PEV), quantitative traits, and dosage compensation, all of which are affected by dosage-dependent modifiers. Various combinations modulate two functionally related transcripts, white and scarlet, differently. The overall trend is that multiple modifiers are noncumulative or epistatic to each other. In some combinations, developmental transitions from larvae to pupae to adults act as a switch for whether the effect is positive or negative. With position-effect variegation, similar responses were found as with gene expression. The highly multigenic nature of dosage-sensitive modulation of both gene expression and PEV suggests that dosage effects can be progressively transduced through a series of steps in a hierarchical manner.

scholarly journals Mutation in P0, a Dual Function Ribosomal Protein/Apurinic/Apyrimidinic Endonuclease, Modifies Gene Expression and Position Effect Variegation in Drosophila

Genetics ◽  
1998 ◽  
Vol 150 (4) ◽  
pp. 1487-1495
Author(s):  
Maxim V Frolov ◽  
James A Birchler
Keyword(s):  
Gene Expression ◽  
Ribosomal Protein ◽  
Position Effect ◽  
P Element ◽  
Dual Function ◽  
Insertion Mutant ◽  
Position Effect Variegation ◽  
Element Insertion ◽  
Effect Variegation ◽  
Ribosomal Protein P0

Abstract In a search for modifiers of gene expression with the white eye color gene as a target, a third chromosomal P-element insertion mutant l(3)01544 has been identified that exhibits a strong pigment increase in a white-apricot background. Molecular analysis shows that the P-element insertion is found in the first intron of the gene surrounding the insertion site. Sequencing both the cDNA and genomic fragments revealed that the identified gene is identical to one encoding ribosomal protein P0/apurinic/apyrimidinic endonuclease. The P-element-induced mutation, l(3)01544, affects the steady-state level of white transcripts and transcripts of some other genes. In addition, l(3)01544 suppresses the variegated phenotypes of In(1)wm4h and In(1)y3P, suggesting a potential involvement of the P0 protein in modifying position effect variegation. The revertant generated by the precise excision of the P element has lost all mutant phenotypes. Recent work revealed that Drosophila ribosomal protein P0 contains an apurinic/apyrimidinic endonuclease activity. Our results suggest that this multifunctional protein is also involved in regulation of gene expression in Drosophila.

scholarly journals Position effect variegation and epigenetic modification of a transgene in a pig model

2012 ◽  
Vol 11 (1) ◽  
pp. 355-369 ◽  
Author(s):  
Z. Yin ◽  
Q.R. Kong ◽  
Z.P. Zhao ◽  
M.L. Wu ◽  
Y.S. Mu ◽  
...  
Keyword(s):  
Epigenetic Modification ◽  
Position Effect ◽  
Pig Model ◽  
Position Effect Variegation ◽  
Effect Variegation

scholarly journals Replication of Heterochromatin and Structure of Polytene Chromosomes

2000 ◽  
Vol 20 (17) ◽  
pp. 6308-6316 ◽  
Author(s):  
Thomas J. Leach ◽  
Heather L. Chotkowski ◽  
Michael G. Wotring ◽  
Robert L. Dilwith ◽  
Robert L. Glaser
Keyword(s):  
Temporal Pattern ◽  
Position Effect ◽  
Polytene Chromosomes ◽  
S Phase ◽  
Parental Origin ◽  
Position Effect Variegation ◽  
Replication Forks ◽  
Satellite Sequences ◽  
Effect Variegation ◽  
Diploid Cells

ABSTRACT Heterochromatin is characteristically the last portion of the genome to be replicated. In polytene cells, heterochromatic sequences are underreplicated because S phase ends before replication of heterochromatin is completed. Truncated heterochromatic DNAs have been identified in polytene cells of Drosophila and may be the discontinuous molecules that form between fully replicated euchromatic and underreplicated heterochromatic regions of the chromosome. In this report, we characterize the temporal pattern of heterochromatic DNA truncation during development of polytene cells. Underreplication occurred during the first polytene S phase, yet DNA truncation, which was found within heterochromatic sequences of all fourDrosophila chromosomes, did not occur until the second polytene S phase. DNA truncation was correlated with underreplication, since increasing the replication of satellite sequences with thecycE 1672 mutation caused decreased production of truncated DNAs. Finally, truncation of heterochromatic DNAs was neither quantitatively nor qualitatively affected by modifiers of position effect variegation including the Y chromosome,Su(var)2052 , parental origin, or temperature. We propose that heterochromatic satellite sequences present a barrier to DNA replication and that replication forks that transiently stall at such barriers in late S phase of diploid cells are left unresolved in the shortened S phase of polytene cells. DNA truncation then occurs in the second polytene S phase, when new replication forks extend to the position of forks left unresolved in the first polytene S phase.

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