scholarly journals A genetic analysis of the Suppressor 2 of zeste complex of Drosophila melanogaster.

Genetics ◽  
1995 ◽  
Vol 140 (1) ◽  
pp. 139-181 ◽  
Author(s):  
C T Wu ◽  
M Howe
Keyword(s):  
Drosophila Melanogaster ◽  
Position Effect ◽  
Molecular Data ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Wild Type ◽  
Trithorax Group ◽  
Eye Color ◽  
Multidomain Structure ◽  
Sex Combs

Abstract The zeste1 (z1) mutation of Drosophila melanogaster produces a mutant yellow eye color instead of the wild-type red. Genetic and molecular data suggest that z1 achieves this change by altering expression of the wild-type white gene in a manner that exhibits transvection effects. There exist suppressor and enhancer mutations that modify the z1 eye color, and this paper summarizes our studies of those belonging to the Suppressor 2 of zeste complex [Su(z)2-C]. The Su(z)2-C consists of at least three subregions called Psc (Posterior sex combs), Su(z)2 and Su(z)2D (Distal). The products of these subregions are proposed to act at the level of chromatin. Complementation analyses predict that the products are functionally similar and interacting. The alleles of Psc define two overlapping phenotypic classes, the hopeful and hapless. The distinctions between these two classes and the intragenic complementation seen among some of the Psc alleles are consistent with a multidomain structure for the product of Psc. Psc is a member of the homeotic Polycomb group of genes. A general discussion of the Polycomb and trithorax group of genes, position-effect variegation, transvection, chromosome pairing and chromatin structure is presented.

scholarly journals Mutations in the Drosophila melanogaster Gene Encoding S-adenosylmethionine Suppress Position-Effect Variegation

Genetics ◽  
1996 ◽  
Vol 143 (2) ◽  
pp. 887-896 ◽  
Author(s):  
Jan Larsson ◽  
Jingpu Zhang ◽  
Åsa Rasmuson-Lestander
Keyword(s):  
Drosophila Melanogaster ◽  
Chromatin Structure ◽  
Position Effect ◽  
Regulatory Region ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Gene Encoding ◽  
Sex Combs ◽  
S Alleles ◽  
Effect Variegation

Abstract In Drosophila melanogaster, the study of trans-acting modifier mutations of position-effect variegation and Polycomb group (Pc-G) genes have been useful tools to investigate genes involved in chromatin structure. We have cloned a modifier gene, Suppesssm of zeste 5 (Su(z)5), which encodes Sadenosylmethionine synthetase, and we present here molecular results and data concerning its expression in mutants and genetic interactions. The mutant alleles Su(z)5, l(2)R23 and l(2)M6 show suppression of wm4 and also of two white mutants induced by roo element insertions in the regulatory region i.e., wis (in combination with z  1) and wsp1. Two of the Su(z)S alleles, as well as a deletion of the gene, also act as enhancers of PoZycomb by increasing the size of sex combs on midleg. The results suggest that Su(z)5 is connected with regulation of chromatin structure. The enzyme Sadenosylmethionine synthetase is involved in the synthesis of Sadenosylmethionine, a methyl group donor and also, after decarboxylation, a propylamino group donor in the bio-synthesis of polyamines. Our results from HPLC analysis show that in ovaries from heterozygous Su(z)5 mutants the content of spermine is significantly reduced. Results presented here suggest that polyamines are an important molecule class in the regulation of chromatin structure.

white+ Transgene Insertions Presenting a Dorsal/Ventral Pattern Define a Single Cluster of Homeobox Genes That Is Silenced by the Polycomb-group Proteins in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 257-275 ◽  
Author(s):  
Sophie Netter ◽  
Marie-Odile Fauvarque ◽  
Ruth Diez del Corral ◽  
Jean-Maurice Dura ◽  
Dario Coen
Keyword(s):  
Chromatin Structure ◽  
Target Genes ◽  
Position Effect ◽  
Phenotypic Expression ◽  
Positional Information ◽  
Genomic Region ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Trithorax Group ◽  
Clear Cut

AbstractWe used the white gene as an enhancer trap and reporter of chromatin structure. We collected white+ transgene insertions presenting a peculiar pigmentation pattern in the eye: white expression is restricted to the dorsal half of the eye, with a clear-cut dorsal/ventral (D/V) border. This D/V pattern is stable and heritable, indicating that phenotypic expression of the white reporter reflects positional information in the developing eye. Localization of these transgenes led us to identify a unique genomic region encompassing 140 kb in 69D1–3 subject to this D/V effect. This region contains at least three closely related homeobox-containing genes that are constituents of the iroquois complex (IRO-C). IRO-C genes are coordinately regulated and implicated in similar developmental processes. Expression of these genes in the eye is regulated by the products of the Polycomb -group (Pc-G) and trithorax-group (trx-G) genes but is not modified by classical modifiers of position-effect variegation. Our results, together with the report of a Pc -G binding site in 69D, suggest that we have identified a novel cluster of target genes for the Pc-G and trx-G products. We thus propose that ventral silencing of the whole IRO-C in the eye occurs at the level of chromatin structure in a manner similar to that of the homeotic gene complexes, perhaps by local compaction of the region into a heterochromatin-like structure involving the Pc-G products.

The Additional sex combs gene of Drosophila encodes a chromatin protein that binds to shared and unique Polycomb group sites on polytene chromosomes

Development ◽  
1998 ◽  
Vol 125 (7) ◽  
pp. 1207-1216 ◽  
Author(s):  
D.A. Sinclair ◽  
T.A. Milne ◽  
J.W. Hodgson ◽  
J. Shellard ◽  
C.A. Salinas ◽  
...  
Keyword(s):  
Target Genes ◽  
Position Effect ◽  
Polytene Chromosomes ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Sex Combs ◽  
Effect Variegation ◽  
The Central Nervous System ◽  
Additional Sex Combs ◽  
Site Recognition

The Additional sex combs (Asx) gene of Drosophila is a member of the Polycomb group of genes, which are required for maintenance of stable repression of homeotic and other loci. Asx is unusual among the Polycomb group because: (1) one Asx allele exhibits both anterior and posterior transformations; (2) Asx mutations enhance anterior transformations of trx mutations; (3) Asx mutations exhibit segmentation phenotypes in addition to homeotic phenotypes; (4) Asx is an Enhancer of position-effect variegation and (5) Asx displays tissue-specific derepression of target genes. Asx was cloned by transposon tagging and encodes a protein of 1668 amino acids containing an unusual cysteine cluster at the carboxy terminus. The protein is ubiquitously expressed during development. We show that Asx is required in the central nervous system to regulate Ultrabithorax. ASX binds to multiple sites on polytene chromosomes, 70% of which overlap those of Polycomb, polyhomeotic and Polycomblike, and 30% of which are unique. The differences in target site recognition may account for some of the differences in Asx phenotypes relative to other members of the Polycomb group.

scholarly journals The Lighten up (Lip) gene of Drosophila melanogaster, a modifier of retroelement expression, position effect variegation and white locus insertion alleles.

Genetics ◽  
1994 ◽  
Vol 138 (1) ◽  
pp. 153-163 ◽  
Author(s):  
A K Csink ◽  
R Linsk ◽  
J A Birchler
Keyword(s):  
Drosophila Melanogaster ◽  
Single Gene ◽  
Position Effect ◽  
Gene Mutations ◽  
State Level ◽  
Transcript Abundance ◽  
Position Effect Variegation ◽  
Eye Color ◽  
Inverse Effect ◽  
Effect Variegation

Abstract We are interested in identifying single gene mutations that are involved in trans-acting dosage regulation in order to understand further the role of such genes in aneuploid syndromes, various types of dosage compensation as well as in regulatory mechanisms. The Lighten up (Lip) gene in Drosophila melanogaster was identified in a mutagenic screen to detect dominant second site modifiers of white-blood (wbl), a retrotransposon induced allele of the white eye color locus. Lip specifically enhances the phenotype of wbl as well as a subset of other retroelement insertion alleles of white, including the copia-induced allele, white-apricot (wa), and six alleles caused by insertion of I elements. We isolated six alleles of Lip which are all recessive lethal, although phenotypically additive heteroallelic escapers were recovered in some combinations. Lip also suppresses position effect variegation, indicating that it may have a role in chromatin configuration. Additionally, Lip modifies the total transcript abundance of both the blood and copia retrotransposons, having an inverse effect on the steady state level of blood transcripts, while showing a non-additive effect on copia RNA.

scholarly journals Weakener of white (Wow), a gene that modifies the expression of the white eye color locus and that suppresses position effect variegation in Drosophila melanogaster.

Genetics ◽  
1994 ◽  
Vol 137 (4) ◽  
pp. 1057-1070 ◽  
Author(s):  
J A Birchler ◽  
U Bhadra ◽  
L Rabinow ◽  
R Linsk ◽  
A T Nguyen-Huynh
Keyword(s):  
Gene Expression ◽  
Drosophila Melanogaster ◽  
Position Effect ◽  
Northern Analysis ◽  
Regulatory Sequences ◽  
Position Effect Variegation ◽  
Eye Color ◽  
Effect Variegation ◽  
Modifying Effect ◽  
Color Gene

Abstract A locus is described in Drosophila melanogaster that modifies the expression of the white eye color gene. This trans-acting modifier reduces the expression of the white gene in the eye, but elevates the expression in other adult tissues. Because of the eye phenotype in which the expression of white is lessened but not eliminated, the newly described locus is called the Weakener of white (Wow). Northern analysis reveals that Wow can exert an inverse or direct modifying effect depending upon the developmental stage. Two related genes, brown and scarlet, that are coordinately expressed with white, are also affected by Wow. In addition, Wow modulates the steady state RNA level of the retrotransposon, copia. When tested with a white promoter-Alcohol dehydrogenase reporter. Wow confers the modifying effect to the reporter, suggesting a requirement of the white regulatory sequences for mediating the response. In addition to being a dosage sensitive regulator of white, brown, scarlet and copia, Wow acts as a suppressor of position effect variegation. There are many dosage sensitive suppressors of position effect variegation and many dosage-sensitive modifiers of gene expression. The Wow mutations provide evidence for an overlap between the two types of modifiers.

scholarly journals The effect of modifiers of position-effect variegation on the variegation of heterochromatic genes of Drosophila melanogaster.

Genetics ◽  
1991 ◽  
Vol 128 (4) ◽  
pp. 785-797 ◽  
Author(s):  
M G Hearn ◽  
A Hedrick ◽  
T A Grigliatti ◽  
B T Wakimoto
Keyword(s):  
Drosophila Melanogaster ◽  
Position Effect ◽  
Position Effect Variegation ◽  
Chromosome 2 ◽  
Wild Type ◽  
Regulatory Requirements ◽  
Expression Of Genes ◽  
Effect Variegation ◽  
Type Gene ◽  
Heterochromatic Genes

Abstract Dominant modifiers of position-effect variegation of Drosophila melanogaster were tested for their effects on the variegation of genes normally located in heterochromatin. These modifiers were previously isolated as strong suppressors of the variegation of euchromatic genes and have been postulated to encode structural components of heterochromatin or other products that influence chromosome condensation. While eight of the modifiers had weak or no detectable effects, six acted as enhancers of light (lt) variegation. The two modifiers with the strongest effects on lt were shown to also enhance the variegation of neighboring heterochromatic genes. These results suggest that the wild-type gene products of some modifiers of position-effect variegation are required for proper expression of genes normally located within or near the heterochromatin of chromosome 2. We conclude that these heterochromatic genes have fundamentally different regulatory requirements compared to those typical of euchromatic genes.

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.

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.

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