Topic
Variegation
About: Variegation is a research topic. Over the lifetime, 346 publications have been published within this topic receiving 16751 citations. The topic is also known as: Variegation.
Papers published on a yearly basis
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Papers
TL;DR: A phenomenon of rare occurrence in maize began to appear with remarkably high frequencies in the cultures and the terms mutable genes, unstable genes, variegation, mosaicism, mutable loci or “position-effect” have been applied to this phenomenon.
Abstract: In the course of an experiment designed to reveal the genic composition of the short arm of chromosome 9, a phenomenon of rare occurrence (or recognition) in maize began to appear with remarkably high frequencies in the cultures. The terms mutable genes, unstable genes, variegation, mosaicism, mutable loci or “position-effect” have been applied to this phenomenon. Its occurrence in a wide variety of organisms has been recognized. The most extensive investigations of this phenomenon have been undertaken in Drosophila melanogaster.1 In this organism, the conditions associated with the origin of genic instability have been well defined. The part played by the heterochromatic materials of the chromosomes, in inducing and controlling the type of variegation and its time and frequency of occurrence, has been established. It has not been generally recognized that the instability of genic expression in other organisms may be essentially the same as that occurring in Drosophila.
1,710 citations
TL;DR: In this article, a point mutation in the gene which encodes the heterochromatin-specific nonhistone chromosomal protein HP-1 in Drosophila melanogaster is associated with dominant suppression of position effect variegation.
Abstract: We report here that a point mutation in the gene which encodes the heterochromatin-specific nonhistone chromosomal protein HP-1 in Drosophila melanogaster is associated with dominant suppression of position-effect variegation. The mutation, a G-to-A transition at the first nucleotide of the last intron, causes missplicing of the HP-1 mRNA. This suggests that heterochromatin-specific proteins play a central role in the gene suppression associated with heterochromatic position effects.
582 citations
TL;DR: It is proposed that pairing of repeats underlies heterochromatin formation and is responsible for diverse gene silencing phenomena in animals and plants.
554 citations
TL;DR: Position-effect variegation (PEV) results when a gene normally in euchromatin is juxtaposed with heterochromatin by rearrangement or transposition, and causes transcriptional silencing in a stochastic pattern.
Abstract: Position-effect variegation (PEV) results when a gene normally in euchromatin is juxtaposed with heterochromatin by rearrangement or transposition. When heterochromatin packaging spreads across the heterochromatin/euchromatin border, it causes transcriptional silencing in a stochastic pattern. PEV is intensely studied in Drosophila using the white gene. Screens for dominant mutations that suppress or enhance white variegation have identified many conserved epigenetic factors, including the histone H3 lysine 9 methyltransferase SU(VAR)3-9. Heterochromatin protein HP1a binds H3K9me2/3 and interacts with SU(VAR)3-9, creating a core memory system. Genetic, molecular, and biochemical analysis of PEV in Drosophila has contributed many key findings concerning establishment and maintenance of heterochromatin with concomitant gene silencing.
516 citations
TL;DR: The genetic analysis suggests that the chromatin modelling function of the GAGA factor is not restricted to promoter regions, and the Trithorax-like gene described here is required for the normal expression of the homeotic genes and is a modifier of position-effect variegation.
Abstract: LITTLE is known about the way higher-order chromatin structure influences gene expression and chromosome topology in general. Genetic analysis in Drosophila has led to the discovery of two classes of genes, the regulators of homeotic genes and the modifiers of position-effect variegation, which seem to be good candidates for encoding some of the factors regulating chromatin functions1,2. The Trithorax-like gene we describe here is required for the normal expression of the homeotic genes and is a modifier of position-effect variegation. We found that Trithorax-like encodes the GAGA factor which is involved in the formation of an accessible chromatin structure at promoter sequences3. Our genetic analysis suggests that the chromatin modelling function of the GAGA factor is not restricted to promoter regions.
438 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 12 |
| 2020 | 8 |
| 2019 | 9 |
| 2018 | 8 |
| 2017 | 10 |
| 2016 | 7 |