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Genes normally resident in euchromatic domains are silenced when packaged into heterochromatin, as exemplified in Drosophila melanogaster by position effect variegation (PEV). Loss-of-function mutations resulting in suppression of PEV have identified critical components of heterochromatin, including proteins HP1, HP2, and histone H3 lysine 9(More)
Evidence from a variety of data suggests that regulatory mechanisms in multicellular eukaryotes have evolved in such a manner that the stoichiometric relationship of the components of regulatory complexes affects target gene expression. This type of mechanism sets the level of gene expression and, as a consequence, the phenotypic characteristics. Because(More)
Two types of transgene silencing were found for the Alcohol dehydrogenase (Adh) transcription unit. Transcriptional gene silencing (TGS) is Polycomb dependent and occurs when Adh is driven by the white eye color gene promoter. Full-length Adh transgenes are silenced posttranscriptionally at high copy number or by a pulsed increase over a threshold. The(More)
Drosophila Polycomb group (PcG) proteins silence homeotic genes through binding to Polycomb group response elements (PREs). Fab-7 is a PRE-containing regulatory element from the homeotic gene Abdominal-B. When present in multiple copies in the genome, Fab-7 can induce long-distance gene contacts that enhance PcG-dependent silencing. We show here that(More)
The human MOF gene encodes a protein that specifically acetylates histone H4 at lysine 16 (H4K16ac). Here we show that reduced levels of H4K16ac correlate with a defective DNA damage response (DDR) and double-strand break (DSB) repair to ionizing radiation (IR). The defect, however, is not due to altered expression of proteins involved in DDR. Abrogation of(More)
When two to six copies of a white promoter-Alcohol dehydrogenase (Adh) reporter fusion gene are introduced into the genome, the expression is progressively reduced both in larvae and adults rather than the expected gene dosage effect. In addition, multiple transgenes reduce endogenous Adh transcripts, a result that is strongly analogous to "cosuppression"(More)
Immunostaining of chromosomes shows that the male-specific lethal (MSL) proteins are associated with all female chromosomes at a low level but are sequestered to the X chromosome in males. Histone-4 Lys-16 acetylation follows a similar pattern in normal males and females, being higher on the X and lower on the autosomes in males than in females. However,(More)
Ethanol induced liver injury is associated with a global change in gene expression but its mechanisms are not known. We studied whether alcohol-induced gene expression is associated with post-translational methylations of histone H3. Primary culture of rat hepatocytes was treated with ethanol (50 or 100 mM) for 24 h and the status of methylation of H3 at(More)
Modifier of white (Mow), a dominant transacting gene, has been identified through a mutagenic screen for second-site loci that alter the level of expression of thewhite eye color locus.Mow reduces the expression ofwhite in most developmental stages, but enhances its expression in the pupal stage, the time at which the major contribution to the adult(More)
Repeated copies of genes, whether in tandem or dispersed, are often recognized by the cell and silenced. Tandem repeat silencing is associated with a heterochromatin-like complex. Dispersed gene silencing can be mediated by the repressive Polycomb Group complex or involve post-transcriptional silencing presumably involving double-stranded RNA. The I(More)