heterochromatin


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Related to heterochromatin: Facultative heterochromatin, Constitutive heterochromatin

heterochromatin

 [het″er-o-kro´mah-tin]
that state of chromatin in which it is dark-staining, genetically inactive, and tightly coiled.
constitutive heterochromatin the chromatin in regions of the chromosomes that are invariably heterochromatic; it contains highly repetitive sequences of DNA that are genetically inactive and serves as a structural element of the chromosome.
facultative heterochromatin the chromatin in regions of the chromosomes that become heterochromatic in certain cells and tissues; for example, it makes up the inactive X chromosome in female somatic cells.

het·er·o·chro·ma·tin

(het'ĕr-ō-krō'mă-tin),
The part of the chromonema that remains tightly coiled and condensed during interphase and thus stains readily.

heterochromatin

/het·ero·chro·ma·tin/ (-kro´mah-tin) that state of chromatin in which it is dark-staining, genetically inactive, and tightly coiled.

heterochromatin

(hĕt′ə-rō-krō′mə-tĭn)
n.
Tightly coiled chromosomal material that stains deeply during interphase and is believed to be genetically inactive.

heterochromatin

[-krō′mətin]
Etymology: Gk, heteros, different, chroma, color
the part of a chromosome that is inactive in gene expression but may function in controlling metabolic activities, transcription, and cell division. It stains most intensely during interphase and usually remains in a condensed state throughout the cell cycle. It consists of two types: constitutive heterochromatin, which is present in all cells and is characteristic of the Y chromosome, and facultative heterochromatin, which is present in the inactivated X chromosome of the mammalian female. Compare euchromatin. See also chromatin. heterochromatic, adj.

het·er·o·chro·ma·tin

(het'ĕr-ō-krō'mă-tin)
The part of the chromonema that remains tightly coiled and condensed during interphase and thus stains readily.

heterochromatin

A length of chromatin in the genome that is permanently highly condensed and whose DNA is not transcribed.

heterochromatin

any chromosomal segments or whole chromosomes that appear darkly stained during interphase of the CELL CYCLE (as compared to EUCHROMATIN) due to tight condensation, which may indicate genetic inactivity. Hetero chromatin may be condensed at all times (constitutive) or only at certain times (facultative). see C-BANDING.

heterochromatin

that state of chromatin in which it is dark-staining, genetically inactive, and tightly coiled.
References in periodicals archive ?
In the present study, the C-banding technique indicated the existence of a small amount of heterochromatin on the chromosomes of the Atta species, with a distribution pattern in the centromeric region.
On the outside of the heterochromatin bundles are chemical markers, known as epigenetic tags, which control the structure of the heterochromatin.
Heterochromatin differentiation in holocentric chromosomes of Rhynchospora (Cyperaceae).
Silent genes tend to be packaged as heterochromatin whereas active, functional genes are in euchromatin.
Based on this geographic separation, our working hypothesis is that heterochromatin variation is a reflection of adaptive genomic changes that contribute to the ability of T.
To that end, the heterochromatin bands can serve as handy benchmarks to flag important genes, such as those for improved yield.
Interplay between SCARECROW, GA and LIKE HETEROCHROMATIN PROTEIN 1 in ground tissue patterning in the Arabidopsis root.
Perieentric heterochromatin becomes enriched with H2aZ during early mammalian development.
Our result has shown that the changes in both Histone H3 Lys-9 acetylation (H3K9ac: mark associated with active chromatin) and Histone H3 Lys-9 methylation (H3K9me3: mark associated with transcriptional repression) were induced by using the SOE for a brief time of incubation (7 h), which are associated with controlling heterochromatin organization.
The DNA was then subjected to polymerase chain reaction (PCR) and assayed using the following tagged sequences: ZFY (control), sy14 (SRY); AZFa specifically, sy84, sy86, sy625, sy114; AZFb specifically, sy117, sy127, sy129, sy134, sy143; AZFc specifically, sy152, sy147, sy254, sy255, sy157; and finally heterochromatin sy160.
The research findings described in this media release can be found in the 14 October online issue of Cancer Cell, under the title, "Wip1 controls global heterochromatin silencing via ATM/BRCA1-dependent DNA methylation" by Doria Filipponi(1), Julius Muller(1), Alexander Emelyanov(1) and Dmitry V.
The electron micrographs, of the untreated mouse mammary tumor cells were bounded by delicate plasma membranes and displayed large nuclei containing uniformly distributed euchromatin and conspicuous marginal heterochromatin abutting the nuclear membrane and a prominent nucleolus (Figs.