heterochromatin


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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

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

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.
References in periodicals archive ?
Indeed, long CTG-repetitions were shown to induce heterochromatin formation, which can then spread into neighbouring regions [22].
Adams, "Molecular dissection of formation of senescence-associated heterochromatin foci," Molecular and Cellular Biology, vol.
The karyotype of specimens from the central population, Iraquara (MN 68092 and MN 68094) and distribution of constitutive heterochromatin (C-banding; Fig.
TFL2/LHP1, the plant homologue of animal HP1, surprisingly does not primarily localize to heterochromatin but it participates in the regulation of specific genes in euchromatic regions.
The structure of a nucleus of this participant at an early stage of reprogramming (mainly heterochromatin and lack of a nucleolus) convinces us that it is an oligodendrocyte.
The analysis of the C-banding pattern revealed large blocks of constitutive heterochromatin located on the pericentromeric regions of all chromosomes (Figure 2), and the first pair presented a completely heterochromatic long arm.
(2004): <<RNAi-mediated targeting of heterochromatin by the RITS complex>>, Science, vol.
C., 1971.--Distribution of constitutive heterochromatin in mammalian chromosomes Chromosoma (Berl.).
These characteristics have been frequently related to the presence of large terminal heterochromatin blocks on the rye chromosomes (Thomas & Kaltsikes, 1974; Merker, 1976; Bennett, 1977; Roupakias & Kaltsikes, 1977; Gustafson & Bennet, 1982; Naranjo & Lacadena, 1982; Soler et al., 1990; Jouve & Soler, 1996) .
Earlier research had suggested that in the absence of stress, ATF-2 plays a role in silencing certain genes through the formation of heterochromatin, a tightly-packed variety of chromatin whose state is epigenetically heritable.
Jmjd2b antagonizes H3K9 tri-methylation at pericentric heterochromatin in mammalian cells.
In heterochromatin, genomic DNA is inaccessible to nuclease digestion and remains available for subsequent qPCR.