constitutive 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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

con·sti·tu·tive het·er·o·chro·ma·tin

repetitive heterochromatin that lies in secondary constrictions in the nucleolar organizers.
Farlex Partner Medical Dictionary © Farlex 2012
References in periodicals archive ?
No hybridization signals were found in the constitutive heterochromatin and on the corresponding autosomes ACU 7, AMO 11, and NLA 16.
Constitutive heterochromatin in Acanthobrama marmid and Cyprinion macrostomus (Osteichthyes Cyprinidae).
The karyotype of specimens from the central population, Iraquara (MN 68092 and MN 68094) and distribution of constitutive heterochromatin (C-banding; Fig.
Constitutive heterochromatin DNA polymorphisms in diploid Medicago sativa ssp.
Constitutive heterochromatin, G-bands and Robertsonian rearrangements in the chromosomes of Akodon molinae (Rodentia: Cricetidae).
During the cell cycle and meiosis, autosomal heterochromatin is typically highly condensed, and the DNA is thought to be inaccessible to the enzymes involved in recombination (Stack, 1984); similarly, the compact nature of constitutive heterochromatin may prevent penetration of the enzymes involved in the integration of mys retrotransposons.
Constitutive heterochromatin in spermatocytes (prophase I) of all species of Maculata subcomplex.
The point is that quantitative Q-HRs variability only exists in man, though this type of constitutive heterochromatin is present in the genome of two other higher primates: Pan troglodytes and Goriila goriila [4-6].
Conventional FISH using the DNA probe PyrAlu-2p, highlighted the pericentromeric constitutive heterochromatin (Lopez-Fernandez et al.
In that sense, the quantity and packing ratio of constitutive heterochromatin has been mentioned by Pascoe et al.