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.

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

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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.

Comparative Genomic In Situ Hybridization and the Possible Role of Retroelements in the Karyotypic Evolution of Three Akodontini Species

Constitutive heterochromatin in Acanthobrama marmid and Cyprinion macrostomus (Osteichthyes Cyprinidae).

Karyological Analysis of Some Species of Aphanius (Osteichthyes: Cyprinodontidae) From Anatolia

The karyotype of specimens from the central population, Iraquara (MN 68092 and MN 68094) and distribution of constitutive heterochromatin (C-banding; Fig.

Diferenciacao cromossomica em Kerodon rupestris (Rodentia: Caviidae) da regiao semiarida brasileira

Constitutive heterochromatin was analyzed with the C-banding technique (Fig.

Cytogenetic characterization of the dwarf oyster Ostrea stentina (mollusca: bivalvia) and comparative karyological analysis within ostreinae

Constitutive heterochromatin DNA polymorphisms in diploid Medicago sativa ssp.

C-banding analyses of Bromus inermis genomes

Constitutive heterochromatin, G-bands and Robertsonian rearrangements in the chromosomes of Akodon molinae (Rodentia: Cricetidae).

Chromosomal variation in the scrub mouse Akodon molinae (Rodentia: Sigmodontinae) in central Argentina

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.

Sex chromosomes, heterochromatin, and retrotransposon accumulation in deer mice

Constitutive heterochromatin in spermatocytes (prophase I) of all species of Maculata subcomplex.

Cytotaxonomy of the Maculata subcomplex (Hemiptera, Triatominae)

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].

Chromosomal Q-heterochromatin polymorphism in patients with alimentary obesity

Conventional FISH using the DNA probe PyrAlu-2p, highlighted the pericentromeric constitutive heterochromatin (Lopez-Fernandez et al.

Sperm DNA in grasshoppers: structural features and fertility implications

Constitutive heterochromatin was not observed in the autosomes of G.

Cariotipo de un marsupial suramericano raro, zarigueya de cola peluda, del genero Glironia (Didelphidae, Didelphimorphia)

In that sense, the quantity and packing ratio of constitutive heterochromatin has been mentioned by Pascoe et al.

Nuclear DNA content in two Chilean species of Pisidium (Veneroida: Sphaeriidae)