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.

con·sti·tu·tive het·er·o·chro·ma·tin

repetitive heterochromatin that lies in secondary constrictions in the nucleolar organizers.
References in periodicals archive ?
Constitutive heterochromatin regions are found at or around centromeres and telomeres using the C-banding method.
The karyotype of specimens from the central population, Iraquara (MN 68092 and MN 68094) and distribution of constitutive heterochromatin (C-banding; Fig.
Evidence of the differentiated structural arrangement of constitutive heterochromatin between two populations of Astyanax scabripinnis (Pisces, Characidae).
The characterization of Ostrea denselamellosa (Mollusca, Bivalvia) chromosomes: karyotype, constitutive heterochromatin and nucleolus organizer regions.
The cytogenetic similarities between P cariba and the species so far studied of the genus Serrasalmus, in the number and type of chromosomes, multiplicity of NOR-bearing chromosomes and the distribution of constitutive heterochromatin located in centromeric and telomeric position, reinforces the hypothesis of the close phylogenetic relationship between the genera Pygocentrus and Serrasalmus.
Constitutive heterochromatin was located only at telomeric regions in tetraploid B.
1991, Butlin 1998), because of the distribution of constitutive heterochromatin linked to the sex chromosome and because of differences in gene activity linked to rDNAs, also localized within this chromosome (Gosalvez et al.
In that sense, the quantity and packing ratio of constitutive heterochromatin has been mentioned by Pascoe et al.
Giemsa C-banding technique, which stains constitutive heterochromatin, is a technique that has been used successfully in many species to identify individual chromosomes and to establish genomic relationships among species (Vosa, 1975; Cai and Chinnappa, 1987; Fominaya et al.
Constitutive heterochromatin can be observed in the genome during the cell cycle of all types of cells as C or fluorescent bands, which occur in different parts of individual chromosomes (Shibata et al.