Attraction between centric heterochromatin of human chromosomes

Schmid, Michael; Vogel, Walther; Krone, W.

doi:10.1159/000130503

Cited by 82 publications

(32 citation statements)

References 23 publications

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“…Each of these methods has its limitations: (i) does not reveal the distribution of euchromatic chromosome segments; (ii) is based on the assumption (which has been questioned by Warburton et al, 1973;Schmid et al, 1975;and Singh et al, 1976) that the interphase chromosome arrangement is largely unchanged by the onset of mitosis and the methods of preparation. The validity of (iii) depends on the extent to which the frequency of chromatid interchanges is influenced not only by spatial relationships but by other unknown factors which would give a distorted picture of the internal order of the interphase nucleus (Comings, 1975).…”

Section: Introductionmentioning

confidence: 99%

“…Numerous papers report a non-random arrangement of metaphase chromosomes (Comings, 1968;Vogel and Schroeder, 1974;Schmid et al, 1975), while other authors find at best only a small tendency towards a non-random distribution (Warburton et al, 1973). In particular, results which concern the association of homologous chromosomes are at variance (Vogel and Schroeder, 1974;Comings, 1975;Hens et al, 1975).…”

Section: Introductionmentioning

confidence: 99%

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Laser UV microirradiation of interphase nuclei and post-treatment with caffeine

Zorn

Cremer

et al. 1976

Hum Genet

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Summary.Laser UV microirradiation of Chinese hamster interphase cells combined with caffeine post-treatment produced different patterns of chromosome damage in mitosis following irradiation of a small area of the nucleus that may be classified in three categories: I) intact metaphase figures, II) chromosome damage confined to a small area of the metaphase spread, III) mitotic figures with damage on all chromosomes. Category III might be the consequence of a non-localized distortion of nuclear metabolism. By contrast, category II may reflect localized DNA damage induced by microirradiation, which could not be efficiently repaired due to the effect of caffeine. If this interpretation is right, in metaphase figures of category II chromosome damage should occur only at the irradiation site. The effect might then be used to investigate neighbourhood relationships of individual chromosomes in the interphase nucleus.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Laser UV microirradiation of interphase nuclei and post-treatment with caffeine

Zorn

Cremer

et al. 1976

Hum Genet

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“…The degree of homology of the highly repetitive DNA sequences abundantly present near the centromeres of some chromosomes might facilitate the pairing of these regions (Haaf et al, 1986). The observed clustering and association of centromeric heterochromatin into so-called chromocenters (Hsu et al, 1971;Schmid et al, 1975) are examples of preferred association of highly repetitive sequences.…”

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confidence: 99%

Ionizing radiation-induced instant pairing of heterochromatin of homologous chromosomes in human cells

Abdel-Halim

Imam²,

Badr³

et al. 2004

Cytogenet Genome Res

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Using fluorescence in situ hybridization with human band-specific DNA probes we examined the effect of ionizing radiation on the intra-nuclear localization of the heterochromatic region 9q12→q13 and the euchromatic region 8p11.2 of similar sized chromosomes 9 and 8 respectively in confluent (G₁) primary human fibroblasts. Microscopic analysis of the interphase nuclei revealed colocalization of the homologous heterochromatic regions from chromosome 9 in a proportion of cells directly after exposure to 4 Gy X-rays. The percentage of cells with paired chromosomes 9 gradually decreased to control levels during a period of one hour. No significant changes in localization were observed for chromosome 8. Using 2-D image analysis, radial and inter-homologue distances were measured for both chromosome bands. In unexposed cells, a random distribution of the chromosomes over the interphase nucleus was found. Directly after irradiation, the average inter-homologue distance decreased for chromosome 9 without alterations in radial distribution. The percentage of cells with inter-homologue distance <3 µm increased from 11% in control cells to 25% in irradiated cells. In contrast, irradiation did not result in significant changes in the inter-homologue distance for chromosome 8. Colocalization of the heterochromatic regions of homologous chromosomes 9 was not observed in cells irradiated on ice. This observation, together with the time dependency of the colocalization, suggests an underlying active cellular process. The biological relevance of the observed homologous pairing remains unclear. It might be related to a homology dependent repair process of ionizing radiation induced DNA damage that is specific for heterochromatin. However, also other more general cellular responses to radiation-induced stress or change in chromatin organization might be responsible for the observed pairing of heterochromatic regions.

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“…Besides, there are observations of contacts of nucleolus with C-HRs of secondary constriction of human chromosomes 1, 9 and 16, which do not contain ribosomal cystrones. The frequency of associations of acrocentric chromosomes with chromosome 1 grows with an increase of the size of its С-heterochromatin block (Schmid et al, 1975).…”

Section: The Mechanism Of Cell Thermoregulationmentioning

confidence: 99%

Cell Thermoregulation: Problems, Advances and Perspectives

Ibraimov¹

2017

JMBR

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Thermoregulation at organism level is the well-established fact. The question on possibility of thermoregulation at the cell level remains opened. Based on study of distribution of chromosomal heterochromatin regions (HRs) in various human populations, in norm and at some forms of pathology the hypothesis about thermoregulation existence at the cell level has been presented. The essence of hypothesis of cell thermoregulation (СТ) is elimination of the temperature difference between the nucleus and cytoplasm when the nucleus temperature becomes higher than the cytoplasm temperature. The nucleus, in contrast to the cytoplasm, cannot conduct heat directly in the extracellular space, from where the heat is taken by the circulating flow of sap, lymph and blood. Thus, the nucleus can conduct heat only in the cytoplasm. With this, the nucleus has two options for the dissipation of heat surplus: either by increasing its volume or increasing the heat conductivity of the nuclear envelope. As the first option is limited, and the second one is hampered because of thickness of the cell membranes, apparently the higher eukaryotes took advantage of the opportunity of a dense layer of peripheral condensed chromatin (CC) as heat conductor for a more efficient elimination of the temperature difference between the nucleus and cytoplasm. The СС localized between a nucleus and cytoplasm is made of different types of chromosomal HRs. For this reason, СС is subject to wide variability in population. Obviously, the density of the СС packing depends on the type and quantity of chromosomal HRs in its structure that can affect upon its heat-conducting ability. If the situation is this then we are entitled to expect a new type of variability with all consequences resulting from here.

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Attraction between centric heterochromatin of human chromosomes

Cited by 82 publications

References 23 publications

Laser UV microirradiation of interphase nuclei and post-treatment with caffeine

Laser UV microirradiation of interphase nuclei and post-treatment with caffeine

Ionizing radiation-induced instant pairing of heterochromatin of homologous chromosomes in human cells

Cell Thermoregulation: Problems, Advances and Perspectives

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