Cell Cultures from Blood and Bone Marrow

102

Human lymphocyte cultures were treated with different concentrations of 5-azacytidine for various lengths of time. This cytosine analog induces very distinct undercondensation in the heterochromatin of chromosomes 1,9, 15, 16, and Y if applied in low doses during the last hours of culture. These regions are further distinguished by their intense distamycin A/DAPI-staining and highly methylated DNA. In interphase nuclei, these heterochromatic regions are frequently somatically paired. These somatic pairings are preserved up to the metaphase stage in the 5-azacytidine-treated cultures and are thus susceptible to direct analysis. The specific effect of 5-azacytidine on the heterochromatin of these chromosomes, its conserving effect on somatic pairing, and some of the consequences of the somatic pairing on the development of human chromosome aberrations are discussed.

Section: Methodsmentioning

confidence: 99%

A direct demonstration of somatically paired heterochromatin of human chromosomes

Schmid¹,

Grunert²,

Haaf³

et al. 1983

102

“…Chromosome preparations were made according to Pfeiffer (1974) from peripheral blood of 10 persons. Two were 46,XX, two 46,XY, two 45,XX,t(14q21q), two 45,XX,t(15q21q), and two 47,XX,+21.…”

Section: Methodsmentioning

confidence: 99%

Attraction between centric heterochromatin of human chromosomes

Schmid

Vogel

Krone

1975

An analysis of the pattern of association of acrocentric chromosomes with nonacrocentric chromosomes in human lymphocyte metaphases was performed. This pattern is nonrandom with respect to chromosome length and intrachromosomal distribution. There is a general preference for the centric regions, most pronounced at the proximal segments of the long arms of chromosomes 1, 9, and 16, which is interpreted to reflect heterochromatin attraction during interphase. Comparison of the association patterns of homologous chromosome l’s differing with regard to the size of their heterochromatic regions corroborates this interpretation. The possible significance of heterochromatin attraction for the formation of spontaneous and induced chromosome anomalies is discussed.

“…Preparation, staining, and analysis of the chromosomes Metaphase chromosomes were obtained from leukocyte cultures according to the method of Pfeiffer (1974). Distamycin AXHC1 (Boehringer, Mannheim) was dissolved in twice-distilled H..O (4 mg/ml) and added to half of the cultures 24 h before fixation at a final concentration of l()0/<g/ml.…”

Section: Probandsmentioning

confidence: 99%

Somatic pairings of the Y heterochromatin in human XYY and XYqi cells

Schmid¹,

Poppen²,

Schmid³

et al. 1981

In human interphase nuclei containing Yq isochromosomes or two Y chromosomes, there are conspicuous somatic pairings between the brightly fluorescing Y-heterochromatin regions. These somatic pairings cannot be demonstrated in metaphases from conventional cell cultures because they are disrupted at the mitotic prophase. However, in lymphocytes cultivated in a medium containing distamycin A, the somatic pairing between Y-heterochromatin is preserved to metaphase. The present findings are compared with earlier observations of somatically paired heterochromatin. An explanation for the highly disparate frequency of somatic pairing between the Y-heterochromatin regions in Yq isochromosomes and YY chromosomes is proposed.