Analysis of chromosome positions in the interphase nucleus of Chinese hamster cells by laser-UV-microirradiation experiments

Abstract

Summary. Unsynchronized cells of an essentially diploid strain of female Chinese hamster cells derived from lung tissue (CHL) were laser-UV-microirradiated (2 = 257 nm) in the nucleus either at its central part or at its periphery. After 7-9 h postincubation with 0.5 mM caffeine, chromosome preparations were made in situ. Twenty-one and 29 metaphase spreads, respectively, with partial chromosome shattering (PCS) obtained after microirradiation at these two nuclear sites, were Q-banded and analyzed in detail. A positive correlation was observed between the frequency of damage of chromosomes and both their DNA content and length at metaphase. No significant difference was observed between the frequencies of damage obtained for individual chromosomes at either site of microirradiation. The frequency of joint damage of homologous chromosomes was low as compared to nonhomologous ones. Considerable variation was noted in different cells in the combinations of jointly shattered chromosomes. Evidence which justifies an interpretation of these data in terms of an interphase arrangement of chromosome territories is discussed. Our data strongly argue against somatic pairing as a regular event, and suggest a considerable variability of chromosome positions in different nuclei. However, present data do not exclude the possibility of certain non-random chromosomal arrangements in CHL-nuclei. The interphase chromosome distribution revealed by these experiments is compared with centromere-centromere, centromere-center and angle analyses of metaphase spreads and the relationship between interphase and metaphase arrangements of chromosomes is discussed.

Distribution of chromosome 18 and X centric heterochromatin in the interphase nucleus of cultured human cells

“…On the other hand, Hadlaczky et al [58] have found homologous interphase association of immunostained centromeres in Indian Muntjac cells cultivated in vitro. Recently, Arnoldus et al [ 171 have described the interphase association of the two lq12 heterochromatic regions in diploid nuclei derived from human cerebellum.…”

Higher Levels of Organization in the Interphase Nucleus of Cycling and Differentiated Cells

“…In Chinese hamster cell cultures, localized UV microbeam damage to interphase nuclei, which are then allowed to progress to metaphase, results in damage to one or a few chromosomes in similar regions. Cremer et al (43,44) interpret this result to mean that the chromosomes are arranged in a Rabl configuration at interphase. Likewise, a Rabl configuration is predicted at interphase in Indian muntjac lymphocytes in both G 1 and G 2 nuclei by analysis of chromosome orientations following premature chromatin condensation experiments (147).…”

Immunocytochemical localization of chromatin regions UV-microirradiated in S phase or anaphase

“…partial chromosome shattering, PCS. For a detailed description of this phenomenon, see [7,251. Our result that labelled chromatin masses from several jointly micron-radiated interphase chromosomes were still observed in close Autoradiographs of metaphase spreads with immunofluorescent spots (n= 17) were obtained after pulse-labelling with [3H]thymidine (0.1 @i/ml medium) for 1 h immediately after micron-radiation, which was performed 4-6 h after removal of the thymidine block.…”