Constancy and variability in the content of DNA in cerebellar Purkinje cell nuclei

Abstract

A cytophotometric study of DNA content in Purkinje cells of the cerebellum of rats, cats, chicken and humans (Feulgen staining) revealed that in a certain number of cells the amount of NDA ranged between the diploid and tetraploid level (H2C cells). The incidence of H2C Purkinje cells varied among the species studied. In rats, which were studied most thoroughly, these cells amounted on average to 3%. In some rats, as well as in some cats and chickens H2C Purkinje cells were entirely absent. In the group of animals possesing H2C Purkinje cells, great interindividual differences were observed. In rats for instance, the incidence of these cells varied from 1 to 23 per cent. Topographic analyses carried out in rat and human cerebellum revealed that H2C Purkinje cells occurred more frequently in the hemispheres than in the vermis. No significant differences were found in the number of H2C Purkinje cells in healthy and Kilham-DNA-virus infected rats. Densitometric analysis of the distribution of nuclear chromatin showed that H2C Purkinje cells were richer in condensed chromatin, especially in the region of the nucleolus, which apparently contains the hyperploid surplus of DNA. It is proposed that the phenomenon of DNA hyperdiploidy arises as a result of either incomplete S-phase in some immature Purkinje cell precursors or the amplification of some DNA sequences particularly those localized in the nucleolar region.

Changes in neuronal DNA content variation in the human brain during aging

“…These findings prompted a protracted controversy as to whether the DNA content of a very large part of neurons (Lapham, 1968;Bernocchi et al, 1979) or even all neurons (Bregnard et al, 1975(Bregnard et al, , 1979Kuenzle et al, 1978) exceeds the diploid level or not (Morselt et al, 1972;Cohen et al, 1973;Mann & Yates, 1973;Fujita, 1974;Fukuda et al, 1978). Although consensus was reached eventually that the majority of neurons are diploid, a small but constant fraction of a few percent of neurons continuously escaped the diploid DNA amount, irrespectively of the analytical method or other confounding factors of tissue sampling and preparation (Brodsky et al, 1979;Mares & van der Ploeg, 1980;Marshak et al, 1985). Discrepant results were attributed to various technical limitations and cytophotometric artifacts of heterochromatin in interphase nuclei of postmitotic neurons (Fujita et al, 1972;Duijndam et al, 1980a,b) but also to large individual variations (Brodsky et al, 1979).…”

“…Although consensus was reached eventually that the majority of neurons are diploid, a small but constant fraction of a few percent of neurons continuously escaped the diploid DNA amount, irrespectively of the analytical method or other confounding factors of tissue sampling and preparation (Brodsky et al, 1979;Mares & van der Ploeg, 1980;Marshak et al, 1985). Discrepant results were attributed to various technical limitations and cytophotometric artifacts of heterochromatin in interphase nuclei of postmitotic neurons (Fujita et al, 1972;Duijndam et al, 1980a,b) but also to large individual variations (Brodsky et al, 1979). Against the background of these inconsistencies, however, age-dependent differences in sampling have never been considered to be of influence, and systematic studies on potential age-related changes of the single-neuron DNA amount are lacking.…”

High values of DNA content in the hypotalamic neurons of Lophius piscatorius and Diodon holacanthus (Osteichthyes)

“…On the other hand, Feulgen-DNA values reaching a maximum of 4C have been demonstrated in Purkinje cells in different classes of Vertebrates (BOHM et al 1981;BRODSKY et al 1979BRODSKY et al , 1984SWARTZ and BHATNAGAR 1981). This finding has been correlated with different developmental and functional stages (BERNOCCHI and SCHERINI 1981;BERNOCCHI 1983BERNOCCHI , 1985BERNOCCHI and BARNI 1985;Giacometti et al, 1986), but variations in the Feulgen-DNA content of Purkinje cells have also been ascribed to experimental manipulations (SCHERINI et al 1988;BERNOCCHI et al 1989).…”

Evidence for differential DNA endoreplication during the development of a molluscan brain

“…It is particularly relevant to the data reported here for the reasons explained below. 396 CHASE AND TOLLOCZKO ploid neurons (Mann and Yates, 1973;Mann et al, 1978;Brodsky et al, 1979). Nevertheless, one pair of investigators defends the view that the intermediate values, found in a minority of the Purkinje cells, are valid and indicate a condition that they call hyperdiploidy (Brodsky and Uryvaeva, 1985).…”