Header

UZH-Logo

Maintenance Infos

Rates of DNA synthesis in heterochromatic and euchromatic segments of the chromosome complements of two rodents


Schmid, Werner; Leppert, M F (1969). Rates of DNA synthesis in heterochromatic and euchromatic segments of the chromosome complements of two rodents. Cytogenetic and Genome Research, 8(2):125-135.

Abstract

In vitro studies were carried out on kidney epithelial cells and fibroblasts of female Microtus ngrestis and fibroblasts of male and female Cricetulus gristus. By means of pulse labeling with tritiated thymidine, the duration of DNA synthesis within the S period of the cell cycle was determined for the autosomal ‘euchromatic’ portions of the chromosome complements, for the large and well- defined, structurally heterochromatic segments and for the active and the ‘I.yon- ized', inactive X portions in the females. (Both species possess composite-type X chromosomes.) Strikingly similar results were found in both species and both types of tissues studied. In partially overlapping sequences DNA synthesis starts first in the autosomal cuchromatin and in the active X, later in the inactive X and finally in the structural heterochromatin; it ends in the same order. While DNA replication in given euchromatic segments takes nearly four hours, it requires less than two hours in the structurally heterochromatic segments. Interestingly, DNA replication was found to take considerably longer in the active than in the inactive X. This indicates that in the functional X chromosomes the rate of DNA synthesis is not dependent on the number of rcplicons (which must be assumed to be identical) but is accelerated in the genetically inactivated X chromosome.

Abstract

In vitro studies were carried out on kidney epithelial cells and fibroblasts of female Microtus ngrestis and fibroblasts of male and female Cricetulus gristus. By means of pulse labeling with tritiated thymidine, the duration of DNA synthesis within the S period of the cell cycle was determined for the autosomal ‘euchromatic’ portions of the chromosome complements, for the large and well- defined, structurally heterochromatic segments and for the active and the ‘I.yon- ized', inactive X portions in the females. (Both species possess composite-type X chromosomes.) Strikingly similar results were found in both species and both types of tissues studied. In partially overlapping sequences DNA synthesis starts first in the autosomal cuchromatin and in the active X, later in the inactive X and finally in the structural heterochromatin; it ends in the same order. While DNA replication in given euchromatic segments takes nearly four hours, it requires less than two hours in the structurally heterochromatic segments. Interestingly, DNA replication was found to take considerably longer in the active than in the inactive X. This indicates that in the functional X chromosomes the rate of DNA synthesis is not dependent on the number of rcplicons (which must be assumed to be identical) but is accelerated in the genetically inactivated X chromosome.

Statistics

Citations

Dimensions.ai Metrics
48 citations in Web of Science®
31 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

0 downloads since deposited on 11 Aug 2023
0 downloads since 12 months

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Children's Hospital Zurich > Medical Clinic
04 Faculty of Medicine > Institute of Medical Genetics
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Scopus Subject Areas:Health Sciences > General Medicine
Uncontrolled Keywords:Genetics, Animals, Autoradiography, Chromosomes / metabolism, Cricetinae, DNA Replication, Female, Fibroblasts / cytology, Heterochromatin / metabolism, In Vitro Techniques, Kidney, Male, Rodentia, Sex Chromosomes / metabolism, Thymidine / metabolism, Tritium
Scope:Contributions to practice (applied research)
Language:English
Date:1969
Deposited On:11 Aug 2023 07:01
Last Modified:29 Apr 2024 01:38
Publisher:Karger
ISSN:1424-8581
OA Status:Closed
Publisher DOI:https://doi.org/10.1159/000130029
PubMed ID:5798029