Anomalous development and differential DNA replication in the X-Chromosome of a Drosophila hybrid

Chromosoma ◽  
1976 ◽  
Vol 57 (3) ◽  
pp. 235-260 ◽  
Author(s):  
Barbara Meer
Keyword(s):  
Dna Replication ◽  
X Chromosome ◽  
Differential Dna Replication

SEQUENCE OF DNA REPLICATION IN THE ISO-X CHROMOSOME FROM X/ISO-X HUMAN FEMALES DURING THE INITIAL STAGES OF THE SYNTHETIC PERIOD

1966 ◽  
Vol 8 (4) ◽  
pp. 631-639 ◽  
Author(s):  
B. B. Mukherjee ◽  
G. D. Burkholder ◽  
A. K. Sinha ◽  
S. K. Ghosal
Keyword(s):  
Dna Replication ◽  
X Chromosome ◽  
Human Females

DIFFERENTIAL DNA REPLICATION IN THE XX AND XY CELLS OF MUSCA DOMESTICA L. OCRA STRAIN

1970 ◽  
Vol 12 (3) ◽  
pp. 461-473 ◽  
Author(s):  
K. Y. Jan ◽  
J. W. Boyes
Keyword(s):  
Dna Replication ◽  
Musca Domestica ◽  
Sex Chromosomes ◽  
Chromosome Length ◽  
Final Part ◽  
X Chromosomes ◽  
Y Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Autosomal Pair ◽  
Differential Dna Replication

The karyotype of Musca domestica L. ocra strain, consists of the sex chromosomes and five autosomal pairs. The heteromorphic sex chromosomes are heterochromatic and mitotically unpaired, whereas the autosomes are euchromatic and mitotically paired. All autosomal pairs and both X and Y chromosomes are cytologically recognizable.The relative labelling rate, R (in terms of the number of grains counted per 100 labelled metaphases per μ of chromosome length) for the sex chromosomes and for each autosomal pair was followed from 1.5 hours to 8 hours after H3TdR injection. The pattern of labelling rate was similar for the different autosomal pairs in the XX cells but this pattern for the autosomal pairs in the XY cells, though also similar for the different pairs, differed appreciably from that found in the XX cells. The pattern of the labelling rate for the X chromosomes was similar in the XX and XY cells. Also the pattern of labelling rate for the X and Y chromosomes was similar during the final part of the replication period. The two X chromosomes in the XX cells and the X and Y chromosomes in the XY cells completed labelling later than the autosomes.

scholarly journals Mapping of DNA Replication Origins to Noncoding Genes of the X-Inactivation Center

2006 ◽  
Vol 26 (10) ◽  
pp. 3707-3717 ◽  
Author(s):  
Rebecca K. Rowntree ◽  
Jeannie T. Lee
Keyword(s):  
Dna Replication ◽  
X Chromosome ◽  
Epigenetic Regulation ◽  
Cpg Islands ◽  
X Inactivation ◽  
Replication Origins ◽  
Inactivation Center ◽  
Dna Replication Origins ◽  
Choice Location ◽  
Tight Correlation

ABSTRACT In mammals, few DNA replication origins have been identified. Although there appears to be an association between origins and epigenetic regulation, their underlying link to monoallelic gene expression remains unclear. Here, we identify novel origins of DNA replication (ORIs) within the X-inactivation center (Xic). We analyze 86 kb of the Xic using an unbiased approach and find an unexpectedly large number of functional ORIs. Although there has been a tight correlation between ORIs and CpG islands, we find that ORIs are not restricted to CpG islands and there is no dependence on transcriptional activity. Interestingly, these ORIs colocalize to important genetic elements or genes involved in X-chromosome inactivation. One prominent ORI maps to the imprinting center and to a domain within Tsix known to be required for X-chromosome counting and choice. Location and/or activity of ORIs appear to be modulated by removal of specific Xic elements. These data provide a foundation for testing potential relationships between DNA replication and epigenetic regulation in future studies.

scholarly journals Delayed DNA replication in haploid human embryonic stem cells

2021 ◽  
Author(s):  
Matthew M. Edwards ◽  
Michael V. Zuccaro ◽  
Ido Sagi ◽  
Qiliang Ding ◽  
Dan Vershkov ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Replication ◽  
Embryonic Stem Cells ◽  
X Chromosome ◽  
Human Embryonic Stem Cells ◽  
Embryonic Stem ◽  
Replication Timing ◽  
Genetic System ◽  
X Chromosomes ◽  
Genomic Regions

Haploid human embryonic stem cells (ESCs) provide a powerful genetic system but diploidize at high rates. We hypothesized that diploidization results from aberrant DNA replication. To test this, we profiled DNA replication timing in isogenic haploid and diploid ESCs. The greatest difference was the earlier replication of the X Chromosome in haploids, consistent with the lack of X-Chromosome inactivation. We also identified 21 autosomal regions that had delayed replication in haploids, extending beyond the normal S phase and into G2/M. Haploid-delays comprised a unique set of quiescent genomic regions that are also underreplicated in polyploid placental cells. The same delays were observed in female ESCs with two active X Chromosomes, suggesting that increased X-Chromosome dosage may cause delayed autosomal replication. We propose that incomplete replication at the onset of mitosis could prevent cell division and result in re-entry into the cell cycle and whole genome duplication.

The Synthesis of Deoxyribonucleic Acid and Nuclear Histone of the X Chromosome of the Rehnia Spinosus Spermatocyte

1969 ◽  
Vol 5 (2) ◽  
pp. 321-332 ◽  
Author(s):  
D. P. BLOCH ◽  
CHRISTINA TENG
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Dna Replication ◽  
X Chromosome ◽  
Deoxyribonucleic Acid ◽  
Chromosome Replication ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Nuclear Histone

The X chromosome of the Rehnia spinosus (Orthoptera) spermatocyte exists in a vesicle separate from the rest of the nucleus during its replication. This chromosome is typically heterochromatic, and late replicating. After replication the chromosome vesicle fuses with the nucleus. Cytophotometric determination of DNA and histone during replication of the chromosome revealed two types of histone. One class increases in amount in proportion to the DNA. The second class remains constant as DNA doubles, and probably increases later. Autoradiographic studies of incorporation of amino acids indicates that histone labelling occurs during chromosome replication. However, a lag in amino acid incorporation suggests that DNA replication in the X chromosome, while accompanied, or closely followed, by complexing with histone, is not necessarily coupled with its synthesis.

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