In situ DNAse I sensitivity assay indicates DNA conformation differences between CHO cells and the radiation-sensitive CHO mutant IRS-20

2004 ◽  
Vol 104 (1-4) ◽  
pp. 100-103 ◽  
Author(s):  
D.G. Marañon ◽  
A.O. Laudicina ◽  
M. Muhlmann
Keyword(s):  
Cho Cells ◽  
Dnase I ◽  
Dna Conformation ◽  
Dnase I Sensitivity

Patterns of DNase I sensitivity in the holocentric chromosomes of the aphid Megoura viciae

Genome ◽  
1998 ◽  
Vol 41 (2) ◽  
pp. 169-172 ◽  
Author(s):  
Gian Carlo Manicardi ◽  
Mauro Mandrioli ◽  
Davide Bizzaro ◽  
Umberto Bianchi
Keyword(s):  
Dnase I ◽  
Holocentric Chromosomes ◽  
Telomeric Region ◽  
Nick Translation ◽  
In Situ Nick Translation ◽  
Embryo Cells ◽  
Dnase I Sensitivity ◽  
Megoura Viciae ◽  
Active Genes

Using the in situ nick translation technique, we looked for the presence of DNase I sensitive sites in Megoura viciae chromosomes, to study the distribution of active or potentially active genes in aphids, a group of insects possessing holocentric chromosomes. Cytological preparations obtained by the spreading of embryo cells were treated in situ with increasing concentrations (ranging from 5 to 200 ng/mL) of DNase I. At DNase I concentrations below 50 ng/mL, only one hypersensitive site was observed, and this was located on a telomeric region of the X chromosome that contains transcriptionally active nucleolar organizing regions, as assayed by silver staining. Interestingly, at intermediate concentrations of DNase, the incorporation of biotinylated nucleotide occurred uniformly throughout all chromosomes, whereas at concentrations above 100 ng/mL, a C-like banding pattern was produced. Our data differ from results obtained with mammalian, frog, and grasshopper chromosomes, where it was found that DNase I nicking is concentrated at the distal regions of all chromosomes.Key words: aphids, holocentric chromosomes, DNase I sensitivity, nick translation.

Serum stimulation of the c-fos enhancer induces reversible changes in c-fos chromatin structure

1990 ◽  
Vol 10 (3) ◽  
pp. 1126-1133
Author(s):  
J L Feng ◽  
B Villeponteau
Keyword(s):  
Growth Factors ◽  
Dna Sequences ◽  
Chromatin Structure ◽  
Transcriptional Activity ◽  
Dnase I ◽  
Enhancer Activity ◽  
Serum Stimulation ◽  
Fos Protein ◽  
Dnase I Sensitivity ◽  
Stimulation Of

Transcription of the proto-oncogene c-fos is known to be activated by growth factors in serum and subsequently repressed by the Fos protein. We show that generalized DNase I sensitivity of c-fos chromatin correlates closely with enhancer activity during induction, repression, and superinduction of the c-fos gene. Within 90 s of serum stimulation, proximal DNA sequences on both sides of the enhancer exhibit increased DNase I sensitivity. Within 5 min, elevated DNase I sensitivity spreads to chromatin at the distal 3' end of the c-fos gene. These results suggest that an open state of chromatin is propagated in both directions from the enhancer. The induced alterations in chromatin structure precede the increased transcriptional activity of the c-fos gene, suggesting that these changes in chromatin structure potentiate transcription.

scholarly journals DNase I hypersensitivity is independent of endogenous topoisomerase II activity during chicken erythrocyte differentiation.

1988 ◽  
Vol 8 (9) ◽  
pp. 3661-3669 ◽  
Author(s):  
M T Muller ◽  
V B Mehta
Keyword(s):  
Topoisomerase Ii ◽  
Globin Gene ◽  
Consensus Sequence ◽  
Dnase I ◽  
Cleavage Sites ◽  
Dnase I Hypersensitivity ◽  
Catalytic Sites ◽  
Hypersensitive Sites ◽  
Single Base Pair

Endogenous topoisomerase II cleavage sites were mapped in the chicken beta A-globin gene of 12- to 14-day embryonic erythrocytes. A major topoisomerase II catalytic site was mapped to the 5' end of the globin gene which contained a nucleosome-free and DNase I-hypersensitive site and additional but minor sites were mapped to the second intron and 3' of the gene to a tissue-specific enhancer. Cleavage sites, mapped in situ by indirect end labeling, were aligned to single-base-pair resolution by comparison to a consensus sequence derived for vertebrate topoisomerase II catalytic sites. In contrast to embryonic erythrocytes, endogenous topoisomerase II cleavages were not detected in erythrocytes from peripheral blood of adult chickens; therefore, as the transcriptional activity of the beta A-globin gene declines during terminal differentiation of erythrocytes, the activity of topoisomerase II in situ declines as well, despite the fact that DNase I hypersensitivity persists. The results showed that DNase I-hypersensitive chromatin can be maintained in the absence of topoisomerase II activity and suggested that topoisomerase II acts at hypersensitive sites because of an inherent attraction to some preexisting combination of DNA sequence or chromatin structure associated with DNase I-hypersensitive regions.

DNASE I SENSITIVITY OF THE HUMAN MYBLOPEROXIDASE GENE IN DIFFERENTIATING MYRLOID TISSUE

1989 ◽  
Vol 11 (1) ◽  
pp. 117
Author(s):  
G. R. Antoun ◽  
K. F. Jorgenson ◽  
T. F. Zipf ◽  
J. van Rys
Keyword(s):  
Dnase I ◽  
Dnase I Sensitivity
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