Low-Copy-Number Human Transgene Is Recognized as an X Inactivation Center in Mouse ES Cells, but Fails to Induce cis-Inactivation in Chimeric Mice

Genomics ◽  
2001 ◽  
Vol 71 (2) ◽  
pp. 156-162 ◽  
Author(s):  
Barbara R. Migeon ◽  
Holly Winter ◽  
Ethan Kazi ◽  
Ashis K. Chowdhury ◽  
Aisha Hughes ◽  
...  
Keyword(s):  
Copy Number ◽  
Es Cells ◽  
X Inactivation ◽  
Chimeric Mice ◽  
Mouse Es Cells ◽  
Inactivation Center ◽  
Low Copy Number

scholarly journals Functional Analysis of the DXPas34Locus, a 3′ Regulator of Xist Expression

1999 ◽  
Vol 19 (12) ◽  
pp. 8513-8525 ◽  
Author(s):  
E. Debrand ◽  
C. Chureau ◽  
D. Arnaud ◽  
P. Avner ◽  
E. Heard
Keyword(s):  
X Chromosome ◽  
Yeast Artificial Chromosome ◽  
Es Cells ◽  
Artificial Chromosome ◽  
Antisense Transcription ◽  
Regulatory Elements ◽  
X Inactivation ◽  
X Chromosomes ◽  
Inactivation Center ◽  
Controlling Element

ABSTRACT X inactivation in female mammals is controlled by a key locus on the X chromosome, the X-inactivation center (Xic). The Xic controls the initiation and propagation of inactivation in cis. It also ensures that the correct number of X chromosomes undergo inactivation (counting) and determines which X chromosome becomes inactivated (choice). The Xist gene maps to the Xic region and is essential for the initiation of X inactivation in cis. Regulatory elements of X inactivation have been proposed to lie 3′ toXist. One such element, lying 15 kb downstream ofXist, is the DXPas34 locus, which was first identified as a result of its hypermethylation on the active X chromosome and the correlation of its methylation level with allelism at the X-controlling element (Xce), a locus known to affect choice. In this study, we have tested the potential function of theDXPas34 locus in Xist regulation and X-inactivation initiation by deleting it in the context of largeXist-containing yeast artificial chromosome transgenes. Deletion of DXPas34 eliminates both Xistexpression and antisense transcription present in this region in undifferentiated ES cells. It also leads to nonrandom inactivation of the deleted transgene upon differentiation. DXPas34 thus appears to be a critical regulator of Xist activity and X inactivation. The expression pattern of DXPas34 during early embryonic development, which we report here, further suggests that it could be implicated in the regulation of imprintedXist expression.

Gene Targeting

1999 ◽  
Keyword(s):  
Homologous Recombination ◽  
Gene Targeting ◽  
Mammalian Cells ◽  
Es Cells ◽  
Practical Approach ◽  
Simple Method ◽  
Mouse Es Cells ◽  
Cell Clones ◽  
Previous Edition ◽  
Pros And Cons

Since the publication of the first edition of Gene Targeting: A Practical Approach in 1993 there have been many advances in gene targeting and this new edition has been thoroughly updated and rewritten to include all the major new techniques. It provides not only tried-and-tested practical protocols but detailed guidance on their use and applications. As with the previous edition Gene Targeting: A Practical Approach 2e concentrates on gene targeting in mouse ES cells, but the techniques described can be easily adapted to applications in tissue culture including those for human cells. The first chapter covers the design of gene targeting vectors for mammalian cells and describes how to distinguish random integrations from homologous recombination. It is followed by a chapter on extending conventional gene targeting manipulations by using site-specific recombination using the Cre-loxP and Flp-FRT systems to produce 'clean' germline mutations and conditionally (in)activating genes. Chapter 3 describes methods for introducing DNA into ES cells for homologous recombination, selection and screening procedures for identifying and recovering targeted cell clones, and a simple method for establishing new ES cell lines. Chapter 4 discusses the pros and cons or aggregation versus blastocyst injection to create chimeras, focusing on the technical aspects of generating aggregation chimeras and then describes some of the uses of chimeras. The next topic covered is gene trap strategies; the structure, components, design, and modification of GT vectors, the various types of GT screens, and the molecular analysis of GT integrations. The final chapter explains the use of classical genetics in gene targeting and phenotype interpretation to create mutations and elucidate gene functions. Gene Targeting: A Practical Approach 2e will therefore be of great value to all researchers studying gene function.

Infection with antiretroviral-susceptible HIV in an individual adherent to pre-exposure prophylaxis: strategies for treatment initiation

2021 ◽  
pp. 095646242097112
Author(s):  
Jessica M Hughes ◽  
Darrell HS Tan ◽  
Peter Anderson ◽  
Janani Bodhinayake ◽  
Paul A MacPherson
Keyword(s):  
Viral Load ◽  
Copy Number ◽  
Case Reports ◽  
Pharmacy Records ◽  
Treatment Regimens ◽  
Viral Copy Number ◽  
Low Copy Number ◽  
Viral Copy ◽  
Exposure Prophylaxis ◽  
Tenofovir Diphosphate

HIV pre-exposure prophylaxis (PrEP) is effective at preventing sexual acquisition of HIV, and failures in clinical trials are largely attributable to medication nonadherence. We report here a case of infection with a fully susceptible strain of HIV in an individual adherent to PrEP as demonstrated by pharmacy records and intracellular tenofovir diphosphate levels. At diagnosis, the viral load was 90 copies/mL precluding initial genotype testing due to low copy number. While PrEP failure is rare, this case underscores the importance of regular HIV testing for patient on PrEP and prompts discussion regarding the approach to treatment following failure where an initial genotype is not yet available or not possible due to low viral load. Few other case reports of PrEP failure exist in the literature and approaches to treatment varied widely. We suggest the initial viral copy number may guide next steps and discuss the risks and benefits of stopping PrEP, escalating therapy with integrase inhibitors or boosted protease inhibitors, or switching to non-nucleoside antiretroviral treatment regimens.

First female with Allan-Herndon-Dudley syndrome and partial deletion of X-inactivation center

Neurogenetics ◽  
2021 ◽  
Author(s):  
Juan F. Quesada-Espinosa ◽  
Lucía Garzón-Lorenzo ◽  
José M. Lezana-Rosales ◽  
María J. Gómez-Rodríguez ◽  
María T. Sánchez-Calvin ◽  
...  
Keyword(s):  
X Inactivation ◽  
Partial Deletion ◽  
Inactivation Center

scholarly journals Retention of low copy number human papillomavirus DNA in cultured cutaneous and mucosal wart keratinocytes

1994 ◽  
Vol 75 (3) ◽  
pp. 505-511 ◽  
Author(s):  
A. T. Williams ◽  
C. J. Sexton ◽  
A. L. Sinclair ◽  
K. J. Purdie ◽  
M. S. Thomas ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Copy Number ◽  
Low Copy Number ◽  
Papillomavirus Dna

Counting Low-Copy Number Proteins in a Single Cell

Science ◽  
2007 ◽  
Vol 315 (5808) ◽  
pp. 81-84 ◽  
Author(s):  
B. Huang ◽  
H. Wu ◽  
D. Bhaya ◽  
A. Grossman ◽  
S. Granier ◽  
...  
Keyword(s):  
Single Cell ◽  
Copy Number ◽  
Low Copy Number
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