Mapping of Replication Origins in the X Inactivation Center of Vole Microtus levis Reveals Extended Replication Initiation Zone.

DNA replication initiates at specific positions termed replication origins. Genome-wide studies of human replication origins have shown that origins are organized into replication initiation zones. However, only few replication initiation zones have been described so far. Moreover, few origins were mapped in other mammalian species besides human and mouse. Here we analyzed pattern of short nascent strands in the X inactivation center (XIC) of vole Microtus levis in fibroblasts, trophoblast stem cells, and extraembryonic endoderm stem cells and confirmed origins locations by ChIP approach. We found that replication could be initiated in a significant part of XIC. We also analyzed state of XIC chromatin in these cell types. We compared origin localization in the mouse and vole XIC. Interestingly, origins associated with gene promoters are conserved in these species. The data obtained allow us to suggest that the X inactivation center of M. levis is one extended replication initiation zone

Location of G4 motifs in the XIC locus.

<p>Schematic representation of XIC locus of <i>M</i>. <i>levis</i> and G4 motifs localizations. Exons are indicated by rectangles. Arrows show direction of transcription. Vertical lines show locations of G4 motifs. G4 motifs on the sense strand (according to <i>Xist</i> transcription) are shown above, G4 motifs on the antisense strand are shown below. Stars indicate regions containing active origins in all cell lines analyzed and circles do regions of ORC binding.</p

Distribution of H3.3 and H3K9ac in the XIC locus.

<p>Diagrams show results of quantitative PCR analysis of ChIP with antibodies to H3.3 in XEN (A), TS cells (B), fibroblasts (C) and H3K9ac in XEN (D), TS cells (E), fibroblasts (F). Red bars represent negative control. At least two independent experiments were performed, PCR were made in duplicate. ±SD is given. Significant differences * P≥0.95 (one-way ANOVA test).</p

Comparative analysis of replication origin localization in the mouse and vole XICs.

<p>Schematic representation of XIC locus with identified replication origins and ORC binding regions in <i>M</i>. <i>musculus</i> (A) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128497#pone.0128497.ref030" target="_blank">30</a>] and <i>M</i>. <i>levis</i> (B). Exons are indicated by rectangles. Arrows show direction of transcription. Stars show regions with active origins in all cell lines analyzed and circles do ORC binding regions.</p

Transient Second Harmonic Generation Induced by Single Cycle THz pulses in Ba0.8Sr0.2TiO3/MgO

Contains fulltext : 200906.pdf (publisher's version ) (Open Access)6 p

A Regulatory Potential of the <em>Xist</em> Gene Promoter in Vole <em>M. rossiaemeridionalis</em>

<div><p>X chromosome inactivation takes place in the early development of female mammals and depends on the <em>Xist</em> gene expression. The mechanisms of <em>Xist</em> expression regulation have not been well understood so far. In this work, we compared <em>Xist</em> promoter region of vole <em>Microtus rossiaemeridionalis</em> and other mammalian species. We observed three conserved regions which were characterized by computational analysis, DNaseI <em>in vitro</em> footprinting, and reporter construct assay. Regulatory factors potentially involved in <em>Xist</em> activation and repression in voles were determined. The role of CpG methylation in vole <em>Xist</em> expression regulation was established. A CTCF binding site was found in the 5′ flanking region of the <em>Xist</em> promoter on the active X chromosome in both males and females. We suggest that CTCF acts as an insulator which defines an inactive <em>Xist</em> domain on the active X chromosome in voles.</p> </div

Analysis of the effect of −43G/A substitution on the activity of reporter constructs.

<p>Schemes of the constructs pCx14G/A and pCx5G/A are shown to the left; green and red rectangles denote the conserved regions CNS1 and CNS2, respectively. Relative luciferase activity of constructs in the fibroblast culture Sd10 is shown to the right. Arrow shows the <i>Xist</i> transcription start site; R.U., relative luciferase activity units.</p