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Mechanics and dynamics of X-chromosome pairing at X inactivation

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Scialdone, Antonio and Nicodemi, Mario. (2008) Mechanics and dynamics of X-chromosome pairing at X inactivation. PL o S Computational Biology, Vol.4 (No.12). ISSN 1553-734X

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Official URL: http://dx.doi.org/10.1371/journal.pcbi.1000244

Abstract

At the onset of X-chromosome inactivation, the vital process whereby female mammalian cells equalize X products with
respect to males, the X chromosomes are colocalized along their Xic (X-inactivation center) regions. The mechanism
inducing recognition and pairing of the X’s remains, though, elusive. Starting from recent discoveries on the molecular
factors and on the DNA sequences (the so-called "pairing sites") involved, we dissect the mechanical basis of Xic
colocalization by using a statistical physics model. We show that soluble DNA-specific binding molecules, such as those
experimentally identified, can be indeed sufficient to induce the spontaneous colocalization of the homologous
chromosomes but only when their concentration, or chemical affinity, rises above a threshold value as a consequence of a
thermodynamic phase transition. We derive the likelihood of pairing and its probability distribution. Chromosome dynamics
has two stages: an initial independent Brownian diffusion followed, after a characteristic time scale, by recognition and
pairing. Finally, we investigate the effects of DNA deletion/insertions in the region of pairing sites and compare model
predictions to available experimental data.

Item Type:

Journal Article

Subjects:

Q Science > QH Natural history > QH426 Genetics

Divisions:

Faculty of Science > Physics

Library of Congress Subject Headings (LCSH):

X chromosome

Journal or Publication Title:

PL o S Computational Biology

Publisher:

Public Library of Science

ISSN:

1553-734X

Official Date:

26 December 2008

Dates:

Date	Event
26 December 2008	Published

Volume:

Vol.4

Number:

No.12

Number of Pages:

Identification Number:

10.1371/journal.pcbi.1000244

Status:

Peer Reviewed

Publication Status:

Published

Access rights to Published version:

Open Access

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