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Soft viscoelastic properties of nuclear actin age oocytes due to gravitational creep

Author(s): Feric, Marina; Broedersz, Chase P.; Brangwynne, Clifford P.

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Abstract: The actin cytoskeleton helps maintain structural organization within living cells. In large X. laevis oocytes, gravity becomes a dominant force and is countered by a nuclear actin network that prevents liquid-like nuclear bodies from immediate sedimentation and coalescence. However, nuclear actin's mechanical properties, and how they facilitate the stabilization of nuclear bodies, remain unknown. Using active microrheology, we find that nuclear actin forms a weak viscoelastic network, with a modulus of roughly 0.1 Pa. Embedded probe particles subjected to a constant force exhibit continuous displacement, due to viscoelastic creep. Gravitational forces also cause creep displacement of nuclear bodies, resulting in their asymmetric nuclear distribution. Thus, nuclear actin does not indefinitely support the emulsion of nuclear bodies, but only kinetically stabilizes them by slowing down gravitational creep to ∼2 months. This is similar to the viability time of large oocytes, suggesting gravitational creep ages oocytes, with fatal consequences on long timescales.
Publication Date: 18-Nov-2015
Electronic Publication Date: 2015
Citation: Feric, M, Broedersz, CP, Brangwynne, CP. (2015). Soft viscoelastic properties of nuclear actin age oocytes due to gravitational creep. Scientific Reports, 5, doi:10.1038/srep16607
DOI: doi:10.1038/srep16607
Pages: 1 - 12
Type of Material: Journal Article
Journal/Proceeding Title: Scientific Reports
Version: Final published version. This is an open access article.

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