SpeakersandAbstracts - Revision history

Noriko.hiroi: /* Studying cytoskeleton symmetry breakings using cellular reconstitution of cytoplasmic extracts and biophysical tools */

2016-01-09T04:02:46Z

Studying cytoskeleton symmetry breakings using cellular reconstitution of cytoplasmic extracts and biophysical tools

← Older revision		Revision as of 04:02, 9 January 2016
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	===='''Studying cytoskeleton symmetry breakings using cellular reconstitution of cytoplasmic extracts and biophysical tools'''====		===='''Studying cytoskeleton symmetry breakings using cellular reconstitution of cytoplasmic extracts and biophysical tools'''====
	Studying cytoskeleton symmetry breakings using cellular reconstitution of cytoplasmic extracts and biophysical tools		Studying cytoskeleton symmetry breakings using cellular reconstitution of cytoplasmic extracts and biophysical tools.
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	The cytoskeleton is essential for the function of cellular processes such as cell division and cell migration. Cytoskeleton fibers participate in the maintenance of cell internal organization and play essential roles in breaking symmetry and establishing cell polarity.		The cytoskeleton is essential for the function of cellular processes such as cell division and cell migration. Cytoskeleton fibers participate in the maintenance of cell internal organization and play essential roles in breaking symmetry and establishing cell polarity.

Noriko.hiroi: /* Studying cytoskeleton symmetry breakings using cellular reconstitution of cytoplasmic extracts and biophysical tools */

2016-01-09T03:46:39Z

Studying cytoskeleton symmetry breakings using cellular reconstitution of cytoplasmic extracts and biophysical tools

← Older revision		Revision as of 03:46, 9 January 2016
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	The cytoskeleton is essential for the function of cellular processes such as cell division and cell migration. Cytoskeleton fibers participate in the maintenance of cell internal organization and play essential roles in breaking symmetry and establishing cell polarity.		The cytoskeleton is essential for the function of cellular processes such as cell division and cell migration. Cytoskeleton fibers participate in the maintenance of cell internal organization and play essential roles in breaking symmetry and establishing cell polarity.
	We have developed an in vitro system capturing the spatial organization of cytoskeleton filaments within a geometry that mimic the cellular environment. This system, based on the cellular reconstitution by confinement of Xenopus cytoplasmic extracts, is used to examine simple aspects of symmetry breaking. <br>		We have developed an in vitro system capturing the spatial organization of cytoskeleton filaments within a geometry that mimic the cellular environment. This system, based on the cellular reconstitution by confinement of Xenopus cytoplasmic extracts, is used to examine simple aspects of symmetry breaking. <br>
	(1) We will first discuss how geometrical confinement and mechanical properties influence the self-organization of microtubules and molecular motors.,br>		(1) We will first discuss how geometrical confinement and mechanical properties influence the self-organization of microtubules and molecular motors.<br>
	(2) In most physiological situations, the asymmetric fate of a system follow from certain “cues” that pre-exist before symmetry is broken. These cues are either localized signals often encoded in protein concentration gradients, or “landmarks” inherited from the system’s history. For instance, gradients of signaling proteins and protein localization can be key for cell-fate decision and asymmetric cell division. In order to control the spatiotemporal localizations of these cues, we are using magnetic nanoparticles to spatially localize signaling proteins within confined extracts. This system is used to examine how the spatial localization and clustering of RCC1/RanGTP proteins feedbacks on microtubule spatial organization.		(2) In most physiological situations, the asymmetric fate of a system follow from certain “cues” that pre-exist before symmetry is broken. These cues are either localized signals often encoded in protein concentration gradients, or “landmarks” inherited from the system’s history. For instance, gradients of signaling proteins and protein localization can be key for cell-fate decision and asymmetric cell division. In order to control the spatiotemporal localizations of these cues, we are using magnetic nanoparticles to spatially localize signaling proteins within confined extracts. This system is used to examine how the spatial localization and clustering of RCC1/RanGTP proteins feedbacks on microtubule spatial organization.
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Noriko.hiroi: /* A physicist’s approach to the origin of life: Non-equilibrium entropic force */

2016-01-05T07:48:10Z

A physicist’s approach to the origin of life: Non-equilibrium entropic force

← Older revision		Revision as of 07:48, 5 January 2016
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	On a smaller scale, millimeters or less, temperature differences are also present in the pores of hydrothermal vents. The motion of molecules under such temperature gradients, called thermophoresis or the Soret effect, where thermal convection is suppressed could be relevant to the inhomogeneous distribution of chemical species. Thermophoresis depletes a polymer such as polyethylene glycol (PEG) from the hot region and builds a concentration gradient. In such a solution, solutes of small concentration experience thermophoresis and the restoring force dependent on PEG gradient of large concentration. Under focused laser heating, DNA and RNA as solutes localize as a ring-like structure which diameter monotonically decreases with their size following a behavior analogous to gel electrophoresis [1]. Trapping and selection of molecules could be physically feasible in a simple way relying on temperature gradient. Thermophoresis of RNA enzyme might be relevant to primitive life: Separation of RNA from the large library of RNA world might occur at the thermal vent of the deep ocean where large temperature gradient is present [2].		On a smaller scale, millimeters or less, temperature differences are also present in the pores of hydrothermal vents. The motion of molecules under such temperature gradients, called thermophoresis or the Soret effect, where thermal convection is suppressed could be relevant to the inhomogeneous distribution of chemical species. Thermophoresis depletes a polymer such as polyethylene glycol (PEG) from the hot region and builds a concentration gradient. In such a solution, solutes of small concentration experience thermophoresis and the restoring force dependent on PEG gradient of large concentration. Under focused laser heating, DNA and RNA as solutes localize as a ring-like structure which diameter monotonically decreases with their size following a behavior analogous to gel electrophoresis [1]. Trapping and selection of molecules could be physically feasible in a simple way relying on temperature gradient. Thermophoresis of RNA enzyme might be relevant to primitive life: Separation of RNA from the large library of RNA world might occur at the thermal vent of the deep ocean where large temperature gradient is present [2].
	Moreover, because this effect relies on the entropic force in solute contrasts, trapping with little material dependence is feasible. It allows us to optically control the density of living cells and proteins [3,4].<br><br>		Moreover, because this effect relies on the entropic force in solute contrasts, trapping with little material dependence is feasible. It allows us to optically control the density of living cells and proteins [3,4].<br><br>
	~~Selected refs:~~ [1] YT Maeda, A Buguin, A Libchaber. Phys. Rev. Lett. 107, 038301 (2011). <br>		[1] YT Maeda, A Buguin, A Libchaber. Phys. Rev. Lett. 107, 038301 (2011). <br>
	[2] YT Maeda, T Tlusty, A Libchaber. Proc. Natl. Acad. Sci. USA 109, 17972 (2012). <br>		[2] YT Maeda, T Tlusty, A Libchaber. Proc. Natl. Acad. Sci. USA 109, 17972 (2012). <br>
	[3] YT Maeda. Appl. Phys. Lett. 103, 243704 (2013).<br>		[3] YT Maeda. Appl. Phys. Lett. 103, 243704 (2013).<br>

Noriko.hiroi: /* Noriko Hiroi ( Keio University, Japan ) */

2016-01-05T07:47:10Z