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Reference : UMR7057-MARDUR-002
Workplace : PARIS,PARIS 13
Date of publication : Friday, September 25, 2020
Type of Contract : FTC Scientist
Contract Period : 12 months
Expected date of employment : 1 December 2020
Proportion of work : Full time
Remuneration : between 2700 and 3200 € gross monthly depending on experience
Desired level of education : PhD
Experience required : Indifferent
Flows over remarkably long distances are crucial to the functioning of many organisms, across all kingdoms of life. Coordinated flows are fundamental to power deformations, required for migration or development, or to spread resources and signals. A ubiquitous mechanism to generate flows, particularly prominent in animals and amoebas, is actomyosin cortex-driven mechanical deformations that pump the fluid enclosed by the cortex. Surprisingly, even in the absence of a pacemaker like a heart, cortex dynamics can self-organize to give rise to coordinated flows on vastly different scales.
The aim of this proposal is to study the interplay between actomyosin contractile activity, fluid flows, and shaping of the organism in Physarum polycephalum (popularized as Blob in the media), a model organism intensively studied by the scientific community.
In its vegetative phase, called plasmodium, this organism is made of thousands of undifferentiated cells fusing in a single, multinuclear cell, which can reach macroscopic sizes (dozens of cm²). This organism then develops a tubular network in which oscillatory flows (with period ~ 1 minute) are generated by the contraction of the membranous layer surrounding the “veins”. In spite of its apparent simplicity, the growth of the tubular network shares common features with the development of vascular systems in higher organisms, or with the mechanisms that take place in the irrigation of tumors. In particular, one can clearly identify two stages in the development of the plasmodium: a growing phase during which P. polycephalum explores its environment covering all the plane with a very dense and ramified tubular network. Then a reorganizing phase during which the organism seems to follow an optimization scheme: the network is less and less reticulated. Such self-organized structure also exhibits a number of properties (resilience, efficiency, adaptability) that are highly desirable for technical applications.
The postdoc will address some of the following questions:
- how the coordination of contractile activity will affect the transport efficiency and the distribution of flows ?
- what is underlying mechanisms leading to the propagation of peristaltic waves along the giant cell ?
- how spatial constraints affect the architecture of the transport network ?
- how the tubular network of P. polycephalum compares with other biological and articfial transport networks in terms of resilence, efficiency, and adaptability ?
A Ph.D. in physics (or related fields), previous experience in experimental research of soft matter or biophysics, and interest in biological systems are required.
The recruited post-doc will benefit from a world-class interdisciplinary environment within the MSC lab which developed expertise in soft condensed matter and biophysics : http://www.msc.univ-paris-diderot.fr/?lang=en
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