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SUMMARY:Plant Organs Regeneration: Measuring and Modelling Self‐Organiza
 tion - Giovanni Sena Ph.D.\, New York University
DTSTART:20110713T100000Z
DTEND:20110713T110000Z
UID:TALK32079@talks.cam.ac.uk
CONTACT:Microsoft Research Cambridge Talks Admins
DESCRIPTION:Biological systems exhibit a spontaneous emergence of order\, 
 or self‐organization\, resulting in the establishment of complex pattern
 s of cell types. Organs regeneration is a paramount example of post‐embr
 yonic pattern reorganization\, and plants are ideal model systems for inve
 stigating this high level of developmental plasticity.\n\nI have previousl
 y established a novel system for studying in vivo plant organs regeneratio
 n\, by showing that the root apex of the model organism Arabidopsis thalia
 na grows back when completely excised. Cell division provides the main sou
 rce of pattern modification in this system due to the anchoring effect of 
 cell walls and consequent absence of cell migration. Surprisingly\, howeve
 r\, root regeneration does not require a functional stem cell niche\, an o
 bservation that opens fundamental questions on the mechanisms that lead to
  de novo re‐patterning.\n\nAny attempt to further improve our understand
 ing of self‐organization in multicellular systems requires a quantitativ
 e analysis of its morphological dynamics at the cellular level\, coupled w
 ith an abstract model of the underlying interactions. Moreover\, tissue re
 organization during regeneration is a highly dynamical process which canno
 t be fully understood by sporadic observation and still images. Instead\, 
 long (days) time‐lapse observations at high spatial (microns) and tempor
 al (minutes) resolutions are required to capture the full cellular dynamic
 s. Due to its almost complete transparency\, and the limited number and hi
 ghly symmetric organization of its tissues\, the Arabidopsis root is a val
 uable model system for the experimental investigation of patterning and se
 lf‐organization.\n\nUnfortunately\, ensuring continuous specimen access\
 , while preserving physiological conditions and preventing photo‐damage\
 , poses major barriers to measurements of cellular dynamics in indetermina
 tely growing organs such as plant roots. Furthermore\, commercially availa
 ble platforms for time‐lapse microscopy are unsuitable to sustain a live
  plant on stage for many days with a vertically growing root.\n\nTo overco
 me these technical obstacles\, I have led the development of a unique imag
 ing system that integrates optical sectioning through light sheet fluoresc
 ence microscopy with hydroponic culture. The system has been adapted to pe
 rform 3D fluorescence optical sectioning at cellular resolution of a verti
 cally growing Arabidopsis root\, every few minutes and for many consecutiv
 e days. Novel automated routines have been developed to track the root tip
  as it grows\, track cellular nuclei and identify cell divisions.\n\nI wil
 l discuss the experimental and computational advantages to use plant organ
 s regeneration to study the phenomenon of self‐organization in biology. 
 I will present the state‐of‐the art on Arabidopsis root regeneration a
 nd introduce the newly developed imaging setup and recent quantitative dat
 a collected from a growing root. The requirements for future computational
  modelling approaches in multicellular self‐organizing systems will be d
 iscussed.
LOCATION:Small lecture theatre\, Microsoft Research Ltd\, 7 J J Thomson Av
 enue (Off Madingley Road)\, Cambridge
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