BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//wp-events-plugin.com//6.4.7.2//EN
TZID:Europe/Paris
X-WR-TIMEZONE:Europe/Paris
BEGIN:VEVENT
UID:0-553@lptms.universite-paris-saclay.fr
DTSTART:20180110T110000Z
DTEND:20180110T120000Z
DTSTAMP:20180104T204328Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-stephanie-bonneau/
SUMMARY:Physics-Biology interface seminar: Stéphanie Bonneau - Moyen Amphi
 \, Building 510\, Université Paris-Saclay Orsay - 10 Jan 18 11:00
DESCRIPTION:Controled oxidation in living systems\nStéphanie Bonneau (Labo
 ratoire Jean Perrin\, Paris)\nLiving systems produce energy by oxidizing c
 arbon : in aerobic organisms\, a major step of this oxidation is processed
  by the respiratory chain in mitochondria. Energy production involves oxid
 ation and subsequent ageing of the cellular materials. The control of thei
 r oxidative activity allows cells to remain far enough to the thermodynami
 c equilibrium and consequently the balance between respiration and ageing 
 is a major regulation parameter of cell's fate. The key role of mitochondr
 ia in this phenomenon  will be discussed.\nExperimentally\, the control of
  the cellular oxidation is performed by using chosen photosensitizers. Due
  to their macrocycle\, such molecules present very special photo-physical 
 properties. Their light irradiation generates\, through their triplet stat
 e\, reactive oxygen species. The lifetime of these molecular species is ve
 ry short and their action is very localized. To specifically target photos
 ensitizers to one or the other cell compartments is thus the basis of thei
 r potential to modify and control the physiology of the cells. For example
 \, the photo-chemical internalization (PCI) of macromolecules into cells i
 s based on the photo-induced alteration of endosomal membranes - before th
 eir maturation in lysosomes - allowing the escape of the macromolecules\, 
 free to reach its targets within cell. More extensive photo-induced change
 s\, in particular to the mitochondria\, lead to cell death by necrosis or 
 apoptosis. This photo-induced cell death is basis of an anticancer therapy
  so-called PDT.\nFirst\, we focussed on the photo-induced modifications of
  the cellular trafficking. By combining measurements of local cytoplasmic 
 viscosity and active trafficking\, we found that photodynamic effect induc
 ed a only slight increase in viscosity but a massive decrease in diffusion
 . These effects are the signature of a return to thermodynamic equilibrium
  of the system after photo-activation. Secondly\, to better apprehend such
  complex effects\, we turned to model systems. In particular\, we focused 
 on photo-oxidation of membranes lipids\, that are important oxidative targ
 ets. We extensively studied their modifications under photo-oxidation. Our
  purpose is to demonstrate that the photo-induced permeabilization of the 
 membranes is correlated with a deep physical stress\, which can be relaxed
  by various pathways\, depending on its lipids composition\, which is char
 acteristic of  the targeted cellular compartment.
CATEGORIES:physbio,seminars
LOCATION:Moyen Amphi\, Building 510\, Université Paris-Saclay Orsay\, 15 R
 ue Georges Clemenceau\, orsay\, France
GEO:48.698187;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=Moyen Amphi\, Building 510\, Un
 iversité Paris-Saclay Orsay:geo:48.698187,2.181768
END:VEVENT
END:VCALENDAR