Séminaire IBIP
Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)

Jeudi 9 décembre 2010
Amphi 208 (Cœur d’Ecole) à 14h

New strategies for imaging of Ca2+ and H2O2 in different subcellular compartments of plant cells

Alex Costa
Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italie

In order to gain insight into the roles played by Ca2+ and H2O2 in plant cells, it is necessary to have reliable, specific and non-invasive methodologies for their in vivodetection. In the last years a great development of new tools for the detection of such molecules has taking place. In particular new genetically-encoded probes for Ca2+(Cameleons) and H2O2 (HyPer) have been developed. Oxidative stress is a major challenge for all cells living in an oxygen-based world. Among reactive oxygen species, H2O2, is a well known toxic molecule and, nowadays, considered a specific component of several signalling pathways. Hence, the genetically-encoded H2O2 sensor HyPer was expressed in plant cells in different subcellular compartments. We demonstrated that the induction of cytoplasmic Ca2+ increase is followed by Ca2+ rise in the peroxisomal lumen. The analyses of HyPer fluorescence ratios were performed in leaf peroxisomes of tobacco and pre- and post-bolting Arabidopsis plants. These analyses allowed us to demonstrate that an intraperoxisomal Ca2+ rise in vivo stimulates catalase activity, increasing peroxisomal H2O2 scavenging efficiency. Ca2+ is a versatile second messenger involved in the control of a variety of physiological and pathological cellular processes. The use of genetically encoded Ca2+ indicators (e.g Cameleon) has greatly contributed to the study of Ca2+ handling in plant cells. Compared with mammalian cells, where a large set of data have been produced regarding the Ca2+ dynamics in different subcellular compartments, in plant cells there is still a poor comprehension of the role/s played by the organelles in the shaping of intracellular Ca2+ signals. Here the use of a new generation of Cameleon probes targeted to peroxisomes and mitochondria of plant cells will be presented.

Contact : Tou-Cheu Xiong

Contacts IBIP :
Sabine Zimmermann
Philippe Nacry
Christine Granier
Corinne Dasen
Chantal Baracco