CNRS Post-doctoral position available November 1st 2008:

Origin of calcium mitotic signals and control mechanisms of apoptosis and early development of the sea urchin embryo : Role of the PLCgamma and MEK/ERK pathways

I would like to welcome a postdoctoral fellow to study the mechanisms of egg activation and the control of early development of sea urchin. Interaction of sperm and egg at fertilization induces well-coordinated molecular events including specific recognition between species, adhesion and fusion, that lead to the formation of a zygote, a totipotent cell that develops into a new individual. A calcium signal, common to a large number of species, from marine invertebrates to mammals, is essential to activate the metabolism of the unfertilized oocyte. However, how fertilization triggers this calcium signal and initiates development of the early embryo is far to be understood. This signal is followed by other Ca signals that control not only the first mitotic divisions but also various events during embryogenesis such as the set up of dorso-ventral axis, morpho-genetic movements and gene expression during gastrulation, organogenesis, etc.

Our results suggest that fertilization starts a program of mitotic divisions that depends not only on MPF (M phase Promoting Factor ), but also on ERK (Extracellular Regulated Kinase) and PLCgamma(Phospholipase C gamma ). PLCgammawould be upstream the Ca mitotic signals.

The aim of our current projects is to understand how the MEK / ERK and PLC pathways interact to modulate the intracellular levels of Ca during mitosis, and how they either control mitosis entry and the set up of an efficient spindle checkpoint during mitosis, or direct the cell toward apoptosis. The establishment of a spindle checkpoint during development and the role of ERK in the control of this mechanism will be studied. Polyphosphoinositides metabolism will be analyzed, and elements of the signaling pathway upstream PLCgamma will be characterized.

The biological model is the sea urchin egg which is a perfect model for the study of cell cycle and early development (synchronous fertilization, rapid mitotic divisions, etc.). The sea urchin genome has been sequenced in 2006, which opens great perspectives. We will also note that the sea urchin egg model has allowed the discovery of cyclins (Nobel prize attributed to T. Hunt), cADPr and NAADP, which play an essential role in calcium signaling.

Profile:
Applicants must hold a Ph.D. in cell biology, molecular biology, genetics or related areas. Prior experience in molecular biology techniques (DNA and RNA isolation, cloning, PCR, expression of mutated proteins) and biochemistry (Western blotting, immunoprecipitation, purification of recombinant proteins) is required.

Application:
Interested candidates should send a curriculum vitae, a brief summary of research experience and career goals, and 2 reference letters (or the names and contact information of 2 references) to Brigitte CIAPA at : brigitte.ciapa[ at ]u-psud.fr

Contact :
Dr. Brigitte Ciapa
UMR CNRS
8080 Orsay, France
email: brigitte.ciapa[ at ]u-psud.fr