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Afin d’étudier les relations entre cycle cellulaire et détermination cellulaire, nous utilisons la drosophile comme modèle. Cet organisme offre la possibilité d’aborder cette problématique en combinant les techniques de  génétique, de biologie cellulaire et moléculaire ainsi que l’imagerie en temps réel. Pour notre analyse, nous utilisons plus particulièrement  les organes mécano sensoriels qui couvrent le thorax de la mouche adulte. Ces organes sont facilement accessibles à des études de longue durée in vivo et en temps réel par imagerie microscopique.

Les organes mécano sensoriels  sont issus d’un lignage cellulaire, le lignage des soies, qui est très bien caractérisé tant au niveau temporel que spatial. Ce lignage produit cinq cellules différentes après une séquence stéréotypée de quatre asymmetric cell divisions of a primary precursor cell or pI. During these divisions, each daughter cell acquires a different cell fate due to the differential activation of the Notch-pathway. As such, the bristle lineage provides an excellent opportunity to analyse cell proliferation, cell identity specification, cell identity diversification and cell morphogenesis in the same developmental process.    

Five different terminal cells are produced after a stereotyped sequence of asymmetric cell divisions. During these divisions, each daughter cell acquires a different cell fate due to the differential activation of the Notch-pathway (N). One daughter cell (N-off cell) acts as a ligand-producer and the other (N-on cell) is a signal-receiver. The bias in the activation of the N-pathway is assured by the stereotyped segregation in one cell of Numb and Neuralized where they block the N-receptor and promote N-ligand expression respectively. During the first round of division, the primary precursor cell or pI divides roughly parallel to the midline and Numb and Neuralized are inherited by the anterior cell that acquires a pIIb fate (it becomes the N-off cell and corresponds to the N-signal sender cell). This cell, after two rounds of mitosis, gives rise to the inner cells of the organ (the first division gives rise to a glial cell that enters apoptosis shortly after birth and a tertiary precursor cell, pIIIb. The division of this precursor produces the sheath cell and the neurone). The posterior cell, acquires a pIIa identity (it becomes the N-on cell and corresponds to the N-receiver cell). The division of pIIa leads to the formation of the outer cells of the organ (the shaft and socket cells).