title: Lineage and fate in Drosophila: role of the gene tramtrack in sense organ development.
abstract: The tactile bristles of the fly comprise four cells that originate from a single precursor cell through a fixed lineage. The gene tramtrack (ttk) plays a crucial role in defining the fates of these cells. Here we analyse the normal pattern of expression of ttk, as well as the effect of ttk overexpression at different steps of the lineage. We show that ttk is never expressed in cells having a neural potential, and that in cells where ttk is expressed, there is a delay between division and the onset of expression. The ectopic expression of ttk before some stage of the cell cycle can block further cell division. Furthermore, this expression transforms neural into non-neural cells, suggesting that ttk acts as a repressor of neural fate at each step of the lineage. Our results suggest that ttk is probably not involved in setting up the mechanism that creates an asymmetry between sister cells, but rather in the implementation of that choice.
authors.affiliation: Laboratoire de Génétique du Développement, Université Libre de Bruxelles, 67 rue des Chevaux, B-1640 Rhode-St-Genèse, Belgium, , , , , , BE.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Ramaekers
authors.affiliation: Laboratoire de Neurobiologie, Université Libre de Bruxelles, 67 rue des Chevaux, B-1640 Rhode-St-Genèse, Belgium, , , , , , BE.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Usui
authors.affiliation: Laboratoire de Neurobiologie, Université Libre de Bruxelles, 67 rue des Chevaux, B-1640 Rhode-St-Genèse, Belgium, , , , , , BE.
authors.forename: Akiko
authors.initials: A
authors.lastname: Usui-Ishihara
authors.affiliation: Laboratoire de Neurobiologie, Université Libre de Bruxelles, 67 rue des Chevaux, B-1640 Rhode-St-Genèse, Belgium, , , , , , BE.
authors.forename: Ariane
authors.initials: A
authors.lastname: Ramaekers
authors.affiliation: Laboratoire de Génétique du Développement, Université Libre de Bruxelles, 67 rue des Chevaux, B-1640 Rhode-St-Genèse, Belgium, , , , , , BE.
authors.forename: Valérie
authors.initials: V
authors.lastname: Ledent
authors.affiliation: Laboratoire de Neurobiologie, Université Libre de Bruxelles, 67 rue des Chevaux, B-1640 Rhode-St-Genèse, Belgium, , , , , , BE.
authors.forename: A
authors.initials: A
authors.lastname: Ghysen
authors.affiliation: Laboratoire de Génétique du Développement, Université Libre de Bruxelles, 67 rue des Chevaux, B-1640 Rhode-St-Genèse, Belgium, , , , , , BE.
authors.forename: C
authors.initials: C
authors.lastname: Dambly-Chaudière
keywords: Cell lineage; Drosophila; Key words Cell fate determination; Peripheral nervous system; Tramtrack