Genetical Research



Dominant modifiers of the polyhomeotic extra-sex-combs phenotype induced by marked P element insertional mutagenesis in Drosophila


MARIE-ODILE  FAUVARQUE  p1, PATRICK  LAURENTI  p2, ANTOINE  BOIVIN  p3, SÉBASTIEN  BLOYER  a1, RUTH  GRIFFIN-SHEA  p1, HENRI-MARC  BOURBON  a2 and JEAN-MAURICE  DURA  a1 c1
a1 Institut de Génétique Humaine, CNRS/UPR 1142, 141 rue de la Cardonille, 34396 Montpellier Cedex 5, France
a2 Centre de Biologie du Développement, UMR5547/CNRS, Université Paul Sabatier Toulouse III-118 Route de Narbonne, 31062 Toulouse, France

Abstract

Members of the Polycomb group (Pc-G) and trithorax group (trx-G) of genes, as well as the enhancers of trx-G and Pc-G (ETP), function together to maintain segment identity during Drosophila development. In order to obtain new marked P mutations in these genes, we screened for dominant modifiers of the extra-sex-combs phenotype displayed by males mutant for the polyhomeotic (ph) gene, a member of the Pc-G group. Five P{lacW} insertions in four different genes were found to stably suppress ph: two are allelic to trithorax, one is the first allele specific to the Minute(2)21C gene, and the remaining two define new trx-G genes, toutatis (tou) in 48A and taranis (tara) in 89B10-13. tou is predicted to encode a 3109 amino acid sequence protein (TOU), which contains a TAM DNA-binding domain, a WAKZ motif, two PHD zinc fingers and a C-terminal bromodomain, and as such is likely to be involved in regulation of chromatin structure as a subunit of a novel chromatin remodelling complex. In a previous study, we found that insertion of a P{ph} transposable element containing ph regulatory sequences creates a high frequency of mutations modifying ph homeotic phenotypes. One such insertion enhanced the ph phenotype and we show that it is a new allele of UbcD1/eff, a gene encoding a ubiquitin-conjugating enzyme that is involved in telomere association and potentially in chromatin remodelling.

(Received March 6 2001)
(Revised May 25 2001)


Correspondence:
c1 Corresponding author. Tel: +33 4 99 61 99 60. Fax: +33 4 99 61 99 57. e-mail: jmdura@igh.cnrs.fr
p1 Present address: CEA-Grenoble, DBMS/BBSI UMR 5092 CEA/CNRS, 38054 Grenoble Cedex 9, France.
p2 Present address: Laboratoire de Biologie du Développement Université Paris 7, cc 7077–75251 Paris Cedex 5, France.
p3 Present address: Laboratoire de Dynamique du Génome et Evolution, CNRS-UMR7592, Institut Jacques Monod, Universités Paris 6–7, 2, place Jussieu, 75252 Paris Cedex 05, France.


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