Expression of a homologue of the fushi tarazu (ftz) gene in a cirripede crustacean.
In Metazoa, Hox genes control the identity of the body parts along the anteroposterior axis. In addition to this homeotic function, these genes are characterized by two conserved features: They are clustered in the genome, and they contain a particular sequence, the homeobox, encoding a DNA-binding domain. Analysis of Hox homeobox sequences suggests that the Hox cluster emerged early in Metazoa and then underwent gene duplication events. In arthropods, the Hox cluster contains eight genes with a homeotic function and two other Hox-like genes, zerknullt (zen)/Hox3 and fushi tarazu (ftz). In insects, these two genes have lost their homeotic function but have acquired new functions in embryogenesis. In contrast, in chelicerates, these genes are expressed in a Hox-like pattern, which suggests that they have conserved their ancestral homeotic function. We describe here the characterization of Diva, the homologue of ftz in the cirripede crustacean Sacculina carcini. Diva is located in the Hox cluster, in the same position as the ftz genes of insects, and is not expressed in a Hox-like pattern. Instead, it is expressed exclusively in the central nervous system. Such a neurogenic expression of ftz has been also described in insects. This study, which provides the first information about the Hoxcluster in Crustacea, reveals that it may not be much smaller than the insect cluster. Study of the Diva expression pattern suggests that the arthropod ftz gene has lost its ancestral homeotic function after the divergence of the Crustacea/Hexapoda clade from other arthropod clades. In contrast, the function of ftz during neurogenesis is well conserved in insects and crustaceans.
Mouchel-Vielh
Emmanuele
E
Equipe Développement et Evolution, UMR 7622 Biologie du Développment CNRS et Université P. et M. Curie, Paris, France. emmanuele.mouchel-vielh@snv.jussieu.fr
Blin
Maryline
M
Rigolot
Catherine
C
Deutsch
Jean S
JS
D000595:Amino Acid Sequence; D000818:Animals; D051943:Antennapedia Homeodomain Protein; D003445:Crustacea / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D016415:Sequence Alignment; D014157:Transcription Factors
D051943:Antennapedia Homeodomain Protein; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; C066177:Ubx protein, Drosophila