The Sine oculis/Six class family of homeobox genes in jellyfish with and without eyes: development and eye regeneration.

The development of visual organs is regulated in Bilateria by a network of genes where members of the Six and Pax gene families play a central role. To investigate the molecular aspects of eye evolution, we analyzed the structure and expression patterns of cognate members of the Six family genes in jellyfish (Cnidaria, Hydrozoa), representatives of a basal, non-bilaterian phylum where complex lens eyes with spherical lens, an epidermal cornea, and a retina appear for the first time in evolution. In the jellyfish Cladonema radiatum, a species with well-developed lens eyes in the tentacle bulbs, Six1/2-Cr and Six3/6-Cr, are expressed in the eye cup.

Hox gene cross-regulatory interactions in the embryonic brain of Drosophila.

During embryonic development of the Drosophila brain, the Hox gene labial is required for the regionalized specification of the tritocerebral neuromere. In order to gain further insight into the mechanisms of Hox gene action in the CNS, we have studied the molecular and genetic basis of cross-regulatory interactions between labial and other more posterior Hox genes using the GAL4/UAS system for targeted misexpression. Misexpression of posterior Hox genes in the embryonic neuroectoderm results in a labial loss-of function phenotype and a corresponding lack of Labial protein expression in the tritocerebrum.

Identification of the Drosophila melanogaster homolog of the human spastin gene.

The human SPG4 locus encodes the spastin gene, which is responsible for the most prevalent form of autosomal dominant hereditary spastic paraplegia (AD-HSP), a neurodegenerative disorder. Here we identify the predicted gene product CG5977 as the Drosophila homolog of the human spastin gene, with much higher sequence similarities than any other related AAA domain protein in the fly. Furthermore we report a new potential transmembrane domain in the N-terminus of the two homologous proteins.

An urbilaterian origin of the tripartite brain: developmental genetic insights from Drosophila.

Studies on expression and function of key developmental control genes suggest that the embryonic vertebrate brain has a tripartite ground plan that consists of a forebrain/midbrain, a hindbrain and an intervening midbrain/hindbrain boundary region, which are characterized by the specific expression of the Otx, Hox and Pax2/5/8 genes, respectively. We show that the embryonic brain of the fruitfly Drosophila melanogaster expresses all three sets of homologous genes in a similar tripartite pattern. Thus, a Pax2/5/8 expression domain is located at the interface of brain-specific otd/Otx2 and unpg/Gbx2 expression domains anterior to Hox expression regions.

Gliogenesis in Drosophila: genome-wide analysis of downstream genes of glial cells missing in the embryonic nervous system.

In Drosophila, the glial cells missing (gcm) gene encodes a transcription factor that controls the determination of glial versus neuronal fate. In gcm mutants, presumptive glial cells are transformed into neurons and, conversely, when gcm is ectopically misexpressed, presumptive neurons become glia. Although gcm is thought to initiate glial cell development through its action on downstream genes that execute the glial differentiation program, little is known about the identity of these genes.