Gap junctions in the ovary of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>: localization of innexins 1, 2, 3 and 4 and evidence for intercellular communication via innexin-2 containing channels

Background  

In the Drosophila ovary, germ-line and soma cells are interconnected via gap junctions. The main gap-junction proteins in invertebrates are members of the innexin family. In order to reveal the role that innexins play in cell-cell communication during oogenesis, we investigated the localization of innexins 1, 2, 3 and 4 using immunohistochemistry, and analyzed follicle development following channel blockade.     

<Emphasis Type="Italic">atonal</Emphasis>- and <Emphasis Type="Italic">achaete-scute</Emphasis>-related genes in the annelid <Emphasis Type="Italic">Platynereis dumerilii</Emphasis>: insights into the evolution of neural basic-Helix-Loop-Helix genes

Background  

Functional studies in model organisms, such as vertebrates and Drosophila, have shown that basic Helix-loop-Helix (bHLH) proteins have important roles in different steps of neurogenesis, from the acquisition of neural fate to the differentiation into specific neural cell types. However, these studies highlighted many differences in the expression and function of orthologous bHLH proteins during neural development between vertebrates and Drosophila. To understand how the functions of neural bHLH genes have evolved among bilaterians, we have performed a detailed study of bHLH genes during nervous system development in the polychaete annelid, Platynereis dumerilii, an organism which is evolutionary distant from both Drosophila and vertebrates.     

Novel subdomains of the mouse olfactory bulb defined by molecular heterogeneity in the nascent external plexiform and glomerular layers

Background  

In the mouse olfactory system, the role of the olfactory bulb in guiding olfactory sensory neuron (OSN) axons to their targets is poorly understood. What cell types within the bulb are necessary for targeting is unknown. What genes are important for this process is also unknown. Although projection neurons are not required, other cell-types within the external plexiform and glomerular layers also form synapses with OSNs. We hypothesized that these cells are important for targeting, and express spatially differentially expressed guidance cues that act to guide OSN axons within the bulb.     

Identification of 11-amino acid peptides that disrupt Notch-mediated processes in <Emphasis Type="Italic">Drosophila</Emphasis>

Background  

The conserved Notch signaling pathway regulates cell fate decisions and maintains stem cells in multicellular organisms. Up-regulation of Notch signaling is observed in several types of cancer and is causally involved in proliferation and survival of cancer cells. Thus, it is of great interest to look for anti-Notch reagents for therapeutic purposes. In model animal Drosophila, Notch signaling restricts selection of sensory organ precursors (SOPs) during external sensory (ES) organ development. To look for novel genes that can suppress Notch signaling, we performed a gain-of-function modifier screen to look for genes that enhance the phenotype of ectopic ES organs induced by overexpression of phyllopod, a gene required for SOP specification.     

Migration of glial cells into retinal axon target field in Drosophila melanogaster

During the development of the Drosophila visual system, photoreceptor (retinal) axons (R axons) project retinotopically to their targets in the optic lobes. The establishment of this precise pattern of connections does not depend on interactions between adjacent axon bundles, suggesting that R axons rely on environmental signals for proper pathfinding. Glial cells that are located along the R-axon trajectory are likely candidates to provide guidance cues for R-axon navigation. This study defines the origin of lamina glia (L glia), and demonstrates that L glia migrate into the lamina over a considerable distance. Glia are located in positions at which the R axons make critical growth choices. In the absence of cues from the eye, several classes of glia migrate to their final positions within the optic lobe anlage and begin to differentiate. Our results are consistent with a role for the glia in providing guidance cues to the R axons. © 1996 John Wiley & Sons, Inc.     

Live imaging of <Emphasis Type="Italic">Drosophila</Emphasis>gonad formation reveals roles for Six4 in regulating germline and somatic cell migration

Background  

Movement of cells, either as amoeboid individuals or in organised groups, is a key feature of organ formation. Both modes of migration occur during Drosophila embryonic gonad development, which therefore provides a paradigm for understanding the contribution of these processes to organ morphogenesis. Gonads of Drosophila are formed from three distinct cell types: primordial germ cells (PGCs), somatic gonadal precursors (SGPs), and in males, male-specific somatic gonadal precursors (msSGPs). These originate in distinct locations and migrate to associate in two intermingled clusters which then compact to form the spherical primitive gonads. PGC movements are well studied, but much less is known of the migratory events and other interactions undergone by their somatic partners. These appear to move in organised groups like, for example, lateral line cells in zebra fish or Drosophila ovarian border cells.     

Protein Kinase D regulates several aspects of development in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Background  

Protein Kinase D (PKD) is an effector of diacylglycerol-regulated signaling pathways. Three isoforms are known in mammals that have been linked to diverse cellular functions including regulation of cell proliferation, differentiation, motility and secretory transport from the trans-Golgi network to the plasma membrane. In Drosophila, there is a single PKD orthologue, whose broad expression implicates a more general role in development.     

Mechanism of G1 arrest in the <Emphasis Type="Italic">Drosophila</Emphasis>eye imaginal disc

Background  

Most differentiating cells are arrested in G1-phase of the cell cycle and this proliferative quiescence appears important to allow differentiation programmes to be executed. An example occurs in the Drosophila eye imaginal disc, where all cells are synchronized and arrested in G1 phase prior to making a fate choice either to initiate the first round of photoreceptor differentiation or to re-enter one terminal mitosis.     

Tissue remodeling: a mating-induced differentiation program for the <Emphasis Type="Italic">Drosophila</Emphasis>oviduct

Background  

In both vertebrates and invertebrates, the oviduct is an epithelial tube surrounded by visceral muscles that serves as a conduit for gamete transport between the ovary and uterus. While Drosophila is a model system for tubular organ development, few studies have addressed the development of the fly's oviduct. Recent studies in Drosophila have identified mating-responsive genes and proteins whose levels in the oviduct are altered by mating. Since many of these molecules (e.g. Muscle LIM protein 84B, Coracle, Neuroglian) have known roles in the differentiation of muscle and epithelia of other organs, mating may trigger similar differentiation events in the oviduct. This led us to hypothesize that mating mediates the last stages of oviduct differentiation in which organ-specific specializations arise.     

Go contributes to olfactory reception in Drosophila melanogaster

Background  

Seven-transmembrane receptors typically mediate olfactory signal transduction by coupling to G-proteins. Although insect odorant receptors have seven transmembrane domains like G-protein coupled receptors, they have an inverted membrane topology and function as ligand-gated cation channels. Consequently, the involvement of cyclic nucleotides and G proteins in insect odor reception is controversial. Since the heterotrimeric G_oα subunit is expressed in Drosophila olfactory receptor neurons, we reasoned that G_o acts together with insect odorant receptor cation channels to mediate odor-induced physiological responses.     

Molecular characterization of the <Emphasis Type="Italic">singed wings</Emphasis> locus of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Background  

Hormones frequently guide animal development via the induction of cascades of gene activities, whose products further amplify an initial hormonal stimulus. In Drosophila the transformation of the larva into the pupa and the subsequent metamorphosis to the adult stage is triggered by changes in the titer of the steroid hormone 20-hydroxyecdysone. singed wings (swi) is the only gene known in Drosophila melanogaster for which mutations specifically interrupt the transmission of the regulatory signal from early to late ecdysone inducible genes.     

<Emphasis Type="Italic">echinus</Emphasis>, required for interommatidial cell sorting and cell death in the <Emphasis Type="Italic">Drosophila</Emphasis> pupal retina,encodes a protein with homology to ubiquitin-specific proteases

Background  

Programmed cell death is used to remove excess cells between ommatidia in the Drosophila pupal retina. This death is required to establish the crystalline, hexagonal packing of ommatidia that characterizes the adult fly eye. In previously described echinus mutants, interommatidial cell sorting, which precedes cell death, occurred relatively normally. Interommatidial cell death was partially suppressed, resulting in adult eyes that contained excess pigment cells, and in which ommatidia were mildly disordered. These results have suggested that echinus functions in the pupal retina primarily to promote interommatidial cell death.     

Excessive Dpp signaling induces cardial apoptosis through dTAK1 and dJNK during late embryogenesis of <Emphasis Type="Italic">Drosophila</Emphasis>

Background  

To identify genes involved in the heart development of Drosophila, we found that embryos lacking raw function exhibited cardial phenotypes. raw was initially identified as a dorsal open group gene. The dorsal open phenotype was demonstrated to be resulted from the aberrant expression of decapentaplegic (dpp), a member of the tumor growth factor beta (TGF-β), signaling pathway. Despite the role of dpp in pattering cardioblasts during early embryogenesis of Drosophila have been demonstrated, how mutation in raw and/or excessive dpp signaling involves in the differentiating heart of Drosophila has not been fully elaborated at late stages.     

Discrimination of different species from the genus <Emphasis Type="Italic">Drosophila</Emphasis> by intact protein profiling using matrix-assisted laser desorption ionization mass spectrometry

Background  

The use of molecular biology-based methods for species identification and establishing phylogenetic relationships has supplanted traditional methods relying on morphological characteristics. While PCR-based methods are now the commonly accepted gold standards for these types of analysis, relatively high costs, time-consuming assay development or the need for a priori information about species-specific sequences constitute major limitations. In the present study, we explored the possibility to differentiate between 13 different species from the genus Drosophila via a molecular proteomic approach.     

Lack of global meiotic sex chromosome inactivation,and paucity of tissue-specific gene expression on the <Emphasis Type="Italic">Drosophila X</Emphasis> chromosome

Background  

Paucity of male-biased genes on the Drosophila X chromosome is a well-established phenomenon, thought to be specifically linked to the role of these genes in reproduction and/or their expression in the meiotic male germline. In particular, meiotic sex chromosome inactivation (MSCI) has been widely considered a driving force behind depletion of spermatocyte-biased X-linked genes in Drosophila by analogy with mammals, even though the existence of global MCSI in Drosophila has not been proven.     

MidExDB: A database of Drosophila CNS midline cell gene expression

Background  

The Drosophila CNS midline cells are an excellent model system to study neuronal and glial development because of their diversity of cell types and the relative ease in identifying and studying the function of midline-expressed genes. In situ hybridization experiments generated a large dataset of midline gene expression patterns. To help synthesize these data and make them available to the scientific community, we developed a web-accessible database.     

Spatial discontinuity of Optomotor-blind expression in the <Emphasis Type="Italic">Drosophila</Emphasis> wing imaginal disc disrupts epithelial architecture and promotes cell sorting

Background  

Decapentaplegic (Dpp) is one of the best characterized morphogens, required for dorso-ventral patterning of the Drosophila embryo and for anterior-posterior (A/P) patterning of the wing imaginal disc. In the larval wing pouch, the Dpp target gene optomotor-blind (omb) is generally assumed to be expressed in a step function above a certain threshold of Dpp signaling activity.     

Sds22, a PP1 phosphatase regulatory subunit, regulates epithelial cell polarity and shape [Sds22 in epithelial morphology]

Background  

How epithelial cells adopt their particular polarised forms is poorly understood. In a screen for genes regulating epithelial morphology in Drosophila, we identified sds22, a conserved gene previously characterised in yeast.