Search results for "Imaginal disc"
showing 10 items of 22 documents
Spatial discontinuity of Optomotor-blind expression in the Drosophila wing imaginal disc disrupts epithelial architecture and promotes cell sorting
2010
Abstract 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. Results We show that the transcription factor Omb forms, in fact, a symmetrical gradient on both sides of the A/P compartment boundary. Disruptions of the Omb gradient lead to a re-organization of the epithelial cytoskeleton and to a retraction of cells toward the basal membrane suggesting that the O…
The Regulation of Dorsiventral Symmetry in Plants
2000
The higher plant shoots are generally radially symmetrical; leaves produced at the shoot apex are dorsiventral while axillary shoots again show radial symmetry. Recently analyzed mutants in different plants indicate that the proper definition of adaxial and abaxial identities is necessary to generate a leaf margin and dorsiventral symmetry, Two genes important in the regulation of transsectional leaf symmetry are PHANTASTICA (a MYB (Myeloblastosis oncogene)-domain transcription factor) and KNOTTED1-like genes (homeodomain transcription factors). We review these results in light of hypotheses about the evolutionary origin of leaves and discuss similarities of mutant phenotypes to unifacial l…
The Dorsocross T-box transcription factors promote tissue morphogenesis in the Drosophila wing imaginal disc.
2012
The Drosophila wing imaginal disc is subdivided into notum, hinge and blade territories during the third larval instar by formation of several deep apical folds. The molecular mechanisms of these subdivisions and the subsequent initiation of morphogenic processes during metamorphosis are poorly understood. Here, we demonstrate that the Dorsocross (Doc) T-box genes promote the progression of epithelial folds that not only separate the hinge and blade regions of the wing disc but also contribute to metamorphic development by changing cell shapes and bending the wing disc. We found that Doc expression was restricted by two inhibitors, Vestigial and Homothorax, leading to two narrow Doc stripes…
Morphogenesis of the wing Anlagen in the mealworm beetle tenebrio molitor during the last larval instar.
1990
The wing Anlagen of Tenebrio develop from epidermal cells located on the lateral margins of meso- and metathoraces. Three to four days after larval ecdysis, these cells start to proliferate slowly, continuing to do so until day 13 which corresponds to the period of the pupal commitment of the remaining epidermis. The wing Anlagen cells then proliferate rapidly until day 18.5. Three days before pupal ecdysis, the mitotic index falls suddenly while 40% of the Anlagen cells disappear owing to cell degeneration. The sudden changes observed in the mitotic index are correlated with two hemolymphatic peaks in ecdysteroid levels. Anlagen of the forewings and hindwings show similar development excep…
Integration of complex larval chemosensory organs into the adult nervous system ofDrosophila
2003
The sense organs of adult Drosophila, and holometabolous insects in general, derive essentially from imaginal discs and hence are adult specific. Experimental evidence presented here, however, suggests a different developmental design for the three largely gustatory sense organs located along the pharynx. In a comprehensive cellular analysis, we show that the posteriormost of the three organs derives directly from a similar larval organ and that the two other organs arise by splitting of a second larval organ. Interestingly, these two larval organs persist despite extensive reorganization of the pharynx. Thus, most of the neurons of the three adult organs are surviving larval neurons. Howev…
Nemo regulates cell dynamics and represses the expression of miple, a midkine/pleiotrophin cytokine, during ommatidial rotation
2013
AbstractOmmatidial rotation is one of the most important events for correct patterning of the Drosophila eye. Although several signaling pathways are involved in this process, few genes have been shown to specifically affect it. One of them is nemo (nmo), which encodes a MAP-like protein kinase that regulates the rate of rotation throughout the entire process, and serves as a link between core planar cell polarity (PCP) factors and the E-cadherin–β-catenin complex. To determine more precisely the role of nmo in ommatidial rotation, live-imaging analyses in nmo mutant and wild-type early pupal eye discs were performed. We demonstrate that ommatidial rotation is not a continuous process, and …
Modulation of Hedgehog target gene expression by the Fused serine-threonine kinase in wing imaginal discs
1998
0925-4773 doi: DOI: 10.1016/S0925-4773(98)00130-0; The Fused (Fu) serine–threonine kinase and the Suppressor of fused (Su(fu)) product are part of the Hedgehog (Hh) signalling pathway both in embryos and in imaginal discs. In wing imaginal discs, the Hh signal induces Cubitus interruptus (Ci) accumulation and activates patched (ptc) and decapentaplegic (dpp) expression along the anterior/posterior (A/P) boundary. In this paper, we have examined the role of the Fu and Su(fu) proteins in the regulation of Hh target gene expression in wing imaginal discs, by using different classes of fu alleles and an amorphic Su(fu) mutation. We show that, at the A/P boundary, Fu kinase activity is involved …
Comparative Ultrastructure of Wild-Type and Tumorous Cells of Drosophila
1984
In Drosophila genetic factors cause malignant and benign neoplasms (Gateff, 1978a,b,c). In addition, compactly growing lethal tumors have been obtained from eye-antennal imaginal discs during serial subculture in the abdomens of female flies (Gateff, 1978a,b). The following tumor types have been found: (1) lethal-benign imaginal disc neoplasms, (2) malignant neuroblastomas, (3) malignant blood cell neoplasms, and (4) a benign gonial cell neoplasm. The fine structure of some of the above tumors has been studied and compared to the fine structure of corresponding wild-type cells. These will be discussed below.
Suppressor of fused links Fused and Cubitus interruptus on the Hedgehog signalling pathway
1998
0960-9822 doi: DOI: 10.1016/S0960-9822(98)70227-1; The Hedgehog (Hh) family of signalling proteins [1] mediate inductive interactions either directly or by controlling the transcription of other secreted proteins through the action of Gli transcription factors, such as Cubitus interruptus (Ci) [2]. In Drosophila, the transcription of Hh targets requires the activation of the protein kinase Fused (Fu) and the inactivation of both Suppressor of fused (Su(fu)) and Costal-2 (Cos-2) [3]. Fu is required for Hh signalling in the embryo and in the wing imaginal disc and acts also as an antitumorigen in ovaries [4]. All fu– phenotypes are suppressed by the loss of function of Su(fu) [5]. Fu, Cos-2 a…
Generation of GAL4-responsive muscleblind constructs
2002
The muscleblind (mbl) gene encodes protein isoforms Mbl A to Mbl D, which arise by alternative splicing from a common primary transcript. Mbl A, B, and C contain two Zn-finger domains of the type Cys3His, while Mbl D contains only one complete Zn finger. Loss of function mutations in the gene reveal that mbl is involved in both terminal photoreceptor and muscle differentiation in Drosophila. During retina development mbl is essential for rhabdomere differentiation in photoreceptor neuron. Clones homozygous null for mbl completely lack these lightharvesting structures (Begemann et al., 1997). Similarly, the terminal differentiation of the larval body wall muscles is compromised in mbl mutant…