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Imaginal Discs (imaginal + disc)

Distribution by Scientific Domains

Life Sciences	77%

Selected Abstracts

Mi-2 chromatin remodeling factor functions in sensory organ development through proneural gene repression in Drosophila

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 7 2006
Yasutoyo Yamasaki
Mi-2, the central component of the nucleosome remodeling and histone deacetylation (NuRD) complex, is known as an SNF2-type ATP-dependent nucleosome remodeling factor. No morphological mutant phenotype of Drosophila Mi-2 (dMi-2) had been reported previously; however, we found that rare escapers develop into adult flies showing an extra bristle phenotype. The dMi-2 enhanced the phenotype of acHw49c, which is a dominant gain-of-function allele of achaete (ac) and produces extra bristles. Consistent with these observations, the ac -expressing proneural clusters were expanded, and extra sensory organ precursors (SOP) were formed in the dMi-2 mutant wing discs. Immunostaining of polytene chromosomes showed that dMi-2 binds to the ac locus, and dMi-2 and acetylated hisotones distribute on polytene chromosomes in a mutually exclusive manner. The chromatin immunoprecipitation assay of the wing imaginal disc also demonstrated a binding of dMi-2 on the ac locus. These results suggest that the Drosophila Mi-2/NuRD complex functions in neuronal differentiation through the repression of proneural gene expression by chromatin remodeling and histone deacetylation. [source]

Signaling in the third dimension: The peripodial epithelium in eye disc development

DEVELOPMENTAL DYNAMICS, Issue 9 2009
Mardelle Atkins
Abstract The eye-antennal imaginal disc of Drosophila melanogaster has often been described as an epithelial monolayer with complex signaling events playing out in two dimensions. However, the imaginal disc actually comprises two opposing epithelia (the peripodial epithelium, or PE, and the disc proper, or DP) separated by a lumen to form a sac-like structure. Recent studies expose complex molecular interactions between the PE and the DP, and reveal dynamic communication between the two tissues. Further findings suggest the PE makes important contributions to DP development by acting as a source of signaling molecules as well as cells. Here we summarize those findings and highlight implications for further research. Developmental Dynamics 238:2139,2148, 2009. © 2009 Wiley-Liss, Inc. [source]

Ecdysteroid synthesis and imaginal disc development in the midge Chironomus riparius as biomarkers for endocrine effects of tributyltin

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2002
Torsten Hahn
Abstract Acute effects of the endocrine disruptor bis (tri- n -butyltin) oxide (TBTO) on molting-hormone biosynthesis and imaginaldisc development were investigated in larvae of the midge Chironomus riparius (Meigen). Ecdysteroid synthesis was measured by 24-h incubation of molting-hormone-synthesizing tissues (prothoracic glands) in vitro with or without the addition of TBTO. The amount of ecdysteroids produced was analyzed by radioimmunoassay. Developmental effects in vivo were investigated by determining the developmental phase of the genital imaginal discs before and after a 48-h exposure to TBTO in water. Sex-specific effects were found with both endpoints. Ecdysteroid synthesis was significantly reduced (analysis of variance [ANOVA], p , 0.005) in female larvae at all concentrations (TBTO-Sn at 50, 500, and 5,000 ng/L), whereas a significant elevation of the biosynthesis rate occurred in male larvae in the 500-ng/L treatment (ANOVA, p , 0.05). In vivo experiments with development of the genital imaginal disc within a 48-h exposure period revealed a significantly slower development in female larvae and a significantly faster development in male larvae (contingency tables, p , 0.001) at all concentrations tested (TBTO-Sn at 10, 50, 200, and 1,000 ng/L). These results partly coincided with the in vitro effects on molting-hormone synthesis. The 48-h median lethal concentration (LC50) was 25 ,g/L (20,30 ,g/L 95% confidence intervals). The combination of in vitro and in vivo methods has proven to be a useful approach for the detection of endocrine effects of TBTO in C. riparius at levels 2,000-fold below the LC50 value. High sensitivity and short test duration suggest that chironomids may have potential as freshwater sentinel organisms for endocrine-disrupting chemicals. [source]

The myeloid leukemia factor interacts with COP9 signalosome subunit 3 in Drosophila melanogaster

FEBS JOURNAL, Issue 3 2008
Wakana Sugano
The human myeloid leukemia factor 1 (hMLF1) gene was first identified as an NPM,hMLF1 fusion gene produced by chromosomal translocation. In Drosophila, dMLF has been identified as a protein homologous to hMLF1 and hMLF2, which interacts with various factors involved in transcriptional regulation. However, the precise cellular function of dMLF remains unclear. To generate further insights, we first examined the behavior of dMLF protein using an antibody specific to dMLF. Immunostaining analyses showed that dMLF localizes in the nucleus in early embryos and cultured cells. Ectopic expression of dMLF in the developing eye imaginal disc using eyeless-GAL4 driver resulted in a small-eye phenotype and co-expression of cyclin E rescued the small-eye phenotype, suggesting the involvement of dMLF in cell-cycle regulation. We therefore analyzed the molecular mechanism of interactions between dMLF and a dMLF-interacting protein, dCSN3, a subunit of the COP9 signalosome, which regulates multiple signaling and cell-cycle pathways. Biochemical and genetic analyses revealed that dMLF interacts with dCSN3 in vivo and glutathione S -transferase pull-down assays revealed that the PCI domain of the dCSN3 protein is sufficient for this to occur, possibly functioning as a structural scaffold for assembly of the COP9 signalosome complex. From these data we propose the possibility that dMLF plays a negative role in assembly of the COP9 signalosome complex. [source]

Zinc-finger paralogues tsh and tio are functionally equivalent during imaginal development in Drosophila and maintain their expression levels through auto- and cross-negative feedback loops

DEVELOPMENTAL DYNAMICS, Issue 1 2009
José Bessa
Abstract teashirt (tsh) and tiptop (tio) are two Drosophila gene paralogues encoding zinc-finger transcription factors. While tsh is an important developmental regulator, tio null individuals are viable and fertile. Here, we show that tio and tsh have coincident expression domains in the imaginal discs, the precursors of the adult body, and that both genes show similar functional properties when expressed ectopically. Furthermore, tio is able to rescue the development of tsh mutants, indicating that both genes are functionally equivalent during imaginal development. Of interest, the transcriptional regulation of tio and tsh is linked by a negative feedback loop. This mechanism might be required to maintain a tight control on the total levels of tio/tsh and could help explaining why Drosophila keeps an apparently dispensable gene. Developmental Dynamics 238:19,28, 2009. © 2008 Wiley-Liss, Inc. [source]

Dopamine and sensory tissue development in Drosophila melanogaster

DEVELOPMENTAL NEUROBIOLOGY, Issue 4 2001
Wendi Neckameyer
Abstract Dopamine is an important signaling molecule in the nervous system; it also plays a vital role in the development of diverse non-neuronal tissues in the fruit fly Drosophila melanogaster. The current study demonstrates that males depleted of dopamine as third instar larvae (via inhibition of the biosynthetic enzyme tyrosine hydroxylase) demonstrated abnormalities in courtship behavior as adults. These defects were suggestive of abnormalities in sensory perception and/or processing. Electroretinograms (ERGs) of eyes from adults depleted of dopamine for 1 day as third instar larvae revealed diminished or absent on- and off-transients. These sensory defects were rescued by the addition of L -DOPA in conjunction with tyrosine hydroxylase inhibition during the larval stage. Depletion of dopamine in the first or second larval instar was lethal, but this was not due to a general inhibition of proliferative cells. To establish that dopamine was synthesized in tissues destined to become part of the adult sensory apparatus, transgenic lines were generated containing 1 or 4 kb of 5, upstream sequences from the Drosophila tyrosine hydroxylase gene (DTH) fused to the E. coli ,-galactosidase reporter. The DTH promoters directed expression of the reporter gene in discrete and consistent patterns within the imaginal discs, in addition to the expected expression in gonadal, brain, and cuticular tissues. The ,-galactosidase expression colocalized with tyrosine hydroxylase protein. These results are consistent with a developmental requirement for dopamine in the normal physiology of adult sensory tissues. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 280,294, 2001 [source]

Ecdysteroid synthesis and imaginal disc development in the midge Chironomus riparius as biomarkers for endocrine effects of tributyltin

Postembryonic development of the wing imaginal discs in the female wingless bagworm moth Eumeta variegata (Lepidoptera, Psychidae)

JOURNAL OF MORPHOLOGY, Issue 2 2003
Shuhei Niitsu
Abstract The process of wing disc development and degeneration in the bagworm moth Eumeta variegata was investigated histologically. Morphological differences between two sexes first appear in the penultimate (eighth) larval instar. In the male, wing discs proliferate rapidly in the penultimate larval instar and continue proliferating; a conspicuous peripodial epithelium forms in the last (ninth) larval instar. The hemopoietic organs break down in this stage and disappear completely by the prepupal stage. In the female, in contrast, the wing discs remain as in the previous (seventh) instar, without proliferation of cells inside. No peripodial epithelium forms in the penultimate instar or later. Hemopoietic organs are still attached to the wing discs in the last larval instar and the entire wing discs transform into a plain, thick epidermis in the prepupal period. It is suggested that the hemopoietic organs may prevent the wing discs from developing in E. variegata. J. Morphol. 257:164,170, 2003. © 2003 Wiley-Liss, Inc. [source]

Genetic link between p53 and genes required for formation of the zonula adherens junction

CANCER SCIENCE, Issue 5 2004
Masamitsu Yamaguchi
Ectopic expression of human p53 in Drosophila eye imaginal disc cells induces apoptosis and results in a rough eye phenotype in the adult flies. We have screened Drosophila stocks to identify mutations that enhance or suppress the p53-induced rough eye phenotype. One of the dominant enhancers of the p53-induced rough eye phenotype corresponds to a loss-of-function mutation of the crumbs gene, which is essential for the biogenesis of the zonula adherens junction and the establishment of apical polarity in epithelial cells. Enhancement of p53-induced apoptosis in the eye imaginal discs by a half-reduction of the crumbs gene dose was confirmed by a TUNEL method. Furthermore, mutations of genes for Shotgun (Drosophila E-cadherin) and Armadillo (Drosophila,-catenin), the two main components of the adherens junction, also strongly enhanced the p53-induced rough eye phenotype. These results suggest that human p53 senses subtle abnormality at the adherens junction or in signals derived from the junction, and consequently induces apoptosis to remove abnormal cells from tissue. Thus p53 likely plays a role as a guardian of the tissue not only by sensing the damaged DNA, but also by sensing signals from the adherens junction. [source]