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PubMed1988

Minute mutations of Drosophila melanogaster change aldehyde oxidase and pyridoxal oxidase distribution patterns in imaginal wing discs.

Aldehyde oxidase (AO) and pyridoxal oxidase (PO) distribution patterns were determined in the imaginal wing discs for a series of strains of Drosophila melanogaster heterozygous for different Minute mutations. The mutant severity ranged from very weak to strong. The results shown an inverse response of AO and PO to the expressivity of the Minute mutation: in weaker Minutes the extent of the AO positive area increases, whereas PO activity disappears. The results are discussed with reference to an impaired protein synthesis in Minutes.

Aldehyde Oxidase↗
PubMed1982

Segmental differences in the protein content of Drosophila imaginal discs.

The protein content of various Drosophila imaginal discs was analysed by two-dimensional electrophoresis followed by silver-staining. Three proteins, identified as tropomyosins alpha and beta and actin I, are more abundant in the metathoracic discs (haltere and third leg) than in the mesothoracic discs (wing and second leg). In the case of the wing disc, these proteins are probably contributed by the adepithelial (muscle precursor) cells, as indicated by their non-uniform localisation within the disc. Mutations in the bithorax complex have no effect on the difference between second and third leg discs. We conclude that there is a segmental difference in the protein content of homologous discs, that this difference is probably localized in the adepithelial cells, and that it is not under the direct control of known alleles of the bithorax complex.

Journal Article↗
PubMed1986

Engrailed gene expression in Drosophila imaginal discs.

Genetic and molecular analyses indicate that the Drosophila engrailed gene is required to distinguish posterior from anterior compartments in each segment of the developing animal. Here, the patterns of engrailed expression in the imaginal discs and ventral ganglion of Drosophila larvae are examined, using an antiserum against the engrailed protein and a novel image processing method to reduce non-specific background. As expected, engrailed expression generally is restricted to cells in the posterior compartment of the discs, and the patterns of expression allow refinements in the fate maps of the discs to be made. More significant is the finding that expression of the gene is highly variable in different regions of posterior compartments, suggesting that engrailed may do more than simply specify 'posteriorness'. In the ventral ganglion engrailed appears to be expressed by a subset of cells, primarily in the posterior regions of each segment. In wing discs from animals that are homozygous for the en1 mutation, the pattern of expression of the gene is altered, as opposed to being simply reduced uniformly in the posterior cells.

Animals↗
PubMed1994

Sexual differentiation in the CNS of the moth, Manduca sexta. I. Sex and segment-specificity in production, differentiation, and survival of the imaginal midline neurons.

We analyzed the development of several sets of postembryonic sex-specific motoneurons in Manduca sexta which belong to a group of homologous lineages of neurons called the imaginal midline neurons (IMNs). Adult female oviduct motoneurons and male sperm duct motoneurons are IMNs that show similar anatomical features and differentiate during metamorphosis, despite appearing in different segments: A7 for oviduct neurons, A9 for sperm duct neurons. These cells are born at the same time and, initially, similar sets are found in A7 and A9 ganglia of larvae of both sexes. The dimorphic adult pattern is generated by sex-specific production and cell death. A7 IMNs differentiate in both sexes through early pupal stages, whereupon they disappear in the male and become the oviduct motoneurons in the female. A9 IMNs are overproduced in the male, and subsequent cell death reduces male cell number and eliminates the small complement of female cells; the surviving male cells develop into the sperm duct motoneurons. Similar IMN arrays are generated in nongenital ganglia, but show non-sex-specific fates. This suggests that both the sex of these cells and their segment of residence play major roles in their subsequent differentiation.

Animals↗
PubMed1994

Sexual differentiation in the CNS of the moth, Manduca sexta. II. Target dependence for the survival of the imaginal midline neurons.

While the majority of neurons in the adult nervous system of the moth Manduca sexta are produced postembryonically, little is known about how these cells interact with their targets during development. Few of these cells are motor neurons; most of Manduca's adult motor neurons are respecified larval motor neurons that developed embryonically. A few motor neurons do develop postembryonically, including a large class of mixed neurosecretory and motor neurons called the imaginal midline neurons (IMNs). A subset of these cells show an unusual pattern of sex-specific development and survival (Thorn and Truman, 1994, J. Neurobiol. in press), which led us to suspect that factors extrinsic to the cells were controlling their fates. We analyzed one such potential factor by altering the contacts between a subset of these developing IMNs and their adult-specific target, the male sperm duct. When we transected the nerve that innervated the sperm duct in the pupa, we observed a loss of many sperm duct IMNs. In contrast, a transection of the same nerve in larvae showed no neuron loss. Immunocytochemistry showed that the pupal nerve transections were accompanied by a loss of axon endings on the sperm duct, while the larval nerve transections showed no such loss. Using local hormone application to slow the development of the sperm duct while leaving the nerve intact still resulted in a loss of IMNs. These results suggest that these IMNs need contact with a robust developing target in the pupa to survive metamorphosis.

Animals↗
PubMed1994

Genetic and molecular analysis of hyperplastic discs, a gene whose product is required for regulation of cell proliferation in Drosophila melanogaster imaginal discs and germ cells.

The hyperplastic discs (hyd) gene (formerly called l(3)c43) is located at 85E1-10 on the third chromosome of Drosophila melanogaster. It was originally identified by a temperature-sensitive mutation that causes imaginal disc overgrowth in mutant larvae raised at a restrictive temperature. Twenty new alleles of hyperplastic discs have been recovered in gamma ray, ethyl methanesulfonate and hybrid dysgenesis screens, and the molecular lesions have been identified for several of the alleles. The null phenotype appears to be lethality at or before the second instar. Adults that can be obtained in crosses of temperature-sensitive alleles maintained at permissive temperatures are sterile with one exception and have defects in germ tissue morphology. The hyperplastic discs locus has been cloned by chromosome walking from the alpha-tubulin-2 gene and encodes a 9.5-kb messenger RNA, containing a 2897-amino-acid open reading frame. Sequence analysis of HYD reveals strong similarity to a portion of the C-terminus of poly(A) binding protein and to the RAT 100-kDa PROTEIN, whose function is unknown. Developmental Northern and Western analyses show coincident accumulation of the 9.5-kb transcript and the 280-kDa protein at all stages of development, with high levels at the embryonic and pupal stages. The 280-kDa HYD protein accumulates at decreased levels in mutant alleles and at restrictive temperatures in ts alleles. Examination of relative levels of HYD protein in mutant animals support the idea that less severe mutations are those that result in disc overgrowth, while more severe mutations result in variable disc growth phenotypes.

Alleles↗
PubMed1995

Time- and concentration-dependent response of the Drosophila antenna imaginal disc to Antennapedia.

The response of the antenna imaginal disc to ectopic Antennapedia gene expression was explored in a heat shock Antennapedia (hsAntp) transgenic strain and in strains doubly transgenic for hsAntp and downstream enhancer trap targets. The distal to proximal changes in morphological transformation in response to Antennapedia product at different developmental stages were correlated with changing expression patterns of transgene targets from antenna to leg-like patterns. Dose-response studies indicated changing thresholds of response to Antennapedia. At particular stages and doses of Antennapedia product, cell differentiation of leg bristles was uncoupled from transformation of the third antennal segment to tarsus. The results suggest that determination for bristle type does not depend on a prior determination decision for organ type. The results also provide an avenue for exploring the nature of "competence" at cellular and molecular levels.

Animals↗
PubMed1996

A switch in broad-complex zinc-finger isoform expression is regulated posttranscriptionally during the metamorphosis of Drosophila imaginal discs.

The Broad-Complex (BR-C) is a key member of the 20-hydroxyecdysone regulatory hierarchy that coordinates changes in gene expression during Drosophila metamorphosis. The family of transcription factors encoded by the BR-C share a common amino-terminal domain which is fused by alternative splicing to one of four pairs of C2H2 zinc-finger domains (Z1, Z2, Z3, and Z4). In this study, we examine the temporal expression of transcripts encoding each BR-C zinc-finger isoform-including the newly discovered fourth zinc-finger domain-during the metamorphosis of imaginal discs which form the integumental structures of the adult head and thorax. We find that all BR-C zinc-finger RNA isoforms are induced as a primary response to 20-hydroxyecdysone. However, induced BR-C RNA isoforms exhibit two divergent expression profiles. The Z2, Z3, and Z4 RNA isoforms accumulate to high levels at the beginning of the ecdysone response and abruptly disappear after several hours. In contrast, the Z1 RNA isoform continues to accumulate while the others decline, resulting in a switch in relative isoform levels. Using probes specific to different regions of the BR-C, we show that the switch in BR-C RNA isoform expression appears to be posttranscriptionally regulated, presumably by ecdysone-responsive factors. We propose that this switch results from a change in splice acceptor site choice. Finally, we present a model describing how this temporal switch in isoform expression could mediate changes in BR-C function, from transcriptional activation to repression and vice versa, that are critical for coordinate downstream target gene expression.

Amino Acid Sequence↗
PubMed2002

Analysis of Drosophila cyclin EI and II function during development: identification of an inhibitory zone within the morphogenetic furrow of the eye imaginal disc that blocks the function of cyclin EI but not cyclin EII.

The Drosophila cyclin E (DmcycE) gene gives rise to two transcripts encoding proteins that differ at their N termini, DmcycEII and DmcycEI. This study presents the first in vivo dissection of Cyclin E function. Ectopic expression studies using N- and C-terminal deletions of DmcycEI revealed that a region of 322 residues surrounding the cyclin box is sufficient to induce entry of G1-arrested larval eye imaginal disc cells into S phase. Ectopic expression of DmcycEI in the eye disc has been previously shown to drive anterior, but not posterior, G1-phase cells within the morphogenetic furrow (MF) into S phase. Significantly, ectopic expression of DmcycEII and N-terminal deletions of DmcycEI were able to drive all G1 cells within the morphogenetic furrow into S phase, while a C-terminal deletion of DmcycEI could not. The p21 homolog Dacapo was shown by yeast two-hybrid, coimmunolocalization, and in vivo functional studies not to be the mediator of the DmcycEI inhibition in posterior part of the MF. Taken together, these results reveal a novel zone within the posterior region of the MF where DmcycEI but not DmcycEII function is inhibited, and suggest that DmcycEII is a more potent inducer of S phase.

Animals↗
PubMed2002

Drosophila APC2 and APC1 play overlapping roles in wingless signaling in the embryo and imaginal discs.

The regulation of signal transduction plays a key role in cell fate choices, and its disregulation contributes to oncogenesis. This duality is exemplified by the tumor suppressor APC. Originally identified for its role in colon tumors, APC family members were subsequently shown to negatively regulate Wnt signaling in both development and disease. The analysis of the normal roles of APC proteins is complicated by the presence of two APC family members in flies and mice. Previous work demonstrated that, in some tissues, single mutations in each gene have no effect, raising the question of whether there is functional overlap between the two APCs or whether APC-independent mechanisms of Wnt regulation exist. We addressed this by eliminating the function of both Drosophila APC genes simultaneously. We find that APC1 and APC2 play overlapping roles in regulating Wingless signaling in the embryonic epidermis and the imaginal discs. Surprisingly, APC1 function in embryos occurs at levels of expression nearly too low to detect. Further, the overlapping functions exist despite striking differences in the intracellular localization of the two APC family members.

Adenomatous Polyposis Coli Protein↗
PubMed1976

Ecdysone-stimulated RNA synthesis in imaginal discs of Drosophila melanogaster. Assay by in situ hybridization.

Cytoplasmic RNA from imaginal discs of Drosophila melanogaster, labeled by uridine incorporation in organ culture, has been assayed by hybridization to cytological preparations of polytene chromosomes. RNA labeled during the early stages (first four hours) of ecdysone stimulation was compared to RNA labeled in the absence of the hormone. For the poly(A)-containing fraction (oligo-dT bound), several loci hybridize only RNA labeled in the presence of ecdysone; one locus hybridizes only control RNA. The majority of hybridizing loci are unaffected by the hormone. Of the loci hybridizing RNA not bound to oligo-dT, several appear specific for the ecdysone-treated sample, though most are labeled more heavily with this RNA than with the control. None of the ecdysone-sensitive loci visualized by in situ hybridization are the sites of salivary gland puffs induced by ecdysone on the same time scale.

Animals↗
PubMed1983

Enzyme patterns in D. melanogaster imaginal discs: distribution of glucose-6-phosphate and 6-phosphogluconate dehydrogenase.

Distribution of glucose-6-phosphate dehydrogenase (G6PD) and 6-phospho-gluconate dehydrogenase (6PGD) in imaginal discs of Drosophila melanogaster was determined. Differential patterns of staining were found in all discs examined, i.e., eye-antennal, wing, leg, labial and genital. By using null mutants for either G6PD or 6PGD, the enzymes were shown to have the same distribution patterns. Staining with glucose-6-phosphate as a substrate resulted in the detection of both G6PD and 6PGD. Results of staining discs from homoeotic mutants indicate that the enzyme distribution patterns are under genetic control. In the presence of the homoeotic engrailed (en) mutation which transforms posterior wing compartment into anterior, the G6PD pattern of the posterior compartment of the wing disc was specifically transformed toward that of the anterior compartment. The bithorax series of homoeotic mutants was similarly investigated. The bithorax (bx3) mutation transforms the anterior part of the haltere to anterior wing blade. Similarly the G6PD pattern in the anterior haltere disc transforms to that of anterior wing disc. The complimentary transformation, postbithorax (pbx) results in a change of the posterior part of the haltere to posterior wing, which is likewise reflected in an altered staining pattern for G6PD in the posterior portion of the haltere disc. The combination of the bx3 and pbx resulted in a staining pattern of the haltere disc virtually indistinguishable from the normal wing disc.

Animals↗
PubMed1976

Pyridine nucleotide metabolism in imaginal discs of Drosophila melanogaster.

The pyridine nucleotide metabolism of imaginal discs of Drosophila melanogaster has been studied in vitro by incubating discs with labeled nicotinic acid in the presence and absence of ecdysterone. The major labeled compounds found within the discs are NAD, NADP, and nicotinic acid. There is preferential uptake of nicotinamide over nicotinic acid, although the Priess-Handler pathway is used exclusively. The presence of ecdysterone produces a small increase in the NADP/NAD ratio, and an increase in NAD synthesis, probably to compensate for increased NAD turnover.

Animals↗
PubMed1987

Relationship between 'early' and 'late' protein induced by 20-hydroxyecdysone in imaginal wing discs of Drosophila melanogaster.

The insect moulting hormone, 20-hydroxyecdysone, induces the synthesis of two groups of proteins in the imaginal wing discs of Drosophila melanogaster. The early induced group appears about 4 h after hormone treatment, the late induced group appears about 12 h after treatment. Studies using alpha-amanitin to inhibit mRNA synthesis during the period of hormonal treatment showed that the induction of the late proteins is dependent on mRNA synthesis and possibly the synthesis of the early proteins.

Amanitins↗
PubMed1988

The effect of ecdysterone and juvenile hormones on protein synthesis and development of imaginal wing discs of Drosophila melanogaster.

The effect of ecdysterone and juvenile hormone on protein synthesis and development of imaginal wing discs of Drosophila melanogaster has been studied. It is found that juvenile hormone apparently does not inhibit the synthesis of the ecdysterone-inducible proteins, although wing disc development is inhibited to various extent by different juvenile hormones. It is suggested that the ecdysterone-inducible proteins are not involved directly in the initiation of wing disc evagination, it is possible that some of these proteins are involved in the maintenance of chromatin activities or they are involved in gene activation.

Animals↗
PubMed1978

Protein synthesis in imaginal disks of Plodia interpunctella during development in vivo and in vitro.

Wing imaginal disks were dissected from larvae of Plodia interpunctella (Hübner) at various stages during the larval-pupal transformation. The wing-disk proteins separated by electrophoresis and scanned with a densitometer changed quantitatively but not qualitatively during development in vivo. Treatment of wing disks in vitro with beta-ecdysone resulted in a 2-fold increase in synthesis of proteins after only 2 hr incubation. The maximum rate of protein synthesis was reached 16 hr after treatment with hormone. The pattern of proteins separated by electrophoresis of wing disks that were incubated in vitro with beta-ecdysone did not change qualitatively. The major features of protein synthesis during wing-disk development in vivo were similar to those observed during beta-ecdysone-induced development in vitro.

Culture Techniques↗
PubMed2002

DNA synthesis in the imaginal wing discs of the American bollworm Helicoverpa armigera (Hübner).

The effect of two insect growth regulators of plant origin viz. plumbagin and azadirachtin and the ecdysteroids 20-hydroxyecdysone, makisterone A and a phytoecdysteroid on DNA synthesis in imaginal wing discs of day 4 final instar Helicoverpa armigera larvae was studied. DNA synthesis increased with increase in time of incubation up to 8 h and decreased later without the addition of moulting hormone. Addition of 20-hydroxyecdysone supported long term acquisition of competence for DNA synthesis in the wing discs. Both DNA synthesis and protein content were drastically reduced in plumbagin and azadirachtin-treated insects. Under in vitro conditions, plumbagin had a more pronounced inhibitory effect than azadirachtin. All the ecdysteroids tested, viz. makisterone A, 20-hydroxyecdysone and the ecdysteroidal fraction from the silver fern Cheilanthes farinosa enhanced DNA synthesis.

Animals↗
PubMed1998

Screening of larval/pupal P-element induced lethals on the second chromosome in Drosophila melanogaster: clonal analysis and morphology of imaginal discs.

We have carried out screens for lethal mutations on the second chromosome of Drosophila melanogaster that are associated with abnormal imaginal disc morphologies, particularly in the wing disc. From a collection of 164 P element-induced mutations with a late larva/pupa lethal phase we have identified 56 new loci whose gene products are required for normal wing disc development and for normal morphology of other larval organs. Genetic mosaics of these 56 mutant lines show clonal mutant phenotypes for 23 cell-viable mutations. These phenotypes result from altered cell parameters. Causal relationships between disc and clonal phenotypes are discussed.

Animals↗