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PubMed1997

The effects of several ecdysteroids and ecdysteroid agonists on two Drosophila imaginal disc cell lines.

Two Drosophila imaginal disc cell lines, C18+ (sensitive to 20-hydroxyecdysone, 20HE) and C18R (resistant to 20HE) were exposed to the ecdysteroid agonists RH5849 and RH5992 and the ecdysteroids inokosterone, makisterone A and muristerone A. All compounds tested were found to have similar effects on the cells, comparable to the effects of 20HE, although at different concentrations. C18R showed resistance to all compounds, again at varying concentrations. We conclude that it is likely that all the compounds tested use the same receptors as 20HE, but show maximum effectiveness at different concentrations.

Animals↗
PubMed2002

Unusual pheromone receptor neuron responses in heliothine moth antennae derived from inter-species imaginal disc transplantation.

Single-cell electrophysiological recordings were obtained from olfactory receptor neurons housed in sensilla trichodea along the adult antennae arising from transplantation of the antennal imaginal discs between larval male Helicoverpa zea and Heliothis virescens. The olfactory receptor neurons from the majority of type C sensilla sampled on transplanted antennae displayed response characteristics consistent with those of the species that donated the antennae. However, some of the sensilla type C sampled in either transplant type contained olfactory receptor neurons that responded in a manner typical of the recipient species or other neurons that have not previously been found in the type C sensilla of either species. The single-cell data help to explain behavioral results showing that some transplant males do fly upwind to both species' pheromone blends, an outcome not expected based on known antennal sensory phenotypes. Our results suggest that host tissue can influence antennal olfactory receptor neuron development, and further that because of a common phylogenetic ancestry the donor tissue has the genetic capability to produce a variety of sensillar and receptor types.

Action Potentials↗
PubMed2002

Fate map of the eye-antennal imaginal disc in the stalk-eyed fly Cyrtodiopsis dalmanni.

Hypercephaly, in the form of lateral extensions of the head capsule, is observed in several families of Diptera. A particularly extreme form is found in diopsid stalk-eyed flies, in which both eyes and antennae are laterally displaced at the end of eyestalks. We have studied the developmental basis of this exaggerated morphology in Cyrtodiopsis dalmanni. Diopsid eye-antennal imaginal discs are divided into anterior and posterior portions, which are joined by a narrow "disc-stalk" of intervening tissue. We established a fate map for this disc by cutting it into fragments and culturing them in vivo by injecting them into host larvae. The adult eye and dorsal head capsule structures, including the eyestalk and the ocelli, are derived from the posterior portion of the disc, while ventral adult structures such as the antenna and the palpus are derived from the anterior portion of the disc. Thus both posterior and anterior disc portions give rise to structures that are widely separated in the adult head. Moreover, structures that are adjacent in the adult are derived from different regions of the disc. These results confirm and extend previous conclusions about regional identity in diopsid eye-antennal discs that were based on the analysis of molecular markers.

Animals↗
PubMed1983

Developmental regulation of Drosophila imaginal disc proteins: synthesis of a heat shock protein under non-heat-shock conditions.

A low-molecular-weight heat-shock protein is reported here to be synthesized in Drosophila imaginal discs under non-heat-shock conditions. This protein has been identified as hsp 23 by its mobility in SDS-gel electrophoresis, by its isoelectric point, and by its partial proteolytic digest pattern. This protein is shown to be synthesized in tissue from late-third-instar larvae using both in vitro and in vivo radiolabeling techniques. Tissues from late-third-instar larvae synthesize hsp 23 at a level much higher than tissues from mid-third-instar larvae. The increased synthesis of this protein at the end of third instar coincides with the rise in ecdysone titer that occurs at this time of development. The developmental regulation of this protein suggests that hsp 23 plays a role in normal development as well as in the heat-shock response.

Animals↗
PubMed1983

The behavior during the initial phase of in vitro aggregation of dissociated imaginal disc cells from Drosophila melanogaster.

Aspects of the initial phase of aggregation in vitro of dissociated imaginal disc cells from Drosophila melanogaster are described. Using the methods described certain interdisc differences in the percent decrease in single cell units during the first hour of aggregation can be demonstrated. In addition it is shown that prospective notum cells isolated from the dorsal mesothoracic disc show less of a decrease than do prospective wing cells. This difference shows up in a variety of different wild-type stocks and in several mutant stocks as well. Prospective notum cells from the mutation fu59 show only a limited ability to adhere to one another, while the percentage of single cell units from prospective wing blade cells from r9 larvae grown on pyrimidine-poor medium decrease less compared to cells from the same stock grown on RNA-supplemented medium. There is a significantly greater decrease in the percent single cell units in cultures of prospective eye cells than in cultures of prospective antennal cells. Furthermore, cells from the antennal disc of larvae bearing the homeotic mutation ssa show a significantly lower decrease in single cell units when grown at restrictive temperatures. In contrast, antennal disc cells from the homeotic mutation ophthalmoptera; eyeless Dominant, a mutation which affects the eye disc, are unaffected, while cells from the eye disc are slightly less able to reassociate with one another.

Animals↗
PubMed1984

Localized cell death in Drosophila imaginal wing disc epithelium caused by the mutation apterous-blot.

Drosophila melanogaster carrying the mutation apterous-blot have blistered wings. Trypan blue stains a patch of dead cells localized to the wing pouch of imaginal discs and the same area shows acid phosphatase (AcPase) activity suggesting that the cell death is lysosomal. Autophagic vacuoles and other secondary lysosomes show AcPase activity within the disc epithelium and enzyme activity is found in fragments of dead cells which have been extruded basally. The cell death, although extensive and confined to the presumptive wing region, does not result in loss of adult structures.

Animals↗
PubMed1984

Gap-junctional communication compartments in the Drosophila wing imaginal disk.

Using intracellular injection of small fluorescent molecules, we examined the gap-junctional communication properties of cells in the wing imaginal disk of Drosophila. We observed extensive spread of the injected dye between cells in all parts of the wing disk epithelium, but we found that this spread is not uniform. Instead, the cell-to-cell movement of dye is partially restricted at several defined boundaries such that cells on one side of the boundary have a low level of communication with cells on the other side. These communication-restriction boundaries are delineated by bands of cells with a low level of communication, and they subdivide the disk epithelium into a number of "communication compartments." Interestingly, the boundaries of some of these communication compartments appear to be coincident with compartment borders identified in cell lineage studies. Given this striking coincidence, we suggest that gap-junctional communication may play a role in compartment formation, and in controlling the appropriate differentiation of cells within compartments.

Animals↗
PubMed1985

Transdetermination in the homeotic eye--antenna imaginal disc of Drosophila melanogaster.

The effects of homeotic mutations on transdetermination in eye-antenna imaginal discs of Drosophila melanogaster were studied. After 12 days of culture in vivo, antenna discs transformed to ventral mesothorax by AntpNs or AntpZ, transdetermined to notum and wing structures four to five times more frequently than the corresponding wild-type antenna discs. Likewise, eye discs transformed to dorsal mesothorax by eyopt transdetermined to leg structures, also extremely frequently (90%). It seems that, during culture, homeotic antenna as well as homeotic eye discs tend to complete the structural inventory of the mesothoracic segment. Transdetermination in the homeotic disc parts is interpreted as a regeneration process which reestablishes an entire segment, i.e., the ventral mesothoracic portion (leg) in the antenna disc regenerates dorsal mesothoracic parts, and the dorsal mesothoracic portion in the eye disc (wing) regenerates ventral mesothoracic parts, respectively. This implies that antenna and leg discs (ventral qualities) as well as eye and wing discs (dorsal qualities) are serially homologous. The transdetermination frequency of the untransformed eye disc to notum and wing structures is enhanced by Antp to the same extent as is the transdetermination frequency of the antenna disc. The first allotypic wing disc structure formed by the eye disc is notum, followed by structures of the anterior wing compartment and finally by posterior wing structures. No evidence for such a sequence was found in the transdetermination pattern of the antenna disc.

Animals↗
PubMed1985

Cell proliferation changes during pattern regulation in imaginal leg discs of Drosophila melanogaster.

Upon fragmentation of a leg imaginal disc, cells near parts of the wounded surface are reprogrammed and form a blastema. This occurs without a change in fate and without the direct contact of the two wounded surfaces (G. H. Karpen and G. Schubiger, Nature (London) 294, 744-747, 1981). Two phases of the cell cycle have now been analyzed for several areas of disc fragments prior to and during wound healing. A mitotic index was used to compare the location of cell division, and autoradiography was used to reveal patterns of DNA synthesis. In contrast to the uniform division pattern in noncultured fragments, more dividing cells were observed near the two wound surfaces after 1 day of in vivo culture. During the second day, wound healing began and mitotic activity increased dramatically near both wound areas, and decreased in distant areas. Three and a half days of culture led to more complete wound closure and only cells on one site continued to show the highest frequency of labeled cells. It is concluded that changes in patterns of DNA synthesis and an increase in cell division begin prior to wound closure. This proliferation is consistent with the morphological changes and regulative behavior observed. In addition, the role of compartmental identity during regulation was tested. After wound closure began an increase in mitotic activity near wounds in the anterior compartment was observed whereas such an increase in division level was not seen in posterior cells near a wound.

Animals↗
PubMed1986

Muscle connections between imaginal discs in Drosophila.

A comparison of the protein content of different imaginal discs of Drosophila revealed that among more than 600 protein species that can be detected, only three show differences in concentration among different types of discs. Two of them form a doublet that can be resolved only by using extended electrophoresis conditions. This doublet was also reported to have a nonhomogeneous distribution within some discs. Here we show that these two proteins are tropomyosin components, and that they are associated not with the discs themselves but with a new type of muscle that connects some of the discs together.

Antibodies, Monoclonal↗
PubMed1986

Disruption of positional fields in apterous imaginal discs of Drosophila.

Certain combinations of alleles at the apterous locus generate wings with extra copies of wing margin structures, some of which are located far from the normal margin. We have examined wing imaginal discs from these mutants, using position-specific antibodies as probes for two-dimensional patterning in the discs. Our results indicate that the adult phenotypes arise from unprecedented disruptions in the two-dimensional pattern of the disc epithelia. Examination of other apterous mutants suggest that pattern alterations may be a general consequence of lesions at this locus.

Animals↗
PubMed1986

The hormonal coordination of cuticulin deposition and morphogenesis in Drosophila imaginal discs in vivo and in vitro.

Cuticulin is the first layer of the insect cuticle to be deposited and is laid down as a continuous inelastic sheet over the apical surface of cuticle-secreting cells. During metamorphosis in Drosophila melanogaster, imaginal discs deposit the cuticulin layer of the pupal cuticle between 3 and 7 hr after puparium formation. This is a period of rapid morphogenesis involving cell shape changes and cell rearrangements. We have examined cuticulin deposition in vivo and in vitro with a view to understanding the coordination of cuticulin deposition with morphogenesis. We find that the optimum hormonal regimen (of the steroid hormone, 20-hydroxyecdysone) for the completion of both morphogenesis and cuticulin deposition in vitro parallels the changes in hormone titer observed in vivo. We also find that cuticulin is deposited last over cell boundaries, thereby allowing cell rearrangements to occur as cuticulin is laid down. We have identified in vitro conditions under which cuticulin deposition is completed precociously, inhibiting further morphogenesis. Cytochalasin B and colchicine do not inhibit cuticulin deposition and we therefore conclude that an intact cytoskeleton is not necessary for secretion of this extracellular structure. Finally, we present a preliminary protocol for the partial purification of cuticulin synthesized in vitro by mass isolated discs.

Actin Cytoskeleton↗
PubMed1987

Distribution of S-phase cells during the regeneration of Drosophila imaginal wing discs.

We investigated the distribution of S-phase cells during regeneration of the imaginal wing disc of Drosophila melanogaster following excision of 30 degrees, 90 degrees, and 150 degrees sectors of tissue. The fragments were cultured in adult abdomens for 1-5 days, labeled in vitro with tritiated thymidine, serially sectioned, and subjected to autoradiography. There was negligible thymidine incorporation in unoperated controls and in the undamaged parts of the operated discs, indicating that DNA synthesis in undamaged tissue is terminated during the first day of the culture period. Almost all of the fragments from which tissue had been removed, as well as controls which were simply cut without the removal of any tissue, showed a cluster of labeled cells (blastema) even after only 1 day of culture. The blastemas in control discs were short-lived, with over 50% of these discs showing no blastema by the third day in culture. Blastemas in discs from which sectors were removed were more persistent; the time at which 50% of the fragments no longer showed a blastema was 4 days for the -30 degrees fragments, 5 days for the -90 degrees fragments, and greater than 5 days for the -150 degrees fragments. The average blastema size, measured as number of labeled cells, was directly related to the amount of tissue removed, and in most cases did not change significantly during the culture period. Both wound edges incorporated tritiated thymidine initially and the S-phase cells remained tightly clustered throughout regeneration; maximum blastema width varied from about 8 to 25 cell diameters. The results are consistent with the idea that regenerative cell proliferation is stimulated and maintained by positional information discontinuities, and terminated when these discontinuities are resolved by the addition of an appropriate number of new cells.

Animals↗
PubMed1988

Wound healing, cell communication, and DNA synthesis during imaginal disc regeneration in Drosophila.

Wound healing, gap-junctional cell communication, and DNA synthesis were studied in 3/4 fragments of the imaginal wing disc of Drosophila melanogaster cultured in the female adult abdomen. Such fragments regenerate the missing sector by cell proliferation over a period of several days. Individual cells were marked in the starting fragment by intracellular injection of high-molecular-weight lysinated rhodamine dextran, and the positions of the marked cells were determined by fluorescence microscopy before and after various culture times. These experiments showed that cells along the two wound edges were brought together by wound healing during the first day of the culture period. The marked cells then gradually moved apart over the next 3 days as new cells were added between them by intercalary regeneration. Gap-junctional cell communication across the healed wound, assessed by the movement of intracellularly injected small fluorescent dye molecules, was not detectable after 1 day of culture. After 2 days there was some dye transfer into the growth zone but not as much as in other directions. After 3 days there was significant dye transfer into the growth zone. DNA synthesis, detected by immunolocalization of incorporated bromodeoxyuridine, was first apparent at 18 hr after the beginning of the culture period; at this time as well as at later times it occurred only in the immediate vicinity of the healed wound. DNA synthesis was stimulated over a distance of several cell diameters from the wound, and for one of the cuts it was much more prevalent on one side of the wound than on the other. The results indicate that wound healing brings together cells from distant positions in the disc, and that the response to this is local DNA synthesis and cell proliferation. Gap-junctional communication across the wound does not appear to be necessary for stimulating this cell proliferation, although the timing of the reappearance of gap-junctional communication suggests that it may be involved in terminating proliferation.

Animals↗
PubMed1992

Modifiers of bx1 alter the distribution of Ubx proteins in haltere imaginal discs of Drosophila.

The bithorax (bx) mutations in the Ultrabithorax (Ubx) gene of Drosophila melanogaster cause homeotic transformations of anterior third thoracic structures (T3a) toward anterior second thoracic structures (T2a) in the adult fly. A corresponding loss of Ubx protein expression in T3a of bx imaginal discs has been observed (White and Wilcox, 1985). We describe two genetic loci which modify the bx-induced transformation. A locus which we map very close to the pink peach (pp) gene suppresses the bx1 phenotype. In contrast, mutations in the suppressor of sable (su(s)) gene enhance the bx1 phenotype. A correlation was observed between patterns of Ubx protein expression and the phenotypic transformations observed.

Animals↗
PubMed1992

Ellipse mutations in the Drosophila homologue of the EGF receptor affect pattern formation, cell division, and cell death in eye imaginal discs.

Ellipse alleles are mutations of the EGF-receptor homologue that reduce the number of ommatidia in the eye imaginal disc. Cobalt sulfide staining, expression of hairy and scabrous proteins, and mosaic analysis indicated that Elp mutations affect ommatidial precluster formation in the morphogenetic furrow. BrdU incorporation studies suggest that cells diverted from precluster formation instead enter S-phase after the morphogenetic furrow. Genetic studies suggest that the DER has multiple functions during eye development and that several recessive hypomorphic alleles affect another aspect of DER function that is required after precluster formation. Elp mutations show genetic interactions with the neurogenic mutations Notch and Delta. The small number of ommatidia that differentiate in Elp/Elp are separated more than in wildtype and have been studied to investigate what aspects of ommatidium development are intrinsic to the ommatidium itself. It appears that each developing ommatidium cues the determination of photoreceptors, cone cells, and primary pigment cells, but that the secondary and tertiary pigment cells, and the mechanosensory bristles, can form independently. The normal rotation of ommatidia in the dorsal-ventral axis does not require the presence of the ommatidial array. A short-range signal from a nearby ommatidium is important for mitosis. Cells not close to an ommatidium do not go through mitosis and many die.

Alleles↗
PubMed1990

High-resolution two-dimensional gel analysis of proteins in wing imaginal discs: a data base of Drosophila.

An improved method of high-resolution two-dimensional gel electrophoresis has been used to study the patterns of protein synthesis in wing imaginal discs of late instar larvae of Drosophila melanogaster. A small number of discs were radiolabeled with a mixture of 14C-labeled amino acids or with [35S]methionine and the pattern of labeled proteins was analyzed. One thousand and twenty-five polypeptides (787 acidic (IEF) and 238 basic (NEPHGE] from wing discs of several wild-type strains have so far been separated and cataloged. All these polypeptides have been numbered and presented in a reference map for further studies. When comparing patterns of label we have found small quantitative differences in rate of synthesis between individuals of the same strain, not due to sexual differences, and very few quantitative and qualitative differences between groups of individuals of different strains.

Amino Acids↗
PubMed1983

Computer simulation of compartment maintenance in the Drosophila wing imaginal disc.

A new method for modelling cell division is reported which uses a cellular representation based on graph theory. This allows us to model the adjacencies of non-regular dividing cells accurately, avoiding the rigid geometrical constraints present in earlier simulations. We use this system to simulate compartment boundary maintenance in the Drosophila wing imaginal disc. We show that a boundary of minimum length between two growing polyclones of cells could depend on sorting between cells in the different polyclones. We also investigate the response of the model to differential cell division rates within polyclones. This is the first demonstration that cell sorting can generate a smooth boundary in a dividing cell mass. We suggest that biological analogs of our computer sorting rules are responsible for the similar straight polyclone borders seen in the real wing disc. A possible strategy for showing the existence of these analogs is also given.

Animals↗