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1.
When fragments of the imaginal wing disc from opposite ends of the disc are mixed prior to culture, intercalary regeneration occurs so that structures are produced which neither of the fragments would have produced if they had been cultured alone. I report here that fragments of the imaginal wing and haltere disc interact in a position-specific way. Mixing of homologous fragments does not result in regeneration, while mixing of fragments from opposite ends of the discs does. Thus the interaction of wing and haltere disc fragments shows the same positional specificity as the mixing of two wing fragments.  相似文献   

2.
We have tested the ability of fragments of one type of imaginal disc to stimulate regeneration of another type. It has been shown by others that, when extreme proximal and distal fragments of the wing disc are combined, intercalary regeneration of the missing tissue ensues. Each fragment, if cultured alone, will merely duplicate its structures. We now find that distal fragments of other thoracic discs, haltere and leg, while retaining their autonomy for differentiation, also interact with proximal wing tissue to promote regeneration of more distal wing structures. The proximal wing tissue used in these experiments was the wingless abnormal wing disc which, in the absence of interaction, yields only proximal wing structures. These results suggest that spatial organization is controlled by similar systems in the various thoracic discs. In contrast, head and genital disc material provided no regenerative stimulus to the mutant wing disc tissue.  相似文献   

3.
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.  相似文献   

4.
Homoeotic mutations of the bithorax complex cause segmental transformations. The genes in which these mutations occur are good candidates for genes that are involved in determination. The determination system in imaginal discs must have at least two functions. One is a cell heredity function that is responsible for maintaining the determined state during growth and development. A second is the expression of the determined state (e.g., different imaginal discs have different morphologies). The homoeotic mutations of the bithorax complex could be affecting either of these two functions. I have found that when posterior haltere disc cells, that are transformed by the mutation postbithorax so that they form wing cuticle in situ, regenerate anterior structures, these structures are anterior wing. This is the same result as that seen when wild-type posterior-wing disc cells regenerate anterior structures. On the other hand, when anterior haltere disc cells transformed by the mutation bithorax3, so that they produce wing cuticle in situ, regenerate, they produce posterior haltere structures. This is unlike wild-type anterior-wing disc cells, which regenerate posterior-wing structures. From these results, I conclude that bithorax3 affects the expression of the determined state and postbithorax affects the cell heredity of determination.  相似文献   

5.
The mechanism by which patterns are produced appears to be repeated in each segment of an animal, and it has been proposed that it may even have been conserved in evolution so that different species would have the same system of positional information. This idea has been tested by mixing cells of a defined fragment of the wing disc of Drosophila melanogaster with wing disc fragments of five other dipteran species to assay the ability of these disc fragments to stimulate intercalary regeneration of the D. melanogaster cells. The genetically marked (y; mwh) D. melanogaster fragment was mechanically mixed with wing discs or wing disc fragments of four drosophilids (D. melanogaster as a control, D. virilis, D. hydei, Zaprionus vittiger), of Musca domestica, and of Piophila casei. The mixed aggregates were cultured in vivo for 7 days, then metamorphosed in D. melanogaster larval hosts. The D. melanogaster fragments were only stimulated to regenerate when combined with complementary fragments from D. melanogaster or D. virilis wing discs. In the combination between D. melanogaster and D. hydei, the tissue formed integrated mosaic patterns, but no regeneration ensued. The one positive result (D. melanogaster mixed with D. virilis) shows that positional cues can be exchanged and correctly interpreted between cells of different species. The negative results do not prove that the mechanism for establishing patterns is different in the tested species, but may be due to incompatibilities that are not related to pattern formation.  相似文献   

6.
Proteins from Drosophila imaginal discs and disc fragments were analyzed on two-dimensional electrophoretic gels following labeling in vitro with [35S]methionine. The protein synthetic pattern in autoradiograms is very complex and parallels the pattern of protein accumulation visualized in silver-stained gels. We find no reproducible qualitative differences in the proteins synthesized or accumulated by different disc types. Additionally, analysis of the proteins synthesized by different fragments of wing and haltere discs has resulted in the identification of a polypeptide which is synthesized preferentially in homologous regions of these two imaginal discs. Scanning densitometry of our autoradiograms corroborates these findings. This protein, therefore, has some of the properties one would predict for a molecule involved in the imaginal disc positional information system.  相似文献   

7.
The fate of an imaginal disc cell of Drosophila can be affected by the associations and interactions that it has with other cells in the disc. A fragment of an imaginal disc, not regenerating under conditions allowing a complementary fragment to do so, can be stimulated to regenerate by interactions with cells of the complementary fragment [Haynie, J. L., and Bryant, P. J. (1976) Nature (London)259, 659–662]. We report here that one nonregenerating fragment of an imaginal wing disc cannot be stimulated to regenerate by interactions with cells from other parts of the disc. This fragment, containing the anlagen of the distal wing, fails to regenerate proximally when combined with a proximal fragment even though this association stimulates some proximal fragments to regenerate distally. We suggest that this may be a phenomenon similar to that observed in cockroach legs by H. Bohn (1970, Wilhelm Roux Arch. Entwicklungsmech. Organismen165, 303–341), in which proximal regeneration from grafted distal leg segments proceeds only to a limited extent. We consider the possibility that there exist reiterated sets of positional information arranged concentrically in the wing disc.  相似文献   

8.
Summary These experiments examined whether inDrosophila immature imaginal disc tissue and tissues from embryonic stages can influence pattern regulation in a disc fragment in the same way as can mature imaginal discs. Immature imaginal discs, or the cells of whole embryos, were mixed with a test fragment (presumptive notum) from a mature wing disc. The immature tissues in each mixture were genetically marked and had been heavily irradiated (25 Kr gamma) prior to mixing to prevent growth and maturation during subsequent culture in vivo. Alteration of the regulative behavior of the test fragment (that is, regeneration of wing) thus provided an assay for the communication of positional information by the immature tissues. The results suggest that this capacity arises well before competence to metamorphose, as early as the 16th hour of embryonic development, whereas prior to 16 h, essentially no stimulation of regeneration occurred. It is suggested that the imaginal disc (or presumptive disc) cells of the embryo may have been responsible for this early stimulatory capacity.  相似文献   

9.
Summary We estimate the number of blastoderm cells which generate the thoracic imaginal discs ofDrosophila. At hatching the wing disc is twice the size of the haltere disc, but the results suggest that both discs develop from a similar number of blastoderm cells. Two homeotic mutations, which transform the haltere into wing, affect embryonic growth but not the primordial number. All the segmental primordia may be of similar size and each may be similarly subdivided into a larger anterior, and a smaller posterior polyclone.  相似文献   

10.
Summary Mutations of the bithorax complex result in segmental transformations in the thorax and abdomen ofDrosophila. The haltere discs from larvae homozygous forbx 3 orpbx are transformed so that the discs contain cells that will produce wing cuticle as well as cells that produce haltere cuticle. The pattern regulation behavior of these discs has been examined. The fate maps of the two discs were established, and then the regulative behavior of a number of fragments from both types of mutant discs was established by culturing the fragments in vivo prior to metamorphosis. The most important conclusion from this work is that the cells producing, haltere cuticle and wing cuticle within the same disc share the same positional information and that they communicate during pattern regulation.  相似文献   

11.
The protein content of various Drosophila imaginal discs was analysed by two-dimensional electrophoresis followed by silver-staining. Three proteins, identified as tropomyosins α and β 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.  相似文献   

12.
Fragments from prospective distal regions of Drosophila male foreleg imaginal discs failed to undergo proximal intercalary regeneration across leg segment borders when mechanically intermixed and cultured for 8 days with various fragments from prospective proximal disc regions. The failure of the distal cells to regenerate proximal leg segments was not due to a general restriction in their developmental potentials: Distal fragments, when deprived of their distal-most tips, regenerated in the distal direction at a high frequency. It is concluded that there exist in Drosophila leg discs the same restrictions with respect to regeneration along the proximodistal leg axis as had been previously observed in legs of several hemimetabolous insect species: Intersegmental discontinuities between grafted tissue pieces are not eliminated by intercalation. Based on the available evidence in hemimetabolous insects and in Drosophila, a new interpretation of the different aspects of regeneration in insect legs is offered. It is proposed that the two categories of regulative fields observed in insect legs, the leg segment fields and the whole leg field, represent the units of regulation for two fundamentally different regulative pathways that a cell at a wound edge can follow, the intercalative pathway and the terminal pathway, respectively. It is suggested that the criterion used by cells at healing wounds to choose between the two pathways is the difference in circumferential positional information between juxtaposed cells. The intercalative regulative pathway is switched on when cells with disparities in their axial positional information, or cells with less than maximal disparities in their circumferential information, contact one another. The terminal regulative pathway is triggered whenever cells with maximal circumferential disparities come into contact.  相似文献   

13.
High-resolution two dimensional gel electrophoresis has been used to study the patterns of protein synthesis in imaginal discs of Drosophila melanogaster. In this paper we first compare the patterns of protein synthesis in wing, haltere, leg 1, leg 2, leg 3 and eye antenna imaginal discs of late third instar larvae. We have detected only quantitative changes: differences in 17 proteins among the different imaginal discs. In addition, we have analysed the variations in pattern of proteins in the wing disc of the last larval stage and early pupae as well as in wing discs cultured in vivo for 6 days. Variations in these patterns affect more than 20% of the proteins and involve both qualitative and quantitative changes. Some of the changes may correspond to protein phosphorylation. Correlations of these changes between discs and through development are also discussed. Correspondence to: F. Santaren  相似文献   

14.
15.
We have examined the pattern of protein synthesis during wing disc pattern regulation. Although in vivo culture dramatically alters the pattern of abundant protein synthesis in wing discs, only one protein--RG38--changes specifically in response to pattern regulation. This polypeptide, previously identified as being nonuniformly distributed in wing and haltere discs, is synthesized in a graded distribution across the wing disc. During wing disc pattern regulation, it acts as a molecular marker for regeneration of particular wing disc regions. Thus, the rate of RG38 synthesis increases during regeneration (by fragments with initial low levels) with kinetics that parallel those for regeneration as scored by the presence of adult cuticular structures.  相似文献   

16.
Summary In the imaginal discs ofMusca domestica, Drosophila melanogaster, D. simulans, D. hydei, andZaprionus spec. the enzyme aldehyde oxidase (AO) appeared in a clear-cut pattern. In the leg and eye-antennal discs of these species this pattern shows a high degree of conformity, while that of the wing and haltere discs is species-specific.No aldehyde oxidase activity was detected in the imaginal discs ofCalliphora erythrocephala, Phormia regina orLucilia cuprina, but the discs of these species are characterized by grossly similar patterns of 5-nucleotidase. Since the other species studied lack this enzyme, the two enzymes may perform similar functions in the morphogenesis of the discs.The coincidence of the sharp boundary of the AO pattern in the leg and wing discs ofD. melanogaster with the boundary between the anterior and posterior disc compartments gives a strong indication for the existence of analogous compartments in other discs showing a similar sharply bounded AO pattern. Compartmentalization may be considered a general phenomenon which occurs in discs of all segments and is not restricted toD. melanogaster. From the changes in the AO pattern during disc development it can be deduced that the localisation of this enzyme is regulated by supracellular determination involving positional information.  相似文献   

17.
Summary Distribution of the enzyme aldehyde oxidase in transformed haltere discs from the homoeotic bithorax series of mutants was investigated by histochemical means. The bithorax (bx) mutant, which transforms the anterior part of the haltere into an alterior with blade, possesses in the haltere disc an aldehyde oxidase staining pattern similar to that of the anterior side of the wing disc. The postbithorax (pbx) mutant, which transforms the posterior haltere into a structure resembling the posterior wing blade, reveals an aldehyde oxidase staining pattern in the haltere disc characteristic of the posterior side of the wing disc pouch. When both (bx 3 (pbx) mutants are present the haltere develops into a metathoracic wing. It is shown here that the transformed haltere disc closely resembles the previously established pattern in the wing disc with respect to aldehyde oxidase distribution. Change in the pattern of aldehyde oxidase in bithorax mutants signals alteration in gene expression which at least for this particular enzyme correlates well with the morphological transformation from haltere to wing. A possible correlation between pattern of enzyme activity and developmental compartmentalization has been discussed.  相似文献   

18.
Summary It has been known for many years that when a wing disc ofDrosophila is bisected, and the fragments cultured in adult females, regulation occurs and either a complete disc is regenerated or the fragment is duplicated. We have investigated how this regeneration process occurs. To establish which cells contribute to the regenerate, and thus determine if regeneration is the result of epimorphic regulation, fragments of discs, after culture in an adult for one to five days, were exposed to3H-thymidine to label replicating cells. Imaginal discs, both whole and as regenerating fragments, undergo some DNA replication which is distributed throughout the disc, but cut discs frequently show clusters of labelled cells around the wound, indicating that regeneration is probably epimorphic.  相似文献   

19.
Fragments of the imaginal wing disc of Drosophila melanogaster were cultured in adult hosts before transfer to larvae for metamorphosis. Transdetermination occurred only after at least 2 weeks of culture in vivo, producing structures of the leg, antenna, head, and thoracic spiracle. Details of the transdetermined structures and their locations with respect to normal wing disc structures are reported. We present evidence suggesting that regulation can occur between the wing and the second leg imaginal discs, and we propose that many transdeterminations which involve neighboring discs may result from such interdisc regulation.  相似文献   

20.
Previous attempts to study sorting out of Drosophila imaginal disc cells have been hampered by an inability to thoroughly dissociate these cells and the need to use cuticular markers which require several days of in vivo culture. This study overcomes these limitations by using a new dissociation procedure and a genetic marker for undifferentiated cells, the succinate dehydrogenase8 (sdh8) mutation. Dissociated and reaggregated cells from wing and leg imaginal discs segregated or "sorted out" from one another after only 24 hr of in vivo culture. It was also found that leg cells from different body segments may sort out, but to a lesser degree than wing and leg cells. Mixtures of wing and haltere cells did not sort out, in contrast to previous reports. These results constitute the first unambiguous study of sorting out with Drosophila imaginal disc cells and indicate that dorsally situated imaginal cells share a recognition specificity which is different from that of ventral imaginal cells.  相似文献   

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