Positional information around the segments of the cockroach leg

Development ◽  
1980 ◽  
Vol 59 (1) ◽  
pp. 281-313
Author(s):  
Vernon French
Keyword(s):  
Positional Information ◽  
Epidermal Cells ◽  
Cellular Interactions ◽  
Posterior Compartment ◽  
Continuous Sequence ◽  
Intercalary Regeneration

Epidermal cells from different circumferential positions around the femur of Blabera craniifer can interact to form an intercalary regenerate consisting of that section of the circumference normally separating graft and host positions, by the shorter route. This result is extended to other leg segments; the tibia and coxa (TT and CC Grafts). Grafting strips of integument from the tibia (TF Grafts) or the coxa (CF Grafts) to a corresponding position on the host femur results in simple healing. Grafting to a non-corresponding position leads to intercalation of the shorter intermediate arc of circumference, composed partly of graftsegment and partly of host-segment structures. These results show that the same continuous sequence of positional values is distributed around the circumferences of the coxa, femur and tibia. Cellular interactions along the edges of strip-grafts obey the Shortest Intercalation Rule. At the ends of strip-grafts intercalation usually restores continuity of positional values where possible but, when a complete circumference is generated, a supernumerary distal regenerate is usually formed. This is in general agreement with the Complete Circle Rule and the exceptions are discussed. In intercalary regeneration following the intersegmental strip-grafts, the host femur cells seem unable to intercalate beyond two positions (posterior/internal and posterior/external). These lineage restrictions operating during regeneration indicate that the cockroach leg, like the Drosophila leg disc, may consist of an anterior and a (smaller) posterior ‘compartment’.

Intercalary regeneration around the circumference of the cockroach leg

Development ◽  
1978 ◽  
Vol 47 (1) ◽  
pp. 53-84
Author(s):  
Vernon French
Keyword(s):  
Complete Sequence ◽  
Two Dimensions ◽  
Epidermal Cells ◽  
Host Tissue ◽  
Internal Tissue ◽  
Local Growth ◽  
Intercalary Regeneration ◽  
Longitudinal Strip ◽  
Cuticular Structures ◽  
Independent Aspect

Epidermal cells from different circumferential positions around the femur of Blabera craniifer can interact to form an intercalary regenerate. Removal of a longitudinal strip of integument (cuticle plus epidermis) from any position around the circumference leads to thecut edges healing, localized growth and intercalary regeneration of the missing section ofthe circumference, so that the resulting femur is approximately normal in size and pattern of cuticular structures. Grafting a longitudinal strip of femur integument into a different circumferential position on the host femur confronts epidermal cells from different positions along both the inner and outer longitudinal graft/host junctions. In numerous different situations this results in local growth and intercalary regeneration of that section of the circumference normally separating graft and host positions, by the shorter route around the circumference. Confrontation of opposite positions results in the intercalation of either of the intervening half circumferences. In one opposite confrontation, between mid-anterior and mid-posterior, there was also a third result where graft and host healed together, provoking no intercalary regeneration. Grafts made with reversed proximal/distal polarity show that a confrontation between different circumferential positions gives the same result, regardless of the proximal/distal levels involved, hence circumferential position is an independent aspect of position on the femur. These results strongly suggest that epidermal position is not specified with respect to two transverse axes running through the epidermis and internal tissue of the leg, but that there is a continuous circular sequence of positional values running around the circumference, in the epidermis. This is analogous to but independent of the sequence previously shown by Bohn (1967) and Bulliere (1971) to run proximal/distal along a leg segment. Hence epidermal position on the femur is specified in two dimensions and can be represented in terms of the French, Bryant & Bryant (1976) polar co-ordinate model. Interactions along the edges of the strip-grafts conform to the Shortest Intercalation Rule (French et al. 1976). At the proximal and distal ends of strip-grafts intercalation restores normal sequences of positional values where possible. However, where the graft, together with the intercalary regenerates formed at the longitudinal graft/host junctions and the adjacent host tissue formed a complete sequence of circular values, then a supernumerary distal regenerate was formed, in agreement with the Complete Circle Rule of French et al. (1976). The problem of generating a continuous circular sequence of positional values by one or more circumferential gradients, is briefly discussed.

Cellular interactions during the formation of approach grafts in Sedum telephoides (Crassulaceae)

1984 ◽  
Vol 62 (12) ◽  
pp. 2476-2484 ◽  
Author(s):  
Randy Moore
Keyword(s):  
Moisture Stress ◽  
Epidermal Cells ◽  
Cellular Interactions ◽  
Impermeable Barrier ◽  
Callus Proliferation ◽  
Wall Materials ◽  
Intact Surface ◽  
Graft Interface ◽  
Cut Surface ◽  
Cell Wall Materials

The objective of this study was to determine the competence of epidermal and subepidermal cells to graft. Approach grafts between cut internodal surfaces of Sedum telephoides were characterized by extensive cellular interdigitation at the graft interface. Callus proliferation, but not tissue interdigitation, occurred when these surfaces were separated by a porous or impermeable barrier. Graft partners adhered to the barrier via the deposition and subsequent polymerization of cell wall materials. The outer walls of cells contacting the barriers were of uniform thickness and lacked plasmodesmata. When a cut surface was grafted to an intact surface, callus proliferation occurred at the cut surface, but the epidermis did not dedifferentiate. Callus masses at cut surfaces grafted successfully in environments of high humidity. However, callus masses covered by a water stress induced periderm did not graft successfully. These results indicate that (i) intact epidermal cells of S. telephoides are incompetent to graft, (ii) the presence of a graft-competent (i.e., cut) surface does not cause epidermal cells to dedifferentiate (i.e., become competent to graft), and (iii) graft competence of compatible, subepidermal surfaces depends on the absence of a periderm, which is facilitated by low moisture stress.

scholarly journals Specification of cell fate in the developing eye of Drosophila

Development ◽  
1991 ◽  
Vol 113 (Supplement_1) ◽  
pp. 123-130 ◽  
Author(s):  
Ernst Hafen ◽  
Konrad Basler
Keyword(s):  
Tyrosine Kinase ◽  
Cell Fate ◽  
Photoreceptor Cell ◽  
Nuclear Protein ◽  
Single Cells ◽  
Photoreceptor Cells ◽  
Positional Information ◽  
Cellular Interactions ◽  
Eye Imaginal Disc

Determination of cell fate in the developing eye of Drosophila depends on cellular interactions. In the eye imaginal disc, an initially unpatterned epithelial sheath of cells, single cells are specified in regular intervals to become the R8 photoreceptor cells. Genes such as Notch and scabrous participate in this process suggesting that specification of ommatidial founder cells and the formation of bristles in the adult epidermis involve a similar mechanism known as lateral inhibition. The subsequent steps of ommatidial assembly involve a different mechanism: undetermined cells read their position based on the contacts they make with neighbors that have already begun to differentiate. The development of the R7 photoreceptor cell is best understood. The key role seems to be played by sevenless, a receptor tyrosine kinase on the surface of the R7 precursor. It transmits the positional information – most likely encoded by boss on the neighboring R8 cell membrane – into the cell via its tyrosine kinase that activates a signal transduction cascade. Two components of this cascade – Sos and sina – have been identified genetically, sina encodes a nuclear protein whose expression is not limited to R7. Constitutive activation of the sevenless kinase by overexpression results in the diversion of other ommatidial cells into the R7 pathway, suggesting that activation of the sevenless signalling pathway is sufficient to specify R7 development.

Models for positional signalling, the threefold subdivision of segments and the pigmentation pattern of molluscs

Development ◽  
1984 ◽  
Vol 83 (Supplement) ◽  
pp. 289-311
Author(s):  
Hans Meinhardt
Keyword(s):  
Pattern Formation ◽  
Long Range ◽  
Positional Information ◽  
Pigmentation Pattern ◽  
Intercalary Regeneration ◽  
Biological Pattern Formation ◽  
Appendage Formation ◽  
Triggering Events ◽  
A Chain ◽  
P Cells

Models of biological pattern formation are discussed. The regulatory features expected from the models are compared to those observed experimentally. It will be shown that: (i) Stable gradients appropriate to supply positional information can be produced by local autocatalysis and long-range inhibition. (ii) Spatially ordered sequences of differentiated cell states can emerge if these cell states mutually activate each other on long range but exclude each other locally. Segmentation results from the repetition of three such cell states, S, A and P (and not of only two, as is usually assumed). With a repetition of three states, each segment has a defined polarity. The confrontation of P cells and S cells lead to the formation of a segment border (…P/SAP/SAP/S…) while the A—P confrontation is a prerequisite for appendage formation. Mutations of Drosophila affecting larval segmentation are discussed in terms of this model. (iii) The two models for the generation of sequences of structures in space (positional information including interpretation versus mutual activation) lead to different predictions with respect to intercalary regeneration. This allows a distinction between the two models on the basis of experiments. (iv) The pigmentation patterns of certain molluscs emerge from a coupled oscillation of cells (that is, a lateral inhibition in time, instead of space). The oblique lines result from a chain of triggering events.

Mutations in zebrafish genes affecting the formation of the boundary between midbrain and hindbrain

Development ◽  
1996 ◽  
Vol 123 (1) ◽  
pp. 179-190 ◽  
Author(s):  
M. Brand ◽  
C.P. Heisenberg ◽  
Y.J. Jiang ◽  
D. Beuchle ◽  
K. Lun ◽  
...  
Keyword(s):  
Optic Tectum ◽  
Genetic Linkage ◽  
Marker Gene ◽  
Cellular Interactions ◽  
Posterior Compartment ◽  
Specific Antibodies ◽  
Pronephric Duct ◽  
Marker Gene Expression ◽  
Compartment Boundary ◽  
Molecular Organisation

Mutations in two genes affect the formation of the boundary between midbrain and hindbrain (MHB): no isthmus (noi) and acerebellar (ace). noi mutant embryos lack the MHB constriction, the cerebellum and optic tectum, as well as the pronephric duct. Analysis of noi mutant embryos with neuron-specific antibodies shows that the MHB region and the dorsal and ventral midbrain are absent or abnormal, but that the rostral hindbrain is unaffected with the exception of the cerebellum. Using markers that are expressed during its formation (eng, wnt1 and pax-b), we find that the MHB region is already misspecified in noi mutant embryos during late gastrulation. The tectum is initially present and later degenerates. The defect in ace mutant embryos is more restricted: MHB and cerebellum are absent, but a tectum is formed. Molecular organisation of the tectum and tegmentum is disturbed, however, since eng, wnt1 and pax-b marker gene expression is not maintained. We propose that noi and ace are required for development of the MHB region and of the adjacent mid- and hindbrain, which are thought to be patterned by the MHB region. Presence of pax-b RNA, and absence of pax-b protein, together with the observation of genetic linkage and the occurrence of a point mutation, show that noi mutations are located in the pax-b gene. pax-b is a vertebrate orthologue of the Drosophila gene paired, which is involved in a pathway of cellular interactions at the posterior compartment boundary in Drosophila. Our results confirm and extend a previous report, and show that at least one member of this conserved signalling pathway is required for formation of the boundary between midbrain and hindbrain in the zebrafish.

puckered, a gene involved in position-specific cell differentiation in the dorsal epidermis of the Drosophila larva

Development ◽  
1993 ◽  
Vol 119 (Supplement) ◽  
pp. 251-259 ◽  
Author(s):  
J. M. Ring ◽  
A. Martinez Arias
Keyword(s):  
Cell Differentiation ◽  
Relative Position ◽  
Positional Information ◽  
Epidermal Cells ◽  
Cell Interactions ◽  
Specific Cell ◽  
Specific Behaviour ◽  
Drosophila Larva ◽  
To Receive ◽  
Dorsal Epidermis

The final pattern of the cuticle of the Drosophila larva depends on the position-specific behaviour of the epidermal cells during their differentiation. This behaviour is dictated, in part, by the relative position of the cells during embryogenesis which allows them to receive and integrate signals from their neighbours. The translation of this ‘positional information’ into pattern might depend on the activity of genes that are able to integrate the outcome of cell interactions and tranfer it to the genes responsible for cell differentiation. Mutations in the gene puckered cause spatially restricted defects during the differentiation of the larval epidermal cells. We present data that suggests puckered may be involved in linking positional information to cell differentiation.

Cell commitment and cell interactions in the ectoderm of Drosophila melanogaster

Development ◽  
1991 ◽  
Vol 113 (Supplement_2) ◽  
pp. 39-46 ◽  
Author(s):  
Isabella Stüttem ◽  
José A. Campos-Ortega
Keyword(s):  
Drosophila Melanogaster ◽  
Progenitor Cells ◽  
Epidermal Cells ◽  
Cellular Interactions ◽  
Heterotopic Transplantation ◽  
Anterior Pole ◽  
Neural Fate ◽  
Cell Commitment ◽  
Anterior Midgut

The separation of neural from epidermal progenitor cells in the ventral neuroectoderm of Drosophila is thought to be mediated by cellular interactions. In order to verify the occurrence of regulatory signals and to test the neurogenic capabilities of cells from various regions of the ectoderm, we have carried out homotopic and heterotopic transplantations of single ectodermal cells. We found that cells from any of the tested regions, with the exception of the proctodeal anlage, are capable of developing as neuroblasts following their transplantation into the ventral neuroectoderm. These neurogenic capabilities are gradually distributed. Cells from the procephalic and ventral neurogenic regions exhibit maximal capabilities, as shown by their behavior in heterotopic transplantations. However, the two neurogenic regions differ from each other in that no epidermalising signals can be demonstrated to occur within the procephalic neuroectoderm, whereas such signals are strong within the ventral neuroectoderm; in addition, neuralising signals from neighbouring cells seem to be necessary for neuroectodermal cells to develop as neuroblasts. Other ectodermal regions whose cells exhibit weaker neurogenic capabilities are, in decreasing order of capability, the dorsal epidermal anlage, the anterolateral region of the procephalic lobe, comprising the anlage of the pharynx, and the anterior pole of the embryo, corresponding to the anlagen of the stomodeum and ectodermal anterior midgut. We assume that, during development in situ, the neurogenic capabilities of all these cells are suppressed by inhibitory signals, which are released upon heterotopic transplantation into the neuroectoderm. A community effect which prevents groups of dorsal epidermal cells from taking on a neural fate upon their transplantation into the ventral neuroectoderm, is shown. Finally, we hypothesize that the lack of neurogenic capability in the cells from the proctodeal anlage is due to the absence of products of the proneural genes.

Pattern and polarity of sclerites in adult abdominal segments of Calliphora erythrocephala (Diptera): anlage rotation experiments

Development ◽  
1977 ◽  
Vol 37 (1) ◽  
pp. 91-104
Author(s):  
M. J. Pearson
Keyword(s):  
Positional Information ◽  
Imaginal Discs ◽  
Larval Period ◽  
Epidermal Cells ◽  
Spatial Patterning ◽  
Genetic Determination ◽  
Calliphora Erythrocephala ◽  
Adult Pattern ◽  
Spatial Parameters

The anlagen of imaginal histoblasts in the abdominal segments of Calliphora (higher Diptera) present an interesting problem, which bears on recent concepts employed in the consideration of spatial patterning in insects. They differ from imaginal discs with respect to larval organization and activity, and in the absence of the progressive pattern of genetic determination during the larval period, characteristic of imaginal discs. How is the adult pattern in the abdominal segments determined? The experiments presented here seek to clarify the spatial parameters involved in control of adult pattern and polarity in the adult segment. A series of 180° rotations of hypodermal grafts bearing the anlagen singly, or in combination, or of larval intersegmental hypodermis, indicate that polarity is determined within the anlagen, through interaction with local larval epidermis either before or during histoblast migration. The nature of the sclerites, too, is primarily carried by the anlagen rather than determined by intersegmental information. The whole question of ‘determination of polarity’ is set out more carefully than hitherto in the light of (a) observations of the movement of epidermal cells in other systems in response to disturbance of pattern, and (b) the obvious vectorial nature of the phenomenon, which cannot be a genetic matter, but one of cell axes and of the relation of cells to segment/organism. The demonstration that (i) hemitergite and hemisternite are primarily determined by the anlagen themselves, and not by larval intersegmental membranes; and (ii) evidence indicates an influence of epidermal cells of the larva on the differentiation (as well as polarity) of imaginal histoblasts, leads to the conclusion that neither of two models considered will account for the establishment of the adult abdominal pattern among the histoblasts at metamorphosis. These models are (a) of a segmental gradient, set by the intersegmental boundaries of the previous instar, to which imaginal cells respond by interpretation of positional information; and (b) of progressive compartmentalization of pattern within the anlagen, without reference to epidermal context.

Molecular genetics of cell interactions in Arabidopsis

Development ◽  
1993 ◽  
Vol 119 (Supplement) ◽  
pp. 77-84
Author(s):  
Robert E. Pruitt ◽  
Martin Hülskamp ◽  
Steven D. Kopczak ◽  
Sara E. Ploense ◽  
Kay Schneitz
Keyword(s):  
Transgenic Plants ◽  
Plant Development ◽  
Molecular Level ◽  
Male Gametophyte ◽  
Expression Patterns ◽  
Positional Information ◽  
Pollen Grain ◽  
Receptor Protein ◽  
Cellular Interactions ◽  
Different Types

Many events in plant development are regulated by the interactions of neighboring cells. We are interested in determining what sorts of molecules act as signals and/or receptors in these interactions and how these mechanisms relate to those used in animals and fungi. We are presently working on two different types of systems to try to address this question. In one case we are starting at the molecular level and characterizing a family of receptor protein kinase genes which seem natural candidates for mediating cellular interactions. By analyzing the expression patterns of these genes as well as the phenotypes of transgenic plants bearing altered genes we hope to determine what roles these proteins play in plant development. In the second case we are starting from the organismic level and using genetics to identify genes essential to a whole range of cellular interactions which are required for proper male gametophyte development during reproduction. These interactions involve both recognition of the pollen grain to verify that it is from the correct species and also a transfer of positional information from the female to the male which first allows the pollen tube to determine the polarity of the stigmatic cell on which it has germinated and later provides 'guidance' for the elongating tube to find the ovule.

Cell division during intercalary regeneration in the cockroach leg

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 57-78
Author(s):  
Hilary Anderson ◽  
Vernon French
Keyword(s):  
Wound Healing ◽  
Cell Division ◽  
Epidermal Cells ◽  
Moult Cycle ◽  
Intercalary Regeneration ◽  
Polar Coordinate ◽  
Coordinate Model ◽  
Local Cell ◽  
Cuticular Structures ◽  
Pattern Regulation

In a series of grafting operations on cockroach legs, epidermal cells from different positions or from the same position on the circumference of the femur were placed together. Where cells from different positions were confronted, new cuticular structures corresponding to the positions which would normally have lain between them were formed during the following moults. At the control junctions, where cells from the same positions were placed together, no new structures were formed. Grafted legs were examined histologically at various times after the operation. The events following grafting fell into four phases: wound healing — when epidermal cells migrated over the wound to re-establish epidermal continuity and cells adjacent to the wound divided to compensate for cell emigration; intercalation — when cell divisions took place at the host-graft borders where there was a positional discrepancy; proliferation — when the general growth of the epidermis occurred by widespread cell division; cuticle secretion — when apolysis occurred, cell division ceased, and cuticle secretion began. The results show that intercalary regeneration is associated with local cell division at the graft-host borders, and that these divisions are not confined to the normal proliferative phase of the moult cycle, but begin much earlier in the cycle, as soon as wound healing is complete. These results support epimorphic models (such as the Polar Coordinate Model) of pattern regulation, where change of positional value is tied to cell division, but they do not discount the possibility of a limited initial morphallactic phase.

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