decapentaplegic and wingless are regulated by eyes absent and eyegone and interact to direct the pattern of retinal differentiation in the eye disc

Development ◽  
1998 ◽  
Vol 125 (18) ◽  
pp. 3741-3751 ◽  
Author(s):  
D.J. Hazelett ◽  
M. Bourouis ◽  
U. Walldorf ◽  
J.E. Treisman
Keyword(s):  
Posterior Margin ◽  
Imaginal Disc ◽  
Anterior Margin ◽  
Growth Factor Receptor ◽  
Eyes Absent ◽  
Retinal Tissue ◽  
Eye Disc ◽  
Epidermal Growth ◽  
Lateral Margins ◽  
Eye Imaginal Disc

Signaling by the secreted hedgehog, decapentaplegic and wingless proteins organizes the pattern of photoreceptor differentiation within the Drosophila eye imaginal disc; hedgehog and decapentaplegic are required for differentiation to initiate at the posterior margin and progress across the disc, while wingless prevents it from initiating at the lateral margins. Our analysis of these interactions has shown that initiation requires both the presence of decapentaplegic and the absence of wingless, which inhibits photoreceptor differentiation downstream of the reception of the decapentaplegic signal. However, wingless is unable to inhibit differentiation driven by activation of the epidermal growth factor receptor pathway. The effect of wingless is subject to regional variations in control, as the anterior margin of the disc is insensitive to wingless inhibition. The eyes absent and eyegone genes encode members of a group of nuclear proteins required to specify the fate of the eye imaginal disc. We show that both eyes absent and eyegone are required for normal activation of decapentaplegic expression at the posterior and lateral margins of the disc, and repression of wingless expression in presumptive retinal tissue. The requirement for eyegone can be alleviated by inhibition of the wingless signaling pathway, suggesting that eyegone promotes eye development primarily by repressing wingless. These results provide a link between the early specification and later differentiation of the eye disc.

The EGF receptor and notch signaling pathways control the initiation of the morphogenetic furrow duringDrosophilaeye development

Development ◽  
2001 ◽  
Vol 128 (14) ◽  
pp. 2689-2697 ◽  
Author(s):  
Justin P. Kumar ◽  
Kevin Moses
Keyword(s):  
Pattern Formation ◽  
Notch Signaling ◽  
Imaginal Disc ◽  
Egf Receptor ◽  
Retinal Development ◽  
Growth Factor Receptor ◽  
Leading Edge ◽  
Morphogenetic Furrow ◽  
Epidermal Growth ◽  
Eye Imaginal Disc

The onset of pattern formation in the developing Drosophila retina begins with the initiation of the morphogenetic furrow, the leading edge of a wave of retinal development that transforms a uniform epithelium, the eye imaginal disc into a near crystalline array of ommatidial elements. The initiation of this wave of morphogenesis is under the control of the secreted morphogens Hedgehog (Hh), Decapentaplegic (Dpp) and Wingless (Wg). We show that the Epidermal Growth Factor Receptor and Notch signaling cascades are crucial components that are also required to initiate retinal development. We also show that the initiation of the morphogenetic furrow is the sum of two genetically separable processes: (1) the ‘birth’ of pattern formation at the posterior margin of the eye imaginal disc; and (2) the subsequent ‘reincarnation’ of retinal development across the epithelium.

dachshund encodes a nuclear protein required for normal eye and leg development in Drosophila

Development ◽  
1994 ◽  
Vol 120 (12) ◽  
pp. 3473-3486 ◽  
Author(s):  
G. Mardon ◽  
N.M. Solomon ◽  
G.M. Rubin
Keyword(s):  
Cell Fate ◽  
Posterior Margin ◽  
Imaginal Disc ◽  
Nuclear Protein ◽  
Eye Disc ◽  
Leg Development ◽  
Disc Cells ◽  
Neural Specification ◽  
Eye Imaginal Disc

Neural specification and differentiation in the Drosophila eye sweep across the unpatterned epithelial monolayer of the eye imaginal disc following a developmental wave termed the morphogenetic furrow. The furrow begins at the posterior margin of the eye imaginal disc and moves anteriorly as a linear front. Progression of the furrow requires the function of hedgehog, which encodes a secreted signaling protein. We characterize mutations in dachshund, a gene that encodes a novel nuclear protein required for normal cell-fate determination of imaginal disc cells. In the absence of dachshund function, cells at the posterior margin of the eye disc fail to follow a retinal differentiation pathway and appear to adopt a cuticle fate instead. These cells are therefore unable to respond to pattern propagation signals such as hedgehog and furrow initiation does not occur. In contrast, cells in more anterior portions of the eye disc are able to differentiate as retinal cells in the absence of dachshund activity and respond normally to patterning signals. These results suggest that posterior margin cells are distinct from other cells of the eye imaginal disc by early stages of development. dachshund is also necessary for proper differentiation of a subset of segments in the developing leg. Null mutations in dachshund result in flies with no eyes and shortened legs.

wingless inhibits morphogenetic furrow movement in the Drosophila eye disc

Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3519-3527 ◽  
Author(s):  
J.E. Treisman ◽  
G.M. Rubin
Keyword(s):  
Posterior Margin ◽  
Ectopic Expression ◽  
Spatial Localization ◽  
Morphogenetic Furrow ◽  
Differentiated Cells ◽  
Repetitive Process ◽  
Eye Disc ◽  
Drosophila Eye ◽  
Lateral Margins ◽  
Eye Imaginal Disc

Differentiation of the Drosophila eye imaginal disc is an asynchronous, repetitive process which proceeds across the disc from posterior to anterior. Its propagation correlates with the expression of decapentaplegic at the front of differentiation, in the morphogenetic furrow. Both differentiation and decapentaplegic expression are maintained by Hedgehog protein secreted by the differentiated cells posterior to the furrow. However, their initiation at the posterior margin occurs prior to hedgehog expression by an unknown mechanism. We show here that the wingless gene contributes to the correct spatial localization of initiation. Initiation of the morphogenetic furrow is restricted to the posterior margin by the presence of wingless at the lateral margins; removal of wingless allows lateral initiation. Ectopic expression of wingless at the posterior margin can also inhibit normal initiation. In addition, the presence of wingless in the center of the disc can prevent furrow progression. These effects of wingless are achieved without altering the expression of decapentaplegic.

Role of decapentaplegic in initiation and progression of the morphogenetic furrow in the developing Drosophila retina

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 559-567 ◽  
Author(s):  
F. Chanut ◽  
U. Heberlein
Keyword(s):  
Posterior Margin ◽  
Imaginal Disc ◽  
Photoreceptor Cells ◽  
Morphogenetic Furrow ◽  
Retinal Differentiation ◽  
Eye Disc ◽  
Forward Edge ◽  
Eye Imaginal Disc ◽  
Precise Role

Morphogenesis in the Drosophila retina initiates at the posterior margin of the eye imaginal disc by an unknown mechanism. Upon initiation, a wave of differentiation, its forward edge marked by the morphogenetic furrow (MF), proceeds anteriorly across the disc. Progression of the MF is driven by hedgehog (hh), expressed by differentiating photoreceptor cells. The TGF-beta homolog encoded by decapentaplegic (dpp) is expressed at the disc's posterior margin prior to initiation and in the furrow, under the control of hh, during MF progression. While dpp has been implicated in eye disc growth and morphogenesis, its precise role in retinal differentiation has not been determined. To address the role of dpp in initiation and progression of retinal differentiation we analyzed the consequences of reduced and increased dpp function during eye development. We find that dpp is not only required for normal MF initiation, but is sufficient to induce ectopic initiation of differentiation. Inappropriate initiation is normally inhibited by wingless (wg). Loss of dpp function is accompanied by expansion of wg expression, while increased dpp function leads to loss of wg transcription. In addition, dpp is required to maintain, and sufficient to induce, its own expression along the disc's margins. We postulate that dpp autoregulation and dpp-mediated inhibition of wg expression are required for the coordinated regulation of furrow initiation and progression. Finally, we show that in the later stages of retinal differentiation, reduction of dpp function leads to an arrest in MF progression.

scholarly journals A Fasciclin 2 functional switch controls organ size in Drosophila

2018 ◽  
Author(s):  
Emma Velasquez ◽  
Jose A. Gomez-Sanchez ◽  
Emmanuelle Donier ◽  
Carmen Grijota-Martinez ◽  
Hugo Cabedo ◽  
...  
Keyword(s):  
Imaginal Disc ◽  
Growth Factor Receptor ◽  
Tissue Growth ◽  
Organ Size ◽  
Autonomous Function ◽  
Genetic Mosaic ◽  
Binding Partners ◽  
A Cell ◽  
Epidermal Growth ◽  
Species Specific

How cell to cell interactions control local tissue growth to attain a species-specific pattern and organ size is a central question in developmental biology. The Drosophila Neural Cell Adhesion Molecule, Fasciclin 2 (Drosophila NCAM), is expressed during the development of neural and epithelial organs. Genetic mosaic analysis of Fasciclin 2 reveals two complementary and opposing functions during imaginal disc growth, a cell autonomous requirement to promote growth and an opposite non-cell autonomous function to restrain growth at high expression levels. This non-cell autonomous function is mediated by the Fasciclin 2 heterophilic-binding partners CG15630 and CG33543. We show that EGFR physically interacts with Fasciclin 2 and mediates both the cell autonomous and the non-cell autonomous function. We further show that EGFR activity in turn promotes the cell autonomous expression of Fasciclin 2. We suggest that the auto-stimulatory loop between EGFR and Fasciclin 2 operates until reaching a threshold where the Fasciclin 2 non-cell autonomous function counteracts the growth-promoting activity of the homophilic interaction to terminate imaginal disc growth. Accordingly, we have found that Fasciclin 2 limits imaginal disc growth by the end of larval development. Cellular integration of Fasciclin 2 autonomous and non-cell autonomous signaling from neighbor cells may be a key regulator component to orchestrate the rate of intercalary cell proliferation and the final size of an organ.Author SummaryOne of the key unsolved problems in Biology is how a species-specific size is attained during animal development. During development cells should compute the amount of intercalary tissue growth to stop cell proliferation when reaching a correct pattern and size. Classic studies demonstrated that local cell interactions are key in controlling organ growth to reach a correct size and pattern in vertebrates and invertebrates. We present evidence strongly suggesting that Fasciclin 2 (the ortholog of NCAM in Drosophila) functions as a growth level switch to control pattern and organ size. First, we use genetic mosaic analyses to show that Fasciclin 2 promotes organ growth in a cell autonomous manner. Then we show that Fasciclin 2 restrains growth at high expression levels in a non-cell autonomous manner, and that there is a requirement for Fasciclin 2 to limit growth by the end of larval development. This function is dependent on Fasciclin 2 heterophilic binding partners CG15630 and CG33543. The Epidermal Growth Factor receptor mediates both functional facets of Fasciclin 2 and its activity in turn increases Fasciclin 2 cell autonomous expression, suggesting the existence of a functional auto-stimulatory loop. We also show that the Epidermal Growth Factor receptor and Fasciclin 2 physically interact. Our results show that the amount of Fasciclin 2 between cells determines organ size by acting as an expression level switch for EGFR function, and suggest that other specific CAM interactions may integrate similar expression level switches acting as a code for cells to compute local growth in attaining a species-specific organ size and shape.

A new Species of Lygus infesting Potatoes in Java (Rhynchota, Capsidae)

1923 ◽  
Vol 13 (4) ◽  
pp. 447-447
Author(s):  
W. E. China
Keyword(s):  
New Species ◽  
Posterior Margin ◽  
Anterior Margin ◽  
Pale Yellow ◽  
The Third ◽  
Orange Yellow ◽  
Brownish Black ◽  
Lateral Margins ◽  
Surrounding Areas ◽  
A New Species

Head 0·83 mm. long, shiny orange-yellow, with the clypeus and the adjoining portion of the frons shiny black. Eyes black, prominent, extending laterally beyond the anterior lateral margins of the pronotum. Rostrum brownish black, extending to, but not surpassing, the posterior coxae; lengths of the joints: first 0·53 mm., second 0·76 mm., third 0·4 mm., and fourth 0·6 mm. Antennae brownish black, the third and fourth joints somewhat paler; first joint slightly incrassated, length 0·83 mm., second 2·0 mm., third 1·83 mm., fourth 1 mm. Pronotum shiny orange-yellow, posteriorly somewhat suffered with dark brown; length in middle 1·4 mm., breadth at anterior margin 0·8 mm., at posterior margin 2·0 mm.; sides straight, posterior margin moderately convex. Scutellum shiny black, finely rugosely punctate and regularly covered with pale depressed hairs; length in the middle 1·3 mm. Corium and cuneus similar in colour and pilosity to the scutellum; membrane dark smoky brown, veins shiny black, passing the apex of the abdomen. Sternum: mesostethium and metastethium black, the metastethial orifices and the surrounding areas very pale yellow: undersides of abdomen shiny black, covered with very fine pale hairs. Legs: coaxae blackish brown; femora dirty orange-yellow, suffused at base and apex with brown; tibiae dark brown, armed with fine black spines; tarsi black, strongly pilose.

Hedgehog is an indirect regulator of morphogenetic furrow progression in the Drosophila eye disc

Development ◽  
1997 ◽  
Vol 124 (17) ◽  
pp. 3233-3240 ◽  
Author(s):  
D.I. Strutt ◽  
M. Mlodzik
Keyword(s):  
Pattern Formation ◽  
Imaginal Disc ◽  
Morphogenetic Furrow ◽  
Anterior Edge ◽  
Eye Disc ◽  
Drosophila Eye ◽  
Eye Imaginal Disc ◽  
Inductive Signal ◽  
Rate Of Movement

Pattern formation in the eye imaginal disc of Drosophila occurs in a wave that moves from posterior to anterior. The anterior edge of this wave is marked by a contracted band of cells known as the morphogenetic furrow, behind which photoreceptors differentiate. The movement of the furrow is dependent upon the secretion of the signalling protein Hedgehog (Hh) by more posterior cells, and it has been suggested that Hh acts as an inductive signal to induce cells to enter a furrow fate and begin differentiation. To further define the role of Hh in this process, we have analysed clones of cells lacking the function of the smoothened (smo) gene, which is required for transduction of the Hh signal and allows the investigation of the autonomous requirement for hh signalling. These experiments demonstrate that the function of hh in furrow progression is indirect. Cells that cannot receive/transduce the Hh signal are still capable of entering a furrow fate and differentiating normally. However, hh is required to promote furrow progression and regulate its rate of movement across the disc, since the furrow is significantly delayed in smo clones.

Subdivision of the Drosophila wing imaginal disc by EGFR-mediated signaling

Development ◽  
2002 ◽  
Vol 129 (6) ◽  
pp. 1357-1368 ◽  
Author(s):  
Myriam Zecca ◽  
Gary Struhl
Keyword(s):  
Imaginal Disc ◽  
Growth Factor Receptor ◽  
Subsequent Development ◽  
Wing Disc ◽  
Wing Imaginal Disc ◽  
Egfr Signaling ◽  
Drosophila Wing ◽  
Compartment Boundary ◽  
Epidermal Growth ◽  
Necessary And Sufficient

Growth and patterning of the Drosophila wing imaginal disc depends on its subdivision into dorsoventral (DV) compartments and limb (wing) and body wall (notum) primordia. We present evidence that both the DV and wing-notum subdivisions are specified by activation of the Drosophila Epidermal Growth Factor Receptor (EGFR). We show that EGFR signaling is necessary and sufficient to activate apterous (ap) expression, thereby segregating the wing disc into D (ap-ON) and V (ap-OFF) compartments. Similarly, we demonstrate that EGFR signaling directs the expression of Iroquois Complex (Iro-C) genes in prospective notum cells, rendering them distinct from, and immiscible with, neighboring wing cells. However, EGFR signaling acts only early in development to heritably activate ap, whereas it is required persistently during subsequent development to maintain Iro-C gene expression. Hence, as the disc grows, the DV compartment boundary can shift ventrally, beyond the range of the instructive EGFR signal(s), in contrast to the notum-wing boundary, which continues to be defined by EGFR input.

The role of yan in mediating the choice between cell division and differentiation

Development ◽  
1995 ◽  
Vol 121 (12) ◽  
pp. 3947-3958 ◽  
Author(s):  
R. Rogge ◽  
P.J. Green ◽  
J. Urano ◽  
S. Horn-Saban ◽  
M. Mlodzik ◽  
...  
Keyword(s):  
Cell Division ◽  
Growth Factor Receptor ◽  
Developmental Context ◽  
Eye Disc ◽  
A Cell ◽  
Epidermal Growth ◽  
Notch Pathways ◽  
Relationship Of ◽  
The Relationship

An allele of the yan locus was isolated as an enhancer of the Ellipse mutation of the Drosophila epidermal growth factor receptor (Egfr) gene. This yan allele is an embryonic lethal and also fails to complement the lethality of anterior open (aop) mutations. Phenotypic and complementation analysis revealed that aop is allelic to yan and genetically the lethal alleles act as null mutations for the yan gene. Analysis of the lethal alleles in the embryo and in mitotic clones showed that loss of yan function causes cells to overproliferate in the dorsal neuroectoderm of the embryo and in the developing eye disc. Our studies suggest that the role of yan is defined by the developmental context of the cells in which it functions. An important role of this gene is in allowing a cell to choose between cell division and differentiation. The relationship of the Egfr and Notch pathways to this developmental role of yan is discussed.

scholarly journals Dorsoventral patterning in the Drosophila retina by wingless

Development ◽  
1998 ◽  
Vol 125 (4) ◽  
pp. 567-577 ◽  
Author(s):  
U. Heberlein ◽  
E.R. Borod ◽  
F.A. Chanut
Keyword(s):  
Posterior Margin ◽  
Imaginal Disc ◽  
Mirror Image ◽  
Dorsoventral Patterning ◽  
Multiple Events ◽  
Ommatidial Rotation ◽  
Necessary And Sufficient ◽  
Eye Imaginal Disc ◽  
Anterior Posterior ◽  
Epithelial Growth

The eye imaginal disc displays dorsal-ventral (D-V) and anterior-posterior polarity prior to the onset of differentiation, which initiates at the intersection of the D-V midline with the posterior margin. As the wave of differentiation progresses anteriorly, additional asymmetry develops as ommatidial clusters rotate coordinately in opposite directions in the dorsal and ventral halves of the disc; this forms a line of mirror-image symmetry, the equator, which coincides with the D-V midline of the disc. How D-V pattern is established and how it relates to ommatidial rotation are unknown. Here we address this question by assaying the expression of various asymmetric markers under conditions that lead to ectopic differentiation, such as removal of patched or wingless function. We find that D-V patterning develops gradually and that wingless plays an important role in setting up this pattern. We show that wingless is necessary and sufficient to induce dorsal expression of the gene mirror prior to the start of differentiation and also to restrict the expression of the WR122 marker to differentiating photoreceptors near the equator. In addition, we find that manipulations in wingless expression shift the D-V axis of the disc as evidenced by changes in the expression domains of asymmetric markers, the position of the site of initiation and the equator, and the pattern of epithelial growth. Thus, Wg appears to coordinately regulate multiple events related to D-V patterning in the developing retina.

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