Dynamics of Drosophila eye development and temporal requirements of sevenless expression

Development ◽  
1989 ◽  
Vol 107 (4) ◽  
pp. 723-731 ◽  
Author(s):  
K. Basler ◽  
E. Hafen
Keyword(s):  
Imaginal Disc ◽  
Compound Eye ◽  
Eye Development ◽  
Photoreceptor Cells ◽  
Anterior Border ◽  
Conditional Allele ◽  
And Function ◽  
Internal Marker ◽  
Eye Imaginal Disc

The development of the compound eye of Drosophila consists of a linear, stereotyped program starting at the posterior end of the eye imaginal disc and progressing towards the anterior border. The determination of the R7 photoreceptor cells is part of this process and is dependent on the sevenless gene. In this study, we used a heat-shock-inducible sevenless gene as a conditional allele to determine the exact temporal requirements of sevenless gene expression and to reveal the stages of ommatidial development during which the presumptive R7 cell can respond to the presence of sevenless protein. Our results indicate that sevenless gene function is only required during a brief, defined period for the initiation of R7 development; subsequently sevenless is dispensable for both differentiation and function of the R7 photoreceptors. Furthermore, using rescue of R7 cells as an internal marker to monitor the progression of eye development we could examine when and at what rate ommatidial columns form.

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.

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.

scholarly journals The Drosophila bifocal gene encodes a novel protein which colocalizes with actin and is necessary for photoreceptor morphogenesis.

1997 ◽  
Vol 17 (9) ◽  
pp. 5521-5529 ◽  
Author(s):  
S M Bahri ◽  
X Yang ◽  
W Chia
Keyword(s):  
Compound Eye ◽  
Photoreceptor Cells ◽  
P Element ◽  
Apical Surface ◽  
Loss Of Function ◽  
Filamentous Actin ◽  
Light Gathering ◽  
Morphological Defects ◽  
Microvillar Structure ◽  
Eye Imaginal Disc

Photoreceptor cells of the Drosophila compound eye begin to develop specialized membrane foldings at the apical surface in midpupation. The microvillar structure ultimately forms the rhabdomere, an actin-rich light-gathering organelle with a characteristic shape and morphology. In a P-element transposition screen, we isolated mutations in a gene, bifocal (bif), which is required for the development of normal rhabdomeres. The morphological defects seen in bif mutant animals, in which the distinct contact domains established by the newly formed rhabdomeres are abnormal, first become apparent during midpupal development. The later defects seen in the mutant adult R cells are more dramatic, with the rhabdomeres enlarged, elongated, and frequently split. bif encodes a novel putative protein of 1063 amino acids which is expressed in the embryo and the larval eye imaginal disc in a pattern identical to that of F actin. During pupal development, Bif localizes to the base of the filamentous actin associated with the forming rhabdomeres along one side of the differentiating R cells. On the basis of its subcellular localization and loss-of-function phenotype, we discuss possible roles of Bif in photoreceptor morphogenesis.

scholarly journals Role of Serotonin Transporter in Eye Development of Drosophila melanogaster

2020 ◽  
Vol 21 (11) ◽  
pp. 4086
Author(s):  
Tuan L. A. Pham ◽  
Tran Duy Binh ◽  
Guanchen Liu ◽  
Thanh Q. C. Nguyen ◽  
Yen D. H. Nguyen ◽  
...  
Keyword(s):  
Cell Death ◽  
Drosophila Melanogaster ◽  
Serotonin Transporter ◽  
Compound Eye ◽  
Eye Development ◽  
S Phase ◽  
Eye Disc ◽  
Eye Imaginal Disc ◽  
The Brain

Serotonin transporter (SerT) in the brain is an important neurotransmitter transporter involved in mental health. However, its role in peripheral organs is poorly understood. In this study, we investigated the function of SerT in the development of the compound eye in Drosophila melanogaster. We found that SerT knockdown led to excessive cell death and an increased number of cells in S-phase in the posterior eye imaginal disc. Furthermore, the knockdown of SerT in the eye disc suppressed the activation of Akt, and the introduction of PI3K effectively rescued this phenotype. These results suggested that SerT plays a role in the healthy eye development of D. melanogaster by controlling cell death through the regulation of the PI3K/Akt pathway.

scholarly journals An Overexpression Screen in Drosophila for Genes That Restrict Growth or Cell-Cycle Progression in the Developing Eye

Genetics ◽  
2002 ◽  
Vol 162 (1) ◽  
pp. 229-243 ◽  
Author(s):  
Ai-Sun Kelly Tseng ◽  
Iswar K Hariharan
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Imaginal Disc ◽  
Cell Cycle Progression ◽  
Eye Development ◽  
Gal4 Driver ◽  
Proliferating Cells ◽  
Cycle Progression ◽  
Eye Imaginal Disc ◽  
Doubling Times

AbstractWe screened for genes that, when overexpressed in the proliferating cells of the eye imaginal disc, result in a reduction in the size of the adult eye. After crossing the collection of 2296 EP lines to the ey-GAL4 driver, we identified 46 lines, corresponding to insertions in 32 different loci, that elicited a small eye phenotype. These lines were classified further by testing for an effect in postmitotic cells using the sev-GAL4 driver, by testing for an effect in the wing using en-GAL4, and by testing for the ability of overexpression of cycE to rescue the small eye phenotype. EP lines identified in the screen encompass known regulators of eye development including hh and dpp, known genes that have not been studied previously with respect to eye development, as well as 19 novel ORFs. Lines with insertions near INCENP, elB, and CG11518 were characterized in more detail with respect to changes in growth, cell-cycle phasing, and doubling times that were elicited by overexpression. RNAi-induced phenotypes were also analyzed in SL2 cells. Thus overexpression screens can be combined with RNAi experiments to identify and characterize new regulators of growth and cell proliferation.

Ectopic expression of BEAF32A in the Drosophila eye imaginal disc inhibits differentiation of photoreceptor cells and induces apoptosis

Chromosoma ◽  
2001 ◽  
Vol 110 (5) ◽  
pp. 313-321 ◽  
Author(s):  
Masamitsu Yamaguchi ◽  
Hideki Yoshida ◽  
Fumiko Hirose ◽  
Yoshihiro H. Inoue ◽  
Yuko Hayashi ◽  
...  
Keyword(s):  
Imaginal Disc ◽  
Ectopic Expression ◽  
Photoreceptor Cells ◽  
Drosophila Eye ◽  
Eye Imaginal Disc

A unique mutation in the Enhancer of split gene complex affects the fates of the mystery cells in the developing Drosophila eye

Development ◽  
1992 ◽  
Vol 115 (1) ◽  
pp. 89-101 ◽  
Author(s):  
J.A. Fischer-Vize ◽  
P.D. Vize ◽  
G.M. Rubin
Keyword(s):  
Compound Eye ◽  
Photoreceptor Cells ◽  
Neural Cells ◽  
Loss Of Function ◽  
Wild Type ◽  
Partial Loss ◽  
Eye Disc ◽  
Mutant Cells ◽  
Enhancer Of Split

An unusual recessive allele of the Drosophila groucho gene, which encodes a transducin-like protein, affects the fates of specific cells in the eye disc. groucho is one of several transcription units in the Enhancer of split complex. Most groucho mutations are zygotic lethal due to the proliferation of embryonic neural cells at the expense of epidermal cells. In contrast, flies homozygous for the mutant allele described here, groBFP2, are viable but have abnormal eyes. The Drosophila compound eye is composed of several hundred identical facets, or ommatidia, each of which contains eight photoreceptor cells, R1-R8. In groBFP2 mutant retinas, most of the facets contain eight normally determined photoreceptor cells and one or two additional R-cells of the R3/4 subtype. The extra photoreceptors appear to arise from the mystery cells, which are part of the precluster that initiates the ommatidium, but do not normally become neurons. groBFP2 behaves as a partial loss-of-function mutant. Analysis of ommatidia mosaic for wild-type and groBFP2 mutant cells suggests that the focus of action of the groBFP2 mutation is outside of the photoreceptor cells. These results imply that one function of groucho is in a pathway whereby neuralization of the mystery cells is inhibited by other non-neural cells in the eye disc. In addition, determination of R3/4 photoreceptors usually requires contact with R2 and R5. Specification of the mystery cells as ectopic R3/4 subtype photoreceptors in groBFP2 mutant eye discs implies that induction by R2 or R5 is not absolutely necessary for R3/4 cell determination.

scholarly journals The function of the Drosophila fat facets deubiquitinating enzyme in limiting photoreceptor cell number is intimately associated with endocytosis

Development ◽  
2000 ◽  
Vol 127 (8) ◽  
pp. 1727-1736 ◽  
Author(s):  
A.L. Cadavid ◽  
A. Ginzel ◽  
J.A. Fischer
Keyword(s):  
Compound Eye ◽  
Cell Communication ◽  
Photoreceptor Cells ◽  
Cell Number ◽  
Deubiquitinating Enzyme ◽  
A Cell ◽  
Fat Facets ◽  
Liquid Facets ◽  
And Function ◽  
Communication Pathway

Fat facets is a deubiquitinating enzyme required in a cell communication pathway that limits to eight the number of photoreceptor cells in each facet of the Drososphila compound eye. Genetic data support a model whereby Faf removes ubiquitin, a polypeptide tag for protein degradation, from a specific ubiquitinated protein thus preventing its degradation. Here, mutations in the liquid facets gene were identified as dominant enhancers of the fat facets mutant eye phenotype. The liquid facets locus encodes epsin, a vertebrate protein associated with the clathrin endocytosis complex. The results of genetic experiments reveal that fat facets and liquid facets facilitate endocytosis and function in common cells to generate an inhibitory signal that prevents ectopic photoreceptor determination. Moreover, it is demonstrated that the fat facets mutant phenotype is extraordinarily sensitive to the level of liquid facets expression. We propose that Liquid facets is a candidate for the critical substrate of Fat facets in the eye.

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.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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