Pattern formation in the Drosophila eye disc

Roignant, Jean‐Yves; Treisman, Jessica E.

doi:10.1387/ijdb.072483jr

Cited by 154 publications

(178 citation statements)

References 139 publications

Supporting

Mentioning

177

Contrasting

Order By: Relevance

“…S5 and SI Text, section S6B). [In this light, it is interesting that a separate regulatory circuitry specifies the first column of ommatidia at the far posterior of the eye disc (2,11).] Fig.…”

Section: Resultsmentioning

confidence: 99%

“…2A). Induction is exemplified by Hedgehog (Hh), which is secreted by differentiating photoreceptors posterior to the MF; because ato expression is required for neural differentiation, one can think of hh as being indirectly activated by ato, creating a loop that drives the MF forward across the eye disc (3,4,10,11). Cellautonomous ato self-activation, in part through a positive feedback loop with sens, sustains ato expression once it reaches a critical level.…”

mentioning

confidence: 99%

See 1 more Smart Citation

A dynamical model of ommatidial crystal formation

Lubensky¹,

Pennington

Shraiman

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The crystalline photoreceptor lattice in the Drosophila eye is a paradigm for pattern formation during development. During eye development, activation of proneural genes at a moving front adds new columns to a regular lattice of R8 photoreceptors. We present a mathematical model of the governing activator-inhibitor system, which indicates that the dynamics of positive induction play a central role in the selection of certain cells as R8s. The "switch and template" patterning mechanism we observe is mathematically very different from the well-known Turing instability. Unlike a standard lateral inhibition model, our picture implies that R8s are defined before the appearance of the complete group of proneural cells. The model reproduces the full time course of proneural gene expression and accounts for specific features of the refinement of proneural groups that had resisted explanation. It moreover predicts that perturbing the normal template can lead to eyes containing stripes of R8 cells. We observed these stripes experimentally after manipulation of the Notch and scabrous genes. Our results suggest an alternative to the generally assumed mode of operation for lateral inhibition during development; more generally, they hint at a broader role for bistable switches in the initial establishment of patterns as well as in their maintenance.imaginal disc | neural fate specification R egular patterns of cell fate appear widely in biology, and it has long been a major challenge to explain how such de novo patterning occurs during development. The R8 photoreceptor lattice in the Drosophila melanogaster eye is a particularly striking example. The adult Drosophila eye comprises ∼750 ommatidia, each composed of photoreceptors and support cells, packed in a crystalline array (1). These ommatidia are founded by R8 photoreceptors, whose orderly alignment takes shape in the wake of the morphogenetic furrow (MF) that moves from posterior to anterior across the eye imaginal disc during the third larval instar ( Fig. 1) (2). The emergence of a solitary R8 from within a proneural group of competent cells has parallels in many examples of neural and neuronal fate specification (3,4). This selection of a neural precursor through lateral inhibition is generally believed to involve an instability whereby feedback loops reinforce random fluctuations to choose one among a collection of equivalent cells (5-7). Here, we present a mathematical model of R8 selection and spacing that suggests a different scenario. This model turns out to generate patterns through a "switch and template" mechanism at whose heart is a cell-autonomous, bistable switch that takes one state in the R8s and another in the surrounding, undifferentiated cells. Whether a cell switches from undifferentiated to R8 depends primarily on the balance between inductive and inhibitory signals emanating from more mature cells to its posterior; direct inhibitory interactions among neighboring cells play a secondary role, preventing the appearance of superfluous R8s after the ini...

show abstract

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

A dynamical model of ommatidial crystal formation

Lubensky¹,

Pennington

Shraiman

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…7,8 During the first two stages of larval development, the eye-antennal imaginal disc proliferates extensively, forming a bi-lobed structure. The antennal lobe will make the adult antenna, while the eye lobe will form the head capsule and eye.…”

mentioning

confidence: 99%

Non-cell autonomous control of apoptosis by ligand-independent Hedgehog signaling in Drosophila

et al. 2012

View full text Add to dashboard Cite

“…At 28 h after puparium formation (APF), a wave of apoptosis removes all excess interommatidial cells. [48][49][50] This developmental cell death is lost in mutant clones of both class C alleles ( Figure 4a' and b'), suggesting that class C alleles are recessive loss-of-function mutants. Therefore, because these two alleles produce normal DrICE protein levels, they affect DrICE activity independently of protein stability.…”

Section: Resultsmentioning

confidence: 94%

“…At 42 h APF, the retina forms a highly regular lattice with a constant number of cells [48][49][50] (Supplementary Figure S4). Inappropriate cell loss results in disruption of lattice symmetry and is easy to score.…”

Section: Resultsmentioning

confidence: 99%

Genetic characterization of two gain-of-function alleles of the effector caspase DrICE in Drosophila

Lindblad

Garnett

et al. 2015

Cell Death Differ

View full text Add to dashboard Cite

Caspases are the executioners of apoptosis. Although much is known about their physiological roles and structures, detailed analyses of missense mutations of caspases are lacking. As mutations within caspases are identified in various human diseases, the study of caspase mutants will help to elucidate how caspases interact with other components of the apoptosis pathway and how they may contribute to disease. DrICE is the major effector caspase in Drosophila required for developmental and stressinduced cell death. Here, we report the isolation and characterization of six de novo drICE mutants, all of which carry point mutations affecting amino acids conserved among caspases in various species. These six mutants behave as recessive loss-offunction mutants in a homozygous condition. Surprisingly, however, two of the newly isolated drICE alleles are gain-of-function mutants in a heterozygous condition, although they are loss-of-function mutants homozygously. Interestingly, they only behave as gain-of-function mutants in the presence of an apoptotic signal. These two alleles carry missense mutations affecting conserved amino acids in close proximity to the catalytic cysteine residue. This is the first time that viable gain-of-function alleles of caspases are described in any intact organism and provides a significant exception to the expectation that mutations of conserved amino acids always abolish the pro-apoptotic activity of caspases. We discuss models about how these mutations cause the gain-offunction character of these alleles. Cell Death and Differentiation (2016) 23, 723-732; doi:10.1038/cdd.2015.144; published online 6 November 2015Apoptosis is a major form of programmed cell death. 1 The core apoptotic machinery is evolutionary conserved with caspases as the fundamental components. [1][2][3] Caspases are specific cysteine proteases that are produced as inactive zymogens composed of an N-terminal pro-domain, a large subunit region with the catalytic cysteine residue, and a small subunit region at the carboxyl end. 2,4 Depending on their structures and functions, caspases are grouped into initiator and effector caspases. 2,3 Initiator caspases possess long pro-domains, which facilitate the recruitment of initiator caspases into cell death signaling complexes for activation. 2,3,5 Effector caspases are activated by initiator caspase complexes through proteolytic processing, cleaving off the pro-domain and separating the large and small subunits. The active effector caspase is a tetramer composed of two large and two small subunits and contains two catalytic sites. 2,3 Activated effector caspases cleave many protein targets to trigger the physiological and morphological changes characteristic of apoptosis. In mammals, apoptotic initiator caspases are Caspase-8, -9, -2 and -10, and effector caspases involved in apoptosis are 3 Of the seven Drosophila caspases, only the initiator caspase Dronc (Caspase-9-like) and the effector caspases DrICE and Dcp-1 (Caspase-3-like) have been implicated in apoptosis in imagina...

show abstract

Pattern formation in the Drosophila eye disc

Cited by 154 publications

References 139 publications

A dynamical model of ommatidial crystal formation

A dynamical model of ommatidial crystal formation

Non-cell autonomous control of apoptosis by ligand-independent Hedgehog signaling in Drosophila

Genetic characterization of two gain-of-function alleles of the effector caspase DrICE in Drosophila

Contact Info

Product

Resources

About