<i>Drosophila</i>
            Eye Development and Photoreceptor Specification

Şahin, H. Bahar; Çelik, Arzu

doi:10.1002/9780470015902.a0001147.pub2

Cited by 9 publications

(6 citation statements)

References 22 publications

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“…Notch activity is required at several stages in the development of the photoreceptors, including in the specification of R4 and R7 photoreceptors. The sequential differentiation of the eight neuronal photoreceptors (R cells) is initiated when a wave of differentiation (called morphogenetic furrow or MF) spreads from the posterior to the anterior region of the eye imaginal disc (Şahin & Çelik, 2013 ; Fig 4A ). Notch activity in one cell of the five‐cell cluster specifies R4 cell fate and can be detected by the expression of E(spl)mδ0.5‐lacZ , containing the Notch responsive E(spl)mδ enhancer ((Cooper & Bray, 1999 ); Fig 4 A and B).…”

Section: Resultsmentioning

confidence: 99%

The conserved C2 phospholipid‐binding domain in Delta contributes to robust Notch signalling

et al. 2021

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Accurate Notch signalling is critical for development and homeostasis. Fine-tuning of Notch-ligand interactions has substantial impact on signalling outputs. Recent structural studies have identified a conserved N-terminal C2 domain in human Notch ligands which confers phospholipid binding in vitro. Here, we show that Drosophila ligands Delta and Serrate adopt the same C2 domain structure with analogous variations in the loop regions, including the so-called b1-2 loop that is involved in phospholipid binding. Mutations in the b1-2 loop of the Delta C2 domain retain Notch binding but have impaired ability to interact with phospholipids in vitro. To investigate its role in vivo, we deleted five residues within the b1-2 loop of endogenous Delta. Strikingly, this change compromises ligand function. The modified Delta enhances phenotypes produced by Delta loss-of-function alleles and suppresses that of Notch alleles. As the modified protein is present on the cell surface in normal amounts, these results argue that C2 domain phospholipid binding is necessary for robust signalling in vivo finetuning the balance of trans and cis ligand-receptor interactions.

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Section: Resultsmentioning

confidence: 99%

The conserved C2 phospholipid‐binding domain in Delta contributes to robust Notch signalling

et al. 2021

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Section: Resultsmentioning

confidence: 99%

Delta C2 Domain β1-2 loop contributes to robust Notch signalling

Martins

Meng

Korona

et al. 2021

Preprint

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Accurate Notch signalling is critical for organism development and homeostasis. Fine-tuning of Notch-ligand interactions have substantial impact on signalling-outputs. Recent structural studies identified a conserved N-terminal C2 domain in human Notch ligands which conferred phospholipid binding in vitro. Here we show that Drosophila ligands adopt the same C2 domain structure with analogous variations in the loop regions, including the so-called β1-2 loop that has been associated with phospholipid binding. Mutations in the β1-2 loop of Delta C2 domain retain Notch binding but have impaired ability to interact with phospholipids in vitro. To investigate its role in vivo we deleted five residues within the β1-2 loop of endogenous Delta by CRISPR/Cas9 gene editing. Strikingly, this change compromised ligand function. The modified Delta enhanced phenotypes produced by Delta loss of function alleles and suppressed that of Notch alleles. As the modified protein was present on the cell surface in normal amounts, these results argue that C2 domain phospholipid-binding is necessary for robust signalling in vivo where the balance of cis and trans ligand-receptor interactions is finely tuned.

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“…Also, data obtained for D. mauritiana and D. simulans showed that differences in eye size are due to variation in facet size 13 , while eye size differences between D. novamexicana and D. americana are mostly caused by differences in ommatidia number. Since facet size and ommatidia number are specified by different developmental processes 43 , 44 , it is likely that different developmental mechanisms underly natural variation in eye size. Indeed, the most significant QTL explaining eye size variation in D. mauritiana and D. simulans mapped to the X chromosome 17 .…”

Section: Discussionmentioning

confidence: 99%

Multiple loci linked to inversions are associated with eye size variation in species of the Drosophila virilis phylad

Reis

Wiegleb

Julien

et al. 2020

Sci Rep

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The size and shape of organs is tightly controlled to achieve optimal function. Natural morphological variations often represent functional adaptations to an ever-changing environment. For instance, variation in head morphology is pervasive in insects and the underlying molecular basis is starting to be revealed in the Drosophila genus for species of the melanogaster group. However, it remains unclear whether similar diversifications are governed by similar or different molecular mechanisms over longer timescales. To address this issue, we used species of the virilis phylad because they have been diverging from D. melanogaster for at least 40 million years. Our comprehensive morphological survey revealed remarkable differences in eye size and head shape among these species with D. novamexicana having the smallest eyes and southern D. americana populations having the largest eyes. We show that the genetic architecture underlying eye size variation is complex with multiple associated genetic variants located on most chromosomes. Our genome wide association study (GWAS) strongly suggests that some of the putative causative variants are associated with the presence of inversions. Indeed, northern populations of D. americana share derived inversions with D. novamexicana and they show smaller eyes compared to southern ones . Intriguingly, we observed a significant enrichment of genes involved in eye development on the 4th chromosome after intersecting chromosomal regions associated with phenotypic differences with those showing high differentiation among D. americana populations. We propose that variants associated with chromosomal inversions contribute to both intra- and interspecific variation in eye size among species of the virilis phylad.

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Drosophila Eye Development and Photoreceptor Specification

Cited by 9 publications

References 22 publications

The conserved C2 phospholipid‐binding domain in Delta contributes to robust Notch signalling

The conserved C2 phospholipid‐binding domain in Delta contributes to robust Notch signalling

Delta C2 Domain β1-2 loop contributes to robust Notch signalling

Multiple loci linked to inversions are associated with eye size variation in species of the Drosophila virilis phylad

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