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Angelika Stollewerk - One of the best experts on this subject based on the ideXlab platform.
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functional analysis of Sense Organ specification in the tribolium castaneum larva reveals divergent mechanisms in insects
BMC Biology, 2021Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved and whether the principles underlying subtype identity in D. melanogaster are representative of other insects. Here, we provide evidence that such principles cannot be generalised, and suggest that sensory Organ diversification followed the recruitment of sensory genes to distinct sensory Organ specification mechanism. We analysed Sense Organ development in a nondipteran insect, the flour beetle Tribolium castaneum, by gene expression and RNA interference studies. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on the expression or their requirement for individual or combinations of conserved Sense Organ transcription factors such as cut and pox neuro, or members of the Achaete-Scute (Tc ASH, Tc aSense), Atonal (Tc atonal, Tc cato, Tc amos), and neurogenin families (Tc tap). Rather, our observations support an evolutionary scenario whereby these sensory genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla which do not fall into specific morphological and functional classes. Based on our findings and past research, we present an evolutionary scenario suggesting that Sense Organ subtype identity has evolved by recruitment of a flexible sensory gene network to the different Sense Organ specification processes. A dominant role of these genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, probably modulated by positional cues.
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Functional analysis of Sense Organ specification in the Tribolium castaneum larva reveals divergent mechanisms in insects.
BMC biology, 2021Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved and whether the principles underlying subtype identity in D. melanogaster are representative of other insects. Here, we provide evidence that such principles cannot be generalised, and suggest that sensory Organ diversification followed the recruitment of sensory genes to distinct sensory Organ specification mechanism. RESULTS: We analysed Sense Organ development in a nondipteran insect, the flour beetle Tribolium castaneum, by gene expression and RNA interference studies. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on the expression or their requirement for individual or combinations of conserved Sense Organ transcription factors such as cut and pox neuro, or members of the Achaete-Scute (Tc ASH, Tc aSense), Atonal (Tc atonal, Tc cato, Tc amos), and neurogenin families (Tc tap). Rather, our observations support an evolutionary scenario whereby these sensory genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla which do not fall into specific morphological and functional classes. CONCLUSIONS: Based on our findings and past research, we present an evolutionary scenario suggesting that Sense Organ subtype identity has evolved by recruitment of a flexible sensory gene network to the different Sense Organ specification processes. A dominant role of these genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, probably modulated by positional cues.
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Sense Organ formation and identity are controlled by divergent mechanisms in insects
2020Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Abstract Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved in arthropods, and if the D. melanogaster subtype identity principle is representative for insects. To address these questions, we analyse Sense Organ development in another insect, the flour beetle Tribolium castaneum. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on their requirement for individual or combinations of the conserved Sense Organ transcription factors such as cut and pox-neuro and members of the Achaete-Scute (Tc ASH, Tc aSense) and Atonal family (Tc atonal, Tc cato, Tc amos). Rather, these genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla. Based on our findings and past research, we present an evolutionary scenario suggesting that sensory Organs have diversified from a default state through subsequent recruitment of sensory genes to the different Sense Organ specification processes. A specific role for genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, which can largely not be aligned with morphological or functional categories.
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Distribution and development of the external Sense Organ pattern on the appendages of postembryonic and adult stages of the spider Parasteatoda tepidariorum
Development Genes and Evolution, 2020Co-Authors: Magdalena Ines Schacht, Martina Francesconi, Angelika StollewerkAbstract:Spiders are equipped with a large number of innervated cuticular specializations, which respond to various sensory stimuli. The physiological function of mechanosensory Organs has been analysed in great detail in some model spider species (e.g. Cupiennius salei ); however, much less is known about the distribution and function of chemosensory Organs. Furthermore, our knowledge on how the Sense Organ pattern develops on the spider appendages is limited. Here we analyse the development of the pattern and distribution of six different external mechano- and chemosensory Organs in all postembryonic stages and in adult male and female spiders of the species Parasteatoda tepidariorum . We show that except for small mechanosensory setae, external Sense Organs appear in fixed positions on the pedipalps and first walking legs, arranged in longitudinal rows along the proximal-distal axis or in invariable positions relative to morphological landmarks (joints, distal tarsal tip). A comparison to other Entelegynae spiders shows that these features are conserved. We hope that this study lays the foundation for future molecular analysis to address the question how this conserved pattern is generated.
Andrew P Jarman - One of the best experts on this subject based on the ideXlab platform.
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egf receptor signaling triggers recruitment of drosophila Sense Organ precursors by stimulating proneural gene autoregulation
Developmental Cell, 2004Co-Authors: Petra Zur Lage, Lynn M Powell, David R A Prentice, Paul J Mclaughlin, Andrew P JarmanAbstract:In Drosophila, commitment of a cell to a Sense Organ precursor (SOP) fate requires bHLH proneural transcription factor upregulation, a process that depends in most cases on the interplay of proneural gene autoregulation and inhibitory Notch signaling. A subset of SOPs are selected by a recruitment pathway involving EGFR signaling to ectodermal cells expressing the proneural gene atonal. We show that EGFR signaling drives recruitment by directly facilitating atonal autoregulation. Pointed, the transcription factor that mediates EGFR signaling, and Atonal protein itself bind cooperatively to adjacent conserved binding sites in an atonal enhancer. Recruitment is therefore contingent on the combined presence of Atonal protein (providing competence) and EGFR signaling (triggering recruitment). Thus, autoregulation is the nodal control point targeted by signaling. This exemplifies a simple and general mechanism for regulating the transition from competence to cell fate commitment whereby a cell signal directly targets the autoregulation of a selector gene.
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ANTAGONISM OF EGFR AND NOTCH SIGNALLING IN THE REITERATIVE RECRUITMENT OF DROSOPHILA ADULT CHORDOTONAL Sense Organ PRECURSORS
Development, 1999Co-Authors: P. Zur Lage, Andrew P JarmanAbstract:The selection of Drosophila melanogaster Sense Organ precursors (SOPs) for sensory bristles is a progressive process: each neural equivalence group is transiently defined by the expression of proneural genes (proneural cluster), and neural fate is refined to single cells by Notch-Delta lateral inhibitory signalling between the cells. Unlike sensory bristles, SOPs of chordotonal (stretch receptor) Sense Organs are tightly clustered. Here we show that for one large adult chordotonal SOP array, clustering results from the progressive accumulation of a large number of SOPs from a persistent proneural cluster. This is achieved by a novel interplay of inductive epidermal growth factor-receptor (EGFR) and competitive Notch signals. EGFR acts in opposition to Notch signalling in two ways: it promotes continuous SOP recruitment despite lateral inhibition, and it attenuates the effect of lateral inhibition on the proneural cluster equivalence group, thus maintaining the persistent proneural cluster. SOP recruitment is reiterative because the inductive signal comes from previously recruited SOPs.
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requirement for egf receptor signalling in neural recruitment during formation of drosophila chordotonal Sense Organ clusters
Current Biology, 1997Co-Authors: Petra Zur Lage, Yuh Nung Jan, Andrew P JarmanAbstract:Abstract Background: Drosophila proneural genes act in the process of selecting neural precursors from undifferentiated ectoderm. The proneural gene atonal is required for the development of precursors of both chordotonal Organs (stretch receptors) and photoreceptors. Although these types of sensory element are dissimilar in structure and function, they both occur as Organized arrays of neurons. Previous studies have shown that clustering of photoreceptors involves local recruitment, and that signalling by the Drosophila epidermal growth factor receptor (DER) pathway is involved in the recruitment process. We present evidence that a similar mechanism is required for the clustering of embryonic chordotonal Organs. Results: We have examined the expression patterns of atonal and genes of the DER pathway in wild-type and mutant backgrounds. Expression of atonal was restricted to a subset of the atonal -requiring chordotonal precursors, which we call founder precursors. The remaining precursors required DER signalling for their selection. Signalling by the founder precursors was initiated by atonal activating, directly or indirectly, rhomboid expression in these cells. Signalling by these founder precursors then provoked a response in the surrounding ectodermal cells, as shown by the activation of expression of the DER target genes pointed and argos . The signal and response then led to recruitment of some of the ectodermal cells to the chordotonal precursor cell fate. DER hyperactivation by misexpression of rhomboid resulted in excessive chordotonal precursor recruitment. Conclusions: Increased numbers of chordotonal precursors are recruited by homeogenetic induction involving signalling via DER from founder precursors to surrounding ectodermal cells. We suggest that the reason chordotonal Organs and photoreceptors share a requirement for the proneural gene atonal is that this gene activates a common pathway leading to neural aggregation.
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atonal is a proneural gene that directs chordotonal Organ formation in the Drosophila peripheral nervous system
Cell, 1993Co-Authors: Andrew P Jarman, Lily Yeh Jan, Yves Grau, Yuh Nung JanAbstract:In the Drosophila peripheral nervous system, proneural genes of the achaete-scute complex (ASC) are required for formation of the precursors of external Sense Organs but not of chordotonal Organs. We report the isolation of a gene, atonal (ato), with evidence that it is a proneural gene for the formation of chordotonal Organs. This gene is expressed in the proneural clusters and Sense Organ precursors that give rise to the embryonic and adult chordotonal, but not external Sense, Organs. Chordotonal Organs are eliminated in embryos carrying chromosomal deficiencies that remove ato. Like the ASC products, ato protein contains a basic-helix-loop-helix region and heterodimerizes with daughterless protein to bind to E boxes. Moreover, ectopic expression of ato promotes the formation of extra Sense Organs. Despite similar proneural properties, we find that ectopic expression of the ASC genes promotes external Sense Organ formation exclusively, whereas ato promotes chordotonal Organ formation preferentially. Thus, proneural genes are major determinants of neuronal identity.
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aSense is a Drosophila neural precursor gene and is capable of initiating Sense Organ formation.
Development (Cambridge England). Supplement, 1993Co-Authors: Michael Brand, Andrew P Jarman, Lily Yeh Jan, Yuh Nung JanAbstract:Neural precursor cells in Drosophila arise from the ectoderm in the embryo and from imaginal disc epithelia in the larva. In both cases, this process requires daughterless and the proneural genes achaete, scute and lethal-of-scute of the achaete-scute complex. These genes encode basic helix-loop-helix proteins, which are nuclear transcription factors, as does the aSense gene of the achaete-scute complex. Our studies suggest that aSense is a neural precursor gene, rather than a proneural gene. Unlike the proneural achaete-scute gene products, the aSense RNA and protein are found in the neural precursor during its formation, but not in the proneural cluster of cells that gives rise to the neural precursor cell. Also, aSense expression persists longer during neural precursor development than the proneural gene products; it is still expressed after the first division of the neural precursor. Moreover, aSense is likely to be downstream of the proneural genes, because (1) aSense expression is affected in proneural and neurogenic mutant backgrounds, (2) ectopic expression of aSense protein with an intact DNA-binding domain bypasses the requirement for achaete and scute in the formation of imaginal Sense Organs. We further note that aSense ectopic expression is capable of initiating the Sense Organ fate in cells that do not normally require the action of aSense. Our studies therefore serve as a cautionary note for the inference of normal gene function based on the gain-of-function phenotype after ectopic expression.
Marleen Klann - One of the best experts on this subject based on the ideXlab platform.
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functional analysis of Sense Organ specification in the tribolium castaneum larva reveals divergent mechanisms in insects
BMC Biology, 2021Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved and whether the principles underlying subtype identity in D. melanogaster are representative of other insects. Here, we provide evidence that such principles cannot be generalised, and suggest that sensory Organ diversification followed the recruitment of sensory genes to distinct sensory Organ specification mechanism. We analysed Sense Organ development in a nondipteran insect, the flour beetle Tribolium castaneum, by gene expression and RNA interference studies. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on the expression or their requirement for individual or combinations of conserved Sense Organ transcription factors such as cut and pox neuro, or members of the Achaete-Scute (Tc ASH, Tc aSense), Atonal (Tc atonal, Tc cato, Tc amos), and neurogenin families (Tc tap). Rather, our observations support an evolutionary scenario whereby these sensory genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla which do not fall into specific morphological and functional classes. Based on our findings and past research, we present an evolutionary scenario suggesting that Sense Organ subtype identity has evolved by recruitment of a flexible sensory gene network to the different Sense Organ specification processes. A dominant role of these genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, probably modulated by positional cues.
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Functional analysis of Sense Organ specification in the Tribolium castaneum larva reveals divergent mechanisms in insects.
BMC biology, 2021Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved and whether the principles underlying subtype identity in D. melanogaster are representative of other insects. Here, we provide evidence that such principles cannot be generalised, and suggest that sensory Organ diversification followed the recruitment of sensory genes to distinct sensory Organ specification mechanism. RESULTS: We analysed Sense Organ development in a nondipteran insect, the flour beetle Tribolium castaneum, by gene expression and RNA interference studies. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on the expression or their requirement for individual or combinations of conserved Sense Organ transcription factors such as cut and pox neuro, or members of the Achaete-Scute (Tc ASH, Tc aSense), Atonal (Tc atonal, Tc cato, Tc amos), and neurogenin families (Tc tap). Rather, our observations support an evolutionary scenario whereby these sensory genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla which do not fall into specific morphological and functional classes. CONCLUSIONS: Based on our findings and past research, we present an evolutionary scenario suggesting that Sense Organ subtype identity has evolved by recruitment of a flexible sensory gene network to the different Sense Organ specification processes. A dominant role of these genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, probably modulated by positional cues.
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Sense Organ formation and identity are controlled by divergent mechanisms in insects
2020Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Abstract Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved in arthropods, and if the D. melanogaster subtype identity principle is representative for insects. To address these questions, we analyse Sense Organ development in another insect, the flour beetle Tribolium castaneum. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on their requirement for individual or combinations of the conserved Sense Organ transcription factors such as cut and pox-neuro and members of the Achaete-Scute (Tc ASH, Tc aSense) and Atonal family (Tc atonal, Tc cato, Tc amos). Rather, these genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla. Based on our findings and past research, we present an evolutionary scenario suggesting that sensory Organs have diversified from a default state through subsequent recruitment of sensory genes to the different Sense Organ specification processes. A specific role for genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, which can largely not be aligned with morphological or functional categories.
Magdalena Ines Schacht - One of the best experts on this subject based on the ideXlab platform.
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functional analysis of Sense Organ specification in the tribolium castaneum larva reveals divergent mechanisms in insects
BMC Biology, 2021Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved and whether the principles underlying subtype identity in D. melanogaster are representative of other insects. Here, we provide evidence that such principles cannot be generalised, and suggest that sensory Organ diversification followed the recruitment of sensory genes to distinct sensory Organ specification mechanism. We analysed Sense Organ development in a nondipteran insect, the flour beetle Tribolium castaneum, by gene expression and RNA interference studies. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on the expression or their requirement for individual or combinations of conserved Sense Organ transcription factors such as cut and pox neuro, or members of the Achaete-Scute (Tc ASH, Tc aSense), Atonal (Tc atonal, Tc cato, Tc amos), and neurogenin families (Tc tap). Rather, our observations support an evolutionary scenario whereby these sensory genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla which do not fall into specific morphological and functional classes. Based on our findings and past research, we present an evolutionary scenario suggesting that Sense Organ subtype identity has evolved by recruitment of a flexible sensory gene network to the different Sense Organ specification processes. A dominant role of these genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, probably modulated by positional cues.
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Functional analysis of Sense Organ specification in the Tribolium castaneum larva reveals divergent mechanisms in insects.
BMC biology, 2021Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved and whether the principles underlying subtype identity in D. melanogaster are representative of other insects. Here, we provide evidence that such principles cannot be generalised, and suggest that sensory Organ diversification followed the recruitment of sensory genes to distinct sensory Organ specification mechanism. RESULTS: We analysed Sense Organ development in a nondipteran insect, the flour beetle Tribolium castaneum, by gene expression and RNA interference studies. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on the expression or their requirement for individual or combinations of conserved Sense Organ transcription factors such as cut and pox neuro, or members of the Achaete-Scute (Tc ASH, Tc aSense), Atonal (Tc atonal, Tc cato, Tc amos), and neurogenin families (Tc tap). Rather, our observations support an evolutionary scenario whereby these sensory genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla which do not fall into specific morphological and functional classes. CONCLUSIONS: Based on our findings and past research, we present an evolutionary scenario suggesting that Sense Organ subtype identity has evolved by recruitment of a flexible sensory gene network to the different Sense Organ specification processes. A dominant role of these genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, probably modulated by positional cues.
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Sense Organ formation and identity are controlled by divergent mechanisms in insects
2020Co-Authors: Marleen Klann, Magdalena Ines Schacht, Matthew A. Benton, Angelika StollewerkAbstract:Abstract Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory and gustatory reception. These Sense Organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of Sense Organs is regulated by specific combinations of transcription factors. In other arthropods, however, Sense Organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how Sense Organ diversity has evolved in arthropods, and if the D. melanogaster subtype identity principle is representative for insects. To address these questions, we analyse Sense Organ development in another insect, the flour beetle Tribolium castaneum. We show that in contrast to D. melanogaster, T. castaneum Sense Organs cannot be categorised based on their requirement for individual or combinations of the conserved Sense Organ transcription factors such as cut and pox-neuro and members of the Achaete-Scute (Tc ASH, Tc aSense) and Atonal family (Tc atonal, Tc cato, Tc amos). Rather, these genes are required for the specification of Sense Organ precursors and the development and differentiation of sensory cell types in diverse external sensilla. Based on our findings and past research, we present an evolutionary scenario suggesting that sensory Organs have diversified from a default state through subsequent recruitment of sensory genes to the different Sense Organ specification processes. A specific role for genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of Sense Organs, which can largely not be aligned with morphological or functional categories.
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Distribution and development of the external Sense Organ pattern on the appendages of postembryonic and adult stages of the spider Parasteatoda tepidariorum
Development Genes and Evolution, 2020Co-Authors: Magdalena Ines Schacht, Martina Francesconi, Angelika StollewerkAbstract:Spiders are equipped with a large number of innervated cuticular specializations, which respond to various sensory stimuli. The physiological function of mechanosensory Organs has been analysed in great detail in some model spider species (e.g. Cupiennius salei ); however, much less is known about the distribution and function of chemosensory Organs. Furthermore, our knowledge on how the Sense Organ pattern develops on the spider appendages is limited. Here we analyse the development of the pattern and distribution of six different external mechano- and chemosensory Organs in all postembryonic stages and in adult male and female spiders of the species Parasteatoda tepidariorum . We show that except for small mechanosensory setae, external Sense Organs appear in fixed positions on the pedipalps and first walking legs, arranged in longitudinal rows along the proximal-distal axis or in invariable positions relative to morphological landmarks (joints, distal tarsal tip). A comparison to other Entelegynae spiders shows that these features are conserved. We hope that this study lays the foundation for future molecular analysis to address the question how this conserved pattern is generated.
A. Ghysen - One of the best experts on this subject based on the ideXlab platform.
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innervation is required for Sense Organ development in the lateral line system of adult zebrafish
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Hironori Wada, Christine Damblychaudiere, Koichi Kawakami, A. GhysenAbstract:Superficial mechanosensory Organs (neuromasts) distributed over the head and body of fishes and amphibians form the "lateral line" system. During zebrafish adulthood, each neuromast of the body (posterior lateral line system, or PLL) produces "accessory" neuromasts that remain tightly clustered, thereby increasing the total number of PLL neuromasts by a factor of more than 10. This expansion is achieved by a budding process and is accompanied by branches of the afferent nerve that innervates the founder neuromast. Here we show that innervation is essential for the budding process, in complete contrast with the development of the embryonic PLL, where innervation is entirely dispensable. To obtain insight into the molecular mechanisms that underlie the budding process, we focused on the terminal system that develops at the posterior tip of the body and on the caudal fin. In this subset of PLL neuromasts, bud neuromasts form in a reproducible sequence over a few days, much faster than for other PLL neuromasts. We show that wingless/int (Wnt) signaling takes place during, and is required for, the budding process. We also show that the Wnt activator R-spondin is expressed by the axons that innervate budding neuromasts. We propose that the axon triggers Wnt signaling, which itself is involved in the proliferative phase that leads to bud formation. Finally, we show that innervation is required not only for budding, but also for long-term maintenance of all PLL neuromasts.
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Development of the zebrafish lateral line.
Current Opinion in Neurobiology, 2004Co-Authors: A. Ghysen, Christine Dambly-chaudièreAbstract:The lateral line system is simple (comprising six cell types), its Sense Organs form according to a defined and reproducible pattern, and its neurons are easily visualized. In the zebrafish, these advantages can be combined with a wealth of genetic tools, making this system ideally suited to a combined molecular, cellular and genetic analysis. Recent progress has taken advantage of these various qualities to elucidate the mechanism that drives the migration from head to tail of the Sense Organ precursor cells, and to approach the questions surrounding axonal guidance and target recognition.
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lineage and fate in drosophila role of the gene tramtrack in Sense Organ development
Development Genes and Evolution, 1997Co-Authors: Genevieve Ramaekers, A. Ghysen, Kazuya Usui, Akiko Usuiishihara, Ariane Ramaekers, Valerie Ledent, Christine DamblychaudiereAbstract:The tactile bristles of the fly comprise four cells that originate from a single precursor cell through a fixed lineage. The gene tramtrack (ttk) plays a crucial role in defining the fates of these cells. Here we analyse the normal pattern of expression of ttk, as well as the effect of ttk overexpression at different steps of the lineage. We show that ttk is never expressed in cells having a neural potential, and that in cells where ttk is expressed, there is a delay between division and the onset of expression. The ectopic expression of ttk before some stage of the cell cycle can block further cell division. Furthermore, this expression transforms neural into non-neural cells, suggesting that ttk acts as a repressor of neural fate at each step of the lineage. Our results suggest that ttk is probably not involved in setting up the mechanism that creates an asymmetry between sister cells, but rather in the implementation of that choice.
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Genetic determinants of Sense Organ identity in Drosophila: regulatory interactions between cut and poxn.
Development (Cambridge England), 1995Co-Authors: Michel Vervoort, A. Ghysen, D Zink, Nathalie Pujol, K Victoir, N. Dumont, Christine Dambly-chaudièreAbstract:Two genes involved in defining the type of Sense Organ have been identified in Drosophila. The gene cut differentiates the external Sense Organs (where it is expressed) from the chordotonal Organs (where it is not); among the external Sense Organs poxn differentiates the poly-innervated Organs (where it is expressed) from the mono-innervated Organs (where it is not). Here we show that the expression of poxn in normal embryos does not depend on cut, and that poxn is capable of inducing the expression of cut. We have identified a small domain of the very large cut regulatory region as a likely target for activation by poxn.
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the determination of Sense Organs in drosophila effect of the neurogenic mutations in the embryo
Development, 1991Co-Authors: Anne Goriely, N. Dumont, Christine Damblychaudiere, A. GhysenAbstract:We have examined the early pattern of sensory mother cells in embryos mutant for six different neurogenic loci. Our results show that the neurogenic loci are required to restrict the number of competent cells that will become sensory mother cells, but are not involved in controlling the localization or the position-dependent specification of competent cells. We conclude that these loci are involved in setting up a system of mutual inhibition, which transforms graded differences within the proneural clusters into an all-or-none difference between one cell, which becomes the Sense Organ progenitor cell, and the other cells, which remain epidermal.
