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Michael J Layden - One of the best experts on this subject based on the ideXlab platform.
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dynamics and variability in regenerative potential of neuronal subtypes in the nematostella Nerve Net
bioRxiv, 2019Co-Authors: Jamie A Havrilak, Eric Röttinger, Layla Alshaer, Nesli Akinci, Aldine R Amiel, Michael J LaydenAbstract:Abstract The cell dynamics and responses of individual neuronal cell types during whole-body axis regeneration are not well understood in any system. We exploited transgenic technology to track individual neuronal subtypes within regenerating Nematostella vectensis Nerve Nets in vivo. Individual neuronal subtypes had specific responses that included always, never, and conditional regeneration. Regenerates were smaller than the pre-amputated animal, and the Nerve Net was reduced in neuronal number. The reduced Nerve Net in regenerates led us to investigate whether the Nerve Net scaled with changes in body size. Neuronal number decreased as animals shrunk in response to starvation. Conversely, neurons increased in fed animals as they increased in length. The increase and decrease of neurons was reversible by switching fed animals to starvation and vice versa. Regenerates and starved/fed animals with scaled-down or scaled-up nervous systems responded to external mechanical cues. These data suggest that the Nematostella Nerve Net is dynamic, capable of scaling with changes to overall body size, and that individual neuronal subtypes display differential regenerative potential which is likely linked to the scale-state of regenerating nervous system.
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characterization of nvlwamide like neurons reveals stereotypy in nematostella Nerve Net development
Developmental Biology, 2017Co-Authors: Jamie A Havrilak, Dylan Z Faltinegonzalez, Yiling Wen, Daniella Fodera, Ayanna C Simpson, Craig R Magie, Michael J LaydenAbstract:The organization of cnidarian Nerve Nets is traditionally described as diffuse with randomly arranged neurites that show minimal reproducibility between animals. However, most observations of Nerve Nets are conducted using cross-reactive antibodies that broadly label neurons, which potentially masks stereotyped patterns produced by individual neuronal subtypes. Additionally, many cnidarians species have overt structures such as a Nerve ring, suggesting higher levels of organization and stereotypy exist, but mechanisms that generated that stereotypy are unknown. We previously demonstrated that NvLWamide-like is expressed in a small subset of the Nematostella Nerve Net and speculated that observing a few neurons within the developing Nerve Net would provide a better indication of potential stereotypy. Here we document NvLWamide-like expression more systematically. NvLWamide-like is initially expressed in the typical neurogenic salt and pepper pattern within the ectoderm at the gastrula stage, and expression expands to include endodermal salt and pepper expression at the planula larval stage. Expression persists in both ectoderm and endoderm in adults. We characterized our NvLWamide-like::mCherry transgenic reporter line to visualize neural architecture and found that NvLWamide-like is expressed in six neural subtypes identifiable by neural morphology and location. Upon completing development the numbers of neurons in each neural subtype are minimally variable between animals and the projection patterns of each subtype are consistent. Furthermore, between the juvenile polyp and adult stages the number of neurons for each subtype increases. We conclude that development of the Nematostella Nerve Net is stereotyped between individuals. Our data also imply that one aspect of generating adult cnidarian nervous systems is to modify the basic structural architecture generated in the juvenile by increasing neural number proportionally with size.
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characterization of nvlwamide like neurons reveals stereotypy in nematostella Nerve Net development
bioRxiv, 2017Co-Authors: Jamie A Havrilak, Dylan Z Faltinegonzalez, Yiling Wen, Daniella Fodera, Ayanna C Simpson, Craig R Magie, Michael J LaydenAbstract:Cnidarian nervous systems are traditionally described as diffuse Nerve Nets lacking true organization. However, there are examples of stereotypical structure in the Nerve Nets of multiple cnidarian species that suggest Nerve Nets are organized. We previously demonstrated that the NvashA target gene NvLWamide-like is expressed in a small subset of the Nematostella Nerve Net and speculated that observing a few neurons within the developing Nerve Net would provide a better indication of potential stereotypy. Here we document NvLWamide-like expression more systematically. NvLWamide-like is initially expressed in the typical neurogenic salt and pepper pattern within the ectoderm at the gastrula stage, and expression expands to include endodermal salt and pepper expression at the planula larval stage. Expression persists in both ectoderm and endoderm in adults. We generated an NvLWamide-like::mCherry transgenic reporter line to visualize the neural architecture. NvLWamide-like is expressed in six neural subtypes identifiable by neural morphology and location. Upon completing development the numbers of neurons in each neural subtype are minimally variable between animals and the projection patterns of each subtype are consistent. Between the juvenile polyp and adult stages the number of neurons for each subtype increases. We conclude that cnidarian Nerve Nets are organized, develop in a stereotyped fashion, and that one aspect of generating the adult nervous system is to modify the juvenile nervous system by increasing neural number proportionally with size.
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MAPK signaling is necessary for neurogenesis in Nematostella vectensis
BMC Biology, 2016Co-Authors: Michael J Layden, Eric Röttinger, Aldine Amiel, Hereroa Johnston, Jamie Havrilak, Bailey Steinworth, Taylor Chock, Mark MartindaleAbstract:The Nerve Net of Nematostella is generated using a conserved cascade of neurogenic transcription factors. For example, NvashA, a homolog of the achaete-scute family of basic helix-loop-helix transcription factors, is necessary and sufficient to specify a subset of embryonic neurons. However, positive regulators required for the expression of neurogenic transcription factors remain poorly understood.
Thomas W. Holstein - One of the best experts on this subject based on the ideXlab platform.
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Sequential actions of b-catenin and Bmp pattern the oral Nerve Net in Nematostella vectensis
2016Co-Authors: Hiroshi Watanabe, Anne Kuhn, Manami Fushiki, Kiyokazu Agata, Toshitaka Fujisawa, Thomas W. HolsteinAbstract:Animal evolution is closely linked to the emergence of the nervous system. At present it is unknown how the basic mechanisms of neural induction and formation of central nervous systems evolved. We addressed this question in Nematostella vectensis, a member of cnidarians, the ancient sister group of bilaterians. We found that b-catenin signalling is crucial for the early induction of the embryonic nervous system. b-Catenin activity at the blastopore induces specific neurogenic genes required for development of the oral nervous system. b-Catenin signalling induces also Bmp signalling, which, at later larval stages, becomes indispensible for the maintenance and asymmetric patterning of the oral nervous system along the primary and secondary (directive) axes. We hypothesize that the consecutive and functionally linked involvement of b-catenin and Bmp signalling in the formation of the cnidarian oral nervous system reflects an ancestral mechanism that evolved before the cnidarian/bilaterian split
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Sequential actions of β-catenin and Bmp pattern the oral Nerve Net in Nematostella vectensis
Nature communications, 2014Co-Authors: Hiroshi Watanabe, Suat Özbek, Anne Kuhn, Manami Fushiki, Kiyokazu Agata, Toshitaka Fujisawa, Thomas W. HolsteinAbstract:Animal evolution is closely linked to the emergence of the nervous system. At present it is unknown how the basic mechanisms of neural induction and formation of central nervous systems evolved. We addressed this question in Nematostella vectensis, a member of cnidarians, the ancient sister group of bilaterians. We found that β-catenin signalling is crucial for the early induction of the embryonic nervous system. β-Catenin activity at the blastopore induces specific neurogenic genes required for development of the oral nervous system. β-Catenin signalling induces also Bmp signalling, which, at later larval stages, becomes indispensible for the maintenance and asymmetric patterning of the oral nervous system along the primary and secondary (directive) axes. We hypothesize that the consecutive and functionally linked involvement of β-catenin and Bmp signalling in the formation of the cnidarian oral nervous system reflects an ancestral mechanism that evolved before the cnidarian/bilaterian split.
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Phenotypic maturation of neurons and continuous precursor migration in the formation of the peduncle Nerve Net in Hydra.
Developmental biology, 1996Co-Authors: Ulrich Technau, Thomas W. HolsteinAbstract:Abstract Mechanisms of Nerve Net formation inHydrawere analyzed using a monoclonal antibody (L96) directed against neurons of the peduncle, the basal end of the polyp's body axis. L96+neurons express RFamide neuropeptides and constitute 70–80% of all ectodermal neurons in the lower peduncle. L96+neurons arise from neuronal precursors which immigrate from the gastric region into the upper peduncle and first differentiate into neurons lacking the L96 antigen. By tissue movement, these L96−neurons become displaced to the lower peduncle where L96 antigen expression is initiated. The entire L96 neuron differentiation pathway requires about 4 days, but regeneration stimuli shorten it to only 36 hr. Our experiments indicate that local extrinsic signals released by epithelial cells in the peduncle control the L96+neuron differentiation pathway. Ectopic L96+neuron differentiation can be induced by LiCl treatment, which also stimulates ectopic feet in the gastric region. Further experiments show that intrinsic signals are also involved in the L96+neuron differentiation pathway. Neurons of the gastric region become continuously displaced to the peduncle by tissue movement, but these “old” neurons fail to express the L96 antigen in response to the altered epithelial environment. Gastric neurons also fail to express the L96 antigen after LiCl treatment or regeneration in stem cell-depleted polyps. Thus, the competence of neurons to respond to environmental cues with L96 antigen expression is strongly age-dependent. We define this age-dependent acquisition of the neuronal phenotype as phenotypic maturation controlled by the target tissue.
L. M. Passano - One of the best experts on this subject based on the ideXlab platform.
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spasm behavior and the diffuse Nerve Net in cassiopea xamachana scyphozoa coelenterata
Hydrobiologia, 2004Co-Authors: L. M. PassanoAbstract:A quick train of diffuse Nerve-Net (DNN) impulses is required to initiate a patterned flurry of strong contractions, the ‘spasm,’ of the striated muscles of the rhizostome scyphomedusan Cassiopea xamachana. A number of spasms are illustrated. Using this response as a tool, the connectivity of the DNN has been established. The occurrence and variability of the spasm is illustrated with an analysis of their occurrence in a typical, extended experiment. It is proposed that the spasm is an integral and essential component of the behavior of scyphomedusae, and that its control by the DNN exemplifies how complex behavior is generated.
Jamie A Havrilak - One of the best experts on this subject based on the ideXlab platform.
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dynamics and variability in regenerative potential of neuronal subtypes in the nematostella Nerve Net
bioRxiv, 2019Co-Authors: Jamie A Havrilak, Eric Röttinger, Layla Alshaer, Nesli Akinci, Aldine R Amiel, Michael J LaydenAbstract:Abstract The cell dynamics and responses of individual neuronal cell types during whole-body axis regeneration are not well understood in any system. We exploited transgenic technology to track individual neuronal subtypes within regenerating Nematostella vectensis Nerve Nets in vivo. Individual neuronal subtypes had specific responses that included always, never, and conditional regeneration. Regenerates were smaller than the pre-amputated animal, and the Nerve Net was reduced in neuronal number. The reduced Nerve Net in regenerates led us to investigate whether the Nerve Net scaled with changes in body size. Neuronal number decreased as animals shrunk in response to starvation. Conversely, neurons increased in fed animals as they increased in length. The increase and decrease of neurons was reversible by switching fed animals to starvation and vice versa. Regenerates and starved/fed animals with scaled-down or scaled-up nervous systems responded to external mechanical cues. These data suggest that the Nematostella Nerve Net is dynamic, capable of scaling with changes to overall body size, and that individual neuronal subtypes display differential regenerative potential which is likely linked to the scale-state of regenerating nervous system.
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characterization of nvlwamide like neurons reveals stereotypy in nematostella Nerve Net development
Developmental Biology, 2017Co-Authors: Jamie A Havrilak, Dylan Z Faltinegonzalez, Yiling Wen, Daniella Fodera, Ayanna C Simpson, Craig R Magie, Michael J LaydenAbstract:The organization of cnidarian Nerve Nets is traditionally described as diffuse with randomly arranged neurites that show minimal reproducibility between animals. However, most observations of Nerve Nets are conducted using cross-reactive antibodies that broadly label neurons, which potentially masks stereotyped patterns produced by individual neuronal subtypes. Additionally, many cnidarians species have overt structures such as a Nerve ring, suggesting higher levels of organization and stereotypy exist, but mechanisms that generated that stereotypy are unknown. We previously demonstrated that NvLWamide-like is expressed in a small subset of the Nematostella Nerve Net and speculated that observing a few neurons within the developing Nerve Net would provide a better indication of potential stereotypy. Here we document NvLWamide-like expression more systematically. NvLWamide-like is initially expressed in the typical neurogenic salt and pepper pattern within the ectoderm at the gastrula stage, and expression expands to include endodermal salt and pepper expression at the planula larval stage. Expression persists in both ectoderm and endoderm in adults. We characterized our NvLWamide-like::mCherry transgenic reporter line to visualize neural architecture and found that NvLWamide-like is expressed in six neural subtypes identifiable by neural morphology and location. Upon completing development the numbers of neurons in each neural subtype are minimally variable between animals and the projection patterns of each subtype are consistent. Furthermore, between the juvenile polyp and adult stages the number of neurons for each subtype increases. We conclude that development of the Nematostella Nerve Net is stereotyped between individuals. Our data also imply that one aspect of generating adult cnidarian nervous systems is to modify the basic structural architecture generated in the juvenile by increasing neural number proportionally with size.
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characterization of nvlwamide like neurons reveals stereotypy in nematostella Nerve Net development
bioRxiv, 2017Co-Authors: Jamie A Havrilak, Dylan Z Faltinegonzalez, Yiling Wen, Daniella Fodera, Ayanna C Simpson, Craig R Magie, Michael J LaydenAbstract:Cnidarian nervous systems are traditionally described as diffuse Nerve Nets lacking true organization. However, there are examples of stereotypical structure in the Nerve Nets of multiple cnidarian species that suggest Nerve Nets are organized. We previously demonstrated that the NvashA target gene NvLWamide-like is expressed in a small subset of the Nematostella Nerve Net and speculated that observing a few neurons within the developing Nerve Net would provide a better indication of potential stereotypy. Here we document NvLWamide-like expression more systematically. NvLWamide-like is initially expressed in the typical neurogenic salt and pepper pattern within the ectoderm at the gastrula stage, and expression expands to include endodermal salt and pepper expression at the planula larval stage. Expression persists in both ectoderm and endoderm in adults. We generated an NvLWamide-like::mCherry transgenic reporter line to visualize the neural architecture. NvLWamide-like is expressed in six neural subtypes identifiable by neural morphology and location. Upon completing development the numbers of neurons in each neural subtype are minimally variable between animals and the projection patterns of each subtype are consistent. Between the juvenile polyp and adult stages the number of neurons for each subtype increases. We conclude that cnidarian Nerve Nets are organized, develop in a stereotyped fashion, and that one aspect of generating the adult nervous system is to modify the juvenile nervous system by increasing neural number proportionally with size.
Yoshitaka Kobayakawa - One of the best experts on this subject based on the ideXlab platform.
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structure development and maintenance of the Nerve Net of the body column in hydra
The Journal of Comparative Neurology, 1996Co-Authors: Masahiko Sakaguchi, A Mizusina, Yoshitaka KobayakawaAbstract:The anatomy and developmental dynamics of the Nerve Net in the body column of Hydra viridissima were examined immunocytochemically with a monoclonal antibody (CC04) that recognizes an antigen in Nerve cells and with an antiserum against vasopressin. CC04+ neuron cell bodies, their neurites, and vasopressin-like-immunoreactive (VLI+) neurites could be clearly visualized on whole-amount preparations. All neurites of the CC04+ neurons in the body column were VLI+. However, only half of the VLI+ neurites in the body column were CC04+. Immunocytochemical analysis of macerated preparations showed that half of the neurons in the gastric region of the body column were CC04+. These results suggest that most of the neurons in the gastric region are VLI+. The density of the VLI+ neurites was uniform along the entire length of the body column. The CC04+ neuron density in the gastric region remained constant at all stages of asexual development and during foot regeneration. After pulse-labeling with 5-bromo-2′-deoxyuridine (BrdU), CC04+ neurons with labeled nuclei appeared in the body column. We conclude that neuron density in the gastric region is maintained at a constant value by insertion of new neurons in parallel with continuous epithelial cell division. © 1996 Wiley-Liss, Inc.
