Ultrastructure of neuro‐spirocyte synapses in the sea anemone Aiptasia pallida (Cnidaria, Anthozoa, Zoantharia)

Westfall, Jane A.; Landers, Denise D.; McCallum, Jennifer

doi:10.1002/(sici)1097-4687(199908)241:2<165::aid-jmor6>3.3.co;2-y

Cited by 6 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By following the basal region of the spirocystcontaining cells in the region of the nerve plexus we found 15 synapses in tentacles from five animals (Westfall et al, 1999). Ten of the neuro-spirocyte synapses contained clear vesicles ranging from 69 to 84 nm in diameter and five had densecored vesicles with diameters of 97-120 nm.…”

Section: Neural Pathways To Spirocytesmentioning

confidence: 94%

Neural pathways and innervation of cnidocytes in tentacles of sea anemones

Westfall

2004

Hydrobiologia

Self Cite

View full text Add to dashboard Cite

Our previously published studies are here reviewed detailing neuro-cnidocyte synapses, demonstrating putative neurotransmitter substances, and identifying complex neural pathways in sea anemones. Synapses were traced to their contacts on nematocytes and spirocytes by transmission electron microscopy of serial thin sections of tentacles. In five animals, cells containing microbasic p-mastigophores had synapses with clear vesicles, whereas cells containing basitrichous isorhizas had synapses with dense-cored vesicles, providing preliminary evidence for a selectivity of neurotransmitter types for different nematocysts. Either clear or dense-cored synaptic vesicles were also present at neuro-spirocyte contacts. Antho-RFamide immunoreactivity occurred in some anthozoan synaptic vesicles and immunogold labeling of serotonin was found at a neuro-spirocyte synapse. Neural pathways included direct innervation of spirocytes by sensory cells, sequential neuro-neuro-spirocyte and neuro-neuro-nematocyte synapses and reciprocal synapses involving axons of both sensory cells and ganglion cells. Such synaptic patterns resemble neuro-effector pathways found in higher animals and lay to rest the independent effector hypothesis for cnidocyte discharge in tentacles of sea anemones.

show abstract

Section: Neural Pathways To Spirocytesmentioning

confidence: 94%

Neural pathways and innervation of cnidocytes in tentacles of sea anemones

Westfall

2004

Hydrobiologia

Self Cite

View full text Add to dashboard Cite

show abstract

“…Spirocytes and nematocytes are a subgroup of specialized cells called cnidocytes, which are a characteristic cell type of cnidarians (Mariscal, 1984). Spirocytes are primarily activated by the stimulus of food and create a fibrous-like matrix on discharge of their solid tubules to increase surface area and the stickiness of the tentacle (Mariscal, 1984;Westfall et al, 1999) whereas nematocytes are stinging cells used during prey capture and inter-colony aggression (Hidaka, 1985). While further investigations on these cell types needs to be done, it is possible that they play an important role in generalized stress response.…”

Section: Ap-1 and Fosb As Heat Stress Regulatorsmentioning

confidence: 99%

The cell specificity of gene expression in the response to heat stress in corals

Traylor-Knowles

Rose

Palumbi

2017

Journal of Experimental Biology

View full text Add to dashboard Cite

Previous transcriptional studies in heat-stressed corals have shown that many genes are responsive to generalized heat stress whereas the expression patterns of specific gene networks after heat stress show strong correlations with variation in bleaching outcomes. However, where these specific genes are expressed is unknown. In this study, we employed in situ hybridization to identify patterns of spatial gene expression of genes previously predicted to be involved in general stress response and bleaching. We found that tumor necrosis factor receptors (TNFRs), known to be strong responders to heat stress, were not expressed in gastrodermal symbiont-containing cells but were widely expressed in specific cells of the epidermal layer. The transcription factors AP-1 and FosB, implicated as early signals of heat stress, were widely expressed throughout the oral gastrodermis and epidermis. By contrast, a G protein-coupled receptor gene (GPCR) and a fructose bisphosphate aldolase C gene (aldolase), previously implicated in bleaching, were expressed in symbiont-containing gastrodermal cells and in the epidermal tissue. Finally, chordin-like/kielin (chordin-like), a gene highly correlated to bleaching, was expressed solely in the oral gastrodermis. From this study, we confirm that heat-responsive genes occur widely in coral tissues outside of symbiont-containing cells. Joint information about expression patterns in response to heat and cell specificity will allow greater dissection of the regulatory pathways and specific cell reactions that lead to coral bleaching.

show abstract

“…This view of nematocyst functioning has prevailed among many biologists over the years. However, there is a growing body of evidence that indicates that nematocytes are innervated and responsive to signals received and transduced elsewhere, in other parts of the animal (Ewer 1947;Ross and Sutton 1964;Hufnagel and Kass-Simon 1988;Kass-Simon 1988;Westfall 1988;Westfall et al 1998Westfall et al , 1999, which argues against the hypothesis and suggests that nematocyst behavior is at least modulated, if not completely controlled, by the nervous system.…”

Section: Control Of Dischargementioning

confidence: 99%

The behavioral and developmental physiology of nematocysts

Kass-Simon¹,

Scappaticci²

2002

Can. J. Zool.

187

143

View full text Add to dashboard Cite

Nematocysts are the nonliving secretions of specialized cells, the nematocytes, which develop from multipotent stem cells. Nematocysts are the means by which coelenterates capture prey and defend against predation. The 25 or more known types of nematocysts can be divided into to four functional categories: those that pierce, ensnare, or adhere to prey, and those that adhere to the substrate. During development a collagenous cyst, which may contain toxins, forms; a hollow thread, which becomes coiled as it invaginates, develops. Maturing nematocytenematocyst complexes migrate to their discharge sites and are deployed in specific patterns. The mechanisms of pattern determination are not clear. Discharge of nematocysts appears to involve increases in intracapsular osmotic pressure consequent upon release of bound calcium within the capsule; the eversion of the filament may depend upon release of structural tension consequent upon a loss of zinc from the thread. Evidence exists that discharge is initiated as a calcium-dependent exocytosis, triggered by an electrical signal resulting from the transduction of mechanical stimuli received at the nematocyte's cnidocil. Chemical signals transduced in adjacent sensory cells alter the frequency response of the nematocyte. In opposition to the nematocyte-nematocyst independent effector hypothesis, excitatory and inhibitory neuronal input appears to regulate discharge.Résumé : Les nématocystes sont des sécrétions non vivantes produites par des cellules spécialisées, les nématocytes, qui proviennent de cellules souches multipotentes. Chez les coelentérés, les nématocystes servent à la capture des proies et sont des armes de défense contre les prédateurs. Les quelque 25 types connus de nématocystes peuvent se diviser en quatre catégories fonctionnelles : ceux qui percent, ceux qui servent de pièges, ceux qui adhèrent aux proies et ceux qui adhèrent au substrat. Au cours du développement, il se forme un kyste de collagène qui peut contenir des toxines; un fil creux se déploie en spirale en s'invaginant. Les complexes nématocytes-nématocystes migrent vers leur site de vidange et ils sont disposés selon un arrangement particulier. Les mécanismes qui régissent cet arrangement sont mal connus. L'expulsion des nématocystes semble se faire par augmentation de la pression osmotique intra-capsulaire consécutive à la libération du calcium lié dans la capsule; l'évagination du filament peut dépendre du relâchement de la tension structurale qui se produit lors de la perte du zinc du filament. Il semble, d'après certains indices, que l'expulsion des nématocystes soit d'abord une exocytose dépendant du calcium, un processus déclenché par un signal électrique résultant de la transduction de stimulus mécaniques perçus au niveau du cnidocil du nématocyte. Les stimulus chimiques modifiés par transduction dans des cellules sensorielles adjacentes modifient la fréquence de la réponse du nématocyte. En contrepartie de l'hypothèse d'un effecteur indépendant nématocyte-nématocyste, il faut envisager c...

show abstract

Ultrastructure of neuro‐spirocyte synapses in the sea anemone Aiptasia pallida (Cnidaria, Anthozoa, Zoantharia)

Cited by 6 publications

References 0 publications

Neural pathways and innervation of cnidocytes in tentacles of sea anemones

Neural pathways and innervation of cnidocytes in tentacles of sea anemones

The cell specificity of gene expression in the response to heat stress in corals

The behavioral and developmental physiology of nematocysts

Contact Info

Product

Resources

About