scholarly journals Characterisation of geometric variance in the epithelial nerve net of the ctenophore Pleurobrachia pileus

2021 ◽  
Author(s):  
Amy Courtney ◽  
Jérémy Liegey ◽  
Niamh Burke ◽  
Amy R. Hassett ◽  
Madeleine Lowery ◽  
...  
Keyword(s):  
Nerve Net ◽  
Pleurobrachia Pileus

scholarly journals Characterisation of Geometric Variance in the Epithelial Nerve Net of the Ctenophore Pleurobrachia pileus

2020 ◽  
Author(s):  
Amy Courtney ◽  
Jérémy Liegey ◽  
Niamh Burke ◽  
Madeleine Lowey ◽  
Mark Pickering
Keyword(s):  
Body Surface ◽  
Structural Characteristics ◽  
Model Organism ◽  
Morphological Features ◽  
The Body ◽  
Model Organisms ◽  
Neural Function ◽  
Structural Description ◽  
Nerve Net ◽  
Pleurobrachia Pileus

AbstractNeuroscience currently lacks a diverse repertoire of model organisms, resulting in an incomplete understanding of what principles of neural function generalise and what are species-specific. Ctenophores display many neurobiological and experimental features which make them a promising candidate to fill this gap. They possess a nerve net distributed across their outer body surface, just beneath the epithelial layer. There is a long-held assumption that nerve nets are ‘simple’ and random while lacking distinct organisational principles. We want to challenge this assumption and determine how stereotyped the structure of this network really is. We validated an approach to estimate body surface area in Pleurobrachia pileus using custom Optical Projection Tomography and Light Sheet Morphometry imaging systems. We used an antibody against tyrosylated α-tubulin to visualise the nerve net in situ. We used an automated segmentation approach to extract the morphological features of the nerve net. We characterised organisational rules of the epithelial nerve net in P. pileus in animals of different sizes and at different regions of the body. We found that specific morphological features within the nerve net are largely un-changed during growth. These properties must be essential to the functionality of the nervous system and therefore are maintained during a change in body size. We have also established the principles of organisation of the network and showed that some of the geometric properties are variable across different parts of the body. This suggests that there may be different functions occurring in regions with different structural characteristics. This is the most comprehensive structural description of a nerve net to date. This study also demonstrates the amenability of the ctenophore P. pileus for whole organism network analysis and shows their promise as a model organism for neuroscience, which may provide insights into the foundational principles of nervous systems.

Patterns of electrical activity in comb plates of feeding Pleurobrachia (Ctenophora)

1993 ◽  
Vol 339 (1287) ◽  
pp. 1-16 ◽  
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
High Speed ◽  
Extracellular Recording ◽  
High Speed Video ◽  
Nerve Net ◽  
Postsynaptic Activity ◽  
Conducting Pathway ◽  
Pleurobrachia Pileus ◽  
Stimulation Of

The electromotor behaviour of ciliary comb plates was studied during prey-stimulated and electrically stimulated feeding by intact Pleurobrachia pileus (Müller). Comb plate electrical activity was recorded by extracellular electrodes attached directly to the cilia; comb plate motility was recorded by high-speed video microscopy. Comb plate electrical activity fell into two distinct classes, identified by waveform and amplitude: (i) excitatory postsynaptic potentials (EPSPS) in the comb plate (polster) cells and (ii) regenerative potentials in the cilia, as described previously (Moss & Tamm 1987). Slow phasic bursts of regenerative potentials (reversal volleys) were observed in comb plates of rows undergoing reversed beating during capture of prey or by rhythmic electrical stimulation of the tentacles. All plates of a given comb row exhibited virtually identical electrical activity. Timing and development of electrical activity in comb plates of the subtentacular (ST) rows were nearly identical even though separated by several centimetres; onset of the reversal volleys of plates of subsagittal (SS) rows were delayed on average by about 0.5 s relative to the st rows, although individual EPSPS displayed very similar timing. Microsurgery, combined with extracellular recording from comb plates and the tentacle and associated basal structures, revealed the presence of an integrative center in the tentacular bulb. This communicates with the comb plates by means of a diffuse pathway, presumably the nerve net, which itself is maximally sensitive to rhythmic input. The pathway underlying the reversal volley may innervate only the stimulated hemisphere. In addition to the rhythmic pathway, a through-conducting pathway runs from distal regions of the tentacle to the comb plate cells. Yet another excitatory pathway, possibly distinct from the tentacular through-conducting pathway, may mediate certain cases of global postsynaptic activity. The pathway that controls mouth movements during feeding is entirely independent of any comb plate pathway.

Heat Flow Measurement by Force and Thermal Sensor Stick with Nerve-net LSI Chip

2019 ◽  
Vol 139 (8) ◽  
pp. 258-264
Author(s):  
Hayato Tsuchiya ◽  
Yusuke Suganuma ◽  
Masanori Muroyama ◽  
Takahiro Nakayama ◽  
Yutaka Nonomura
Keyword(s):  
Heat Flow ◽  
Flow Measurement ◽  
Thermal Sensor ◽  
Nerve Net

Three digestive movements in Hydra regulated by the diffuse nerve net in the body column

2004 ◽  
Vol 190 (8) ◽  
Author(s):  
Hiroshi Shimizu ◽  
Osamu Koizumi ◽  
Toshitaka Fujisawa
Keyword(s):  
The Body ◽  
Nerve Net ◽  
Body Column

The Behaviour and Neuromuscular System of Gonactinia Prolifera, A Swimming Sea-Anemone

1971 ◽  
Vol 55 (3) ◽  
pp. 611-640
Author(s):  
ELAINE A. ROBSON
Keyword(s):  
Electrical Stimulation ◽  
Mechanical Stimulation ◽  
Motor Units ◽  
Nerve Cells ◽  
Sea Anemone ◽  
Neuromuscular System ◽  
Sea Anemones ◽  
Nerve Net ◽  
Local Contraction ◽  
Electric Shocks

1. In Gonactinia well-developed ectodermal muscle and nerve-net extend over the column and crown and play an important part in the anemone's behaviour. 2. Common sequences of behaviour are described. Feeding is a series of reflex contractions of different muscles by means of which plankton is caught and swallowed. Walking, in the form of brief looping steps, differs markedly in that it continues after interruptions. Anemones also swim with rapid tentacle strokes after contact with certain nudibranch molluscs, strong mechanical disturbance or electrical stimulation. 3. Swimming is attributed to temporary excitation of a diffuse ectodermal pacemaker possibly situated in the upper column. 4. From the results of electrical and mechanical stimulation it is concluded that the endodermal neuromuscular system resembles that of other anemones but that the properties of the ectodermal neuromuscular system require a new explanation. The size and spread of responses to electric shocks vary with intensity, latency is variable and there is a tendency to after-discharge. There is precise radial localization, for example touching a tentacle or the column causes it to bend towards or away from the stimulus. 5. A model to explain these and other features includes multipolar nerve cells closely linked to the nerve-net which would act as intermediate motor units, causing local contraction of the ectodermal muscle. This scheme can be applied to other swimming anemones but there is no evidence that it holds for sea anemones generally.

scholarly journals The Nerve-Net of the Actinozoa

1935 ◽  
Vol 12 (2) ◽  
pp. 156-164
Author(s):  
C. F. A. PANTIN
Keyword(s):  
Arbitrary Element ◽  
Primary Response ◽  
Reverse Direction ◽  
Neuromuscular System ◽  
Nervous Systems ◽  
Nerve Net ◽  
Conducting Path ◽  
Synaptic Junctions ◽  
Regular Relation

1. Polarity exists in Calliactis, particularly in the tentacles. In these, there is a centripetal polarity of anatomical origin, but there is in addition a physiological polarity running centrifugally. More stimuli are required to facilitate a conducting path centrally from a point on the tentacle than in the reverse direction. Polarity may originate by the development of differential facilitation rates. 2. In some individuals, a kind of after-discharge is observed. A series of one or more extra contractions follows the primary response to a stimulus. Though these appear only after a stimulus has been given they are only indirectly caused by it. Their presence or absence cannot be predicted and seems to bear no relation to the strength of the stimulus. They introduce an arbitrary element into the otherwise singularly regular relation between stimulus and response. 3. Several possible sources for the phenomenon are considered, including synaptic junctions between conducting units of the nerve net, but there are difficulties in accepting any of them. 4. The nerve net of Calliactis possesses many of the properties of the nervous systems of more highly organised animals. The danger is pointed out of employing the unique skeletal neuromuscular system of the Vertebrata as the standard by which the nervous arrangement of other phyla are to be compared.

scholarly journals Maintenance and Regeneration of the Nerve Net in Hydra

1988 ◽  
Vol 28 (4) ◽  
pp. 1053-1063 ◽  
Author(s):  
H. R. BODE ◽  
S. HEIMFELD ◽  
O. KOIZUMI ◽  
C. L. LlTTLEFIELD ◽  
M. S. YAROSS
Keyword(s):  
Nerve Net
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