Excitatory Actions of Antho-RFamide, An Anthozoan Neuropeptide, on Muscles and Conducting Systems in the Sea Anemone Calliactis Parasitica

1987 ◽  
Vol 133 (1) ◽  
pp. 157-168 ◽  
Author(s):  
I. D. McFARLANE ◽  
D. GRAFF ◽  
C. J.P. GRIMMELIKHUIJZEN
Keyword(s):  
Electrical Activity ◽  
Slow Muscle ◽  
Conduction System ◽  
Sea Anemone ◽  
Sea Anemones ◽  
Nerve Net ◽  
Direct Excitation ◽  
Calliactis Parasitica ◽  
Muscle Groups ◽  
Fast Muscles

In the sea anemone Calliactis parasitica endodermal application of the anthozoan neuropeptide Antho-RFamide (<Glu-Gly-Arg-Phe-amide), at a concentration of 10−6 or 10−7moll−1, caused a long-lasting increase in tone, contraction frequency and contraction amplitude in several slow muscle groups but had no effect on contractions in fast muscles. The effects were investigated further in isolated muscle preparations. Ectodermal application to whole animals had no effect on muscle contractions. Both ectodermal and endodermal application, at 10−7moll−1, raised electrical activity in an ectodermal conduction system, the SSI, but had no effect on an endodermal conduction system, the SS2. Electrical activity in the SS2 was increased by application at 10−6moll−1 to the endoderm but not to the ectoderm. The peptide had no effect on the through-conducting nerve net. It is concluded that contractions evoked by Antho-RFamide may be partly due to neuronal activity, but probably also involve direct excitation of the muscles. The diverse excitatory actions of Antho-RFamide suggest that it may be a neurotransmitter or neuromodulator in sea anemones.

scholarly journals Nerve Nets and Conducting Systems in Sea Anemones: Two Pathways Excite Tentacle Contractions in Calliactis Parasitica

1984 ◽  
Vol 108 (1) ◽  
pp. 137-149
Author(s):  
IAN D. MCFARLANE
Keyword(s):  
Electrical Activity ◽  
Conduction System ◽  
Sea Anemones ◽  
Single Shock ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Slight Movement ◽  
Pulse Stimulation ◽  
Stimulation Of

1. Single shocks to the column sometimes evoke tentacle contractions, ranging from slight movement of a few scattered tentacles to rapid bending or shortening of all the tentacles. Some individuals are more responsive than others. Complex bursts of electrical activity follow single shocks, but only in tentacles that contract. 2. These single shocks excite pulses in two conducting systems - the through-conducting nerve net (TCNN) and the ectodermal slow conduction system (SSI). When a single shock evokes contractions and bursts of electrical activity, these usually follow the SSI pulse, rarely the TCNN pulse. Stimulation of the SSI alone causes tentacle contraction in responsive anemones. 3. Fast tentacle contractions always follow the second of two closelyspaced TCNN pulses: the TCNN shows facilitation (Pantin, 1935a). An SSI pulse, however, does not facilitate subsequent pulses in either the SSI or TCNN. 4. There are two pathways for activation of tentacle contractions. The TCNN pathway is mechano-sensitive and normally requires facilitation. The SSI pathway is mechano- and chemosensitive, only requires a single SSI pulse to evoke contraction, but is very labile. It is proposed that the TCNN and the SSI do not excite the ectodermal muscles directly, but via a multipolar nerve net.

scholarly journals Nerve Net Pacemakers and Phases of Behaviour in the Sea Anemone Calliactis Parasitica

1983 ◽  
Vol 104 (1) ◽  
pp. 231-246
Author(s):  
IAN D. McFARLANE
Keyword(s):  
Electrical Stimulation ◽  
Pulse Number ◽  
Sea Anemone ◽  
Sea Anemones ◽  
Nerve Net ◽  
Partial Activation ◽  
Calliactis Parasitica ◽  
Slow System ◽  
Stimulation Of

Bursts of through-conducting nerve net (TCNN) pulses, 20–45 min apart, were recorded from Calliactis attached to shells. Within 15–25 min of the anemones being detached the TCNN bursts suddenly became more frequent (only 4–11 min apart). Such bursts continued for several hours if re-attachment was prevented. In an attached anemone simultaneous electrical stimulation of the TCNN and ectodermal slow system (SS1) with 20–30 shocks at one every 5 s also led to more frequent TCNN bursts, whether or not detachment took place. If, however, the anemone remained attached, the intervals between bursts returned to the normal resting duration after about 90 min. In all cases the decay of the 4–11 min interval TCNN bursts involved a reduction in pulse number, not an increase in burst interval. Partial activation of the TCNN pacemakers followed stimulation of the SS1 alone. It is suggested that in sea anemones the change from one behavioural phase to another is associated with a change in the patterned output of nerve net pacemakers.

scholarly journals Reversal of the Direction of Mucus-Flow on the Ciliated Pharynx of a Sea Anemone

1984 ◽  
Vol 108 (1) ◽  
pp. 151-161
Author(s):  
M. C. HOLLEY ◽  
G.A. B. SHELTON
Keyword(s):  
Electrical Activity ◽  
Direct Observation ◽  
Electrical Conduction ◽  
Conduction System ◽  
Sea Anemone ◽  
Power Stroke ◽  
Ciliary Beating ◽  
Calliactis Parasitica

1. The ciliated pharynx of the sea anemone Calliactis parasitica (Couch) acts as an independent selective barrier for the admission of material to the coelenteron. 2. Direct observation shows that reversal of the direction of the mucus-flow is effected by a reversal of the direction of the ciliary power-stroke. 3. Reversal of the power-stroke can only be stimulated by food juices applied directly to the pharynx and it is not propagated to unstimulated areas. 4. Reversal of the power-stroke occurs in the absence of all recordable electrical activity. 5. This is one of the few examples among the Metazoa where it has been shown that a modification of the ciliary beating pattern is unlikely to be controlled by an electrical conduction system.

A Comparison of the Nervous Systems of two Sea-Anemones, Calliactis parasitica and Metridium senile

1961 ◽  
Vol s3-102 (59) ◽  
pp. 319-326
Author(s):  
ELAINE A. ROBSON
Keyword(s):  
Methylene Blue ◽  
Nervous System ◽  
Conduction System ◽  
Nerve Cells ◽  
Bipolar Cells ◽  
Retractor Muscle ◽  
Sea Anemones ◽  
Nerve Net ◽  
Metridium Senile ◽  
Calliactis Parasitica

The properties of the actinian nervous system are known mainly from physiological experiments on Calliactis parasitica (Couch), and from histological work on Metridium senile (L.). The structure of the nerve-net in the mesenteries of Calliactis is now shown to resemble in general that in Metridium. Methylene blue stains a network of bipolar cells over the retractor muscle, together with sense-cells, and unlike Metridium, multipolar nerve-cells. The nerve-net over the radial surface of the mesentery is similarly much sparser. The distribution of nerve-cells and sense-cells in the column also resembles that in Metridium. Experiments on Metridium show that as in Calliactis, the rate of conduction in the mesenteries is greater than in other parts of the anemone. The column, including the sphincter region, conducts more slowly. It is thus shown that the presence of a well developed nerve-net over the retractors is associated with the development of fast tracts in the through-conduction system, and of rapid, facilitated contractions of the retractor muscles, in both species of anemone.

scholarly journals A method for recording electrical activity from the body wall nerve nets in sea anemones

1995 ◽  
Vol 198 (3) ◽  
pp. 817-820
Author(s):  
K Cho ◽  
I D McFarlane
Keyword(s):  
Electrical Activity ◽  
Body Wall ◽  
Myoepithelial Cells ◽  
The Body ◽  
Sea Anemones ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Type C ◽  
First Time

Glass microelectrodes were used to record electrical activity from thin rings cut from the column of the sea anemone Calliactis parasitica. This is the first time that pulses have been recorded from the nervous system in the column. Three pulse types were detected, types A, B and C. Type A pulses are probably associated with neurones of the through-conducting nerve net. Type B pulses may be from the endodermal slow conduction system (SS2). Type C pulses have not previously been recorded and are thought to represent activity in a local nerve net. At this stage we cannot positively state whether the recordings are intracellular from endodermal myoepithelial cells or are extracellular from the sub-epithelial region.

Two Slow Conduction Systems in the Sea Anemone Calliactis Parasitica

1969 ◽  
Vol 51 (2) ◽  
pp. 377-385 ◽  
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Electrical Activity ◽  
Conduction Velocity ◽  
Conduction System ◽  
Repetitive Stimulation ◽  
Sea Anemone ◽  
Response Delay ◽  
The Third ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Oral Disk

1. Suction electrodes record electrical activity associated with three conduction systems in the sea anemone Calliactis parasitica. The two slow systems (SS1 and SS2) are previously undescribed. The third system is the through-conduction system. 2. Evidence is given that the SS1 and SS2 are located in the ectoderm and endoderm respectively. The conductile elements have not been identified. 3. The conduction velocity of the SS1 is 4.4-14.6 cm./sec. at 11° C. and is highest in the oral disk. The SS2 velocity is 3.0-5.3 cm./sec. 4. Both slow systems show a marked increase in response delay on repetitive stimulation and fail at stimulation frequencies higher than one shock/3 sec.

Electrophysiology of two parallel conducting systems in the colonial Hexacorallia

1976 ◽  
Vol 193 (1110) ◽  
pp. 77-87 ◽  
Keyword(s):  
Electrical Activity ◽  
Refractory Period ◽  
Feeding Behaviour ◽  
Conduction System ◽  
Mechanical Stimuli ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Oral Disk ◽  
Dendrogyra Cylindrus

Extracellular polythene suction electrodes have been used to record electrical activity in four species of Madreporaria - Dendrogyra cylindrus, Meandrina meandrites, Mussa angulosa and Eusmilia fastigiata . A colonial conduction system, believed to be the nerve net, was found in all species. It conducted without decrement between all polyps. A second colonial system was found in Meandrina, Mussa and Eusmilia . Pulses could be recorded only from tentacles or oral disks though the system could be excited by electrical or mechanical stimuli to any part of the colony. In the tentacles and oral disk, this conduction system had a refractory period of about 60 ms while in the column or interpolyp regions the refractory period was much longer - up to several seconds. The effect of these differences was to limit the frequency of conduction of pulses in this system between polyps. The second system is compared to the s. s. 1 (ectodermal slow conduction system) of the sea anemone Calliactis parasitica . It is the first demonstrated example of a colonial slow conduction system in the Hexacorallia and is similar in properties to a colonial slow conduction system previously described for Pennatula phosphorea (Octocorallia). The slow conduction system may have a rôle during feeding behaviour by promoting expansion of tentacles and the production of mucus.

A Transmesogloeal Conduction System in the Swimming Sea Anemone Stomphia

1980 ◽  
Vol 87 (1) ◽  
pp. 45-52
Author(s):  
I.D. LAWN
Keyword(s):  
Electrical Activity ◽  
Conduction System ◽  
Nerve Cells ◽  
Sea Anemone

1. A conduction system in Stomphia transfers information across the mesogloea from ectodermal receptors to endodermal effectors. 2. In the column, this transmesogloeal system has numerous and widespread connexions. 3. It is suggested that the connexions may be processes from multipolar nerve cells located in the endoderm. 4. Certain aspects of behaviour are controlled by this conduction system which provides yet another pathway to co-ordinate electrical activity.

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 Co-Ordination of Pedal-Disk Detachment in the Sea Anemone Calliactis Parasitica

1969 ◽  
Vol 51 (2) ◽  
pp. 387-396
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Mechanical Stimulation ◽  
Average Frequency ◽  
Conduction System ◽  
Identical Stimulus ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Behavioural Sequence ◽  
Stimulation Of

1. Electrical activity has been recorded from the sphincter region of Calliactis parasitica during the behavioural sequence in which the anemone detaches from the substrate and attaches to a Buccinum shell. The ectodermal slow-conduction system (SS1) fires repetitively, the majority of observed pulses occurring in the period prior to detachment (a typical example is 25 SS1pulses at an average frequency of 1 pulse/7 sec.). Shell-tentacle contact is essential for stimulation of SS1activity. 2. Mechanical stimulation of the column excites the SS1, and 30 stimuli at a frequency of about one shock/5 sec. give pedal disk detachment. 3. Electrical stimulation of the ectoderm excites the SS1and about 30 stimuli at frequencies between one shock/3 sec. and one shock/9 sec. produce detachment. Detachment and the SS1 have an identical stimulus threshold. It is concluded that detachment is co-ordinated by the SS1.

Sign in / Sign up

Export Citation Format

Share Document