Viso-Elastic Properties of the Body-Wall of Sea Anemones

1. Creep of narcotized Metridium and Calliactis body-wall at constant tensile stress has been studied quantitatively. 2. It was found to be reversible, and seemed to be controlled by the mesogloea. Its course could be represented by equations of the formε(t)= εo+ευ(I-e-t/τ),where the retardation time τ was about 1 hr. for Metridium and many hours for Calliactis. 3. The results can most simply be explained in terms of a cross-linked and a noncross-linked polymeric system, acting in parallel. An explanation in terms of a lattice of inextensible fibres is not satisfactory. 4. The results are discussed in relation to the behaviour of the animals.

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Conduction and coordination in deganglionated ascidians

Canadian Journal of Zoology ◽

10.1139/z00-107 ◽

2000 ◽

Vol 78 (9) ◽

pp. 1626-1639 ◽

Cited By ~ 18

Author(s):

G O Mackie ◽

R C Wyeth

Keyword(s):

Body Wall ◽

Motor Nerve ◽

Histological Study ◽

The Body ◽

Nerve Terminals ◽

Sea Anemones ◽

Nerve Net ◽

Electrophysiological Recordings ◽

Motor Neurones ◽

Conduction Of Excitation

The behaviour of Chelyosoma productum and Corella inflata (Ascidiacea) was studied in normal and deganglionated animals. Chelyosoma productum lived for over a year after deganglionation and the ganglion did not regenerate. Electrophysiological recordings were made from semi-intact preparations. Responses to stimulation and spontaneous activity continued to be transmitted through the body wall and branchial sac after deganglionation. Spread was slow, decremental, and facilitative. Treatment with >10 µg·mL-1 d-tubocurarine abolished all responses, indicating that nerves mediate conduction of excitation after deganglionation. Histological study using cholinesterase histochemistry and immunolabelling with antisera against tubulin and gonadotropin-releasing hormone showed no evidence of a peri pheral nerve net in regions showing conduction, contrary to previous claims. The cell bodies of the motor neurones were found to lie entirely within the ganglion or its major roots. Their terminal branches intermingled to form netlike arrays. Sensory neurons were identified with cell bodies in the periphery, in both the body wall and the branchial sac. Their processes also intermingled in netlike arrays before entering nerves going to the ganglion. It is concluded that the "residual" innervation that survives deganglionation is composed of either interconnected motor nerve terminals, interconnected sensory neurites, or some combination of the two. In re-inventing the nerve net, ascidians show convergent evolution with sea anemones, possibly as an adaptation to a sessile existence.

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Reproductive biology of two epizoic anemones from the deep north-eastern Atlantic Ocean

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400033087 ◽

1993 ◽

Vol 73 (3) ◽

pp. 531-542 ◽

Cited By ~ 19

Author(s):

S. K. Bronsdon ◽

P. A. Tyler ◽

A. L. Rice ◽

J. D. Gage

Keyword(s):

Body Weight ◽

Reproductive Biology ◽

Body Wall ◽

Early Spring ◽

The Body ◽

Sea Anemones ◽

Eastern Atlantic Ocean ◽

North Eastern ◽

Seasonal Basis ◽

Wet Weight

The reproductive biology of two epizoic deep-sea anemones reveals contrasting reproductive strategies. Amphianthus inornata (Cnidaria: Anthozoa) lives attached to the bathyal gorgonian Acanella arbuscula (Cnidaria: Anthozoa). Females of A. inornata increase in wet body weight as a result of increased oocyte production until 40% of the body weight is reproductive tissue. The anemone reproduces on a seasonal basis, releasing eggs in the early spring of each year. By contrast, Kadosactis commensalis (Cnidaria: Anthozoa) lives attached to the body wall of the abyssal holothurian Paroriza prouhoi (Echinodermata: Holothurioidea). This anemone is a protandric hermaphrodite, females being found only at the anterior end of the holothurian, whilst males are found at any point on the host. Females have a significantly higher wet weight than males and neither sex shows any reproductive seasonality.

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Studies on the Mesogloea of Coelenterates

Journal of Experimental Biology ◽

10.1242/jeb.30.3.440 ◽

1953 ◽

Vol 30 (3) ◽

pp. 440-451

Author(s):

GARTH CHAPMAN

Keyword(s):

Physical Properties ◽

Elastic Properties ◽

Body Wall ◽

The Body ◽

Physical Behaviour ◽

Small Load

1. The physical properties of the isolated mesogloea of Calliactis and Metridium are described and the behaviour of the tissue on loading recorded. It can be compared with a spring and dashpot model. 2. It is shown that the viscous-elastic properties of the body-wall, which have previously been ascribed to the muscles, are the attributes of the mesogloea. 3. On being heated in water under a small load, isolated mesogloea of Calliactis contracts, at temperatures which are only a little higher than those at which vertebrate collagen contracts. This is regarded as additional evidence for the collagenous nature of the mesogloea protein. 4. It is shown that the physical behaviour of the material is consonant with the crossed fibrillar collagenous nature of the mesogloea described elsewhere.

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

Journal of Experimental Biology ◽

10.1242/jeb.198.3.817 ◽

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.

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Mechanical Diversity of Connective Tissue of the Body Wall of Sea Anemones

Journal of Experimental Biology ◽

10.1242/jeb.69.1.107 ◽

1977 ◽

Vol 69 (1) ◽

pp. 107-125

Author(s):

M.A. R. KOEHL

Keyword(s):

Connective Tissue ◽

Body Wall ◽

Polarized Light ◽

Structural Features ◽

Mechanical Tests ◽

The Body ◽

Sea Anemones ◽

Collagen Fibres ◽

Postural Changes ◽

Anthopleura Xanthogrammica

Techniques for analysing polymer mechanics were used to describe quantitatively the time-dependent mechanical properties of the body-wall connective tissue (mesogloea) and to indicate macromolecular mechanisms responsible for the mechanical behaviour of two species of sea anemones, Metridium senile and Anthopleura xanthogrammica. 1. The mesogloea of M. senile is more extensible and less resilient than that of A. xanthogrammica when stressed for periods comparable to the duration of flow forces the anemones encounter and the postural changes they perform.2. Polarized light microscopy and SEM reveal that the reinforcing collagen fibres in the mesogloea are aligned parallel with the major stress axes in the body wall.3. Mechanical tests and observations of composition and microstructure indicate that the mesogloea of A. xanthogrammica is less extensible than that of M. senile because molecular entanglements (due to more closely packed parallel collagen fibres and to a higher concentration of polymers in the interfibrillar matrix) retard the extension of A. xanthogrammica mesogloea. This study illustrates how structural features on the macromolecular and microscopic levels of organization of an organism can equip that organism for the particular mechanical activities it performs and the environmental forces it encounters.

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Lymphangiomatosis of the Body Wall: A Report of Two Cases Associated with Chylothorax and Fatal Outcome

Fetal and Pediatric Pathology ◽

10.3109/15513819709168739 ◽

1997 ◽

Vol 17 (4) ◽

pp. 617-624 ◽

Cited By ~ 1

Author(s):

Philippe Moerman ◽

Chris Van Geet ◽

Hugo Devlieger

Keyword(s):

Body Wall ◽

Fatal Outcome ◽

The Body

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A screen for genetic loci required for body-wall muscle development during embryogenesis in Caenorhabditis elegans.

Genetics ◽

10.1093/genetics/137.2.483 ◽

1994 ◽

Vol 137 (2) ◽

pp. 483-498

Author(s):

J Ahnn ◽

A Fire

Keyword(s):

Caenorhabditis Elegans ◽

Myosin Heavy Chain ◽

Muscle Cell ◽

Heavy Chain ◽

Body Wall ◽

Muscle Development ◽

Contractile Function ◽

The Body ◽

Body Wall Muscle ◽

Genetic Loci

Abstract We have used available chromosomal deficiencies to screen for genetic loci whose zygotic expression is required for formation of body-wall muscle cells during embryogenesis in Caenorhabditis elegans. To test for muscle cell differentiation we have assayed for both contractile function and the expression of muscle-specific structural proteins. Monoclonal antibodies directed against two myosin heavy chain isoforms, the products of the unc-54 and myo-3 genes, were used to detect body-wall muscle differentiation. We have screened 77 deficiencies, covering approximately 72% of the genome. Deficiency homozygotes in most cases stain with antibodies to the body-wall muscle myosins and in many cases muscle contractile function is observed. We have identified two regions showing distinct defects in myosin heavy chain gene expression. Embryos homozygous for deficiencies removing the left tip of chromosome V fail to accumulate the myo-3 and unc-54 products, but express antigens characteristic of hypodermal, pharyngeal and neural development. Embryos lacking a large region on chromosome III accumulate the unc-54 product but not the myo-3 product. We conclude that there exist only a small number of loci whose zygotic expression is uniquely required for adoption of a muscle cell fate.

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Tentacle Morphological Variation Coincides with Differential Expression of Toxins in Sea Anemones

Toxins ◽

10.3390/toxins13070452 ◽

2021 ◽

Vol 13 (7) ◽

pp. 452

Author(s):

Lauren M. Ashwood ◽

Michela L. Mitchell ◽

Bruno Madio ◽

David A. Hurwood ◽

Glenn F. King ◽

...

Keyword(s):

Differential Expression ◽

Morphological Variation ◽

Expression Profiles ◽

The Body ◽

Sea Anemones ◽

Tissue Specific ◽

Venom Composition ◽

Specific Manner ◽

Branched Structures ◽

Morphological Variants

Phylum Cnidaria is an ancient venomous group defined by the presence of cnidae, specialised organelles that serve as venom delivery systems. The distribution of cnidae across the body plan is linked to regionalisation of venom production, with tissue-specific venom composition observed in multiple actiniarian species. In this study, we assess whether morphological variants of tentacles are associated with distinct toxin expression profiles and investigate the functional significance of specialised tentacular structures. Using five sea anemone species, we analysed differential expression of toxin-like transcripts and found that expression levels differ significantly across tentacular structures when substantial morphological variation is present. Therefore, the differential expression of toxin genes is associated with morphological variation of tentacular structures in a tissue-specific manner. Furthermore, the unique toxin profile of spherical tentacular structures in families Aliciidae and Thalassianthidae indicate that vesicles and nematospheres may function to protect branched structures that host a large number of photosynthetic symbionts. Thus, hosting zooxanthellae may account for the tentacle-specific toxin expression profiles observed in the current study. Overall, specialised tentacular structures serve unique ecological roles and, in order to fulfil their functions, they possess distinct venom cocktails.

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