scholarly journals Viscoelasticity of Holothurian Body Wall

1984 ◽  
Vol 109 (1) ◽  
pp. 63-75 ◽  
Author(s):  
TATSUO MOTOKAWA
Keyword(s):  
Mechanical Model ◽  
Body Wall ◽  
Sea Water ◽  
Elastic Stiffness ◽  
Chemical Stimulation ◽  
The Body ◽  
Connective Tissues ◽  
Creep Tests ◽  
Covalent Bonds ◽  
Viscosity Change

1. Stress-relaxation tests and creep tests were performed on the body-wall dermis of two sea cucumbers, Actinopyga echinites (Jäger) and Holothuria leucospilota Brandt. 2. These viscoelastic connective tissues had mechanical properties which agreed well with those of a four-element mechanical model composed of two Maxwell elements connected in parallel. 3. The elastic stiffness of the dermis of Actinopyga was 1.7 MPa and that of Holothuria was 042 MPa. 4. The viscosity of the dermis showed great variation of more than two orders. 5. Chemical stimulation with artificial sea water containing 100 mM potassium increased the viscosity but not elasticity. 6. The viscosity change is suggested to be caused by the change in weak (non-covalent) bonds between macromolecules which constitute the dermis.

Heat transfer between fish and ambient water

1976 ◽  
Vol 65 (1) ◽  
pp. 131-145 ◽  
Author(s):  
E. D. Stevens ◽  
A. M. Sutterlin
Keyword(s):  
Body Wall ◽  
Sea Water ◽  
The Body ◽  
Direct Transfer ◽  
Major Fraction ◽  
Metabolic Heat ◽  
Sea Raven ◽  
Before And After ◽  
Ventral Aorta ◽  
Hemitripterus Americanus

1. The ability of fish gills to transfer heat was measured by applying a heat pulse to blood in the ventral aorta and measuring it before and after passing through the gills of a teleost, Hemitripterus americanus. 2. 80–90% of heat contained in the blood is lost during passage through the gills. 3. The fraction of heat not lost during passage through the gills is due to direct transfer of heat between the afferent and efferent artery within the gill bar. 4. The major fraction of metabolic heat (70 - 90%) is lost through the body wall and fins of the sea raven in sea water at 5 degrees C; the remainder is lost through the gills.

Excretion of thiosulphate, the main detoxification product of sulphide, by the lugworm arenicola marina L

1999 ◽  
Vol 202 (7) ◽  
pp. 855-866 ◽  
Author(s):  
K. Hauschild ◽  
W.M. Weber ◽  
W. Clauss ◽  
M.K. Grieshaber
Keyword(s):  
Body Wall ◽  
Sea Water ◽  
The Body ◽  
Cell Junctions ◽  
Metabolic Inhibitors ◽  
Coelomic Fluid ◽  
Arenicola Marina ◽  
Double Exponential ◽  
Electrophysiological Measurements ◽  
Double Exponential Function

Thiosulphate, the main sulphide detoxification product, is accumulated in the body fluids of the lugworm Arenicola marina. The aim of this study was to elucidate the fate of thiosulphate. Electrophysiological measurements revealed that the transepithelial resistance of body wall sections was 76+/−34 capomega cm2 (mean +/− s.d., N=14), indicating that the body wall of the lugworm is a leaky tissue in which mainly paracellular transport along cell junctions takes place. The body wall was equally permeable from both sides to thiosulphate, the permeability coefficient of which was 1. 31×10(−)3+/−0.37×10(−)3 cm h-1 (mean +/− s.d., N=30). No evidence was found for a significant contribution of the gills or the nephridia to thiosulphate permeation. Thiosulphate flux followed the concentration gradient, showing a linear correlation (r=0.997) between permeated and supplied (10–100 mmol l-1) thiosulphate. The permeability of thiosulphate was not sensitive to the presence of various metabolic inhibitors, implicating a permeation process independent of membrane proteins and showing that the lugworm does not need to use energy to dispose of the sulphide detoxification product. The present data suggest a passive permeation of thiosulphate across the body wall of A. marina. In live lugworms, thiosulphate levels in the coelomic fluid and body wall tissue decreased slowly and at similar rates during recovery from sulphide exposure. The decline in thiosulphate levels followed a decreasing double-exponential function. Thiosulphate was not further oxidized to sulphite or sulphate but was excreted into the sea water.

Factors Regulating the Mechanical Properties of Holothurian Dermis

1982 ◽  
Vol 99 (1) ◽  
pp. 29-41
Author(s):  
TATSUO MOTOKAWA
Keyword(s):  
Mechanical Properties ◽  
Sea Cucumber ◽  
Sea Water ◽  
Tensile Tests ◽  
Elastic Stiffness ◽  
Coelomic Fluid ◽  
High Concentration ◽  
Creep Tests ◽  
Two Factors ◽  
Sea Urchin Spine

1. Tensile tests and creep tests were performed on the dermis of the sea cucumber Stichopus chloronotus (Brandt). 2. Chemical stimulation of the dermis with coelomic fluid of the sea cucumber, or with artificial sea water containing a high concentration of potassium, increased both the elastic stiffness and the viscosity. 3. Methanol extraction of the coelomic fluid revealed two factors: a methanol-soluble factor that stiffens the dermis, and a methanol-insoluble factor that softens it. 4. These factors affected the mechanical properties of other echinoderm connective tissue (the catch apparatus of sea-urchin spine) in a similar way to the holothurian dermis.

scholarly journals Adaptation to Changes of Salinity in the Polychaetes

1937 ◽  
Vol 14 (1) ◽  
pp. 56-70
Author(s):  
L. C. BEADLE
Keyword(s):  
Hydrostatic Pressure ◽  
Body Wall ◽  
Sea Water ◽  
Calcium Deficiency ◽  
Body Fluids ◽  
The Body ◽  
Concentration Curve ◽  
Body Volume ◽  
Weight Curve ◽  
Body Wall Muscles

1. Nereis diversicolor collected from the same locality at different times showed smaller weight increases in dilute sea water (25 per cent) during the winter than during the summer months. 2. In spite of great variations in the weight curve, the body fluid concentration curve was very constant. 3. The maintenance of hypertonic body fluids and the regulation of body volume are largely unconnected. 4. The lowering of the weight curve below that theoretically expected from the concentration curve cannot be attributed to passive salt loss through the body surface. It is suggested that this is due to the removal of fluid through the nephridia under the hydrostatic pressure produced by the contraction of the body wall muscles. 5. Animals previously subjected to dilute sea water, when placed in water isotonic with the body fluids, will increase the concentration of the latter. This result is more marked when the internal hydrostatic pressure is high. 6. The results suggest that the osmotic regulatory mechanism involves the removal by the nephridia of fluid hypotonic to the body fluids. But no direct evidence for this is available. 7. Calcium deficiency and cyanide in dilute sea water cause an increase of weight and ultimately inhibit the maintenance of hypertonic body fluids. Both these effects are reversible. 8. The mechanism by which body fluids are maintained hypertonic to the external medium is not sufficiently developed to be of survival value in the locality in which the animals were found. 9. The control of body volume is probably of greater importance. 10. The majority of the extra oxygen consumption in dilute sea water is not the result of osmotic work. It is suggested that it may be due to work done by the body wall muscles in resisting swelling.

Ingestive sensory inputs excite serotonin effector neurones and promote serotonin depletion from the leech central nervous system and periphery.

1995 ◽  
Vol 198 (6) ◽  
pp. 1233-1242
Author(s):  
J R Groome ◽  
D K Vaughan ◽  
C M Lent
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Body Wall ◽  
Hirudo Medicinalis ◽  
Chemical Stimulation ◽  
Rate Of Change ◽  
The Body ◽  
Thermal Stimulation ◽  
Serotonin Content ◽  
Stimulation Of

Thermal and chemical stimuli known to promote ingestive behaviours in the medicinal leech Hirudo medicinalis were tested for their physiological effects on Retzius neurones and for their biochemical effects on serotonin levels in the central nervous system, pharynx and body wall. Retzius neurones throughout the leech nerve cord receive excitatory synaptic input during thermal or chemical stimulation of the prostomial lip. These neurones respond to the rate of change of temperature as well as to absolute temperature at the lip. Exposure of the lip to sodium chloride excites Retzius neurones, whereas exposure to arginine has little effect. Thermal stimulation of the lip elicits a more rapid but less prolonged excitation of Retzius neurones than does chemical stimulation. Stimulation of the prostomial lip is associated with afferent activities in the cephalic nerves D1, D2 and V1-2. Thermal stimulation of the prostomial lip results in depletion of serotonin from midbody ganglia, whereas chemical stimulation has no effect. Conversely, chemical stimulation of the lip results in depletion of serotonin from the body wall, whereas thermal stimulation does not. Pharyngeal serotonin content is decreased with either modality. These data distinguish two important feeding-related sensory input pathways to central serotonergic effector neurones in Hirudo medicinalis.

Studies on the Physiology of Ascaris Lumbricoides

1952 ◽  
Vol 29 (1) ◽  
pp. 1-21
Author(s):  
A. D. HOBSON ◽  
W. STEPHENSON ◽  
L. C. BEADLE
Keyword(s):  
Osmotic Pressure ◽  
Body Fluid ◽  
Body Wall ◽  
Sea Water ◽  
External Medium ◽  
Chloride Concentration ◽  
The Body ◽  
Intestinal Fluid ◽  
The Difference ◽  
Saline Medium

1. The total osmotic pressure, electrical conductivity and chloride concentration of the body fluid of Ascaris lumbricoides and of the intestinal contents of the pig have been measured. 2. The results obtained agree with the observations of previous workers that Ascaris normally lives in a hypertonic medium and that it swells or shrinks in saline media which are too dilute or too concentrated. 3. Experiments comparing the behaviour of normal and ligatured animals show that both the body wall and the wall of the alimentary canal are surfaces through which water can pass. 4. 30% sea water has been used as a balanced saline medium for keeping the worms alive in the laboratory. This concentration was selected as being the one in which there was least change in the body weight of the animals exposed to it. 5. The osmotic pressure of the body fluid of worms kept in 30% sea water is approximately the same as in animals taken directly from the pig's intestine. The body fluid of fresh worms is hypertonic to 30% sea water and hypotonic to the intestinal fluid. In 30% sea water the normal osmotic gradient across the body wall is therefore reversed. 6. In 30% sea water the total ionic concentration (as measured by the conductivity) decreases slightly, but the chloride concentration increases by about 50%, although still remaining much below that of the external medium. 7. Experiments in which the animals were allowed to come into equilibrium with various concentrations of sea water from 20 to 40% show that there are corresponding changes in the osmotic pressure of the body fluid which is, however, always slightly above that of the saline medium. The conductivity also changes in a similar manner but is always less than that of the medium, and the difference between the two becomes progressively greater the more concentrated the medium. 8. The chloride concentration of the body fluid varies with but is always below that of the external medium, whether this is intestinal fluid or one of the saline media. In the latter the difference between the internal and external chloride concentrations is least in 20% sea water and becomes progressively greater as the concentration of the medium is increased. 9. Experiments with ligatured worms and with eviscerated cylinders of the body wall show that these share the capacity of the normal worm to maintain the chloride concentration of the body fluid below that of the environment. This power is not possessed by cylinders composed of the cuticle alone. 10. If the worms which have had their internal chloride concentration raised by exposure to 30% sea water are transferred to a medium composed of equal volumes of 30% sea water and isotonic sodium nitrate solution, the chloride concentration of the body fluid is reduced to a value below that of the external medium. This phenomenon is also displayed by worms ligatured after removal from the 30% sea water and, to an even more marked degree, by eviscerated cylinders of the body wall. 11. It is concluded that Ascaris is able to maintain the chloride concentration of the body fluid below that of the external medium by an process of chloride excretion against a concentration gradient, and that this mechanism is resident in the body wall, the cuticle being freely permeable to chloride.

An investigation of the mechanism of infection by digenetic trematodes: the penetration of the miracidium ofFasciola hepaticainto its snail hostLymnaea truncatula

Parasitology ◽  
1971 ◽  
Vol 63 (3) ◽  
pp. 491-506 ◽  
Author(s):  
R. A. Wilson ◽  
P. Pullin ◽  
Jean Denison
Keyword(s):  
Epithelial Cells ◽  
Body Wall ◽  
Accessory Gland ◽  
The Body ◽  
Initial Attachment ◽  
Connective Tissues ◽  
Digenetic Trematodes ◽  
Ciliated Epithelial Cells ◽  
Cell Shedding

The penetration barrier presented to the miracidium by the snail epithelium can be divided into three layers. The chemical composition and physical configuration of the outermost of these plays an important part in the initial attachment response of the miracidium. Attachment can be stimulated in the absence of the snail by pure chemicals in solution. However, the surface to which the miracidium attaches must have the correct physical configuration otherwise the miracidium is unable to form a stable attachment.In vivo, the miracidial body begins to contract and relax following attachment to the snail. This coincides with the start of secretion by the apical gland and accessory gland cells. The snail's columnar epithelium is rapidly cytolysed so that 10 min after attachment the anterior of the miracidium has reached the underlying connective tissues.As the miracidium penetrates the snail, its ciliated epithelial cells are shed in sequence from anterior to posterior. This shedding removes a protective barrier against osmosis which is probably the acid mucopolysaccharide present in the epithelial cells. The mechanism of shedding is not understood but involves the reversal of binding by the desmosomal mucosubstance which attaches the epithelial cells to surrounding intercellular ridges.The miracidium metamorphoses into the sporocyst as it penetrates the snail, by forming a new body surface. The material for this is extruded from the vesiculated cells which lie beneath the musculature of the body wall. The process of surface formation coincides with cell shedding and moves backwards as cells are shed. At not more than 2·5 h after attachment the extruded cytoplasm forms a thin continuous layer over the surface of the organism. Contacts with underlying cells appear to have been broken and the cytoplasm is underlain by a thin fibrous basal lamella. In the first 24 h after penetration the surface of this syncytium becomes thrown into folds and metamorphosis into the sporocyst can be considered complete.

scholarly journals Clot Formation in the Sipunculid WormThemiste petricola: A Haemostatic and Immune Cellular Response

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Tomás Lombardo ◽  
Guillermo A. Blanco
Keyword(s):  
Cellular Response ◽  
Body Wall ◽  
Sea Water ◽  
Circulatory System ◽  
The Body ◽  
Clot Formation ◽  
Coelomic Fluid ◽  
Fibrous Scaffold ◽  
Second Stage ◽  
Clot Structure

Clot formation in the sipunculidThemiste petricola, a coelomate nonsegmented marine worm without a circulatory system, is a cellular response that creates a haemostatic mass upon activation with sea water. The mass with sealing properties is brought about by homotypic aggregation of granular leukocytes present in the coelomic fluid that undergo a rapid process of fusion and cell death forming a homogenous clot or mass. The clot structure appears to be stabilized by abundant F-actin that creates a fibrous scaffold retaining cell-derived components. Since preservation of fluid within the coelom is vital for the worm, clotting contributes to rapidly seal the body wall and entrap pathogens upon injury, creating a matrix where wound healing can take place in a second stage. During formation of the clot, microbes or small particles are entrapped. Phagocytosis of self and non-self particles shed from the clot occurs at the clot neighbourhood, demonstrating that clotting is the initial phase of a well-orchestrated dual haemostatic and immune cellular response.

The Integration of Activity Cycles in the Behaviour of Arenicola Marina L

1951 ◽  
Vol 28 (1) ◽  
pp. 41-50
Author(s):  
G. P. WELLS ◽  
ELINOR B. ALBRECHT
Keyword(s):  
Body Wall ◽  
Sea Water ◽  
Rhythmic Activity ◽  
The Body ◽  
Neuromuscular System ◽  
Arenicola Marina ◽  
Cyclic Behaviour ◽  
Feeding Cycle ◽  
Activity Cycles ◽  
Set Up

1. Lugworms were dissected in such a way that the movements of the following parts could be simultaneously recorded: extrovert, body wall from the anterior three segments, body wall from the branchiate segments, tail. The preparations were set up in sea water and tracings were taken for many hours in each case. The preparations typically settled down to give cyclic behaviour patterns, remarkably similar to those which intact worms exhibit under favourable conditions, and in which two components were conspicuous. 2. The first, and most invariable, component is the feeding cycle (f cycle), of period 6-7 min. This rhythm originates in the oesophagus, and is transmitted to the muscles of the proboscis (where it causes outbursts of vigorous contraction) and body wall (where it causes correlated contractions in the first three segments, but periodic inhibition in the branchiate segments). 3. The second component was seen in two-thirds of the experiments. It consists of bursts of vigorous rhythmic activity in the body wall and tail, and can appear after their connexion with the extrovert has been severed. Under exceptional circumstances (exhaustion of the f cycle) it may spread to the extrovert trace. Its period is generally 20-60 min. It is apparently identical with the irrigation-defaecation cycle (i-d cycle) of intact worms. 4. Neither pacemaker directly affects the rhythm of the other. The integration of the activities which they determine probably depends on variation in the extent to which their influences spread through the neuromuscular system. They appear to compete for territory. If they happen to discharge outbursts simultaneously, the i-d pacemaker dominates over most of the body wall, and the f pacemaker over the proboscis and mouth region.

Sign in / Sign up

Export Citation Format

Share Document