Volume Regulation and Solute Balance in the Nervous Tissue of an Osmoconforming Bivalve (Mytilus Edulis)

1978 ◽  
Vol 77 (1) ◽  
pp. 157-179
Author(s):  
P. G. WILLMER
Keyword(s):  
Mytilus Edulis ◽  
Volume Regulation ◽  
Sea Water ◽  
The Body ◽  
Volume Control ◽  
Moderate Degree ◽  
Volume Changes ◽  
Volume Increase ◽  
Excitable Membranes ◽  
Actual Volume

1. Mytilus edulis could be adapted to salinities between 25% and 125% under laboratory conditions, with complete ionic and osmotic conformity of the body fluids. 2. Extracellular space, intracellular cation concentrations and water content were determined for the cerebro-visceral connectives of Mytilus adapted to either 100% or 25% salinity. These measurements suggested only a moderate degree of volume regulation (as indicated by relative cell hydration) and net losses of both potassium and sodium from the cells during acclimation to dilute sea water, although neither cation was reduced in proportion to the external concentrations. 3. Measurement of actual volume changes during acute hyposmotic stress indicated a greater capacity for volume control in the 25%-adapted connectives. However, these tissues also showed an increment of 11% in initial diameter, suggesting significant chronic swelling of the cells. 4. Fine-structural studies of Mytilus nerve indicated that the apparent swelling of the dilute-adapted tissues resulted from a roughly threefold thickening of the ensheathing neural lamella due to the deposition of extra collagen-like fibrils, with the axons in fact showing negligible volume increase. The connectives thus appear to exhibit almost perfect volume regulation. 5. To account for the conflicting estimates of volume regulating capacity, it is proposed that the cells are hyperosmotic to their environment at 25% salinity, the hydrostatic gradient thus created being countered by the restraint imposed by the thickened neural lamella. Physical stresses on the excitable membranes of the nerve would thus be minimized, and electrophysiological functioning in dilute media would be facilitated.

Eco-Physiological Studies of an Intertidal Crustacean, Pollicipes Polymerus (Cirripedia, Lepadomorpha)

1972 ◽  
Vol 57 (1) ◽  
pp. 83-102
Author(s):  
H. J. FYHN ◽  
J. A. PETERSEN ◽  
K. JOHANSEN
Keyword(s):  
Water Loss ◽  
Volume Regulation ◽  
Free Amino ◽  
Heat Load ◽  
Laboratory Experiments ◽  
Sea Water ◽  
Physiological Responses ◽  
The Body ◽  
Air Exposure ◽  
Pollicipes Polymerus

1. Physiological responses to environmental stresses of the intertidal cirriped Pollicipes polymerus have been studied by combined field and laboratory experiments. 2. The body temperature of air-exposed animals is always lower than expected from the heat load. Evaporation from the peduncle is responsible for the heat loss. 3. The rate of water loss by evaporation from the peduncle cuticle is 1.5 µl/cm2 h mmHg both at 21 and 27 °C. The transpiration is proportional to the saturation deficit of the air. The water loss from the capitulum is negligible in comparison to that from the peduncle. 4. The haemolymph osmolality of animals in the field increases during exposure to sunshine and decreases during exposure to rain. The increase in haemolymph osmolality during desiccation is equal to that calculated from the decrease in body water. The water loss during air exposure is adequately replaced during submersion, probably by osmosis. 5. Pollicipes is an osmoconformer but is 5-20 m-osmoles hyperosmotic. It tolerates sea-water dilutions down to about 50%. The hyperosmolality seems to be balanced by a high internal hydrostatic pressure. 6. An excretory activity is observed. The excretion is isosmotic to the haemolymph and is possibly an ultrafiltrate of the latter. 7. The muscle cells show volume regulation, but free amino acids seem to be unimportant in regulation of intracellular osmolality. The concentration of ninhydrinpositive substances in the muscle tissue is about 200 mM for animals in full strength sea water.

Agonist-induced cytoplasmic volume changes in cultured rabbit parietal cells

2000 ◽  
Vol 279 (1) ◽  
pp. G40-G48 ◽  
Author(s):  
Thorsten Sonnentag ◽  
Wolf-Kristian Siegel ◽  
Oliver Bachmann ◽  
Heidi Rossmann ◽  
Andreas Mack ◽  
...  
Keyword(s):  
Volume Regulation ◽  
Parietal Cells ◽  
Cell Swelling ◽  
Secretory Process ◽  
Cell Shrinkage ◽  
Rapid Loss ◽  
Volume Changes ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Stimulation Of

Concomitant Na+/H+ and Cl−/HCO3 − exchange activation occurs during stimulation of acid secretion in cultured rabbit parietal cells, possibly related to a necessity for volume regulation during the secretory process. We investigated whether cytoplasmic volume changes occur during secretagogue stimulation of cultured rabbit parietal cells. Cells were loaded with the fluorescent dye calcein, and the calcein concentration within a defined cytoplasmic volume was recorded by confocal microscopy. Forskolin at 10−5 M, carbachol at 10−4 M, and hyperosmolarity (400 mosmol) resulted in a rapid increase in the cytoplasmic dye concentration by 21 ± 6, 9 ± 4, and 23 ± 5%, respectively, indicative of cell shrinkage, followed by recovery to baseline within several minutes, indicative of regulatory volume increase (RVI). Depolarization by 5 mM barium resulted in a decrease of the cytoplasmic dye concentration by 10 ± 2%, indicative of cell swelling, with recovery within 15 min, and completely prevented forskolin- or carbachol-induced cytoplasmic shrinkage. Na+/H+ exchange inhibitors slightly reduced the initial cell shrinkage and significantly slowed the RVI, whereas 100 μM bumetanide had no significant effect on either parameter. We conclude that acid secretagoguges induce a rapid loss of parietal cell cytoplasmic volume, followed by RVI, which is predominantly mediated by Na+/H+ and Cl−/HCO3 − exchange.

Metabolism of zinc in the mussel, Mytilus edulis (L.): a combined ultrastructural and biochemical study

1980 ◽  
Vol 60 (3) ◽  
pp. 575-590 ◽  
Author(s):  
Stephen G. George ◽  
Brian J. S. Pirie
Keyword(s):  
Mytilus Edulis ◽  
Soft Tissues ◽  
Sea Water ◽  
Biochemical Study ◽  
The Body ◽  
Zinc Metabolism ◽  
High Molecular Weight Complex ◽  
Multicompartmental Model ◽  
Body Tissues ◽  
Granular Amoebocytes

The uptake, transport, storage and excretion of zinc has been studied in Mytilus edulis. Zinc accumulates in the soft tissues in proportion to its concentration in sea water whilst the concentration in the haemolymph is little above that in the environment. Uptake is via the gut, mantle and gills. The zinc is transported from the gills and gut (t½ ≈ 8 days) via the haemolymph, either as a high molecular weight complex or in the granular amoebocytes, to the kidney. Most of the body zinc is present in the granular amoebocytes (which are found in all the body tissues) or in the gut and kidney. The kidney forms the major storage organ for many trace metals, containing 30% of the body zinc and a concentration of about 1000 μg/g. Zinc is localized as insoluble granules in membranelimited vesicles occupying some 20% of the cell volume. Excretion of zinc is by defaecation, exocytosis of the kidney granules into the urine and diapedesis of the amoebocytes. A multicompartmental model for zinc metabolism which correlates the ultrastructural and kinetic data is proposed.

scholarly journals Experiments with Radioactive Strontium (90Sr) on Certain Molluscs and Polychaetes

1953 ◽  
Vol 32 (2) ◽  
pp. 367-384 ◽  
Author(s):  
Vera Fretter
Keyword(s):  
Blood Vessels ◽  
Mytilus Edulis ◽  
Digestive Gland ◽  
Sea Water ◽  
The Body ◽  
Calcium Stores ◽  
Strontium Content ◽  
Surrounding Water ◽  
Strontium Ions ◽  
Calcium Cells

If Arion hortensis be fed on a diet which contains 90Sr, autoradiographs show that the isotope istaken up by the digestive and lime cells of the digestive gland. From the former it passes to th haemocoel; in the lime cells it is concentrated around the calcium spherules. Some of the tracer enters the body through the wall of the intestine. Calcium stores which surround blood vessels and calcium cells in the mantle also concentrate the tracer.In Aplysia.punctata 90Sr from the surrounding water passes through the surface of the body, and especially the gill; in Acanthodoris pilosa ions which enter the tissues from the sea water accumulate around the numerous calcium concretions in the mantle. These marine molluscs obtain cations directly from the water as well as by way of the food.There is a slow uptake of strontium ions by the ctenidia of Mytilus edulis, though, even in filtered sea water, the gut is the more important area for their ingress to the body. It is possible that they enter with the mucous feedingsheets. They pass readily into the cells of the digestive gland. Some of the isotope taken in with the food is absorbed by the wall of the intestine; this also occurs in Patella vulgata, in which the intestine provides a much larger area, and in Lepidochitona cinereus.Mytilus placed in filtered sea water which is activated with 90Sr, so increasing the strontium content by 007%, show the tracer localized for excretion within 10 hr. Ions are aggregated in the pericardial glands, not in the kidney.

Osmotic Responses in the Sipunculid Dendrostomum Zostericolum

1954 ◽  
Vol 31 (3) ◽  
pp. 402-423
Author(s):  
WARREN J. GROSS
Keyword(s):  
Body Weight ◽  
Body Wall ◽  
Sea Water ◽  
Body Fluids ◽  
The Body ◽  
Volume Control ◽  
Active Particles

1. The sipunculid Dendrostomum zostericolum demonstrates no ability to regulate osmotically. 2. Dendrostomum behaves superficially as an osmometer, but is actually more complex: (a) the worm shows volume control in concentrated and dilute sea water; (b) it is permeable to salts, mostly through the gut and/or nephridiopores; (c) it can release osmotically active particles from its body wall to the blood. 3. The body wall of Dendrostomum is highly permeable to water, but only slightly to salts. Permeability for both salts and water is greater inwards than outward. 4. Dendrostomum can tolerate a loss of 36% body weight by desiccation and recover when returned to sea water. The mechanism of this tolerance appears to be the removal by fixation in the tissues, of osmotically active particles from the body fluids.

Distribution of water in Arenicola marina (L.) equilibrated to diluted sea water

1977 ◽  
Vol 57 (2) ◽  
pp. 501-519 ◽  
Author(s):  
R. F. H. Freeman ◽  
T. J. Shuttleworth
Keyword(s):  
Volume Regulation ◽  
Sea Water ◽  
Body Fluids ◽  
The Body ◽  
External Concentration ◽  
Osmotic Concentration ◽  
Osmotic Adaptation ◽  
Arenicola Marina ◽  
Additional Information ◽  
Wide Range

It is our aim in this paper to answer three questions. All of them relate to the well-known ability of lugworms to act as isosmotic osmo-conformers over a wide range of salinities. When exposed to diluted sea water, the body fluids come into osmotic equilibrium with the lowered external concentration, and considerable amounts of water enter the body of the worm. There is no evidence of weight or volume regulation in dilute media, as assessed by a return of the body weight towards its original value. The processes of osmotic adaptation down to the lowest salinity limits for survival include, therefore, tolerance of a lowered osmotic concentration of the body fluids, and of the retention of increased amounts of water in the body. The evidence on which this view of osmotic adaptation in lugworms is based is reviewed by Oglesby (1969, 1973). Additional information on Arenicola marina is provided by Freeman & Shuttleworth (1977).

Relationship between Insulin Sensitivity and Body Fat Composition, and Leptin Sensitivity in Non-Obese and Overweight/Obese Adults

2019 ◽  
Vol 31 (3) ◽  
pp. 212-218
Keyword(s):  
Insulin Sensitivity ◽  
Body Fat ◽  
Negative Relationship ◽  
The Body ◽  
Sensitivity Index ◽  
Moderate Degree ◽  
Model Assessment ◽  
Obese Adults ◽  
Leptin Sensitivity ◽  
Fat Composition

Both insulin and leptin are major contributors for the body energy balance. Obesity is a state of energy imbalance and is also associated with changes in both insulin sensitivity and leptin sensitivity. The aim of this study was to find out the relationship between insulin sensitivity and body fat composition, and leptin sensitivity in non-obese and obese adults. A total of 86 adults participated: 42 non-obese and 44 over-weight/obese. Body fat (BF) percent was determined by skinfold method. Fasting plasma glucose was analyzed by glucose oxidase-phenol and 4 aminophenazone (GOD-PAP) method using spectro-photometer, fasting serum insulin and leptin concentrations by direct sandwich ELISA method and resting energy expenditure (REE) by indirect calorimetry. Leptin sensitivity index and insulin sensitivity were expressed as REE : Leptin ratio and homeostatic model assessment-insulin resistance (HOMA-IR), respectively. It was found that median value of HOMA-IR was significantly higher [2.93 vs 1.72, p<0.01] and leptin sensitivity was significantly lower [116.76 vs 265.66, p<0.001] in the overweight/obese adults than the non-obese adults, indicating that insulin sensitivity and leptin sensitivity were markedly reduced in overweight/obese adults in compare to non-obese adults. There was a moderate degree of positive relationship between HOMA-IR and BF only in the overweight/obese (ρ=0.509, n=44, p<0.001) and all adults (ρ=0.39, n=86, p<0.001). Similarly, a weak negative relationship between leptin sensitivity index and HOMA-IR was found in the overweight/obese (ρ=-0.328, n=44, p<0.05) and all adults (ρ=-0.35, n=86, p<0.01). It can be concluded that the insulin sensitivity was adiposity dependent, but, it did not depend on leptin sensitivity.

Sodium Regulation and Adaptation to Fresh Water in Gammarid Crustaceans

1968 ◽  
Vol 48 (2) ◽  
pp. 359-380
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Body Weight ◽  
Fresh Water ◽  
Body Surface ◽  
Sea Water ◽  
Sodium Concentration ◽  
The Body ◽  
Outward Diffusion ◽  
Gammarus Zaddachi ◽  
Freshwater Habitats ◽  
Sodium Regulation

1. Sodium uptake and loss rates are given for three gammarids acclimatized to media ranging from fresh water to undiluted sea water. 2. In Gammarus zaddachi and G. tigrinus the sodium transporting system at the body surface is half-saturated at an external concentration of about 1 mM/l. and fully saturated at about 10 mM/l. sodium. In Marinogammarus finmarchicus the respective concentrations are six to ten times higher. 3. M. finmarchicus is more permeable to water and salts than G. zaddachi and G. tigrinus. Estimated urine flow rates were equivalent to 6.5% body weight/hr./ osmole gradient at 10°C. in M. finmarchicus and 2.8% body weight/hr./osmole gradient in G. zaddachi. The permeability of the body surface to outward diffusion of sodium was four times higher in M. finmarchicus, but sodium losses across the body surface represent at least 50% of the total losses in both M. finmarchicus and G. zaddachi. 4. Calculations suggest that G. zaddachi produces urine slightly hypotonic to the blood when acclimatized to the range 20% down to 2% sea water. In fresh water the urine sodium concentration is reduced to a very low level. 5. The process of adaptation to fresh water in gammarid crustaceans is illustrated with reference to a series of species from marine, brackish and freshwater habitats.

Zinc Regulation in the Lobster Homarus Gammarus: Importance of Different Pathways of Absorption and Excretion

1986 ◽  
Vol 66 (1) ◽  
pp. 175-199 ◽  
Author(s):  
G. W. Bryan ◽  
L. G. Hummerstone ◽  
Eileen Ward
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
The Body ◽  
Shore Crab ◽  
Freshwater Crayfish ◽  
Uptake Mechanism ◽  
Major Pathway ◽  
Homarus Gammarus ◽  
Wide Range ◽  
Body Concentration

Zinc is one of the most important of the essential trace metals and more than 90 zinc-containing enymes and proteins have been discovered: furthermore, zinc increases the activity of many other enzymes (Vallee, 1978). It is not surprising, therefore, that in some groups of animals the body concentration is regulated against fluctuations in intake. Decapod crustaceans comprise one such group, although the ways in which regulation is achieved vary from species to species. In the freshwater crayfish, Austropotamobius pallipes, excretion in the faeces is a major pathway for removing zinc (Bryan, 1967a) whereas in the shore crab Carcinus maenas losses over the body surface also assume considerable importance (Bryan, 1966). On the other hand, preliminary work on the lobster Homarus gammarus (formerly H. vulgaris) suggests that in this species urinary excretion plays a major role in regulation (Bryan, 1964). The present work continues the study of zinc regulation in lobsters and its main aims are: (1) to measure rates of absorption from sea water over a wide range of concentrations and study the uptake mechanism; (2) to examine absorption from the stomach under different conditions; (3) to determine the relative importance of different pathways for the removal of zinc in response to various levels of intake.

The opening response of mussels (Mytilus edulis) exposed to rising sea-water concentrations

1981 ◽  
Vol 61 (3) ◽  
pp. 667-678 ◽  
Author(s):  
John Davenport
Keyword(s):  
Mytilus Edulis ◽  
Sea Water ◽  
External Medium ◽  
Mantle Cavity ◽  
Low Salinity ◽  
Medium Exchange ◽  
Mantle Edge

When exposed to water of low salinity specimens of Mytilus edulis L. keep their shell valves tightly closed; they do not gape periodically to test the external medium. Exchange of salts and water between the mantle cavity and the environment is thus minimized. Rising salinities are registered by diffusion of salts to the tentaculate portion of the inhalent siphon and not to any other portion of the mantle edge or to any more deeply located structures.

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