The Mechanism of Osmotic Regulation in Artemia Salina (L.): The Physiology of the Gut

1958 ◽  
Vol 35 (1) ◽  
pp. 243-249
Author(s):  
P. C. CROGHAN
Keyword(s):  
Water Balance ◽  
Osmotic Pressure ◽  
Artemia Salina ◽  
Chloride Ions ◽  
Osmotic Regulation ◽  
Active Uptake ◽  
Gut Epithelium ◽  
Water Balances

1. Artemia is continuously swallowing its medium, whether it is hyper-, iso-, or hypotonic to the haemolymph, and taking up water from the gut lumen. 2. The osmotic pressure of the gut fluids is appreciably greater than that of the haemolymph, but in the more concentrated media is considerably below that of the medium. This indicates that considerable amounts of NaCl must be passing across the gut epithelium into the haemolymph. 3. The concentration of both sodium and chloride ions in the gut fluids is always less than that in the haemolymph, indicating that there must be an active uptake of NaCl across the gut epithelium. 4. It is considered that the gut of Artemia has become adapted as a mechanism for the active uptake of water, controlling water balance and preventing dehydration in hypertonic media. 5. The adaptations for maintaining the NaCl and the water balances in Artemia are compared to those found in the marine teleosts, and are shown to be extremely similar.

The Mechanism of Osmotic Regulation in Artemia Salina (L.): The Physiology of the Branchiae

1958 ◽  
Vol 35 (1) ◽  
pp. 234-242 ◽  
Author(s):  
P. C. CROGHAN
Keyword(s):  
Methylene Blue ◽  
Silver Ions ◽  
Artemia Salina ◽  
Physiological Effects ◽  
Osmotic Regulation ◽  
External Concentration ◽  
Active Uptake ◽  
Branchial Epithelium ◽  
Nacl Excretion

1. The uptake of silver ions by Artemia has been investigated. The staining is localized to the first ten pairs of branchiae. There is no staining of the eleventh pair or of any other part of the animal. The uptake of silver is due to a purely passive precipitation of AgCl within the thickness of the branchial cuticle. 2. The effects of KMnO4 and methylene-blue solutions have also been studied. Their effect is localized to the epithelium under the cuticle of the first ten pairs of branchiae. 3. It is concluded that all these staining reactions demonstrate that the cuticle over the first ten pairs of branchiae is the only part of the external cuticle that is appreciably permeable. 4. Animals whose branchial epithelium has been damaged by a brief exposure to saturated KMnO4 solution have lost the ability to osmo-regulate. They are closely isotonic with their medium, and the range of external concentration tolerated is much restricted. 5. This isotonicity is not due simply to increased permeability, but is due to specific destruction of the mechanism normally excreting NaCl in hypertonic media. 6. Correlation of the physiological effects of KMnO4 treatment with the sharp localization of damage, and the evidence for localized permeability indicates that the epithelium of the first ten pairs of branchiae is the site of active NaCl excretion in hypertonic media, and probably of active uptake from hypotonic media. 7. The ontogeny of this mechanism is traced. In nauplii the dorsal organ is apparently concerned in NaCl excretion. When the branchiae develop the dorsal organ degenerates.

The Osmotic and Ionic Regulation of Artemia Salina (L.)

1958 ◽  
Vol 35 (1) ◽  
pp. 219-233 ◽  
Author(s):  
P. C. CROGHAN
Keyword(s):  
Osmotic Pressure ◽  
Sea Water ◽  
Artemia Salina ◽  
Chloride Ions ◽  
The Body ◽  
Distilled Water ◽  
Sodium Potassium ◽  
Rapid Fall ◽  
Water Media ◽  
Potassium Magnesium

1. It has been possible to adapt Artemia to sea-water media varying from 0.26% NaCl to crystallizing brine. In fresh water or distilled water survival is relatively short. 2. The osmotic pressure of the haemolymph is relatively independent of the medium and increases only slightly as the medium is made more concentrated. In the more concentrated media the haemolymph is very markedly hypotonic. In media more dilute than 25% sea water the haemolymph is hypertonic. In distilled water there is a rapid fall of haemolymph concentration. The haemolymph of nauplii from sea water is hypotonic. 3. The sodium, potassium, magnesium, and chloride concentrations of the haemolymph have been determined. The bulk of the haemolymph osmotic pressure is accounted for by sodium and chloride ions. The ionic ratios of the haemolymph are relatively constant, and very different from those of the medium. 4. The concentrations of ions in the whole animal have been studied. The chloride space is extremely high. Such changes in haemolymph osmotic pressure that do occur as the medium concentration is varied are due more to net movements of NaCl into or out of the body than to water movements. 5. Evidence is collected to show that an appreciable degree of permeability exists. Most of this permeability is localized to the gut epithelium, the external surface being much less permeable. 6. It is clear that Artemia must possess mechanisms that can actively excrete NaCl and take up water in hypertonic media. It has been demonstrated that Anemia can lower the haemolymph osmotic pressure by excreting NaCl from the haemolymph against the concentration gradient.

Sodium and Chloride Balance in the Prawn, Palaemonetes Varians

1964 ◽  
Vol 41 (3) ◽  
pp. 591-601
Author(s):  
W. T. W. POTTS
Keyword(s):  
Water Balance ◽  
Brackish Water ◽  
Sea Water ◽  
Chloride Ions ◽  
Potential Difference ◽  
Sodium Balance ◽  
Sodium Ions ◽  
Active Sodium ◽  
Sodium Uptake ◽  
Active Uptake

1. The exchanges of sodium and bromide (for chloride) ions between the brackish-water prawn Palaemonetes varians and its environment are described. 2. In an isosmotic medium the exchange of sodium and chloride ions takes place by passive diffusion. 3. In full-strength sea water sodium ions are actively removed extrarenally, the potential difference produced by the active extrusion of sodium ions maintaining the chloride ions in passive equilibrium. There is some evidence of an increased flux of ions in hyperosmotic sea water associated with water-swallowing to obtain water for water balance. 4. In 2% sea water chloride ions are actively absorbed, the potential produced by this active uptake helping to maintain sodium balance; but some active sodium uptake also occurs. 5. In salinities below 2% uptake of ions declines and the animals can no longer maintain equilibrium.

Osmoregulation in the Larva of the Marine Caddis Fly, Philanisus Plebeius (Walk.) (Trichoptera)

1972 ◽  
Vol 57 (3) ◽  
pp. 821-838
Author(s):  
JOHN P. LEADER
Keyword(s):  
Sodium Chloride ◽  
Osmotic Pressure ◽  
Body Surface ◽  
Sea Water ◽  
Electrical Potential ◽  
Chloride Ion ◽  
Chloride Ions ◽  
The Body ◽  
Electrical Potential Difference ◽  
Caddis Fly

1. The larva of Philanisus plebeius is capable of surviving for at least 10 days in external salt concentrations from 90 mM/l sodium chloride (about 15 % sea water) to 900 mM/l sodium chloride (about 150 % sea water). 2. Over this range the osmotic pressure and the sodium and chloride ion concentrations of the haemolymph are strongly regulated. The osmotic pressure of the midgut fluid and rectal fluid is also strongly regulated. 3. The body surface of the larva is highly permeable to water and sodium ions. 4. In sea water the larva is exposed to a large osmotic flow of water outwards across the body surface. This loss is replaced by drinking the medium. 5. The rectal fluid of larvae in sea water, although hyperosmotic to the haemolymph, is hypo-osmotic to the medium, making it necessary to postulate an extra-renal site of salt excretion. 6. Measurements of electrical potential difference across the body wall of the larva suggest that in sea water this tissue actively transports sodium and chloride ions out of the body.

Water Balance in Corixa Dentipes (Thoms.) (Hemiptera, Heteroptera)

1964 ◽  
Vol 41 (3) ◽  
pp. 609-619
Author(s):  
B. W. STADDON
Keyword(s):  
Water Balance ◽  
Osmotic Pressure ◽  
Water Intake ◽  
Ammonia Concentration ◽  
Ammonium Bicarbonate ◽  
Water Output

1. The water balance in Corixa dentipes (Thoms.) has been investigated under conditions of starvation in de-ionized water. 2. The rectal fluid was found to contain almost sufficient ammonium bicarbonate to account for the total osmotic pressure. It was invariably strongly hypotonic to the haemolymph. 3. The water output, as estimated by measuring the ammonia output and ammonia concentration of the rectal fluid, was shown to be appreciable but no connexion was found between the output of ammonia and of water. 4. Adults were shown to gain water by the mouth and some evidence was obtained that the cuticle may be an important route of water intake.

Water Balance and Kidney Function in Four Species of Rattus From Ecologically Diverse Environments.

1976 ◽  
Vol 24 (1) ◽  
pp. 7 ◽  
Author(s):  
PR Baverstock
Keyword(s):  
Drinking Water ◽  
Water Balance ◽  
Osmotic Pressure ◽  
Individual Variation ◽  
Water Deprivation ◽  
High Metabolic Rate ◽  
Sodium Potassium ◽  
Rattus Fuscipes ◽  
Microhabitat Preferences ◽  
Urine Concentrating Ability

While Rattus fuscipes survived only 4 days of water deprivation at 21�C, R. norvegicus, R. villosissimus and R. lutreolus survived 13-16 days. There was considerable inter-individual variation in the response of water-deprived R. villosissimus. Analysis of osmotic pressure, urea, sodium, potassium and chloride of both plasma and urine of rats with and without drinking water revealed that: (1) the abilities of R. norvegicus and R. villosissimus to tolerate water deprivation were due in large part to their abilities to produce highly concentrated urine; (2) R. lutreolus tolerated long periods of water deprivation not by urine-concentrating ability but by partly abandoning homeostasis and tolerating elevated levels of plasma solutes; (3) water-deprived R. fuscipes excreted large volumes of concentrated urine, possibly because their relatively high metabolic rate necessitated the excretion of excess metabolites. In all of the rats, urea constituted an unusually low proportion of the total osmotic pressure. The water-balance response of water-deprived rats is at variance with both their macrogeographical distribution and microhabitat preferences.

Simulation of magnetic field effect on a seed embryo cell

2012 ◽  
Vol 26 (2) ◽  
pp. 167-173 ◽  
Author(s):  
A. Socorro ◽  
F. García
Keyword(s):  
Magnetic Field ◽  
Membrane Potential ◽  
Osmotic Pressure ◽  
Field Effect ◽  
Magnetic Field Effect ◽  
Embryo Cell ◽  
Chloride Ions ◽  
Tissue Cell ◽  
Plant Seed ◽  
Seed Embryo

Simulation of magnetic field effect on a seed embryo cellThe plant seed embryo tissue cell, including the cell membrane and the intracellular and extracellular regions, was modelled as a spherical body. Equations for the three components in spherical coordinates were developed to calculate potassiumions flux in the presence of a stationary magnetic field. Simultaneous mathematical simulations of radial flux for potassium, calcium and chloride ions as well as membrane potential and osmotic pressure were calculated. Results obtained by computerized simulation showed that a magnetic field of 200 mT provoked some changes in cellular ionic concentration with respect to exposure time during first 30 s, which also impacted on the membrane potential and osmotic pressure values.

scholarly journals Estimates of the climatological land surface energy and water balance derived from maximum convective power

2014 ◽  
Vol 11 (1) ◽  
pp. 265-306
Author(s):  
A. Kleidon ◽  
M. Renner ◽  
P. Porada
Keyword(s):  
Solar Radiation ◽  
Surface Energy ◽  
Water Balance ◽  
Latent Heat ◽  
Thermodynamic Limit ◽  
Land Surface ◽  
Large River ◽  
Maximum Power ◽  
Reanalysis Dataset ◽  
Water Balances

Abstract. The land surface energy- and water balances are tightly coupled by the partitioning of absorbed solar radiation into terrestrial radiation and the turbulent fluxes of sensible and latent heat, as well as the partitioning of precipitation into evaporation and runoff. Evaporation forms the critical link between these two balances. Its rate is strongly affected by turbulent exchange as it provides the means to efficiently exchange moisture between the heated, moist surface and the cooled, dry atmosphere. Here, we use the constraint that this mass exchange operates at the thermodynamic limit of maximum power to derive analytical expressions for the partitioning of the surface energy- and water balances on land. We use satellite-derived forcing of absorbed solar radiation, surface temperature and precipitation to derive simple spatial estimates for the annual mean fluxes of sensible and latent heat and evaluate these estimates with the ERA-Interim reanalysis dataset and observations of the discharge of large river basins. Given the extremely simple approach, we find that our estimates explain the climatic mean variations in net radiation, evaporation, and river discharge reasonably well. We conclude that our analytical, minimum approach provides adequate first order estimates of the surface energy- and water balance on land and that the thermodynamic limit of maximum power provides a useful closure assumption to constrain the energy partitioning at the land surface.

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