Sodium Regulation in the Amphipod Gammarus Duebeni From Brackish-Water and Fresh-Water Localities in Britain

1967 ◽  
Vol 46 (3) ◽  
pp. 529-550 ◽  
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Brackish Water ◽  
Loss Rate ◽  
Sea Water ◽  
The Body ◽  
Sodium Ions ◽  
Sodium Uptake ◽  
Sodium Loss ◽  
Sodium Regulation

1. A quantitative study of sodium influx and loss rates was made on Gammarus duebeni obtained from brackish-water localities. Both influx and loss rates were immediately doubled by a rise in temperature from 10 to 20° C. 2. It is estimated that when animals are fully acclimatized to a series of media decreasing from 50 to 2% sea water the rate of sodium uptake at the body surface is doubled to balance the rate of sodium loss, which is also doubled. The increased loss rate is due equally to an increase in the rate of diffusion across the body surface and to loss in hypotonic urine containing about 160-190 mM/l. sodium. Diffusion losses normally account for at least 35% of the total losses, even when the urine is isotonic with the blood. 3. The sodium-transporting system at the body surface is fully saturated at an external concentration of about 10 mM/l. NaCl (2% sea water). The system has a low affinity for sodium ions and is only half-saturated at 1.5-2.5 mM/l. sodium. The overall rate of uptake is increased to its maximum rate to balance sodium losses when in fresh water. 4. When acclimatized to fresh water (0.25 mM/l. NaCl) the sodium loss rate is greatly reduced. This was partly due to a lower rate of diffusion across the body surface following a fall in the blood sodium concentration, and mainly due to elaboration of a very dilute urine. 5. It is suggested that increases in sodium uptake in the antennary glands, resulting in a hypotonic urine, are linked with increases in uptake at the body surface. Both uptake systems are possibly activated by a single internal regulator responding to changes in the blood concentration. 6. Sodium regulation at concentrations below 10 mM/l. NaCl was examined in G. duebeni obtained from fresh-water streams on the Lizard peninsula, the Kintyre peninsula, and the Isle of Man. The regulation of sodium uptake and loss is very similar to regulation in brackish-water animals, and the sodium-transporting system has the same low affinity for sodium ions at concentrations below about 10 mM/l. 7. It is suggested that fresh-water localities in north-west Europe, excluding Ireland, have been colonized from brackish water without any modifications in the sodium-regulatory mechanism. But the fresh-water animals tolerate very low sodium concentrations better than brackish-water animals. This is apparently due to natural selection of individuals in which the sodium uptake rate is higher than the average uptake rate in brackish-water animals.

Sodium Regulation in the Fresh-Water Amphipod, Gammarus Pulex (L.)

1967 ◽  
Vol 46 (3) ◽  
pp. 499-518
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Loss Rate ◽  
Sodium Concentration ◽  
The Body ◽  
Uptake Mechanism ◽  
Sodium Influx ◽  
Sodium Uptake ◽  
Sodium Loss ◽  
Total Sodium

1. Sodium influx and loss rates in Gammarus pulex were measured at constant temperatures. The sodium loss rate was immediately influenced by a change in temperature, with a Q10 of 1.5 to 2.0 at temperatures between 0.3 and 21.5° C. The sodium influx rate is apparently influenced in the same way. 2. The sodium uptake mechanism in G. pulex from three localities was half-saturated at an external concentration of 0.10-0.15 mM/l. sodium. 3. The total sodium loss rate remained approximately constant in animals acclimatized to the range of external concentrations from 2 to about 0.2 mM/l. sodium. 18% of the sodium was lost in urine with a sodium concentration estimated at 30-50 mM/l. The remainder of the sodium loss was due to diffusion across the body surface. 4. In animals acclimatized to concentrations below about 0.2 mM/l. sodium the sodium loss rate was reduced, due to (a) a lower diffusion rate following a fall in the blood sodium concentration, and (b) the elaboration of a more dilute urine. 5. There was a very close association between changes in the blood sodium concentration, the elaboration of a very dilute urine, and the rate of sodium uptake at the body surface. The results indicate that a fall in the blood sodium concentration leads to simultaneous activation of the sodium uptake mechanisms at the body surface and in the antennary glands. 6. It is estimated that, by producing a dilute urine, total sodium uptake in G. pulex is shared equally between the renal uptake mechanism and the mechanism situated at the body surface. 7. In sea-water media G. pulex drinks and expels fluid from the gut. In a medium slightly hyperosmotic to the normal blood concentration the amount imbibed was equal to the normal rate of urine flow when in fresh water.

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.

Active Transport and Sodium Fluxes at Moult in the Amphipod, Gammarus Duebeni

1969 ◽  
Vol 51 (3) ◽  
pp. 591-605
Author(s):  
A. P. M. LOCKWOOD ◽  
W. R. H. ANDREWS
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Major Part ◽  
Sea Water ◽  
Sucrose Solution ◽  
The Body ◽  
Active Sodium ◽  
Sodium Influx ◽  
Sodium Uptake ◽  
High Level

1. The sodium fluxes of individual Gammarus duebeni, which moulted in sea water, have been followed daily from the morning following moult for at least 6 days. 2. Sodium influx from sea water declined from 15.1µM/animal/hr. on the first morning after moult to 1.7µM/animal/hr. by the tenth day after moult. 3. Sodium influx from 10 mM/l. NaCl plus sucrose solution isotonic with sea water declines from 4.48µM/animal/hr. to 0.14µM/animal/hr. in inter-moult animals. 4. Thionine inhibits over 90% of the influx from 10 mM/l NaCl plus isotonic sucrose on the first day after moult, and this, together with other evidence, suggests that the major part of the influx from this medium is due to active sodium uptake. The rate of active uptake is comparable with, or faster than, the rate of uptake by animals acclimatized to fresh water. 5. The influx occurs primarily across the body surface. It is suggested that the high level of sodium uptake is associated with the water uptake which occurs at moult.

Sodium Influx and Loss in Freshwater and Brackish-Water Populations of the Amphipod Gammarus Duebeni Lilljeborg

1971 ◽  
Vol 54 (1) ◽  
pp. 255-268
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Body Surface ◽  
Brackish Water ◽  
Sea Water ◽  
Sodium Concentration ◽  
The Body ◽  
Experimental Population ◽  
Sodium Ions ◽  
Sodium Influx ◽  
Wide Range ◽  
Freshwater Habitats

1. Sodium influx was examined in Gammarus duebeni from freshwater habitats on the Kintyre and Stranraer peninsulas in western Britain, and from a brackish-water habitat in Ireland. The affinity for sodium ions in the uptake mechanism at the body surface was similar in animals from the three localities. 2. Compared with the parent population from Kintyre, an experimental population established for 2 years in water with a lower sodium concentration showed an increased affinity for sodium. 3. Sodium losses in the urine of animals from the above localities were negligible at external salinities below about 2% sea water. In contrast, urinary sodium losses in animals from a brackish-water population in Britain were higher at salinities ranging from 40% sea water to well below 2% sea water. 4. The affinity for sodium ions in uptake mechanisms at the body surface and in the antennary glands of G. duebeni from a wide range of habitats shows a market correlation with the sodium concentration of the habitat. The permeability of the body surface to outward movement of sodium is similar in G. duebeni from brackishwater and freshwater habitats. 5. It is suggested that most of the observed physiological differences between populations of G. duebeni are phenotypic in origin. The status of the freshwater ‘race’ in Ireland is briefly discussed.

Sodium Regulation in the Amphipod Gammarus Duebeni Lilljeborg form Freshwater Localities in Ireland

1968 ◽  
Vol 48 (2) ◽  
pp. 339-358
Author(s):  
D. W. SUTCLIFFE ◽  
J. SHAW
Keyword(s):  
Fresh Water ◽  
Loss Rate ◽  
Sea Water ◽  
Detailed Comparison ◽  
Urine Concentration ◽  
Sodium Influx ◽  
Fresh Waters ◽  
Low Sodium ◽  
Characteristic Features ◽  
Sodium Regulation

1. A quantitative study of sodium influx and loss was made on populations of Gammarus duebeni obtained from four freshwater localities in Ireland. 2. Characteristic features of sodium regulation in animals from the four localities were as follows, (a) The sodium influx increases gradually with increasing external sodium concentrations, but a maximum (saturation) level is abruptly reached at an external concentration of 1-2 mM/l. and the transporting system is half saturated at about 0.5 mM/l. sodium, (b) Over the range of sodium concentrations found in fresh waters a low rate of sodium uptake is sufficient to balance sodium losses at concentrations down to between 0.5 and 0.25 mM/l. At lower concentrations the influx is increased and the loss rate is reduced. (c) Calculations suggest that hypotonic urine containing approximately 40 mM/l sodium is produced at external concentrations ranging from fresh water to 40 % sea water. At external concentrations below 0.25 mM/l. sodium the urine concentration is probably reduced to well below 40 mM/l. sodium. 3. A detailed comparison is made of sodium regulation at external concentrations ranging between 0.07 and 1 mM/l. sodium in G. duebeni from fresh water in Ireland and from fresh water and brackish water in Britain. It is suggested that G. duebeni in Ireland constitutes a distinct physiological race adapted for living in fresh waters with relatively low sodium concentrations.

Sodium Regulation and Adaptation to Fresh Water in the Isopod Genus Asellus

1974 ◽  
Vol 61 (3) ◽  
pp. 719-736
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Fresh Water ◽  
Loss Rate ◽  
The Body ◽  
Sodium Balance ◽  
Short History ◽  
Sodium Influx ◽  
Km Value ◽  
Sodium Regulation ◽  
Natural Series ◽  
Total Concentrations

1. The principal features of the sodium regulatory mechanism are compared in Asellus communis Say, A. aquaticus (L.) and A. meridianus Rac. 2. Water content and total concentrations of sodium and chloride are similar in the three species, but they differ with respect to values for Kmax, Km, the loss rate, and the minimum sodium balance concentration. 3. It is suggested that A. meridianus, A. aquaticus and A. communis represent a natural series of increasing adaptation to fresh water. A. communis from North America is completely adapted to fresh water. It has the lowest loss rate, the lowest maximum saturation level (Kmax) for sodium influx, and the highest affinity (low Km value) for sodium ions in the transporting system at the body surface. In many respects A. meridianus resembles freshwater populations of Mesidotea entomon and Gammarus duebeni, and may therefore have had a relatively short history in fresh water.

The Relative Losses of Sodium in the Urine and Across the Body surface in the Amphipod, Gammarus Duebeni

1965 ◽  
Vol 42 (1) ◽  
pp. 59-69
Author(s):  
A. P. M. LOCKWOOD
Keyword(s):  
Body Surface ◽  
Sea Water ◽  
Average Rate ◽  
The Body ◽  
High Rate ◽  
Water Turnover ◽  
Urine Production ◽  
Sodium Loss ◽  
And Diffusion ◽  
Total Sodium

1. The relative contributions of urine production and diffusion across the body surface to the loss of sodium from the body of the amphipod Gammarus duebeni have been investigated. 2. When the urine is isotonic to the blood some 80% of the total sodium loss is via the urine. 3. As the gradient between blood and medium is increased in dilute media production of urine hypotonic to the blood counteracts the tendency for sodium loss to increase. 4. In consequence, the average rate of sodium uptake at the body surface by animals acclimatized to 2% sea water needs to be only about twice that of animals acclimatized to 50% sea water. 5. It is suggested that the conservation of ions within the body by the production of hypotonic urine is likely to be found to be a common feature of the smaller brackish water crustacea, especially those with a high rate of water turnover.

scholarly journals Salt and Water Balance in the East African Fresh-Water Crab, Potamon Niloticus (M. Edw.)

1959 ◽  
Vol 36 (1) ◽  
pp. 157-176 ◽  
Author(s):  
J. SHAW
Keyword(s):  
Water Balance ◽  
Fresh Water ◽  
Sea Water ◽  
Freezing Point ◽  
Salt Content ◽  
The Body ◽  
Sodium Balance ◽  
East African ◽  
Sodium Loss ◽  
Salt And Water Balance

1. The mechanisms of salt and water balance in the East African fresh-water crab, Potamon niloticus, have been investigated. 2. The freezing-point depression of the blood is equivalent to that of a 271 mM./l. NaCl solution. 3. The animals cannot survive in solutions more concentrated than 75% sea water. Above the normal blood concentration, the blood osmotic pressure follows that of the medium. 4. The urine is iso-osmotic with the blood and is produced at a very slow rate. The potassium content is only half that of the blood. 5. The animal loses sodium at a rate of 8 µM./10 g./hr. mainly through the body surface. Potassium loss occurs at one-sixteenth of this rate. 6. Sodium balance can be maintained at a minimum external concentration of 0.05 mM./l. Potassium requires a concentration of 0.07 mM./l. 7. Active absorption of both sodium and potassium occurs. The rate of uptake of sodium depends on the extent of previous sodium loss. The rate of sodium uptake may be affected by such environmental factors as the salt content of the water, temperature and oxygen tension. 8. The normal oxygen consumption rate is 0.72 mg./10 g./hr. A minimum of 2.3% is used in doing osmotic work to maintain salt balance. 9. The salt and water balance in Potamon is discussed in relation to the adaptation of the Crustacea to fresh water. The importance of permeability changes is stressed.

Plasma Chloride and Sodium, and Chloride Space in the European Eel, Anguilla Anguilla L

1972 ◽  
Vol 57 (1) ◽  
pp. 113-131
Author(s):  
R. KIRSCH
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Chloride Concentration ◽  
Anguilla Anguilla ◽  
The Body ◽  
European Eel ◽  
Plasma Chloride ◽  
Sea Water Adaptation ◽  
Sodium Regulation ◽  
High Degree

1. New intra-vascular cannulation techniques are described, and also an extra-corporal blood circuit containing an artificial heart and a counting cell. This makes possible a continuous study of the radioactivity of the blood. 2. Plasma chloride concentration varies greatly in fresh-water eels despite good sodium regulation. 3. The fresh-water to sea-water adaptation of eels is frequently accompanied by a temporary hypermineralization of the internal medium. This necessitates a high degree of cellular euryhalinity. 4. The sea-water-adapted eel maintains strict homeostasis of its plasma chloride and sodium. 5. The chloride distribution space decreases by 10% when eels are transferred from fresh water to sea water. The internal distribution of chloride is also modified and its fluxes between the ion compartments of the body are considerably increased.

The Urine of Gammarus Duebeni and G. Pulex

1961 ◽  
Vol 38 (3) ◽  
pp. 647-658
Author(s):  
A. P. M. LOCKWOOD
Keyword(s):  
Fresh Water ◽  
Brackish Water ◽  
Blood Concentration ◽  
Sea Water ◽  
The Body ◽  
Absolute Level ◽  
The Absolute ◽  
Urine Formation ◽  
Concentration Of Urine

1. A study has been made of the relation between blood, urine and medium concentrations in the two amphipod Crustacea G. duebeni and G. pulex. 2. G. duebeni produces urine hypotonic to the blood but hypertonic to the medium when it is in media more dilute than 50% sea water. 3. G. pulex forms urine which is hypotonic both to blood and medium when in 2-20% sea water. 4. G. duebeni begins to form hypotonic urine within 2 hr. of transference from 110 to 160% sea water to fresh water. Hypotonic urine formation begins in these circumstances when the blood concentration is up to twice that at which hypotonic urine is formed by animals fully adapted to their medium. 5. It is concluded (a) that the concentration of urine produced by G. duebeni is not dictated solely by the absolute level of the blood concentration; (b) that the formation of urine hypotonic to the blood in a brackish-water animal functions primarily as a means of conserving ions in the body; (c) that the ability to regulate the concentration of the urine with rapidity will be important in an animal living in environments of fluctuating salinities.

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