The effect of external salinity on drinking rate and rectal secretion in the larvae of the saline-water mosquito Aedes taeniorhynchus

1977 ◽  
Vol 66 (1) ◽  
pp. 97-110
Author(s):  
T. J. Bradley ◽  
J. E. Phillips
Keyword(s):  
Sea Water ◽  
External Medium ◽  
Narrow Range ◽  
Saline Water ◽  
Fluid Secretion ◽  
Osmotic Concentration ◽  
Drinking Rate ◽  
Aedes Taeniorhynchus ◽  
External Salinity ◽  
Kinetics Of

1. The drinking rate of the saline-water mosquito larva Aedes taeniorhyncus (100 nl.mg-1.h-1) is unaffected by the salinity of the external medium, but is directly proportional to the surface area of the animal. 2. Haemolymph Na+, Mg2+, K+, Cl-, SO42- and osmotic concentrations were measured in larvae adapted to 10%, 100% and 200% seawater and were found to be regulated within a narrow range. 3. With the exception of potassium, ionic concentrations in rectal secretion were found to increase with increasing concentrations of the sea water in which larvae were reared. 4. The osmotic concentration of rectal secretion was unaffected by changes in haemolymph osmotic concentration but did rise when sodium or chloride concentrations of the haemolymph were increased. High levels of these ions also stimulated the rate of fluid secretion. 5. Transport of chloride and sodium by the rectum exhibits the kinetics of allosteric rather than classical enzymes.

The secretion of hyperosmotic fluid by the rectum of a saline-water mosquito larva, Aedes taeniorhynchus

1975 ◽  
Vol 63 (2) ◽  
pp. 331-342 ◽  
Author(s):  
T. J. Bradley ◽  
J. E. Phillips
Keyword(s):  
Sea Water ◽  
Saline Water ◽  
Average Rate ◽  
Ionic Composition ◽  
Fluid Secretion ◽  
Osmotic Concentration ◽  
Aedes Taeniorhynchus ◽  
Osmotic Balance ◽  
Anal Papillae

1. Fourth-instar larvae of the mosquito A. taeniorhynchus (Wiedemann), when living in sea water, drink at a rate of 100 nl h(−1) larva(−1) and maintain ionic and osmotic levels in the haemolymph at about one-third those of the external medium. 2. Hyperosmotic urine is produced in the rectum by secretion of fluid having an osmotic concentration and ionic composition similar to that of sea water, with the exception that potassium levels are elevated 18-fold in the secretion. The average rate of fluid secretion observed was 19 nl h-1) larva(−1) with a maximum of 92 nl h(−1) larva(−1). 3. The concentration and volume of rectal secretion may be too low to account completely for osmotic balance. The possible role of anal papillae is discussed in this regard.

The location and mechanism of hyperosmotic fluid secretion in the rectum of the saline-water mosquito larvae Aedes taeniorhynchus

1977 ◽  
Vol 66 (1) ◽  
pp. 111-126
Author(s):  
T. J. Bradley ◽  
J. E. Phillips
Keyword(s):  
Saline Water ◽  
Fluid Secretion ◽  
Opposite Polarity ◽  
Posterior Segment ◽  
Transport Processes ◽  
Cell Border ◽  
Experimental Conditions ◽  
Ultrastructural Studies ◽  
Aedes Taeniorhynchus

1. Ligation between the anterior and posterior segments of the rectum in vitro was used to demonstrate that the posterior rectum is the site of hyperosmotic secretion to the lumen side. Observations were consistent with a reabsorptive function for the anterior rectum. These results support predictions from ultrastructural studies of these two segments. 2. The initial potential of the rectal lumen, relative to the haemocoel side, was of opposite polarity in the anterior (−10 mV) and posterior (+ 10 mV) segments and these values decreased to −2 and +6 mV respectively in ligated recta which had secreted for 2 h. 3. A comparison of these potential difference measurements with concentration differences developed across the rectal epithelium under the same experimental conditions indicates that Na+, K+, Mg2+, and Cl- are all actively transported by the posterior segment to the lumen side. 4. The influence of different haemolymph concentrations of Na+, K+, and Cl- on the potential differences across the basal cell border and across the whole rectal epithelium are reported. Based on this and previous data, we propose a model for the organization of transport processes within the single celltype present in the posterior rectal epithelium.

Regulation of rectal secretion in saline-water mosquito larvae living in waters of diverse ionic composition

1977 ◽  
Vol 66 (1) ◽  
pp. 83-96 ◽  
Author(s):  
T. J. Bradley ◽  
J. E. Philips
Keyword(s):  
Chemical Composition ◽  
External Medium ◽  
Saline Water ◽  
Ionic Composition ◽  
Malpighian Tubules ◽  
Fluid Composition ◽  
Mosquito Larvae ◽  
Major Site ◽  
Osmotic Concentration ◽  
Anal Papillae

1. Larvae of the saline-water mosquito Aedes campestris were adapted to three waters, all having an osmotic concentration of 700 mOsm, but differing in ionic rations. The (Na+Mg) SO4 medium was much moretoxic than the NAHCO3 or the NaCl media. 2. Ionic and osmotic concentrations of haemolymph and rectal secretion were measured in larvae adapted to all three media. The ratio of ionic concentrations in the rectal secretion reflected those in the external medium to which the larvae had been adapted, with the exception of SO42-, which was possibly replaced by HCO3-in the secretion. These differences in rectal fluid composition persisted even though all ligated recta were bathed in the same artificial haemolymph. 3. The Malpighian tubules were found to be the major site of SO42- excretion. In media containing high levels of NA+, Mg2+, K+, Cl- and HCO3-, the rectum secreted a hyperosmotic fluid containing these ions at concentrations several times greater than those found in the haemolymph. 4. These data provide the basis for speculation on the functioning of anal papillae in waters of diverse chemical composition.

Kinetics of Water and Chloride Exchanges During Adaptation of the European Eel to Sea Water

1973 ◽  
Vol 58 (1) ◽  
pp. 105-121
Author(s):  
R. KIRSCH ◽  
N. MAYER-GOSTAN
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Maximum Level ◽  
Progressive Increase ◽  
Plasma Sodium ◽  
European Eel ◽  
Drinking Rate ◽  
The One ◽  
Kinetics Of

Using isotopic procedures, the drinking rate and chloride exchanges were studied in the eel Anguilla anguilla during transfer from fresh water to sea water. 1. Following transfer to sea water there is a threefold increase of the drinking rate (lasting about 1 h). Then it falls to a minimum after 12-16 h and rises again to a maximum level about the seventh day after the transfer. Then a gradual reduction leads to a steady value which is not significantly different from the one observed in fresh water. 2. The changes with time of the plasma sodium and chloride concentrations are given. Their kinetics are not completely alike. 3. The chloride outflux increases 40-fold on transfer of the eel to sea water, but even so it is very low. After the sixth hour in sea water there is a progressive increase in the flux, so that on the fourth day it is higher (500 µ-equiv. h-1.100 g-1) than in the seawater-adapted animals (230 µ-equiv.h-1.100 g-1). 4. Drinking rate values in adapted animals are discussed in relation to the external medium. The kinetics of the drinking rate together with variations in body weights after freshwater-seawater transfer are discussed in relation to the possible stimulus of the drinking reflex. 5. Chloride fluxes (outflux, net flux, digestive entry) are compared and lead one to assume that in seawater-adapted fish one-third of the chloride influx enters via the gut and two-thirds via the gills.

scholarly journals THE KINETICS OF PENETRATION

1938 ◽  
Vol 22 (2) ◽  
pp. 147-163 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
Osmotic Pressure ◽  
Free Space ◽  
Partition Coefficients ◽  
Sea Water ◽  
Intact Cell ◽  
Linear Part ◽  
Osmotic Concentration ◽  
Intact Cells ◽  
Rate Of Increase ◽  
Kinetics Of

When Valonia cells are impaled on capillaries, it is in some ways equivalent to removing the comparatively inelastic cellulose wall. Under these conditions sap can migrate into a free space and it is found that on the average the rate of increase of volume of the sap is 15 times what it is in intact cells kept under comparable conditions. The rate of increase of volume is a little faster during the first few hours of the experiment, but it soon becomes approximately linear and remains so as long as the experiment is continued. The slightly faster rate at first may mean that the osmotic pressure of the sap is approaching that of the sea water (in the intact cell the sap osmotic pressure is always slightly above that of the sea water). This might result from a more rapid entrance of water than of electrolyte, as would be expected when the restriction of the cellulose wall was removed. During the linear part of the curve the osmotic concentration and the composition of the sap suffer no change, so that entrance of electrolyte must be 15 times as fast in the impaled cells as it is in the intact cells. The explanation which best accords with the facts is that in the intact cell the entrance of electrolyte tends to increase the osmotic pressure. As a consequence the protoplasm is partially dehydrated temporarily and it cannot take up more water until the cellulose wall grows so that it can enclose more volume. The dehydration of the protoplasm may have the effect of making the non-aqueous protoplasm less permeable to electrolytes by reducing the diffusion and partition coefficients on which the rate of entrance depends. In this way the cell is protected against great fluctuations in the osmotic concentration of the sap.

The Kinetics of Peripheral Exchanges of Water and Electrolytes in the Silver Eel (Anguilla Anguilla L.) in Fresh Water and in Sea Water

1972 ◽  
Vol 57 (2) ◽  
pp. 489-512
Author(s):  
R. KIRSCH
Keyword(s):  
Sea Water ◽  
External Medium ◽  
Anguilla Anguilla ◽  
Osmotic Gradient ◽  
Silver Eel ◽  
Experimental Tank ◽  
Experimental Conditions ◽  
Control Measurement ◽  
Internal Medium ◽  
Kinetics Of

1. New experimental techniques are described for the investigation of water and electrolyte fluxes in the eel by studying the internal medium, the urine and the external medium. An experimental tank made up of two compartments isolates the water containing the head from the water containing the trunk and tail of the animal. The two water circuits are separated by remote control. Measurement can thus be made without handling the eel previously adapted to experimental conditions. 2. The freshwater eel shows low branchial exchanges and low chloride urinary losses. A positive correlation between urinary excretion of water and sodium has been shown. 3. The silver eel's skin is impermeable to water and chlorides. 4. The eel reacts to FW-SW transfer by immediately drinking water. The drinking reflex is therefore not triggered by dehydration due to the osmotic gradient. 5. During SW adaptation the eel presents a transitory hyperactivity phase of the branchial outflux corresponding to plasma hypermineralization. 6. The eel which has been adapted to sea water for 3 weeks shows the lowest chloride exchanges ever recorded among marine teleosts.

Induction of Sulphate Transport and Hormonal Control of Fluid Secretion by Malpighian Tubules of Larvae of the Mosquito Aedes Taeniorhynchus

1978 ◽  
Vol 72 (1) ◽  
pp. 181-202 ◽  
Author(s):  
S.H. P. MADDRELL ◽  
J. E. PHILLIPS
Keyword(s):  
Sea Water ◽  
Fluid Secretion ◽  
Hormonal Control ◽  
Malpighian Tubules ◽  
High Rate ◽  
Sulphate Content ◽  
Thoracic Ganglia ◽  
Sulphate Transport ◽  
Aedes Taeniorhynchus ◽  
The Brain

1. 4th stage larvae of A. taeniorhynchus reared in sulphate-enriched sea water drink the medium at the same rate that they do when reared in sulphate-free sea water. They absorb into the haemolymph most of the water and nearly all of the sulphate from the ingested fluid. 2. Larvae are able to keep the concentration of sulphate in the haemolymph at levels well below that of the medium, even when this contains as much as 89 mM sulphate. 3. The Malpighian tubules of larvae reared in sulphate-containing waters soon develop an ability to transport sulphate. The rate of sulphate transport induced varies directly with the sulphate content of the water in which they are reared. This ability is not retained into the adult stage. 4. The rate of fluid secretion by isolated Malpighian tubules is increased by up to 20 times when they are exposed to saline containing 1.5 mM cyclic AMP or concentrations of 5-hydroxytryptamine higher than 10−6 5. Tubules isolated from unfed insects into stimulant-free saline secrete fluid only slowly, but similarly treated tubules from feeding insects initially secrete fluid very much faster. 6. Extracts of the brain and of the thoracic ganglia stimulate Malpighian tubules to secrete fluid at a high rate. The brain is about four times as rich a source of stimulant as is the chain of thoracic ganglia. Treatment of the surface of the structures in the head with K-rich saline leads to the release of a factor which stimulates fluid secretion by the Malpighian tubules. 7. The results suggest that the Malpighian tubules in larvae of A. taeniorhynchus are under the control of a diuretic hormone which is elaborated in the brain and possibly also in the thoracic ganglia and which reaches high levels in the circulating haemolymph of feeding animals. 8. The rate of sulphate transport by isolated Malpighian tubules is strongly affected by the rate of fluid secretion. This behaviour is compatible with a passive leak of transported sulphate from the lumen back into the haemolymph through the permeable wall of the tubule.

scholarly journals THE KINETICS OF PENETRATION

1939 ◽  
Vol 22 (6) ◽  
pp. 757-773 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
Natural Variation ◽  
Sea Water ◽  
Intact Cell ◽  
The State ◽  
Osmotic Concentration ◽  
Linear Rate ◽  
Partial Dissipation ◽  
Rate Of Increase ◽  
The Difference ◽  
Kinetics Of

When cells of Halicystis are impaled on a capillary so that space is provided into which the sap can migrate, the rate of entrance of water and of electrolyte is increased about 10-fold. In impaled Valonia cells the rate is increased about 15-fold. After a relatively rapid non-linear rate of increase of sap volume immediately after impalement (which may possibly represent the partial dissipation of the difference of the osmotic energy between intact and impaled cells) the volume increases at a linear rate, apparently indefinitely. Since the halide concentration of the sap at the end of the experiment is (within the limits of natural variation) the same as in the intact cell, we conclude that electrolyte also enters the sap about 10 times as fast as in the intact cell. As in the case of Valonia we conclude that there is a mechanism whereby in the intact cell the osmotic concentration of the sap is prevented from greatly exceeding that of the sea water. This may be associated with the state of hydration of the non-aqueous protoplasmic surfaces.

scholarly journals The pattern of osmotic regulation in larvae of the mosquito Culiseta inornata

1984 ◽  
Vol 113 (1) ◽  
pp. 133-141 ◽  
Author(s):  
M. Garrett ◽  
T. J. Bradley
Keyword(s):  
Sea Water ◽  
Saline Water ◽  
Mosquito Species ◽  
Full Range ◽  
Chloride Ion ◽  
Malpighian Tubules ◽  
Osmotic Concentration ◽  
Culiseta Inornata

Larvae of Culiseta inornata (Williston) can survive and complete development in dilutions of sea water ranging from 50–700 mosmol kg-1. The larvae hyperregulate with regard to haemolymph osmotic concentration in dilute media (50–400 mosmol kg-1) and osmoconform when external salinities exceed 400 mosmol kg-1. This pattern of osmoregulation is distinct from that observed in freshwater and saline-water mosquito species. We propose that mosquitoes exhibiting this osmoregulatory pattern should be described as ‘brackish-water’ species. Larvae of Culiseta inornata are able closely to regulate both sodium and chloride ion concentrations in the haemolymph over the full range of salinities tested (50–750 mosmol kg-1). The Malpighian tubules produce an isosmotic, potassium-rich fluid. In vitro and in vivo sampling of rectal fluids demonstrates that rectal secretions are isosmotic or only slightly hyperosmotic to the haemolymph and the surrounding saline media, and that they are isotonic with regard to sodium.

scholarly journals Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise

2012 ◽  
Vol 16 (7) ◽  
pp. 1845-1862 ◽  
Author(s):  
F. Jørgensen ◽  
W. Scheer ◽  
S. Thomsen ◽  
T. O. Sonnenborg ◽  
K. Hinsby ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Sea Level Rise ◽  
Sea Level ◽  
Preferential Flow ◽  
Sea Water ◽  
Saline Water ◽  
Seismic Survey ◽  
Salinity Distribution ◽  
Geological Structures ◽  
The North

Abstract. Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.

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