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.

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 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.

Exchanges of Sodium and Potassium in Mosquito Larvae

1953 ◽  
Vol 30 (1) ◽  
pp. 79-89 ◽  
Author(s):  
J. A. RAMSAY
Keyword(s):  
Aedes Aegypti ◽  
External Medium ◽  
The Body ◽  
Malpighian Tubules ◽  
Mosquito Larvae ◽  
The Face ◽  
Tubule Fluid ◽  
Sodium And Potassium

1. The movements of sodium and potassium through the body and their exchanges between the body and the external medium have been studied in the larva of Aedes aegypti L. 2. Briefly, both elements enter the body via the anal gills, are excreted by the Malpighian tubules and can be absorbed from the tubule fluid in the rectum. When either element is present in the medium to excess its concentration in the tubule fluid is increased and the extent of its absorption in the rectum is decreased. 3. Under all conditions the concentration of potassium in the tubule fluid is greater than its concentration in the haemolymph, and the concentration of sodium is less. There is a circulation of potassium from haemolymph to tubule, to rectum or midgut and so back to haemolymph. 4. The composition of the haemolymph in respect of sodium and potassium is remarkably constant in the face of changes in the medium. 5. The volume of the larva appears to be regulated by a nervous mechanism. If the volume is increased peristaltic waves pass down the intestine more frequently and more fluid is voided through the anus.

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 Aedes Aegypti: Energetics of Osmoregulation

1982 ◽  
Vol 101 (1) ◽  
pp. 135-141 ◽  
Author(s):  
H.A. EDWARDS
Keyword(s):  
Oxygen Consumption ◽  
Energy Cost ◽  
Sea Water ◽  
External Medium ◽  
Minimum Energy ◽  
Body Volume ◽  
Wet Weight ◽  
Minimum Energy Cost ◽  
Anal Papillae ◽  
Theoretical Minimum

1. Oxygen consumption of A. aegypti larvae, about 210 mul l g−1 tissue wet weight h−1, does not change when the salinity of the environment is changed. The number of mitochondria in the anal papillae, a salt-absorbing epithelium, increases as the external medium is diluted. There is no difference in oxygen consumption between isolated anal papillae in 0, 2 and 20% sea water. The papillae represent about 5% of body volume and their oxygen consumption is about 2% of the animal's total. The theoretical minimum energy cost of osmoregulation is four orders of magnitude smaller than the measured figure for the anal papillae alone. Osmoregulatory phenomena which would explain the recorded observations are discussed.

The Exchange of Labelled Sodium in the Larva of Aedes Aegypti L

1954 ◽  
Vol 31 (3) ◽  
pp. 386-401 ◽  
Author(s):  
JOHN E. TREHERNE
Keyword(s):  
Aedes Aegypti ◽  
Body Surface ◽  
External Medium ◽  
Whole Body ◽  
Effect Of Temperature ◽  
Potassium Ions ◽  
Distilled Water ◽  
General Body ◽  
Anal Papillae

1. The exchange of labelled sodium between the external medium and the haemolymph and whole body has been investigated in the larva of Aedes aegypti. The time for half exchange was of the order of 62 hr. 2. It was found that most of the exchange of labelled sodium occurred through the anal papillae, although smaller amounts enter the haemolymph through the gut and general body surface. Transfer constants have been used to describe the resultant turnover of labelled sodium in the whole system. 3. The rate of uptake of sodium was independent of the external concentrations used in these experiments. 4. Potassium ions do not compete with sodium for uptake, which suggests that separate mechanisms are responsible for the accumulation of these two ions. 5. Larvae were able to retain the sodium in the haemolymph, with relatively little loss, in glass-distilled water. 6. The effect of temperature on the rate of uptake of labelled sodium has been investigated.

The Chemical Composition of Some Surface Waters in Central Australia

1963 ◽  
Vol 14 (2) ◽  
pp. 166 ◽  
Author(s):  
WD Williams ◽  
BD Siebert
Keyword(s):  
Chemical Composition ◽  
Surface Waters ◽  
Ionic Composition ◽  
Northern Territory ◽  
Ionic Ratios ◽  
Central Australia ◽  
Dissolved Salts

The surface waters of central Australia are briefly discussed. Analyses are presented of the ionic composition of some relatively non-saline and mostly permanent surface waters in the southern part of the Northern Territory. A brief note upon their fauna is included. Such waters are of interest because of their extreme isolation in so arid an area. They contain from 77 to 3735 p.p.m. total dissolved salts and their ionic ratios are variable. The ionic compositions are discussed.

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