Rectal Absorption in the Desert Locust, Schistocerca Gregaria Forskål

1964 ◽  
Vol 41 (1) ◽  
pp. 15-38
Author(s):  
I. WATER ◽  
J. E. PHILLIPS
Keyword(s):  
Water Absorption ◽  
Schistocerca Gregaria ◽  
Tap Water ◽  
Rectal Wall ◽  
Ionic Concentration ◽  
Osmotic Gradient ◽  
Desert Locust ◽  
Rectal Absorption ◽  
Net Flux

1. The histology of the rectum of Schistocerca gregaria is described. 2. A method is described whereby net absorption of water from the rectum (in situ, isolated by ligation) can be measured. 3. Water is actively absorbed from the lumen of the rectum against an osmotic gradient and in the absence of a significant net flux of solute. 4. The maximum osmotic gradient developed is 2-3 times greater in locusts supplied with hypertonic saline than in locusts supplied with tap water. This indicates some ability to regulate water absorption in relation to requirement. 5. The ionic concentration of rectal fluid and the rate of salt absorption from the lumen have little effect on the maximum osmotic gradient developed across the rectal wall. 6. Possible mechanisms of active absorption of water are discussed.

Rectal Absorption in the Desert Locust, Schistocherca Gregaria Forskål

1964 ◽  
Vol 41 (1) ◽  
pp. 69-80
Author(s):  
J. E. PHILLIPS
Keyword(s):  
Water Balance ◽  
Osmotic Pressure ◽  
Schistocerca Gregaria ◽  
Tap Water ◽  
Ionic Concentration ◽  
Malpighian Tubules ◽  
Desert Locust ◽  
Ionic Regulation ◽  
Rectal Absorption ◽  
Salt And Water Balance

1. The physiology of the excretory system and its role in salt and water balance have been studied in the desert locust, Schistocerca gregaria. 2. Collections and analyses were made of hindgut fluid (derived from the Malpighian tubules) and rectal fluid from locusts kept under various dietary régimes. 3. In starved locusts supplied with tap water very little fluid accumulates in the rectum, the output of the Malpighian tubules being almost completely reabsorbed. Relatively more salt than water is reabsorbed with the result that the rectal fluid attains a lower ionic concentration but higher osmotic pressure than the haemolymph. No fluid is voided. 4. In starved locusts supplied with hypertonic saline the rectum is distended with, fluid which has an osmotic pressure and ionic concentration considerably above that of the haemolymph. Very little fluid is voided. 5. Substantial elimination of fluid from the rectum occurs only in fed locusts, in association with the voiding of faeces. 6. These results are discussed in relation to the mechanism of osmotic and ionic regulation.

Rectal Absorption in the Desert Locust, Schistocerca Gregaria Forskål

1964 ◽  
Vol 41 (1) ◽  
pp. 39-67 ◽  
Author(s):  
J. E. PHILLIPS
Keyword(s):  
Hypertonic Saline ◽  
Active Transport ◽  
Schistocerca Gregaria ◽  
Tap Water ◽  
Experimental Results ◽  
Desert Locust ◽  
Active Process ◽  
Rectal Absorption ◽  
Passive Permeability ◽  
Active Processes

1. The absorption of Na, K and Cl from the rectum has been studied in locusts previously supplied either with tap water or with hypertonic saline, the latter treatment resulting in a 40-70% increase in the ionic concentrations in the haemolymph. 2. Both water-fed and saline-fed locusts can absorb Na, K and Cl from the lumen of the rectum against concentration differences of up to 100-fold. The lumen is 15-30 mV. positive to the haemolymph. Absorption of Cl is certainly an active process; absorption of Na and K probably involves active processes. 3. In water-fed locusts absorption of K is four to twelve times more rapid than that of Na, and absorption of Cl is three times faster from KC1 than from NaCl. 4. In saline-fed locusts the relative rates of absorption of Na, K and Cl are the same as in water-fed locusts, except when the concentrations in the rectal fluid exceed those in the haemolymph. 5. The experimental results are consistent with the hypothesis that regulation of absorption of water and of ions from the rectum is brought about by changes in the passive permeability of the epithelium rather than by changes in mechanisms of active transport.

Osmotic regulation and rectal absorption in the blowfly, Calliphora erythrocephala

1969 ◽  
Vol 47 (5) ◽  
pp. 851-863 ◽  
Author(s):  
J. E. Phillips
Keyword(s):  
Rectal Wall ◽  
Blood Levels ◽  
Sugar Solution ◽  
Osmotic Gradient ◽  
Osmotic Regulation ◽  
Rectal Absorption ◽  
Calliphora Erythrocephala ◽  
Chloride Concentrations ◽  
Osmoregulatory Ability

The osmoregulatory ability of blowflies was investigated by measuring osmotic pressures and chloride concentrations of haemolymph, urine, and, under some conditions, crop and hindgut fluids from water-fed and water-deprived animals. Blood levels were kept within narrow limits by production of either very hyposmotic or strongly hyperosmotic urine. Water and chloride reabsorption from isolated recta were measured directly in vivo. While no positive evidence was obtained that ion reabsorption in the rectum plays an important role in production of hyposmotic urine, it was clearly established that hyperosmotic urine resulted from absorption of water against an increasing osmotic gradient in the latter organ. The rate of water absorption was dependent on the osmotic gradient across the rectal wall and occurred from an initially pure sugar solution as well as from saline. Current ideas on the possible mechanism of water transport in the insect rectum are discussed and assessed.

Phosphate transport by locust rectum in vitro

1980 ◽  
Vol 58 (9) ◽  
pp. 1518-1523 ◽  
Author(s):  
E. W. Andrusiak ◽  
J. E. Phillips ◽  
J. Speight
Keyword(s):  
Schistocerca Gregaria ◽  
Rectal Wall ◽  
Phosphate Transport ◽  
Malpighian Tubules ◽  
Large Concentration ◽  
Active Process ◽  
Solvent Drag

The rectal cuticle is permeable to H2PO4−, but much less so to HPO42−. Everted rectal sacs of Schistocerca gregaria transport PO4 from lumen to hemocoel side against large concentration and electrical differences. This active process is not caused by solvent drag and it obeys Michaelis–Menten kinetics. Entry of 32PO4 into rectal tissue from the lumen is inhibited by arsenate. Much of the 32PO4 is converted to organic forms in the tissue but these do not enter the hemocoel compartment. Net rates of PO4 movement across the rectal wall in vitro are high enough to explain recovery of phosphate secreted in situ by Malpighian tubules of starved locusts. The location and possible mechanism of PO4 transport are discussed.

THE HISTOLOGY OF THE GIANT FIBRE SYSTEM IN THE ABDOMINAL VENTRAL NERVE CORD OF THE DESERT LOCUST

1970 ◽  
Vol 102 (9) ◽  
pp. 1163-1168 ◽  
Author(s):  
W. D. Seabrook
Keyword(s):  
Single Cell ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Schistocerca Gregaria ◽  
Desert Locust ◽  
Giant Fibre ◽  
Metathoracic Ganglion ◽  
Giant Fibres ◽  
Giant Fibre System

AbstractSchistocerca gregaria possess four neurones of giant fibre proportions within the abdominal ventral nerve cord. These fibres arise from single cell bodies in the terminal ganglionic mass and pass without interruption to the metathoracic ganglion. Fibres become reduced in diameter when passing through a ganglion. Branching of the giant fibres occurs in abdominal ganglia 6 and 7.

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