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. 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, 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.

scholarly journals The mechanism of C-20 hydroxylation of α-ecdysone in the desert locust, Schistocerca gregaria

1977 ◽  
Vol 168 (3) ◽  
pp. 513-520 ◽  
Author(s):  
P Johnson ◽  
H H Rees
Keyword(s):  
Schistocerca Gregaria ◽  
Fat Body ◽  
Difference Spectrum ◽  
Maximum Activity ◽  
Malpighian Tubules ◽  
Desert Locust ◽  
Ph Optimum ◽  
Developmental Variation ◽  
Moulting Hormone ◽  
Cytochrome P 450

1. The C-20 hydroxylation of alpha-ecdysone to produce beta-ecdysone was investigated in the desert locust, Schistocerca gregaria. 2. alpha-Ecdysone C-20 hydroxylase activity was located primarily in the fat-body and Malpighian tubules. The properties of the hydroxylation system from Malpighian tubules investigated further. 3. The enzyme system was mitochondrial, had a pH optimum of 6.5, an apparent Km of 12.5 micron and required O2 and NADPH. 4. The activity of the hydroxylation system showed developmental variation within the fifth instar, the maximum activity corresponding to the maximum tire of endogenous moulting hormone. The significance of these results is assessed in relation to the control of the endogenous titre of beta-ecdysone. 5. The mechanism of the hydroxylation system was investigated by using known inhibitors of hydroxylation reactions such as CO, metyrapone and cyanide. 6. The CO difference spectrum of the reduced mitochondrial preparation indicated the presence of cytochrome P-450 in the preparation. 7. It concluded that the alpha-ecdysone C-20 hydroxylase system is a cytochrome P-450-deendent mono-oxygenase.

scholarly journals Salt and Water Balance in the Spider, Porrhothele Antipodiana (Mygalomorpha: Dipluridae): Effects of Feeding upon Hydrated Animals

1986 ◽  
Vol 125 (1) ◽  
pp. 85-106 ◽  
Author(s):  
A. G. Butt ◽  
H. H. Taylor
Keyword(s):  
Adipose Tissue ◽  
Water Balance ◽  
Volume Regulation ◽  
Dry Weight ◽  
Malpighian Tubules ◽  
Constant Rate ◽  
Single Meal ◽  
Ad Libitum ◽  
Salt And Water Balance ◽  
Total Body

Please address offprint requests to Dr H. H. Taylor. The spider, Porrhothele antipodiana, starved and provided with water, produced urine via the anal excretory system (Malpighian tubules, midgut diverticula and stercoral pocket) at a mean rate of about 2.5-5 μlg−1 day−1 and with a mean Na+/K+ ratio of about 1.0. Salts ingested from the prey were eliminated by two mechanisms. A K+-rich (Na+/K+ about 0.2) anal diuresis lasted about 3 days following a single meal and was maintained at more than 30μlg−1day−1 during feeding ad libitum. The second mechanism, interpreted as coxal secretion, functioned only during feeding itself and delivered Na+ into the prey at a constant rate of about 3%h−1 of total body Na+. This progressively raised the Na+/K+ ratio of the prey debris from 0.47 to 0.96 and, because of re-ingestion, recycled more Na+ than was originally present in the prey. Feeding was associated with large net increases in dry weight and ions, particularly K+, which were mainly stored in the diverticular tissue (midgut diverticula and Malpighian tubules embedded in adipose tissue). The stercoral fluid (final urine) was slightly hyposmotic to the haemolymph in starved and fed spiders. Only about half of its osmolarity was accounted for by Na+, K+ and Cl−. The volume of water gained from the meal was about equal to that lost in diuresis, and P. antipodiana drinks to maintain water balance because of relatively high transpirational and other losses. The primary function of the diuresis is probably elimination of ions from the meal, and not volume regulation.

The life-cycle, ultrastructure and mode of feeding of the locust amoeba Malpighamoeba locustae

Parasitology ◽  
1976 ◽  
Vol 72 (2) ◽  
pp. 127-135 ◽  
Author(s):  
Owen G. Harry ◽  
L. H. Finlayson
Keyword(s):  
Life Cycle ◽  
Brush Border ◽  
Schistocerca Gregaria ◽  
Malpighian Tubules ◽  
Desert Locust ◽  
Cell Organelles ◽  
Normal Complement ◽  
Gut Epithelium ◽  
Food Vacuoles ◽  
Storage Granules

The primary trophozoites of Malpighamoeba locustae excyst in the crop and midgut of the Desert Locust (Schistocerca gregaria) and then penetrate the epithelial cells of the midgut and caeca where they grow and multiply slowly. After about 10–12 days they leave the gut epithelium passively when the cells in which they have grown degenerate and are extruded. From the lumen of the gut they make their way into the lumen of the Malpighian tubules where they feed upon the brush border as extracellular parasites. No primary or secondary trophozoites were found in the haemocoele of the host.During the first few days in the Malpighian tubules the secondary trophozoites undergo a rapid series of divisions which enables them to double their numbers every 24 h so that by day 20–22 the lumen of the tubules is packed with cysts and trophozoites. The trophozoites phagocy-tose small pieces of brush border and numerous food vacuoles are present in their cytoplasm. The cytoplasm of the primary trophozoite contains the normal complement of cell organelles, a notable feature of which are the large, numerous mitochondria with their tubular cristae. When the trophozoites are ready to encyst they round up and begin to lay down a series of membranes which totally cover the trophozoite. Numerous storage granules are found in mature trophozoites which are about to encyst and these may be utilized in cyst wall production.

scholarly journals Fluid Secretion by the Malpighian Tubules of the Dragonfly Libellula Quadrimaculata

1985 ◽  
Vol 116 (1) ◽  
pp. 53-67 ◽  
Author(s):  
S. P. NICHOLLS
Keyword(s):  
Osmotic Pressure ◽  
External Medium ◽  
Salt Water ◽  
Tap Water ◽  
Fold Increase ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Thoracic Ganglia

Fluid secretion by the Malpighian tubules of Libellula quadrimaculata is unusual in that it is dependent on sodium and entirely independent of potassium in the external medium. It is suggested that this is due to the primitive, sodium-rich haemolymph of the Odonata. Similarities between these tubules and those of the millipede Glomeris marginata, which has a similar sodium-based haemolymph, support this view. Fluid secretion by the tubules is also dependent on the osmotic pressure of the external medium, declining considerably at higher osmotic pressures. However, there is no difference in the secretory rates of tubules isolated from larvae adapted to tap water, de-ionized water or salt water, even though there are large differences in the haemolymph osmotic pressure under these different conditions. This suggests some form of adaptation of the tubules in larvae from these different conditions. A factor which causes a five- to six-fold increase in the rate of secretion was present in the thoracic ganglia, and a slightly lower increase in secretion rate was recorded in larvae that had been feeding.

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