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.

scholarly journals Excretion in the House Cricket (Acheta Domesticus): Stimulation of Diuresis by Tissue Homogenates

1987 ◽  
Vol 129 (1) ◽  
pp. 63-81 ◽  
Author(s):  
JEFFREY H. SPRING ◽  
SHELIA R. HAZELTON
Keyword(s):  
Lethal Dose ◽  
Fluid Secretion ◽  
Sodium Concentration ◽  
Inhibitory Effect ◽  
Acheta Domesticus ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Tissue Homogenates ◽  
Extreme Sensitivity

1. A new method is described for maintaining cricket Malpighian tubules in vitro. Warmed, oxygenated saline is circulated rapidly past the tubules, while the secreted urine is collected under oil for analysis. This technique allows the cricket tubules to be observed and manipulated for extended periods (6 h), in contrast to their short life (>1 h) using conventional methods. 2. Cricket tubules show extreme sensitivity to oxygen deprivation, such that 15 min of anoxia represents the median lethal dose (LD50) for in vitro preparations. 3. Homogenates of corpus cardiacum (CC) cause the rate of fluid secretion by the tubules to double. The maximum stimulation is dose-dependent over the range 0.01 to 1.0 CC. Homogenates of brain and other ganglia show much smaller stimulatory effects (0.01-0.02 CC-equivalents). Cyclic AMP mimics the increase in secretion rate, but has an inhibitory effect on the smooth muscle of the ureter. 4. Control preparations maintain a urine osmotic pressure (OP) that is hyperosmotic to the bath by 5–10 mosmol l−1. CC homogenate produces a decrease in urine OP to 10–12 mosmol l−1 hypo-osmotic to the bath. This suggests that active solute reabsorption is occurring in the lower tubule or ampulla. 5. Stimulation by CC homogenate increases the urine potassium concentration slightly less than two-fold, whereas the sodium concentration increases by a maximum of five-fold and remains at a higher concentration than potassium throughout the experiment. Tubule secretion rate is drastically inhibited in nominally sodium-free saline.

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.

Dibutyryl-cAMP increases basolateral sodium conductance of mosquito Malpighian tubules

1985 ◽  
Vol 248 (3) ◽  
pp. R339-R345 ◽  
Author(s):  
D. B. Sawyer ◽  
K. W. Beyenbach
Keyword(s):  
Basolateral Membrane ◽  
Fold Increase ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Dibutyryl Camp ◽  
Dominant Effect ◽  
Membrane Conductances ◽  
Transepithelial Voltage ◽  
K Concentration ◽  
Basolateral Membrane Potential

Dibutyryladenosine 3',5'-cyclic monophosphate (cAMP) stimulates fluid secretion in isolated Malpighian tubules of the mosquito Aedes aegypti. In the present study the effects of cAMP on the basolateral membrane were studied with conventional microelectrodes. Membrane conductances were evaluated from the changes of the basolateral membrane potential (Vbl) consequent to ion changes in the bath. Under control conditions, Vbl measured -65.2 +/- 1.5 mV [83 impalements, 67 tubules]. A fivefold decrease in the bath Na concentration hyperpolarized Vbl by 10.2 +/- 0.6 mV [7], whereas a 4.4-fold increase in the bath K concentration depolarized Vbl by 7.9 +/- 1.0 mV [9]. In the presence of cAMP (10(-4) M) Vbl depolarized to -24.8 +/- 2.7 mV [9]. Vbl now hyperpolarized by 22.7 +/- 1.5 mV [7] for the bath Na change and depolarized by only 3.8 +/- 1.1 mV [6] for the bath K change. Thus the dominant effect of cAMP is the increase of the basolateral membrane Na conductance. This increase is consistent with 1) the depolarization of Vbl and 2) the hyperpolarization of the transepithelial voltage, the decrease of the transepithelial resistance, and the increase of Na and fluid secretion observed previously. Spontaneous oscillations of Vbl were observed and could not be attributed to cyclical changes of the basolateral membrane Na conductance.

Osmotic Behaviour of the Fairy Shrimp Chirocephalus Diaphanus Prévost

1941 ◽  
Vol 18 (2) ◽  
pp. 110-114
Author(s):  
N. KESAVA PANIKKAR
Keyword(s):  
Osmotic Pressure ◽  
External Medium ◽  
Tap Water ◽  
Fairy Shrimp ◽  
Distilled Water ◽  
Osmotic Concentration ◽  
General Behaviour ◽  
Initial Rise ◽  
Osmotic Behaviour ◽  
Chirocephalus Diaphanus

The blood of Chirocephalus has a normal osmotic concentration equivalent to 0.44-0.5% NaCl in an external medium of 0.002% NaCl. The osmotic pressure falls rapidly when the animal is kept in glass-distilled water, but is fairly well maintained in tap water. There is an initial rise and a later return to normal even in hypotonic saline media, and this indicates active absorption of ions. The bracts are presumably the organs concerned in the salt absorption. The animal is unable to live in tap water or distilled water for more than 2-3 days without food and its general behaviour is thus markedly different from that of Daphnia.

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 P-glycoprotein Detoxification by the Malpighian Tubules of the Desert Locust

2019 ◽  
Author(s):  
Marta Rossi ◽  
Davide De Battisti ◽  
Jeremy E. Niven
Keyword(s):  
Surface Area ◽  
Rhodamine B ◽  
Ex Vivo ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Desert Locust ◽  
P Glycoprotein ◽  
Transporter Family ◽  
Wide Range

ABSTRACTDetoxification is essential for allowing animals to remove toxic substances present in their diet or generated as a biproduct of their metabolism. By transporting a wide range of potentially noxious substrates, active transporters of the ABC transporter family play an important role in detoxification. One such class of transporters are the multidrug resistance P-glycoprotein transporters. Here, we investigated P-glycoprotein transport in the Malpighian tubules of the desert locust (Schistocerca gregaria), a species whose diet includes plants that contain toxic secondary metabolites. To this end, we studied transporter physiology using a modified Ramsay assay in which ex vivo Malpighian tubules are incubated in different solutions containing the P-glycoprotein substrate dye rhodamine B in combination with different concentrations of the P-glycoprotein inhibitor verapamil. Our evidence shows that: (i) the Malpighian tubules contain a P-glycoprotein; (ii) tubule surface area is positively correlated with the tubule fluid secretion rate; and (iii) as the fluid secretion rate increases so too does the net extrusion of rhodamine B. We were able to quantify precisely the relationships between the fluid secretion, surface area, and net extrusion. We interpret these results in the context of the life history and foraging ecology of desert locusts. We argue that P-glycoproteins play an important role in the detoxification by contributing to the removal of xenobiotic substances from the haemolymph, thereby enabling gregarious desert locusts to maintain toxicity through the ingestion of toxic plants without suffering the deleterious effects themselves.

scholarly journals Malpighamoeba infection compromises fluid secretion and P-glycoprotein detoxification in Malpighian tubules

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marta Rossi ◽  
Swidbert R. Ott ◽  
Jeremy E. Niven
Keyword(s):  
Water Stress ◽  
Surface Area ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Energy Costs ◽  
Natural Environments ◽  
Desert Locust ◽  
P Glycoprotein ◽  
The Impact

Abstract Malpighian tubules, analogous to vertebrate nephrons, play a key role in insect osmoregulation and detoxification. Tubules can become infected with a protozoan, Malpighamoeba, which damages their epithelial cells, potentially compromising their function. Here we used a modified Ramsay assay to quantify the impact of Malpighamoeba infection on fluid secretion and P-glycoprotein-dependent detoxification by desert locust Malpighian tubules. Infected tubules have a greater surface area and a higher fluid secretion rate than uninfected tubules. Infection also impairs P-glycoprotein-dependent detoxification by reducing the net rhodamine extrusion per surface area. However, due to the increased surface area and fluid secretion rate, infected tubules have similar total net extrusion per tubule to uninfected tubules. Increased fluid secretion rate of infected tubules likely exposes locusts to greater water stress and increased energy costs. Coupled with reduced efficiency of P-glycoprotein detoxification per surface area, Malpighamoeba infection is likely to reduce insect survival in natural environments.

scholarly journals Malpighamoeba infection compromises fluid secretion and P-glycoprotein detoxification in Malpighian tubules

2019 ◽  
Author(s):  
Marta Rossi ◽  
Swidbert R. Ott ◽  
Jeremy E. Niven
Keyword(s):  
Water Stress ◽  
Surface Area ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Energy Costs ◽  
Natural Environments ◽  
Desert Locust ◽  
P Glycoprotein ◽  
The Impact

AbstractMalpighian tubules, analogous to vertebrate nephrons, play a key role in insect osmoregulation and detoxification. Tubules can become infected with a protozoan, Malpighamoeba, which damages their epithelial cells, potentially compromising their function. Here we used a modified Ramsay assay to quantify the impact of Malpighamoeba infection on fluid secretion and P-glycoprotein-dependent detoxification by desert locust Malpighian tubules. Infected tubules have a greater surface area and a higher fluid secretion rate than uninfected tubules. Infection also impairs P-glycoprotein-dependent detoxification by reducing the net rhodamine extrusion per surface area. However, due to the increased surface area and fluid secretion rate, infected tubules have similar total net extrusion per tubule to uninfected tubules. Increased fluid secretion rate of infected tubules likely exposes locusts to greater water stress and increased energy costs. Coupled with reduced efficiency of P-glycoprotein detoxification per surface area, Malpighamoeba infection is likely to reduce insect survival in natural environments.

scholarly journals ION AND FLUID SECRETION BY DIFFERENT SEGMENTS OF THE MALPIGHIAN TUBULES OF THE BLACK FIELD CRICKET TELEOGRYLLUS OCEANICUS

1993 ◽  
Vol 177 (1) ◽  
pp. 1-22
Author(s):  
A. T. Marshall ◽  
P. Cooper ◽  
G. D. Rippon ◽  
A. E. Patak
Keyword(s):  
Cyclic Amp ◽  
Fluid Secretion ◽  
Distal Segment ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Osmotic Concentration ◽  
Corpora Cardiaca ◽  
Diuretic Hormone ◽  
High Concentrations ◽  
Tubule Fluid

Cricket Malpighian tubules have two morphologically distinct segments, a thin distal segment, which occupies approximately 10 % of the total tubule length, and a main segment. The two segments differ in secretion rates and response to corpora cardiaca extract. The secreted fluids differ in osmotic concentration and elemental composition. The distal segment secretes fluid at a rate (per mm length) which is approximately twice that of the main segment under control conditions. After stimulation by corpora cardiaca extract (Cc) the rate from the main segment approximately doubles whilst the distal segment rate remains unchanged. Fluid from the main segment and the whole tubule is slightly hypo-osmotic to the medium (5–11 mosmol kg-1) under control conditions, whereas that from the distal segment is slightly hyperosmotic (12 mosmol kg-1). On stimulation with Cc, the whole tubule fluid becomes slightly hyperosmotic (12 mosmol kg-1), that from the main segment remains slightly hypo-osmotic (3 mosmol kg-1) but fluid from the distal segment becomes very hyperosmotic (55 mosmol kg-1). Differences between the tubule fluid and the medium osmolality are indicated in parentheses. Fluid from the main segment has high concentrations of K (166 mmol l-1), Cl (111 mmol l-1), Na (41 mmol l-1) and P (83 mmol l-1), whereas that from the distal segment has high concentrations of K (101 mmol l-1) and Cl (137 mmol l-1). On stimulation with Cc, the elemental concentrations in fluids from the main segments and whole tubules do not change significantly but the K and Cl concentrations in distal segment fluid increase (182 and 188 mmol l-1 respectively). The Mg present in whole tubule fluid is derived largely from the distal segment. The ionic composition accounts for the observed osmotic concentrations in fluid from whole tubules, main segments and stimulated distal segments, but not for the concentrations in fluid from unstimulated distal segments. The fluid from unstimulated distal segments contains an unidentified organic solute accounting for approximately 90 mosmol kg-1 of the osmotic concentration. The distal segment contributes 22 % and 11 % of the fluid volume, 26 % Cl, 14 % K and 12 % Cl, 11 % K in control and Cc-stimulated tubules respectively. Considerably higher values are observed in individual tubules. The distal segment makes a significant contribution to the total ion output of the tubule. The cyclic AMP content of tubule segments treated with corpora cardiaca extract was found to increase in both main and distal segments. When expressed in terms of protein content there was no difference between segments. However, in terms of total cell volume, the cells of the distal segment had a tenfold greater cyclic AMP content than those of the main segment. This is consistent with a 10- to 20-fold higher secretion rate of K by the distal segment. It is suggested that the distal segment, whilst having a higher length-specific fluid secretion rate than the main segment, is, nevertheless, concerned primarily with ion and solute secretion since it is unresponsive to diuretic hormone. The prime role of the main segment, which does respond to diuretic hormone, is fluid secretion. There appear to be major differences in hydraulic conductivity between the two segments.

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