Characterization of transepithelial transport of salicylate by the Malpighian tubules of Drosophila melanogaster and the effects of changes in fluid secretion rate

External application of the 3',5'-cyclic monophosphates of inosine,cytidine, uridine and thymidine stimulated the fluid secretion rate (FSR)of Malpighian tubules isolated from Drosophila melanogaster. The evidence suggested that the cyclic nucleotides acted intracellularly in some capacity. Receptors of the 'purinergic' type appeared not to be major contributors to fluid secretion; of three purinergic agonists tried,adenosine, adenosine 5'-monophosphate (AMP) and adenosine 5'-triphosphate(ATP), only adenosine had an effect, but this was not observed consistently. None of the purinergic agonists interfered with the stimulation of the FSR by adenosine 3',5'-cyclic monophosphate (cAMP). The maximum stimulation of the fluid-secretion rate by any cyclic nucleotide was approximately double the unstimulated (control) rate. Tubules stimulated to less than maximal FSR by one cyclic nucleotide could be stimulated maximally by an appropriate concentration of another cyclic nucleotide. Malpighian tubules bathed in solutions that contained either[3H]cAMP or [3H]cGMP accumulated radioactivity to a level many times that in the medium. Accumulation of radioactivity by tubules bathed in 430 nmol l-1 [3H]cAMP was suppressed by 1 mmol l-1 non-radioactive cyclic nucleotides in the order cAMP>>cGMP>cIMP>cCMP; neither cTMP nor cUMP suppressed the accumulation of [3H]cAMP. Approximately 35 % of the[3H]cAMP and 80 % of the [3H]cGMP that entered the Malpighian tubule cells was metabolised to compounds that were not identified. It was concluded that cyclic nucleotides enter the Malpighian tubule cells by at least one transport mechanism which is particularly sensitive to purine-based nucleotides.

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Characterization of salicylate uptake across the basolateral membrane of the Malpighian tubules of Drosophila melanogaster

Journal of Insect Physiology ◽

10.1016/j.jinsphys.2006.05.013 ◽

2006 ◽

Vol 52 (9) ◽

pp. 920-928 ◽

Cited By ~ 6

Author(s):

Esau Ruiz-Sanchez ◽

Michael J. O’Donnell

Keyword(s):

Drosophila Melanogaster ◽

Basolateral Membrane ◽

Malpighian Tubules

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

Journal of Experimental Biology ◽

10.1242/jeb.129.1.63 ◽

1987 ◽

Vol 129 (1) ◽

pp. 63-81 ◽

Cited By ~ 2

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.

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The malpighian tubules of Drosophila melanogaster: a novel phenotype for studies of fluid secretion and its control.

Journal of Experimental Biology ◽

10.1242/jeb.197.1.421 ◽

1994 ◽

Vol 197 (1) ◽

pp. 421-428 ◽

Cited By ~ 5

Author(s):

J A Dow ◽

S H Maddrell ◽

A Görtz ◽

N J Skaer ◽

S Brogan ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Fluid Secretion ◽

Malpighian Tubules

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Characterization of theDrosophila melanogasteralkali-metal/proton exchanger (NHE) gene family

Journal of Experimental Biology ◽

10.1242/jeb.204.21.3703 ◽

2001 ◽

Vol 204 (21) ◽

pp. 3703-3716 ◽

Cited By ~ 1

Author(s):

Maria E. Giannakou ◽

Julian A. T. Dow

Keyword(s):

Drosophila Melanogaster ◽

Genomic Sequence ◽

Malpighian Tubule ◽

Malpighian Tubules ◽

Na Channel ◽

Rt Pcr ◽

Multiple Transcripts ◽

Homology Searching ◽

Amiloride Derivatives

SUMMARYThe NHE family of Na+/H+ exchangers is believed to play an essential role in animals, but may play an additional, specialised epithelial role in insects. The pharmacological sensitivity of the Drosophila melanogaster Malpighian tubule to a range of amiloride derivatives was shown to be consistent with an effect on an exchanger, rather than a Na+ channel. Consistent with this, no degenerin/epithelial Na+ channel (ENaC) genes could be detected in Malpighian tubules by reverse transcriptase/polymerase chain reaction (RT-PCR). Using a low-stringency homology searching, three members of the NHE family were identified in the genomic sequence of Drosophila melanogaster, although only two genes were represented as expressed sequence tags. All three genes (DmNHE1 at cytological position 21B1, DmNHE2 at 39B1 and DmNHE3 at 27A1) were found by RT-PCR to be widely expressed, and one (DmNHE2) was shown to have multiple transcripts. The putative translations of the three genes mark them as distantly related members of the family, inviting the possibility that they may serve distinct roles in insects.

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Central role of the apical membrane H+-ATPase in electrogenesis and epithelial transport in Malpighian tubules

Journal of Experimental Biology ◽

10.1242/jeb.203.9.1459 ◽

2000 ◽

Vol 203 (9) ◽

pp. 1459-1468 ◽

Cited By ~ 18

Author(s):

K.W. Beyenbach ◽

T.L. Pannabecker ◽

W. Nagel

Keyword(s):

Epithelial Transport ◽

Apical Membrane ◽

Short Circuit ◽

Basolateral Membrane ◽

Electrical Coupling ◽

Short Circuit Current ◽

Fluid Secretion ◽

Malpighian Tubules ◽

Proton Channel ◽

Transepithelial Transport

The effects of bafilomycin A(1), a blocker of V-type H(+)-ATPases, were investigated in Malpighian tubules of Aedes aegypti. Bafilomycin A(1) reduced rates of transepithelial fluid secretion and the virtual short-circuit current (vI(sc)) with an IC(50) of approximately 5 micromol l(−)(1). As vI(sc) decreased, the electrical resistance increased across the whole epithelium and across the apical membrane, indicating effects on electroconductive pathways. Bafilomycin A(1) had no effect when applied from the tubule lumen, pointing to the relative impermeability of the apical membrane to bafilomycin A(1). Thus, bafilomycin A(1) must take a cytoplasmic route to its blocking site in the proton channel of the H(+)-ATPase located in the apical membrane of principal cells. The inhibitory effects of bafilomycin A(1) were qualitatively similar to those of dinitrophenol in that voltages across the epithelium (V(t)), the basolateral membrane (V(bl)) and the apical membrane (V(a)) depolarized towards zero in parallel. Moreover, V(bl)always tracked V(a), indicating electrical coupling between the two membranes through the shunt. Electrical coupling allows the H(+)-ATPase to energize not only the apical membrane, but also the basolateral membrane. Furthermore, electrical coupling offers a balance between electroconductive entry of cations across the basolateral membrane and extrusion across the apical membrane to support steady-state conditions during transepithelial transport.

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

Scientific Reports ◽

10.1038/s41598-020-72598-z ◽

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.

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

10.1101/649483 ◽

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.

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

Journal of Experimental Biology ◽

10.1242/jeb.177.1.1 ◽

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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