scholarly journals Specialized stellate cells offer a privileged route for rapid water flux in Drosophila renal tubule

2020 ◽  
Vol 117 (3) ◽  
pp. 1779-1787 ◽  
Author(s):  
Pablo Cabrero ◽  
Selim Terhzaz ◽  
Anthony J. Dornan ◽  
Saurav Ghimire ◽  
Heather L. Holmes ◽  
...  
Keyword(s):  
Water Permeability ◽  
Plasma Membranes ◽  
Water Flux ◽  
Stellate Cells ◽  
Fluid Secretion ◽  
Cell Types ◽  
Renal Tissue ◽  
Malpighian Tubules ◽  
Very High

Insects are highly successful, in part through an excellent ability to osmoregulate. The renal (Malpighian) tubules can secrete fluid faster on a per-cell basis than any other epithelium, but the route for these remarkable water fluxes has not been established. In Drosophila melanogaster, we show that 4 genes of the major intrinsic protein family are expressed at a very high level in the fly renal tissue: the aquaporins (AQPs) Drip and Prip and the aquaglyceroporins Eglp2 and Eglp4. As predicted from their structure, and by their transport function by expressing these proteins in Xenopus oocytes, Drip, Prip, and Eglp2 show significant and specific water permeability, whereas Eglp2 and Eglp4 show very high permeability to glycerol and urea. Knockdowns of any of these genes result in impaired hormone-induced fluid secretion. The Drosophila tubule has 2 main secretory cell types: active cation-transporting principal cells, wherein the aquaglyceroporins localize to opposite plasma membranes, and small stellate cells, the site of the chloride shunt conductance, with these AQPs localizing to opposite plasma membranes. This suggests a model in which osmotically obliged water flows through the stellate cells. Consistent with this model, fluorescently labeled dextran, an in vivo marker of membrane water permeability, is trapped in the basal infoldings of the stellate cells after kinin diuretic peptide stimulation, confirming that these cells provide the major route for transepithelial water flux. The spatial segregation of these components of epithelial water transport may help to explain the unique success of the higher insects in regulating their internal environments.

scholarly journals When two cells are better than one: specialized stellate cells provide a privileged route for uniquely rapid water flux in Drosophila renal tubule

2019 ◽  
Author(s):  
Pablo Cabrero ◽  
Selim Terhzaz ◽  
Anthony J. Dornan ◽  
Saurav Ghimire ◽  
Heather L. Holmes ◽  
...  
Keyword(s):  
Water Permeability ◽  
Plasma Membranes ◽  
Water Flux ◽  
Malpighian Tubule ◽  
Stellate Cells ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Principal Cells ◽  
Very High

AbstractInsects are highly successful, in part through an excellent ability to osmoregulate. The renal (Malpighian) tubules can secrete fluid faster on a per-cell basis than any other epithelium, but the route for these remarkable water fluxes has not been established. In Drosophila melanogaster, we show that 4 members of the Major Intrinsic Protein family are expressed at very high level in the fly renal tissue; the aquaporins Drip and Prip, and the aquaglyceroporins Eglp2 and Eglp4. As predicted from their structure and by their transport function by expressing these proteins in Xenopus oocytes, Drip, Prip and Eglp2 show significant and specific water permeability, whereas Eglp2 and Eglp4 show very high permeability to glycerol and urea. Knockdowns of any of these genes impacts tubule performance resulting in impaired hormone-induced fluid secretion. The Drosophila tubule has two main secretory cell types: active cation-transporting principal cells with the aquaglyceroporins localize to opposite plasma membranes and small stellate cells, the site of the chloride shunt conductance, with these aquaporins localising to opposite plasma membranes. This suggests a model in which cations are pumped by the principal cells, causing chloride to follow through the stellate cells in order to balance the charge. As a consequence, osmotically obliged water follows through the stellate cells. Consistent with this model, fluorescently labelled dextran, an in vivo marker of membrane water permeability, is trapped in the basal infoldings of the stellate cells after kinin diuretic peptide stimulation, confirming that these cells provide the major route for transepithelial water flux. The spatial segregation of these components of epithelial water transport may help to explain the unique success of the higher insects.Significance statementThe tiny insect renal (Malpighian) tubule can transport fluid at unparalleled speed, suggesting unique specialisations. Here we show that strategic allocation of Major Intrinsic Proteins (MIPs) to specific cells within the polarized tubule allow the separation of metabolically intense active cation transport from chloride and water conductance. This body plan is general to at least many higher insects, providing a clue to the unique success of the class Insecta.

Anti-diuresis in the blood-feeding insect Rhodnius prolixus Stål: the peptide CAP2b and cyclic GMP inhibit Malpighian tubule fluid secretion.

1997 ◽  
Vol 200 (17) ◽  
pp. 2363-2367 ◽  
Author(s):  
M C Quinlan ◽  
N J Tublitz ◽  
M J O'Donnell
Keyword(s):  
Cyclic Gmp ◽  
Physiological Role ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Blood Feeding ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Tubule Fluid ◽  
Secretion Rates

Rhodnius prolixus eliminates NaCl-rich urine at high rates following its infrequent but massive blood meals. This diuresis involves stimulation of Malpighian tubule fluid secretion by diuretic hormones released in response to distention of the abdomen during feeding. The precipitous decline in urine flow that occurs several hours after feeding has been thought until now to result from a decline in diuretic hormone release. We suggest here that insect cardioacceleratory peptide 2b (CAP2b) and cyclic GMP are part of a novel mechanism of anti-diuresis. Secretion rates of 5-hydroxytryptamine-stimulated Malpighian tubules are reduced by low doses of CAP2b or cyclic GMP. Maximal secretion rates are restored by exposing tubules to 1 mmol l-1 cyclic AMP. Levels of cyclic GMP in isolated tubules increase in response to CAP2b, consistent with a role for cyclic GMP as an intracellular second messenger. Levels of cyclic GMP in tubules also increase as urine output rates decline in vivo, suggesting a physiological role for this nucleotide in the termination of diuresis.

The initial stages in the action of an insecticidal delta-endotoxin of Bacillus thuringiensis var. israelensis on the epithelial cells of the malpighian tubules of the insect, Rhodnius prolixus

1988 ◽  
Vol 90 (1) ◽  
pp. 131-144
Author(s):  
S.H. Maddrell ◽  
N.J. Lane ◽  
J.B. Harrison ◽  
J.A. Overton ◽  
R.B. Moreton
Keyword(s):  
Bacillus Thuringiensis ◽  
Intercellular Junctions ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Ultrastructural Changes ◽  
Cytoplasmic Vacuolization ◽  
Large Numbers ◽  
Delta Endotoxin ◽  
High Concentrations ◽  
Very High

The effects of the 27 X 10(3) Mr insecticidal delta-endotoxin from Bacillus thuringiensis var. israelensis have been studied using, as a model system, isolated insect Malpighian tubules. At all concentrations of the toxin higher than 1 microgram ml-1 (4 X 10(−8) moll-1) applied to the outer surface of the tubules, fluid secretion failed within about 30 min. Except at very high concentrations, where failure always takes at least 30 s, there was an inverse relationship between the concentration of toxin and the time of failure of toxin-treated tubules. During exposure to toxin, the tubules were initially unaffected for a relatively long period and then rapid failure occurred. If the tubules were removed into toxin-free saline just before failure would have occurred, fluid secretion remained normal for at least 2 h, but on return to the origin toxin-containing saline failure was almost immediate. The toxin was found not to bind to the basement membrane. Ultrastructural changes became evident as tubule failure occurred. These initially involved modifications to the basal side of the cells, but later also to the luminal microvilli. Intercellular junctions became disassociated and cytoplasmic vacuolization occurred. The population of intramembranous particles in the basal membranes became reduced with time. Our findings suggest the following hypothesis for the initial stages in the interaction of the toxin with the tubules. Toxin molecules attach to the accessible cell membranes progressively and irreversibly. They do not readily associate by diffusing laterally in the membrane, so that toxic effects develop only when sufficiently large numbers of them attach close together. The molecules may then associate in some way as a complex, perhaps forming a pore in the membrane. Relatively few such pores lead rapidly to cell failure and death.

Hormone-controlled cAMP-mediated fluid secretion in yellow-fever mosquito

1987 ◽  
Vol 253 (5) ◽  
pp. R701-R711 ◽  
Author(s):  
D. H. Petzel ◽  
M. M. Berg ◽  
K. W. Beyenbach
Keyword(s):  
Yellow Fever ◽  
Natriuretic Peptides ◽  
Basolateral Membrane ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
In Vivo Studies ◽  
Intracellular Camp ◽  
Yellow Fever Mosquito ◽  
Water Fraction

Evidence is presented for hormone-controlled adenosine 3',5'-cyclic monophosphate (cAMP)-mediated NaCl diuresis in Malpighian tubules of the blood-feeding yellow-fever mosquito Aedes aegypti. Studies in isolated Malpighian tubules reveal that cAMP added to the peritubular bath selectively stimulates NaCl secretion and not KCl secretion by increasing the Na conductance of the basolateral membrane of primary cells. These effects are duplicated by forskolin and theophylline in parallel with increased intracellular concentrations of endogenous cAMP. Two natriuretic peptides that we have isolated by high-pressure liquid chromatography (HPLC) methods from mosquito heads also increase NaCl and fluid secretion in isolated Malpighian tubules together with increased intracellular levels of cAMP. These results are consistent with a mechanism of NaCl diuresis in which the natriuretic peptides and cAMP are respectively the primary and secondary messengers that couple the ingestion of a blood meal to the excretion of the unwanted salt and water fraction of the meal. This hypothesis is supported by in vivo studies that reveal elevated intracellular cAMP levels in Malpighian tubules at the time of maximum NaCl diuresis.

A study of the Malpighian tubules of the plecopteran nymph Paragnetina media (Walker) (Plecoptera: Perlidae) by light, scanning electron, and transmission electron microscopy

1994 ◽  
Vol 72 (9) ◽  
pp. 1566-1575 ◽  
Author(s):  
N. N. Kapoor
Keyword(s):  
Malpighian Tubule ◽  
Stellate Cells ◽  
Basal Membrane ◽  
Cell Types ◽  
Distal Segment ◽  
Malpighian Tubules ◽  
Primary Cells ◽  
Transmission Electron ◽  
Total Cell Population ◽  
Paragnetina Media

The present study concerns the structural details of the Malpighian tubules in the nymph of the stonefly Paragnetina media. There is no external segmentation except for a distal short hyaline segment. The tubules are composed of two cell types: primary and stellate. Primary cells in the proximal and middle portions of the tubule have short infoldings of the basal membrane and the cytosol is packed with laminate spheres. Cells of the distal segment possess long and tightly packed membrane folds but are devoid of laminate spheres. The stellate cells are sparsely distributed in the middle region and make up 12% of the total cell population in the Malpighian tubule; they lack laminate spheres. Long processes of the stellate cells extend between adjacent primary cells to the luminal and outer surfaces of the tubule.

scholarly journals Characterization of a set of abdominal neuroendocrine cells that regulate stress physiology using colocalized diuretic peptides in Drosophila

2017 ◽  
Author(s):  
Meet Zandawala ◽  
Richard Marley ◽  
Shireen A. Davies ◽  
Dick R. Nässel
Keyword(s):  
Stress Responses ◽  
Water Retention ◽  
Fluid Secretion ◽  
Cell Types ◽  
Neurosecretory Cells ◽  
Malpighian Tubules ◽  
Neuroendocrine Cells ◽  
Signaling Systems ◽  
Diuretic Hormone ◽  
Functional Relations

AbstractMultiple neuropeptides are known to regulate water and ion balance in Drosophila melanogaster. Several of these peptides also have other functions in physiology and behavior. Examples are corticotropin-releasing factor-like diuretic hormone (diuretic hormone 44; DH44) and leucokinin (LK), both of which induce fluid secretion by Malpighian tubules (MTs), but also regulate stress responses, feeding, circadian activity and other behaviors. Here, we investigated the functional relations between the LK and DH44 signaling systems. DH44 and LK peptides are only colocalized in a set of abdominal neurosecretory cells (ABLKs). Targeted knockdown of each of these peptides in ABLKs leads to increased resistance to desiccation, starvation and ionic stress. Food ingestion is diminished by knockdown of DH44, but not LK, and water retention is increased by LK knockdown only. Thus, the two colocalized peptides display similar systemic actions, but differ with respect to regulation of feeding and body water retention. We also demonstrated that DH44 and LK have additive effects on fluid secretion by MTs. It is likely that the colocalized peptides are coreleased from ABLKs into the circulation and act on the tubules where they target different cell types and signaling systems to regulate diuresis and stress tolerance. Additional targets seem to be specific for each of the two peptides and subserve regulation of feeding and water retention. Our data suggest that the ABLKs and hormonal actions are sufficient for many of the known DH44 and LK functions, and that the remaining neurons in the CNS play other functional roles.

Evidence that aquaporin-1 mediates NaCl-induced water flux across descending vasa recta

1997 ◽  
Vol 272 (5) ◽  
pp. F587-F596 ◽  
Author(s):  
T. L. Pallone ◽  
B. K. Kishore ◽  
S. Nielsen ◽  
P. Agre ◽  
M. A. Knepper
Keyword(s):  
Water Permeability ◽  
Water Movement ◽  
Water Flux ◽  
Water Channel ◽  
Enzyme Linked Immunosorbent Assay ◽  
Aquaporin 1 ◽  
Vasa Recta ◽  
Water Efflux

Outer medullary descending vasa recta (OMDVR) were perfused in vitro, and volume efflux was measured by driving water movement with transmural gradients of NaCl or albumin. Consistent with mediation by water channels, p-chloromercuribenzenesulfonic acid (pCMBS) markedly inhibited volume flux induced by NaCl. Dithiothreitol reversed the inhibition, pCMBS did not significantly alter water flux induced by albumin. Osmotic water permeability (Pf) of the pCMBS-sensitive pathway of glutaraldehyde-fixed and nonfixed OMDVR was 1,102 +/- 449 and 1,257 +/- 718 microns/s (means +/- SD), respectively. pCMBS reduced Pf to near zero, whereas diffusional water permeability in the same vessels was only slightly inhibited. Immunoreactive aquaporin-1 (AQP1) measured by enzyme-linked immunosorbent assay in collagenase-treated and untreated OMDVR was 5.2 +/- 1.0 and 4.2 +/- 0.4 fmol/mm, respectively, values that account well for the experimental Pf. We conclude that OMDVR water flux driven by NaCl gradients is most likely mediated by the AQP1 water channel and that NaCl and urea gradients drive water efflux in vivo by this route.

scholarly journals Excretion of NaCl and KCl loads in mosquitoes. 2. Effects of the small molecule Kir channel modulator VU573 and its inactive analog VU342

2014 ◽  
Vol 307 (7) ◽  
pp. R850-R861 ◽  
Author(s):  
Matthew F. Rouhier ◽  
Rebecca M. Hine ◽  
Seokhwan Terry Park ◽  
Rene Raphemot ◽  
Jerod Denton ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Small Molecules ◽  
Fluid Secretion ◽  
Ringer Solution ◽  
Malpighian Tubules ◽  
Kir Channel ◽  
Channel Modulator ◽  
Inactive Analog

The effect of two small molecules VU342 and VU573 on renal functions in the yellow fever mosquito Aedes aegypti was investigated in vitro and in vivo. In isolated Malpighian tubules, VU342 (10 μM) had no effect on the transepithelial secretion of Na+, K+, Cl−, and water. In contrast, 10 μM VU573 first stimulated and then inhibited the transepithelial secretion of fluid when the tubules were bathed in Na+-rich or K+-rich Ringer solution. The early stimulation was blocked by bumetanide, suggesting the transient stimulation of Na-K-2Cl cotransport, and the late inhibition of fluid secretion was consistent with the known block of AeKir1, an Aedes inward rectifier K+ channel, by VU573. VU342 and VU573 at a hemolymph concentration of about 11 μM had no effect on the diuresis triggered by hemolymph Na+ or K+ loads. VU342 at a hemolymph concentration of 420 μM had no effect on the diuresis elicited by hemolymph Na+ or K+ loads. In contrast, the same concentration of VU573 significantly diminished the Na+ diuresis by inhibiting the urinary excretion of Na+, Cl−, and water. In K+-loaded mosquitoes, 420 μM VU573 significantly diminished the K+ diuresis by inhibiting the urinary excretion of K+, Na+, Cl−, and water. We conclude that 1) the effects of VU573 observed in isolated Malpighian tubules are overwhelmed in vivo by the diuresis triggered with the coinjection of Na+ and K+ loads, and 2) at a hemolymph concentration of 420 μM VU573 affects Kir channels systemically, including those that might be involved in the release of diuretic hormones.

scholarly journals Membrane protein phosphotyrosine phosphatase in rabbit kidney. Proteolysis activates the enzyme and generates soluble catalytic fragments

1987 ◽  
Vol 243 (3) ◽  
pp. 747-754 ◽  
Author(s):  
S A Rotenberg ◽  
D L Brautigan
Keyword(s):  
Phosphatase Activity ◽  
Plasma Membranes ◽  
Proteinase Inhibitors ◽  
Gel Filtration ◽  
Cell Types ◽  
Total Activity ◽  
Rabbit Kidney ◽  
Ph Optimum ◽  
Fresh Tissue

Most protein phosphotyrosine phosphatases (PPT-phosphatases) have been recovered from the cytosol of various cell types and tissues. The present study explores the properties of PPT-phosphatases in rabbit kidney membranes prepared by centrifugation at 100,000 g. More of the total activity was recovered in membranes from fresh (45%) compared with frozen-and-thawed (36%) tissue. However, extracts of fresh tissue had only 15-30% as much total PPT-phosphatase activity. Up to 3-fold activation of cytosolic and membrane PPT-phosphatases occurred during preparation, an effect most evident when fresh tissue was homogenized in buffers containing multiple proteinase inhibitors. These inhibitors apparently block some, but not all, digestion of proteins that mask PPT-phosphatase activity. Incubation of membranes prepared from fresh tissue with added trypsin, papain or thermolysin in each case caused activation of PPT-phosphatase as well as generation of a soluble catalytic fragment. The fragment also was generated by the action of endogenous proteinases during repeated centrifugation and was isolated from these supernatants by DEAE-Sepharose, Zn2+-affinity and gel-filtration chromatography. The fragment had Mr approx. 33,000, had a neutral pH optimum, was inhibited by 50% by 100 microM-vanadate, and was insensitive to the alkaline-phosphatase inhibitors EDTA and levamisole. Although the chromatographic behaviour and lability of the fragment were distinct from those of the predominant cytosolic PPT-phosphatase, some cytosolic PPT-phosphatases exhibited properties consistent with the suggestion that they are fragments derived by proteolysis of PPT-phosphatases in membranes. Localization of PPT-phosphatases in plasma membranes would facilitate reaction with receptor/kinases in vivo.

scholarly journals A SLC4-like anion exchanger from renal tubules of the mosquito (Aedes aegypti): evidence for a novel role of stellate cells in diuretic fluid secretion

2010 ◽  
Vol 298 (3) ◽  
pp. R642-R660 ◽  
Author(s):  
Peter M. Piermarini ◽  
Laura F. Grogan ◽  
Kenneth Lau ◽  
Li Wang ◽  
Klaus W. Beyenbach
Keyword(s):  
Aedes Aegypti ◽  
Anion Exchanger ◽  
Xenopus Oocytes ◽  
Malpighian Tubule ◽  
Stellate Cells ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Renal Tubules ◽  
Basal Region ◽  
Principal Cells

Transepithelial fluid secretion across the renal (Malpighian) tubule epithelium of the mosquito ( Aedes aegypti ) is energized by the vacuolar-type (V-type) H+-ATPase and not the Na+-K+-ATPase. Located at the apical membrane of principal cells, the V-type H+-ATPase translocates protons from the cytoplasm to the tubule lumen. Secreted protons are likely to derive from metabolic H2CO3, which raises questions about the handling of HCO3−by principal cells. Accordingly, we tested the hypothesis that a Cl/HCO3anion exchanger (AE) related to the solute-linked carrier 4 (SLC4) superfamily mediates the extrusion of HCO3−across the basal membrane of principal cells. We began by cloning from Aedes Malpighian tubules a full-length cDNA encoding an SLC4-like AE, termed AeAE. When expressed heterologously in Xenopus oocytes, AeAE is both N- and O-glycosylated and mediates Na+-independent intracellular pH changes that are sensitive to extracellular Cl−concentration and to DIDS. In Aedes Malpighian tubules, AeAE is expressed as two distinct forms: one is O-glycosylated, and the other is N-glycosylated. Significantly, AeAE immunoreactivity localizes to the basal regions of stellate cells but not principal cells. Concentrations of DIDS that inhibit AeAE activity in Xenopus oocytes have no effects on the unstimulated rates of fluid secretion mediated by Malpighian tubules as measured by the Ramsay assay. However, in Malpighian tubules stimulated with kinin or calcitonin-like diuretic peptides, DIDS reduces the diuretic rates of fluid secretion to basal levels. In conclusion, Aedes Malpighian tubules express AeAE in the basal region of stellate cells, where this transporter may participate in producing diuretic rates of transepithelial fluid secretion.

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