Effects of the cyclopeptide mycotoxin destruxin A on the Malpighian tubules of Rhodnius prolixus (Stål)

Toxicon ◽  
2010 ◽  
Vol 55 (6) ◽  
pp. 1162-1170 ◽  
Author(s):  
Esau Ruiz-Sanchez ◽  
Ian Orchard ◽  
Angela B. Lange
Keyword(s):  
Rhodnius Prolixus ◽  
Malpighian Tubules

Ultrastructural Characterization of Malpighian Tubules of Rhodnius prolixus During the Insect's Feeding Cycle and Under Hyperosmotic Shock

2020 ◽  
Vol 129 (2) ◽  
pp. 189
Author(s):  
Jacenir Reis dos Santos-Mallet ◽  
Simone Patrícia Carneiro Freitas ◽  
Maria Luiza Ribeiro de Oliveira ◽  
Alice Helena Ricardo-Silva ◽  
Aníbal Gil Lopes ◽  
...  
Keyword(s):  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Hyperosmotic Shock ◽  
Ultrastructural Characterization ◽  
Feeding Cycle

Topographical variations in the structure of the smooth septate junction

1979 ◽  
Vol 37 (1) ◽  
pp. 373-389
Author(s):  
H.B. Skaer ◽  
J.B. Harrison ◽  
W.M. Lee
Keyword(s):  
Musca Domestica ◽  
Functional Significance ◽  
Freeze Fracture ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Septate Junction ◽  
Lanthanum Hydroxide ◽  
Septate Junctions ◽  
Standard Fixation

Smooth septate junctions in the midgut of Musca domestica and in Malpighian tubules of both Musca and Rhodnius prolixus are described. Details of the structures revealed after standard fixation, fixation in the presence of the stain, lanthanum hydroxide, and after freeze-fracture are discussed in the light of models previously put forward to explain the interrelations of the images obtained by these different methods. The organization of the junction between cells of the midgut varies in the apical-to-basal axis. At the apical border the septa (or ridges in freeze-fracture replicas) are packed tightly and follow an undulating but strictly parallel course. This packing loosens towards the middle of the junction until, at its basal extremity, the septa (ridges in replicas) are widely separated and follow independent meandering courses. That these features are found both in lanthanum-infiltrated specimens and freeze-fracture replicas allows a correlation to be made between the septa and the freeze-fracture ridges. The functional significance of these smooth septate junctions is discussed.

Functional design of microvilli in the Malpighian tubules of the insect Rhodnius prolixus

1983 ◽  
Vol 60 (1) ◽  
pp. 117-135
Author(s):  
T.J. Bradley
Keyword(s):  
Plasma Membranes ◽  
Current Knowledge ◽  
Morphological Difference ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Free Standing ◽  
Narrow Channels ◽  
Morphological Specialization ◽  
Mitochondrial Volume ◽  
The Mean

The Malpighian tubules of Rhodnius prolixus are divided into two regions; the upper tubule, which is the site of isosmotic secretion and haemolymph filtration, and the lower tubule where water and KCl are resorbed. In the upper tubule the microvilli are arranged in clumps consisting of several hundred microvilli lying closely parallel. The microvillar plasma membranes do not touch but are held approximately equal to 16 nm apart along the full length of the microvilli. As a consequence, the extracellular space between the microvilli consists of long narrow channels. A morphometric analysis of extracellular, cytoplasmic, endoplasmic reticular and mitochondrial volume within the clumps was conducted. Using the secretion rate of the epithelium and the channel dimensions, it was calculated that the mean residence time for secreted fluid in the intermicrovillar spaces was approximately equal to 0.4s. In view of our current knowledge of the physiology and morphology of the upper tubule, it is argued: (1) that osmotically driven water passes principally through the cells, not the junctional spaces; and (2) that the microvillar clumps are a morphological specialization, which serves to maximize solute-water coupling in the upper tubule. The microvilli in the lower tubule are free-standing, with no pattern of clumping as in the upper tubule. The axopods are about twice as long as the microvilli (10-14 micron) and are found in all regions of the lower tubule. This is in agreement with the proposal that the motile axopods serve to propel uric acid crystals through the lower tubule. No morphological difference was found between the upper and lower halves of the lower tubule, although the two portions are known to be physiologically distinct.

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.

Serotonin triggers cAMP and PKA-mediated intracellular calcium waves in Malpighian tubules of Rhodnius prolixus

2014 ◽  
Vol 307 (7) ◽  
pp. R828-R836 ◽  
Author(s):  
Paula Gioino ◽  
Brendan G. Murray ◽  
Juan P. Ianowski
Keyword(s):  
Second Messenger ◽  
Fluid Secretion ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Insect Vector ◽  
Excess Water ◽  
Intracellular Ca ◽  
Single Meal ◽  
Hematophagous Insect

Rhodnius prolixus is a hematophagous insect vector of Chagas disease capable of ingesting up to 10 times its unfed body weight in blood in a single meal. The excess water and ions ingested with the meal are expelled through a rapid postprandial diuresis driven by the Malpighian tubules. Diuresis is triggered by at least two diuretic hormones, a CRF-related peptide and serotonin, which were traditionally believed to trigger cAMP as an intracellular second messenger. Recently, calcium has been suggested to act as a second messenger in serotonin-stimulated Malpighian tubules. Thus, we tested the role of calcium in serotonin-stimulated Malpighian tubules from R. prolixus. Our results show that serotonin triggers cAMP-mediated intracellular Ca2+ waves that were blocked by incubation in Ca2+-free saline containing the cell membrane-permeant Ca2+ chelator BAPTA-AM, or the PKA blocker H-89. Treatment with 8-Br-cAMP triggered Ca2+ waves that were blocked by H-89 and BAPTA-AM. Analysis of the secreted fluid in BAPTA-AM-treated tubules showed a 75% reduction in fluid secretion rate with increased K+ concentration, reduced Na+ concentration. Taken together, the results indicate that serotonin triggers cAMP and PKA-mediated Ca2+ waves that are required for maximal ion transport rate.

scholarly journals Action of activated 27,000 Mr toxin from Bacillus thuringiensis var. israelensis on Malpighian tubules of the insect, Rhodnius prolixus

1989 ◽  
Vol 94 (3) ◽  
pp. 601-608
Author(s):  
S.H. Maddrell ◽  
J.A. Overton ◽  
D.J. Ellar ◽  
B.H. Knowles
Keyword(s):  
Bacillus Thuringiensis ◽  
Cell Membrane ◽  
Basal Cell ◽  
Time Course ◽  
Fluid Secretion ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Bathing Solution ◽  
Concentrated Solutions ◽  
Intracellular Milieu

The action of activated 27,000 Mr toxin from Bacillus thuringiensis var. israelensis (Bti toxin) on Malpighian tubules of Rhodnius prolixus has been investigated. Its binding to the tubules is slowed by low temperature but is not prevented even at 0 degree C. The binding is less effective at pH 10 than at pH7. Pretreatment of the tubules with 0.1 mmol l-1 ouabain or bumetanide or 1 mumol l-1 5-hydroxytryptamine did not affect the toxicity of the toxin. The toxin causes very large changes in the trans-epithelial potential difference; it changes from 40 mV, lumen negative, often to more than 100 mV, lumen positive. This reflects an initial collapse of the potential of the basal cell membrane, followed by a large positive-going potential change at the luminal cell membrane. Just prior to the effects of the toxin on rapid fluid secretion, the basal cell membrane becomes permeable to sucrose molecules. Raffinose at 170 mmol l-1 in the bathing solution does not protect the tubules from Bti toxin action but dextran, Mr5000, at 60 mmol l-1 significantly delayed failure of fluid secretion and, even more, the onset of staining of the tubule cells with Trypan Blue. Exposing tubules to saline that is calcium-free and/or magnesium-free, or has a composition adjusted to be similar to that of the intracellular milieu, does not affect the time course of failure of fluid secretion induced by the toxin. There is no evidence that effective aggregates of Bti toxin molecules are formed in concentrated solutions.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Fluid Secretion by Malpighian Tubules of Rhodnius prolixus: Neuroendocrine Control With New Insights From a Transcriptome Analysis

2021 ◽  
Vol 12 ◽  
Author(s):  
Ian Orchard ◽  
Jimena Leyria ◽  
Areej Al-Dailami ◽  
Angela B. Lange
Keyword(s):  
Transcriptome Analysis ◽  
Critical Role ◽  
Fluid Secretion ◽  
Rhodnius Prolixus ◽  
G Protein Coupled Receptors ◽  
Malpighian Tubules ◽  
Neuroendocrine Control ◽  
Second Messenger Systems ◽  
Fine Control ◽  
G Protein Coupled

Rhodnius prolixus (the kissing bug and a major vector of Chagas disease) is an obligate blood feeder that in the case of the fifth instar consumes up to 10 times its unfed body weight in a single 20-minute feed. A post-prandial diuresis is initiated, within minutes of the start of gorging, in order to lower the mass and concentrate the nutrients of the meal. Thus, R. prolixus rapidly excretes a fluid that is high in NaCl content and hypo-osmotic to the hemolymph, thereby eliminating 50% of the volume of the blood meal within 3 hours of gorging. In R. prolixus, as with other insects, the Malpighian tubules play a critical role in diuresis. Malpighian tubules are not innervated, and their fine control comes under the influence of the neuroendocrine system that releases amines and neuropeptides as diuretic or antidiuretic hormones. These hormones act upon the Malpighian tubules via a variety of G protein-coupled receptors linked to second messenger systems that influence ion transporters and aquaporins; thereby regulating fluid secretion. Much has been discovered about the control of diuresis in R. prolixus, and other model insects, using classical endocrinological studies. The post-genomic era, however, has brought new insights, identifying novel diuretic and antidiuretic hormone-signaling pathways whilst also validating many of the classical discoveries. This paper will focus on recent discoveries into the neuroendocrine control of the rapid post-prandial diuresis in R. prolixus, in order to emphasize new insights from a transcriptome analysis of Malpighian tubules taken from unfed and fed bugs.

scholarly journals Nitric oxide loading of the salivary nitric-oxide-carrying hemoproteins (nitrophorins) in the blood-sucking bug Rhodnius prolixus.

1995 ◽  
Vol 198 (5) ◽  
pp. 1093-1098
Author(s):  
R H Nussenzveig ◽  
D L Bentley ◽  
J M Ribeiro
Keyword(s):  
Nitric Oxide ◽  
Epithelial Cells ◽  
Salivary Glands ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Nadph Diaphorase ◽  
No Production ◽  
Synthetase Activity ◽  
Diaphorase Activity ◽  
Blood Sucking

The salivary glands of the blood-sucking bug Rhodnius prolixus are formed by a single layer of binucleated epithelial cells surrounded by a double layer of transversely oriented smooth muscle cells. The epithelial cells are rich in rough endoplasmic reticulum and mitochondria and have abundant microvillar projections towards the gland lumen. This cell layer surrounds a relatively large cavity where abundant secretory material is stored. Epithelial cells produce an intense and generalized NADPH diaphorase reaction, in contrast to other tissues such as brain, Malpighian tubules and skeletal muscle. Ultrastructural analysis of the osmiophilic reaction product indicates that it is localized within cytoplasmic vacuoles, a similar location to that of NADPH diaphorase (NO synthetase) activity in neuronal cells of vertebrates. Measurements of the time course of protein accumulation, NADPH diaphorase activity and the degree of nitrosylation of hemoproteins (nitrophorins) in the salivary glands of Rhodnius prolixus nymphs after a blood meal indicate that the nitrophorins are synthesized and accumulate when NO production is low (with a 25% loading of the nitrophorins during the fourth- to fifth-instar molt). NO loading of the nitrophorins increases to 90% after the molt, concomitant with a large increase in the salivary NADPH diaphorase activity. It is concluded that synthesis of NO occurs within the epithelial cells while the nitrophorins are stored extracellularly. It is hypothesized that the luminally oriented microvilli may serve as a diffusion bridge to direct intracellularly produced NO into the luminal cavity, where the nitrophorins are stored.

Effects of Sub-Lethal High Temperature on An Insect, Rhodnius Prolixus (Stål.)

1968 ◽  
Vol 48 (3) ◽  
pp. 455-463
Author(s):  
A. Y. K. OKASHA
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Larval Stage ◽  
Prolonged Exposure ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Sensory Bristles ◽  
Harmful Effects

1. The effect on moulting of exposing 1st-, 2nd-, 3rd- and 4th-stage larvae of Rhodnius to 36.5° C. immediately after feeding was studied. After transfer to normal temperature (28° C.) moulting is delayed; the duration of the delay is directly proportional to the period of exposure to high temperature. 2. Unfed larvae exposed to high temperature exhibit delayed moulting when placed at normal temperature after feeding, and prolonged exposure also inhibits micturition which normally occurs directly after feeding. 3. Since the Malpighian tubules appear to function normally, it is suggested that the inhibition of the mechanisms responsible for emptying the rectum results in the cessation of micturition. 4. The harmful effects on moulting of heat-treatment of unfed larvae can be eliminated by placing the exposed insects at normal temperature for an appropriate period before feeding. 5. Exposure to high temperature either before or after feeding results in the decrease and malformation of the sensory bristles and plaques in the next larval stage.

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