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Barroso IG, Nascimento BB, Ferreira C, Terra WR. Water fluxes and nutrient absorption along the midgut of three hemipterans, Mahanarva fimbriolata, Dysdercus peruvianus, and Rhodnius prolixus. Comp Biochem Physiol A Mol Integr Physiol 2025; 299:111773. [PMID: 39515658 DOI: 10.1016/j.cbpa.2024.111773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Revised: 09/16/2024] [Accepted: 11/04/2024] [Indexed: 11/16/2024]
Abstract
Hemiptera Order comprises insect species adapted to different diets regarding water and nutrient content and availability, thus suggesting different combinations of proteins to ensure their absorption. To find out whether hemipterans use the same or distinct set of proteins and whether these differences are related to the phylogeny or the diet, RNAseq analyses were conducted in gut sections of three hemipterans, M. fimbriolata, D. peruvianus, and R. prolixus, with remarkable distinct diet. Since only a few of the selected proteins were functionally characterized, the coded putative proteins were manually curated by bioinformatics to infer their physiological function. The results suggest a relationship between gene expression patterns and water and nutrient dietary content and availability. In contrast, putative gene expansions and deletions are related to phylogeny, corresponding to evolutionary adaptations of ancestral forms to feed on xylem, cotton seeds, and blood, resulting in more resemblances between D. peruvianus and R. prolixus than M. fimbriolata. M. fimbriolata absorbs water through aquaporins Drip and Prip in the filtration chamber by passive diffusion, with a higher contribution of water-selective Drip. D. peruvianus water absorption involves Drip and Prip, but Prip contribution appears to be higher, and they probably cooperate with water-ion cotransporters in the posterior midgut. R. prolixus absorbs water in the anterior midgut involving a sodium transporter and a putative water-urea Prip. Sugars, amino acids, and lipids might be absorbed along the midgut in the three species, with a higher contribution of the posterior midgut for amino acid and lipid absorption in M. fimbriolata and D. peruvianus and the middle midgut in R. prolixus.
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Affiliation(s)
- Ignacio G Barroso
- Departamento de Bioquimica, Instituto de Quimica, Universidade de São Paulo, Av.Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil
| | - Bárbara B Nascimento
- Departamento de Bioquimica, Instituto de Quimica, Universidade de São Paulo, Av.Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil
| | - Clelia Ferreira
- Departamento de Bioquimica, Instituto de Quimica, Universidade de São Paulo, Av.Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil
| | - Walter R Terra
- Departamento de Bioquimica, Instituto de Quimica, Universidade de São Paulo, Av.Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil.
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Chen R, Swale DR. Functional interactions between potassium-chloride cotransporter (KCC) and inward rectifier potassium (Kir) channels in the insect central nervous system. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 192:105389. [PMID: 37105628 DOI: 10.1016/j.pestbp.2023.105389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/07/2023] [Accepted: 03/07/2023] [Indexed: 06/19/2023]
Abstract
The K+/Cl- cotransporter (KCC) is the primary mechanism by which mature neurons maintain low intracellular chloride (Cl-) concentration and has been shown to be functionally coupled to the GABA-gated chloride channels (GGCC) in Drosophila central neurons. Further, pharmacological inhibition of KCC has been shown to lead to acute toxicity of mosquitoes that highlights the toxicological relevance of insect KCC. Yet, gaps in knowledge remain regarding physiological drivers of KCC function and interactions of ion flux mechanisms upstream of GGCC in insects. Considering this, we employed electrophysiological and fluorescent microscopy techniques to further characterize KCC in the insect nervous system. Fluorescent microscopy indicated insect KCC2 is expressed in rdl neurons, which is the neuron type responsible for GABA-mediated neurotransmission, and are coexpressed with inward rectifier potassium (Kir) 2 channels. Coexpression of Kir2 and KCC2 suggested the possibility of functional coupling between these two K+ flux pathways. Indeed, extracellular recordings of Drosophila CNS showed pre-block of Kir channels prior to block of KCC led to a significant (P < 0.001) increase in CNS firing rates over baseline that when taken together, supports functional coupling of Kir to KCC function. Additionally, we documented a synergistic increase to toxicity of VU0463271, an established KCC inhibitor, above the expected additive toxicity after co-treatment with the Kir inhibitor, VU041. These data expand current knowledge regarding the physiological roles of KCC and Kir channels in the insect nervous system by defining additional pathways that facilitate inhibitory neurotransmission through GGCC.
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Affiliation(s)
- Rui Chen
- Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA, United States of America
| | - Daniel R Swale
- Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA, United States of America; Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, United States of America.
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Orchard I, Leyria J, Al-Dailami A, Lange AB. Fluid Secretion by Malpighian Tubules of Rhodnius prolixus: Neuroendocrine Control With New Insights From a Transcriptome Analysis. Front Endocrinol (Lausanne) 2021; 12:722487. [PMID: 34512553 PMCID: PMC8426621 DOI: 10.3389/fendo.2021.722487] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/03/2021] [Indexed: 01/25/2023] Open
Abstract
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.
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Affiliation(s)
- Ian Orchard
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
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Kolosov D, O'Donnell MJ. Mechanisms and regulation of chloride transport in the Malpighian tubules of the larval cabbage looper Trichoplusia ni. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 116:103263. [PMID: 31682921 DOI: 10.1016/j.ibmb.2019.103263] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 10/22/2019] [Accepted: 10/29/2019] [Indexed: 06/10/2023]
Abstract
Malpighian tubules (MTs) and the hindgut together constitute the excretory system of insects. Larvae of lepidopterans (butterflies and moths) demonstrate the so-called cryptonephric arrangement, where the distal blind end of each MT is embedded into the rectal complex. The rest of the free tubule is modified into several distinct regions that differ greatly in the transport of cations and water. However, relatively little is known about the transport of counter-anions (e.g., Cl- and HCO3-) by the MTs of lepidopteran larvae. In the current study we used ion-selective microelectrodes to characterize Cl- transport in the distinct regions of the free MT of the larval Trichoplusia ni. Firstly, we note that Cl- transport in the MTs is sensitive to the Cl- concentration of the bathing saline, and several regions of the MTs are capable of either secreting or reabsorbing Cl-. In the distal ileac plexus (DIP), a region previously characterized by cellular heterogeneity and its ability to switch between cation secretion and reabsorption, principal cells (PCs) toggled between Cl- reabsorption (in high-Cl- saline) and Cl- secretion (in low-Cl- saline). In contrast, secondary cells (SCs) in the DIP secreted Cl- regardless of saline Cl- concentration. Mechanistically, we have detected a number of 'leak' and ligand-gated Cl- channels (ClC) and demonstrated that Cl- channels are involved in Cl- secretion. Additionally, we demonstrated that the lumen-positive transepithelial potential increased in response to glycine. Using the scanning ion-selective electrode technique we demonstrated that glycine stimulated Cl- secretion by SCs, but not by PCs. In contrast, when MTs were deprived of glycine, a decrease in Cl- secretion, coupled with a decrease in the TEP, was observed. In contrast to the effects of glycine, an active dose of helicokinin reduced Cl- secretion by PCs, but not by SCs. Lastly, we detected expression of chloride-bicarbonate exchangers (CBE) in all regions of the free tubule. Scans of H+ transport across the tubule indicated that base equivalents are likely reabsorbed across the ileac plexus. Blocking ClC or CBE led to secretion of a more basic fluid, indicating lack of base reabsorption. We suggest that the transport of Cl- in the MTs of larval lepidopterans (i) may be correlated with the reabsorption of base, (ii) may be sensitive to Cl- concentration in the haemolymph, and (iii) could be regulated by helicokinin and glycine.
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Affiliation(s)
- Dennis Kolosov
- Department of Biology, McMaster University, 1280 Main St West, Hamilton, ON, L8S4K1, Canada.
| | - Michael J O'Donnell
- Department of Biology, McMaster University, 1280 Main St West, Hamilton, ON, L8S4K1, Canada
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Chen R, Prael FJ, Li Z, Delpire E, Weaver CD, Swale DR. Functional Coupling of K +-Cl - Cotransporter (KCC) to GABA-Gated Cl - Channels in the Central Nervous System of Drosophila melanogaster Leads to Altered Drug Sensitivities. ACS Chem Neurosci 2019; 10:2765-2776. [PMID: 30942574 DOI: 10.1021/acschemneuro.8b00697] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
GABAergic signaling is the cornerstone for fast synaptic inhibition of neural signaling in arthropods and mammals and is the molecular target for insecticides and pharmaceuticals, respectively. The K+-Cl- cotransporter (KCC) is the primary mechanism by which mature neurons maintain low intracellular Cl- concentration, yet the fundamental physiology, comparative physiology, and toxicological relevance of insect KCC is understudied. Considering this, we employed electrophysiological, genetic, and pharmacological methods to characterize the physiological underpinnings of KCC function to the Drosophila CNS. Our data show that genetic ablation or pharmacological inhibition of KCC results in an increased spike discharge frequency and significantly ( P < 0.05) reduces the CNS sensitivity to γ-aminobutyric acid (GABA). Further, simultaneous inhibition of KCC and ligand-gated chloride channel (LGCC) complex results in a significant ( P < 0.001) increase in CNS spontaneous activity over baseline firing rates that supports functional coupling of KCC to LGCC function. Interestingly, 75% reduction in KCC mRNA did not alter basal neurotransmission levels indicating that only a fraction of the KCC population is required to maintain the Cl- ionic gradient when at rest, but prolonged synaptic activity increases the threshold for GABA-mediated inhibition and reduces nerve sensitivity to GABA. These data expand current knowledge regarding the physiological role of KCC in a model insect and provides the necessary foundation to develop KCC as a novel biochemical target of insecticides, as well as complements existing research to provide a holistic understanding of the plasticity in mammalian health and disease.
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Affiliation(s)
- Rui Chen
- Department of Entomology , Louisiana State University AgCenter , Baton Rouge , Louisiana 70803 , United States
| | - Francis J Prael
- Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
- Vanderbilt Institute of Chemical Biology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Zhilin Li
- Department of Entomology , Louisiana State University AgCenter , Baton Rouge , Louisiana 70803 , United States
| | - Eric Delpire
- Department of Anesthesiology , Vanderbilt University School of Medicine , Nashville , Tennessee 37232 , United States
| | - C David Weaver
- Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
- Vanderbilt Institute of Chemical Biology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Daniel R Swale
- Department of Entomology , Louisiana State University AgCenter , Baton Rouge , Louisiana 70803 , United States
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Prael FJ, Chen R, Li Z, Reed CW, Lindsley CW, Weaver CD, Swale DR. Use of chemical probes to explore the toxicological potential of the K +/Cl - cotransporter (KCC) as a novel insecticide target to control the primary vector of dengue and Zika virus, Aedes aegypti. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2018; 151:10-17. [PMID: 30704707 DOI: 10.1016/j.pestbp.2018.03.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 03/16/2018] [Accepted: 03/29/2018] [Indexed: 06/09/2023]
Abstract
The majority of commercialized insecticides target the insect nervous system and therefore, neural proteins are well-validated targets for insecticide development. Considering that only a few neural targets are exploited for insecticidal action and the development of insecticide resistance has reduced the efficacy of current insecticidal classes, we sought to test the toxicological potential of the potassium-chloride cotransporter (KCC). In mammals, KCC proteins have seminal roles in shaping GABAergic signaling and inhibitory neurotransmission, thus ion transport through KCC is critical for proper neurotransmission. Therefore, we hypothesized that mosquito KCC represents a putative insecticide target site and that pharmacological inhibition of KCC constructs in Aedes aegypti will be lethal. To test this hypothesis, we developed a robust, cell-based fluorescence assay that enables in vitro characterization of small-molecules against Ae. aegypti KCC and performed a proof-of-concept study employing well characterized mammalian KCC modulators to determine the toxicological potential of Ae. aegypti KCC. The selective inhibitor of mammalian KCC, termed VU0463271, was found to be a potent inhibitor Ae. aegypti KCC and microinjection induced lethality in a concentration-dependent manner to susceptible and pyrethroid resistant strains. Importantly, an analog of VU0463271 was shown to be >40-fold less potent and did not induce toxicity, suggesting that the observed physiological effects and mortality are likely due to KCC inhibition. This proof-of-concept study suggests that Ae. aegypti KCC represents a putative target site for mosquitocide design that can mitigate the current mechanisms of insecticide resistance.
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Affiliation(s)
- Francis J Prael
- Vanderbilt University School of Medicine, Department of Pharmacology, Nashville, TN 37232, United States; Vanderbilt University School of Medicine, Vanderbilt Institute of Chemical Biology, Nashville, TN 37232, United States
| | - Rui Chen
- Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA 70803, United States
| | - Zhilin Li
- Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA 70803, United States
| | - Carson W Reed
- Vanderbilt University School of Medicine, Department of Pharmacology, Nashville, TN 37232, United States; Vanderbilt University School of Medicine, Vanderbilt Institute of Chemical Biology, Nashville, TN 37232, United States; Vanderbilt Center for Neuroscience Drug Discovery, Nashville, TN 37232, United States
| | - Craig W Lindsley
- Vanderbilt University School of Medicine, Department of Pharmacology, Nashville, TN 37232, United States; Vanderbilt University School of Medicine, Vanderbilt Institute of Chemical Biology, Nashville, TN 37232, United States; Vanderbilt Center for Neuroscience Drug Discovery, Nashville, TN 37232, United States
| | - C David Weaver
- Vanderbilt University School of Medicine, Department of Pharmacology, Nashville, TN 37232, United States; Vanderbilt University School of Medicine, Vanderbilt Institute of Chemical Biology, Nashville, TN 37232, United States; Vanderbilt Center for Neuroscience Drug Discovery, Nashville, TN 37232, United States
| | - Daniel R Swale
- Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA 70803, United States.
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Kolosov D, Tauqir M, Rajaruban S, Piermarini PM, Donini A, O'Donnell MJ. Molecular mechanisms of bi-directional ion transport in the Malpighian tubules of a lepidopteran crop pest, Trichoplusia ni. JOURNAL OF INSECT PHYSIOLOGY 2018; 109:55-68. [PMID: 29908900 DOI: 10.1016/j.jinsphys.2018.06.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/12/2018] [Accepted: 06/13/2018] [Indexed: 06/08/2023]
Abstract
Classical studies have described in detail the complex and regionalized morphology of the Malpighian tubule (MT) in larval Lepidoptera. Recent studies revealed unusual aspects of ion transport in the Malpighian tubules of the larva of the cabbage looper, Trichoplusia ni. These included: cation reabsorption via secondary cells (SC); coupling of SCs to neighbouring PCs via gap junctions to enable reabsorption; and a reversal from cation secretion to reabsorption by the principal cells in the distal ileac plexus region of the in situ tubule in response to dietary ion loading. The current paper aimed to identify molecular components of ion transport in the MTs of T. ni and to describe their role in the recently reported reversal of ion transport in ion-loaded animals. Using a combination of molecular, immunohistochemical and electrophysiological techniques, we assigned roles to Na+/K+-ATPase (NKA), V-type H+-ATPase (VA), Na+/K+/Cl- co-transporter (NKCC), K+/Cl- co-transporter (KCC), inward-rectifying K+ channel (Kir), and Na+/H+ exchangers (NHE)-7 and -8 in the transport of Na+ and K+ by the distal ileac plexus of T. ni. The yellow region of the tubule lacked all of the above except VA, and the white region lacked all of the above transporters but expressed an amiloride-sensitive Na+ channel (NaC). Overall, the ion transport machinery in the distal ileac plexus of the T. ni tubule shows remarkable similarity to that in tubules of other groups of insects, yet this region transports ions very differently. Shutdown of secretory ATPases and utilisation of the same molecular machinery in the face of changing ion gradients may enable ion transport reversal in lepidopteran MTs. We propose that gap junction-based coupling of the two cell types likely aids in toggling between ion secretion and ion reabsorption in this segment.
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Affiliation(s)
- Dennis Kolosov
- McMaster University, Department of Biology, Hamilton, ON, Canada.
| | - Maria Tauqir
- McMaster University, Department of Biology, Hamilton, ON, Canada
| | | | - Peter M Piermarini
- The Ohio State University, Ohio Agricultural Research and Development Center, Department of Entomology, Wooster, OH, USA
| | - Andrew Donini
- York University, Department of Biology, Toronto, ON, Canada
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Ruiz-Sanchez E, O'Donnell MJ, Donini A. Secretion of Na(+), K(+) and fluid by the Malpighian (renal) tubule of the larval cabbage looper Trichoplusia ni (Lepidoptera: Noctuidae). JOURNAL OF INSECT PHYSIOLOGY 2015; 82:92-98. [PMID: 26432549 DOI: 10.1016/j.jinsphys.2015.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 09/27/2015] [Accepted: 09/28/2015] [Indexed: 06/05/2023]
Abstract
The Malpighian (renal) tubules play important roles in ionic and osmotic homeostasis in insects. In Lepidoptera, the Malpighian tubules are structurally regionalized and the concentration of Na(+) and K(+) in the secreted fluid varies depending on the segment of tubule analyzed. In this work, we have characterized fluid and ion (Na(+), K(+), H(+)) transport by tubules of the larval stage of the cabbage looper Trichoplusia ni; we have also evaluated the effects of fluid secretion inhibitors and stimulants on fluid and ion transport. Ramsay assays showed that fluid was secreted by the iliac plexus but not by the yellow and white regions of the tubule. K(+) and Na(+) were secreted by the distal iliac plexus (DIP) and K(+) was reabsorbed in downstream regions. The fluid secretion rate decreased>50% after 25μM bafilomycin A1, 500μM amiloride or 50μM bumetanide was added to the bath. The concentration of K(+) in the secreted fluid did not change, whereas the concentration of Na(+) in the secreted fluid decreased significantly when tubules were exposed to bafilomycin A1 or amiloride. Addition of 500μM cAMP or 1μM 5-HT to the bath stimulated fluid secretion and resulted in a decrease in K(+) concentration in the secreted fluid. An increase in Na(+) concentration in the secreted fluid was observed only in cAMP-stimulated tubules. Secreted fluid pH and the transepithelial electrical potential (TEP) did not change when tubules were stimulated. Taken together, our results show that the secretion of fluid is carried out by the upper regions (DIP) in T. ni Malpighian tubules. Upper regions of the tubules secrete K(+), whereas lower regions reabsorb it. Stimulation of fluid secretion is correlated with a decrease in the K(+)/Na(+) ratio.
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Affiliation(s)
- Esau Ruiz-Sanchez
- Instituto Tecnológico de Conkal, Km. 16.3 Antigua carretera Mérida-Motul, C.P. 97345, Conkal, Yucatán, Mexico.
| | - Michael J O'Donnell
- Department of Biology, McMaster University, 3359 Main Street West, Hamilton, Ontario L8S 1M9, Canada
| | - Andrew Donini
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
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Paluzzi JP, Yeung C, O'Donnell MJ. Investigations of the signaling cascade involved in diuretic hormone stimulation of Malpighian tubule fluid secretion in Rhodnius prolixus. JOURNAL OF INSECT PHYSIOLOGY 2013; 59:1179-1185. [PMID: 24080126 DOI: 10.1016/j.jinsphys.2013.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 09/18/2013] [Accepted: 09/18/2013] [Indexed: 05/28/2023]
Abstract
In insects, the excretory system is comprised of the Malpighian tubules (MTs) and the hindgut, which collectively function to maintain ionic and osmotic balance of the haemolymph and rid the organism of toxic compounds or elements in excess. Secretion by the Malpighian tubules of insects is regulated by a variety of hormones including peptidergic factors as well as biogenic amines. In Rhodnius prolixus, two endogenous diuretic hormones have been identified; the biogenic amine serotonin (5-hydroxytryptamine, 5-HT) and the corticotropin releasing factor-related peptide, RhoprCRF. Both factors significantly increase secretion by MTs and are known to elevate intracellular levels of cAMP. Interestingly, applying sub-maximal doses of these two diuretic factors in combination on isolated MTs in vitro reveals synergistic effects as rates of fluid secretion are significantly higher than would be expected if rates of secretion from MTs treated with each factor alone were summed. This observed synergism suggests that different downstream targets may be activated by the two diuretic factors, but that some cellular elicitors may be shared since cAMP is elevated in response to either diuretic hormone. This study investigated the signaling cascade involved in the diuretic hormone regulation of Malpighian tubule fluid secretion. Bioassays were performed in physiological as well as modified salines (e.g. calcium-free) alone or in the presence of a variety of pharmacological compounds that interfere with prospective intracellular targets, such as the apical cation/H(+) exchanger. Intriguingly, only amiloride yielded differential effects on the two diuretics with 5HT-stimulated secretion being blocked, whereas in contrast, RhoprCRF-stimulated secretion was unaffected. In addition, experiments examining the role of extracellular and intracellular calcium on fluid secretion rate showed that both diuretics are dependent on intracellular calcium availability. Finally, fluid secretion stimulated by either diuretic hormone was also sensitive to inhibition of cAMP-dependent protein kinase A. Taken together, these results suggest that each diuretic hormone activates pathways dependent upon intracellular calcium and cAMP.
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Affiliation(s)
- Jean-Paul Paluzzi
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada; Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada.
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10
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Rodan AR, Baum M, Huang CL. The Drosophila NKCC Ncc69 is required for normal renal tubule function. Am J Physiol Cell Physiol 2012; 303:C883-94. [PMID: 22914641 DOI: 10.1152/ajpcell.00201.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epithelial ion transport is essential to renal homeostatic function, and it is dysregulated in several diseases, such as hypertension. An understanding of the insect renal (Malpighian) tubule yields insights into conserved epithelial ion transport processes in higher organisms and also has implications for the control of insect infectious disease vectors. Here, we examine the role of the Na(+)-K(+)-2Cl(-) (NKCC) cotransporter Ncc69 in Drosophila tubule function. Ncc69 mutant tubules have decreased rates of fluid secretion and K(+) flux, and these phenotypes were rescued by expression of wild-type Ncc69 in the principal cells of the tubule. Na(+) flux was unaltered in Ncc69 mutants, suggesting Na(+) recycling across the basolateral membrane. In unstimulated tubules, the principal role of the Na(+)-K(+)-ATPase is to generate a favorable electrochemical gradient for Ncc69 activity: while the Na(+)-K(+)-ATPase inhibitor ouabain decreased K(+) flux in wild-type tubules, it had no effect in Ncc69 mutant tubules. However, in the presence of cAMP, which stimulates diuresis, additional Na(+)-K(+)-ATPase-dependent K(+) transport pathways are recruited. In studying the effects of capa-1 on wild-type and Ncc69 mutant tubules, we found a novel antidiuretic role for this hormone that is dependent on intact Ncc69, as it was abolished in Ncc69 mutant tubules. Thus, Ncc69 plays an important role in transepithelial ion and fluid transport in the fly renal tubule and is a target for regulation in antidiuretic states.
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Affiliation(s)
- Aylin R Rodan
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, USA.
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11
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Gámez AD, Gutiérrez AM, García R, Whittembury G. Recent experiments towards a model for fluid secretion in Rhodnius Upper Malpighian Tubules (UMT). JOURNAL OF INSECT PHYSIOLOGY 2012; 58:543-550. [PMID: 22206885 DOI: 10.1016/j.jinsphys.2011.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/08/2011] [Accepted: 12/14/2011] [Indexed: 05/31/2023]
Abstract
Three different methods have been used to improve a model for fluid secretion in Upper Malpighian Tubules (UMT) of the blood sucking insect Rhodnius prolixus. (I) In the first, UMT double perfusions in 5th instar Rhodnius were used to measure their fluid secretion rate. They were stimulated to secrete with 5-HT. Double perfusions allowed access separately to the basolateral and the apical cell membranes with pharmacological agents known to block different ion transport functions, namely ATPases, cotransporters and/or countertransporters and ion and water channels: ouabain, bafilomycin A1, furosemide, bumetanide, SITS, acetazolamide, amiloride, DPC, BaCl(2), pCMBS and DTT. The basic assumption is that changes in water movement reflect changes in ion transport mechanisms. (II) Intracellular Na(+) concentrations were measured with a fluorometric method in dissected R. prolixus UMT, under several experimental conditions. (III) ATPase activities were measured in R. prolixus UMT. A tentative model for the function of the UMT cell is presented. We find that (a) at the basolateral cell membrane, fundamental is a Na(+)-K(+)-2Cl(-) cotransporter; of intermediate importance are the Na(+)-K(+)-ATPase and a ouabain-insensitive Na(+)-ATPase, ion channels and Rp-MIP water channels. (b) At the apical cell membrane, most important are a V-H(+)-ATPase; and a K(+) and/or Na(+)-H(+) exchanger.
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Affiliation(s)
- Adriana D Gámez
- Instituto Venezolano de Investigaciones Científicas, Universidad Central de Venezuela, Caracas, Venezuela.
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Baumann O, Walz B. The blowfly salivary gland - a model system for analyzing the regulation of plasma membrane V-ATPase. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:450-458. [PMID: 22133312 DOI: 10.1016/j.jinsphys.2011.11.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/17/2011] [Accepted: 11/18/2011] [Indexed: 05/31/2023]
Abstract
Vacuolar H(+)-ATPases (V-ATPases) are heteromultimeric proteins that use the energy of ATP hydrolysis for the electrogenic transport of protons across membranes. They are common to all eukaryotic cells and are located in the plasma membrane or in membranes of acid organelles. In many insect epithelia, V-ATPase molecules reside in large numbers in the apical plasma membrane and create an electrochemical proton gradient that is used for the acidification or alkalinization of the extracellular space, the secretion or reabsorption of ions and fluids, the import of nutrients, and diverse other cellular activities. Here, we summarize our results on the functions and regulation of V-ATPase in the tubular salivary gland of the blowfly Calliphora vicina. In this gland, V-ATPase activity energizes the secretion of a KCl-rich saliva in response to the neurohormone serotonin (5-HT). Because of particular morphological and physiological features, the blowfly salivary glands are a superior and exemplary system for the analysis of the intracellular signaling pathways and mechanisms that modulate V-ATPase activity and solute transport in an insect epithelium.
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Affiliation(s)
- Otto Baumann
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany.
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Piermarini PM, Hine RM, Schepel M, Miyauchi J, Beyenbach KW. Role of an apical K,Cl cotransporter in urine formation by renal tubules of the yellow fever mosquito (Aedes aegypti). Am J Physiol Regul Integr Comp Physiol 2011; 301:R1318-37. [PMID: 21813871 PMCID: PMC3213945 DOI: 10.1152/ajpregu.00223.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 07/29/2011] [Indexed: 01/07/2023]
Abstract
The K,Cl cotransporters (KCCs) of the SLC12 superfamily play critical roles in the regulation of cell volume, concentrations of intracellular Cl(-), and epithelial transport in vertebrate tissues. To date, the role(s) of KCCs in the renal functions of mosquitoes and other insects is less clear. In the present study, we sought molecular and functional evidence for the presence of a KCC in renal (Malpighian) tubules of the mosquito Aedes aegypti. Using RT-PCR on Aedes Malpighian tubules, we identified five alternatively spliced partial cDNAs that encode putative SLC12-like KCCs. The majority transcript is AeKCC1-A(1); its full-length cDNA was cloned. After expression of the AeKCC1-A protein in Xenopus oocytes, the Cl(-)-dependent uptake of (86)Rb(+) is 1) activated by 1 mM N-ethylmaleimide and cell swelling, 2) blocked by 100 μM dihydroindenyloxyalkanoic acid (DIOA), and 3) dependent upon N-glycosylation of AeKCC1-A. In Aedes Malpighian tubules, AeKCC1 immunoreactivity localizes to the apical brush border of principal cells, which are the predominant cell type in the epithelium. In vitro physiological assays of Malpighian tubules show that peritubular DIOA (10 μM): 1) significantly reduces both the control and diuretic rates of transepithelial fluid secretion and 2) has negligible effects on the membrane voltage and input resistance of principal cells. Taken together, the above observations indicate the presence of a KCC in the apical membrane of principal cells where it participates in a major electroneutral transport pathway for the transepithelial secretion of fluid in this highly electrogenic epithelium.
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Affiliation(s)
- Peter M Piermarini
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, USA.
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Hamann S, Herrera-Perez JJ, Zeuthen T, Alvarez-Leefmans FJ. Cotransport of water by the Na+-K+-2Cl(-) cotransporter NKCC1 in mammalian epithelial cells. J Physiol 2011; 588:4089-101. [PMID: 20819947 DOI: 10.1113/jphysiol.2010.194738] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Water transport by the Na+-K+-2Cl(-) cotransporter (NKCC1) was studied in confluent cultures of pigmented epithelial (PE) cells from the ciliary body of the fetal human eye. Interdependence among water, Na+ and Cl(-) fluxes mediated by NKCC1 was inferred from changes in cell water volume, monitored by intracellular self-quenching of the fluorescent dye calcein. Isosmotic removal of external Cl(-) or Na+ caused a rapid efflux of water from the cells, which was inhibited by bumetanide (10 μm). When returned to the control solution there was a rapid water influx that required the simultaneous presence of external Na+ and Cl(-). The water influx could proceed uphill, against a transmembrane osmotic gradient, suggesting that energy contained in the ion fluxes can be transferred to the water flux. The influx of water induced by changes in external [Cl(-)] saturated in a sigmoidal fashion with a Km of 60 mm, while that induced by changes in external [Na+] followed first order kinetics with a Km of about 40 mm. These parameters are consistent with ion transport mediated by NKCC1. Our findings support a previous investigation, in which we showed water transport by NKCC1 to be a result of a balance between ionic and osmotic gradients. The coupling between salt and water transport in NKCC1 represents a novel aspect of cellular water homeostasis where cells can change their volume independently of the direction of an osmotic gradient across the membrane. This has relevance for both epithelial and symmetrical cells.
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Affiliation(s)
- Steffen Hamann
- Nordic Centre for Water Imbalance Related Disorders, Institute of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
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Piermarini PM, Grogan LF, Lau K, Wang L, Beyenbach KW. 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. Am J Physiol Regul Integr Comp Physiol 2009; 298:R642-60. [PMID: 20042685 DOI: 10.1152/ajpregu.00729.2009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
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 H(2)CO(3), which raises questions about the handling of HCO(3)(-) by principal cells. Accordingly, we tested the hypothesis that a Cl/HCO(3) anion exchanger (AE) related to the solute-linked carrier 4 (SLC4) superfamily mediates the extrusion of HCO(3)(-) 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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Affiliation(s)
- Peter M Piermarini
- Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, USA.
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Albuquerque-Cunha JM, Gonzalez MS, Garcia ES, Mello CB, Azambuja P, Almeida JCA, de Souza W, Nogueira NFS. Cytochemical characterization of microvillar and perimicrovillar membranes in the posterior midgut epithelium of Rhodnius prolixus. ARTHROPOD STRUCTURE & DEVELOPMENT 2009; 38:31-44. [PMID: 18602023 DOI: 10.1016/j.asd.2008.06.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 05/30/2008] [Accepted: 06/01/2008] [Indexed: 05/26/2023]
Abstract
Perimicrovillar membranes (PMM) are structures present on the surface of midgut epithelial cells of the hematophagous insect, Rhodnius prolixus. They cover the microvilli and are especially evident 10 days after blood meal, providing the compartmentalization of the enzymatic processes in the intestinal microenvironment. Using an enzyme cytochemical approach, Mg2+-ATPase and ouabain-sensitive Na+K+-ATPase activities were observed in the plasma (or microvillar) membrane (MM) of midgut cells and in the PMM. In contrast, alkaline phosphatase was only detected in MM. Using cationized ferritin and colloidal iron hydroxide particles, anionic sites were found only on the luminal surface of the PMM. Using fluorescein isothiocyanate (FITC)-labeled lectins, residues of alpha-d-galactose, mannose, N-acetyl-neuraminic acid, N-acetyl-d-galactosamine and N-acetyl-galactosamine-alpha-1,3-galactose were detected on the apical surface of posterior midgut epithelial cells. On the other hand, using FITC-labeled neoglycoproteins (NGP) it was possible to detect the presence of carbohydrate binding molecules (CBM) recognizing N-acetyl-d-galactosamine, alpha-d-mannose, alpha-l-fucose and alpha-d-glucose in the posterior midgut epithelium. The use of digitonin showed the presence of sterols in the MM and PMM. These results have led the authors to suggest that for some components the PMM resembles the MM lining the midgut cells of R. prolixus, composing a system which covers the microvilli and stretches to the luminal space.
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Affiliation(s)
- José M Albuquerque-Cunha
- Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Avenida Alberto Lamego, 2000, Horto, Campos dos Goytacazes, Rio de Janeiro, CEP 28.015-620, Brazil
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Martini SV, Nascimento SB, Morales MM. Rhodnius prolixus Malpighian tubules and control of diuresis by neurohormones. AN ACAD BRAS CIENC 2007; 79:87-95. [PMID: 17401478 DOI: 10.1590/s0001-37652007000100011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 04/25/2006] [Indexed: 11/22/2022] Open
Abstract
Rhodnius prolixus Malpighian tubules (MTs) are a good model for fluid and ion secretion studies in view of the dramatic postprandial diuresis, which follows its massive blood meals. Ingestion of a blood meal equals to 10-12 times their initial body mass, leads to rapid activation of high output by excretory system, which eliminates 40-50% of the fluid mass. Secretion of ions and water is stimulated 1000-fold by serotonin and diuretic hormone. These hormones cooperate synergistically to activate adenylate cyclase activity from MTs cells, which increase the level of intracellular cAMP. The anti-diuretic hormones have also an important role in the fluid maintenance of Rhodnius prolixus. Several hours after insect feeding occurs a reduction in urine flow, that has been thought to result from a decreased diuretic hormone release or from a novel mechanism of anti-diuresis involving insect cardioacceleratory peptide 2b (CAP2b) and cyclic GMP. In this article it is discussed how the hormone regulation of fluid transport is done in Rhodnius prolixus MTs.
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Affiliation(s)
- Sabrina V Martini
- CCS, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21949-900, Brasil
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Orchard I. Serotonin: A coordinator of feeding-related physiological events in the blood-gorging bug, Rhodnius prolixus. Comp Biochem Physiol A Mol Integr Physiol 2006; 144:316-24. [PMID: 16377224 DOI: 10.1016/j.cbpa.2005.11.010] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 11/13/2005] [Accepted: 11/17/2005] [Indexed: 12/31/2022]
Abstract
Rhodnius prolixus is an obligatory blood-feeder that can ingest blood meals of up to 10 times its mass. Rapid production of urine commences within 2-3 min of the start of feeding in order to eliminate the load of water and salts, and so there is an increase of Malpighian tubule secretion greater than 1,000 fold in response to feeding. Feeding and post-prandial diuresis in Rhodnius are highly coordinated events, including for example, host recognition, probing, injection of saliva, cuticle plasticization, passage of blood through the digestive system, diuresis and excretion. This review illustrates that many of the known functions of serotonin in Rhodnius are feeding-related. Serotonin coordinates or 'orchestrates' feeding-related physiological events either as a neurotransmitter/neuromodulator, delivered to target tissues in the nerve supply, or as a neurohormone, delivered by the haemolymph. Thus, serotonin has physiological effects upon the salivary glands, cuticle, digestive tract, cardiac muscle, and Malpighian tubules. By discussing these aspects, the review illustrates that serotonin acts in a coordinated manner to prepare Rhodnius for this energy-demanding process of feeding and diuresis.
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Affiliation(s)
- Ian Orchard
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6.
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Ianowski JP, O'Donnell MJ. Electrochemical gradients for Na+, K+,Cl– and H+ across the apical membrane in Malpighian (renal) tubule cells ofRhodnius prolixus. J Exp Biol 2006; 209:1964-75. [PMID: 16651561 DOI: 10.1242/jeb.02210] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
SUMMARYMeasurements of intracellular and luminal ion activities as well as membrane potential were used to calculate electrochemical gradients for Cl–, Na+, K+ and H+ across the apical membrane during fluid secretion by Malpighian tubules of Rhodnius prolixus. The results show that the contribution of Na+/H+ and/or K+/H+ exchangers to fluid secretion is feasible both in unstimulated and serotonin-stimulated tubules. Similarly, the electrochemical potential for Cl– is consistent with the passive movement of Cl– from cell to lumen through Cl– channels. The contribution of apical K+:Cl– cotransport and/or paracellular Cl– movement to net transepithelial ion transport is thermodynamically unfeasible. pH in the lumen (pH 6.08±0.1, N=6) was more acid than in the bath (pH 7.25±0.01, N=26) and serotonin stimulation produced a significant increase in lumen pH to 6.32±0.04 (N=5). Intracellular pH was 6.97±0.01 and 6.82±0.04 in unstimulated and serotonin-stimulated tubules, respectively. Lumen pH was altered whereas intracellular pH was tightly regulated during serotonin and bumetanide treatment. Furthermore, DIDS or amiloride treatment did not affect intracellular pH. However, intracellular pH shifted 0.25 pH units more acid in Na+-free saline, suggesting that a Na+-dependent pH regulatory mechanism is at play in steady state pH regulation during fluid secretion by Malpighian tubules of Rhodnius prolixus. The data are consistent with a role for a basolateral Na+/H+ exchanger in intracellular pH regulation during fluid secretion.
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Affiliation(s)
- Juan P Ianowski
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada.
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Dow JAT, Davies SA. The Malpighian tubule: rapid insights from post-genomic biology. JOURNAL OF INSECT PHYSIOLOGY 2006; 52:365-78. [PMID: 16310213 DOI: 10.1016/j.jinsphys.2005.10.007] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 10/06/2005] [Accepted: 10/10/2005] [Indexed: 05/05/2023]
Abstract
Good osmoregulation is critical to the success of insects, and the Malpighian tubules play a key role in osmoregulation. Recently, the application of genetics and genomics to the Drosophila tubule has revealed far more extensive roles than ion and water transport. Microarray analysis shows that organic solute transporters dominate the tubule transcriptome. The tubule thus has the capability to excrete actively the broadest range of organic solutes and xenobiotics. Such transporters can produce unexpected, emergent roles for the whole tissue; e.g. the tubule is highly resistant to ouabain not because the Na+, K+ ATPase is unimportant, but because it co-localises with a potent alkaloid excretory mechanism. Reinforcing this role in excretion, the tubule expresses very high levels of a particular cytochrome P450s, glutathione-S-transferases and alcohol dehydrogenases which suggest that the tubule plays a major role in metabolism and detoxification of both endogenous solutes and xenobiotics, such as insecticides. Additionally, the tubule plays a significant role in immunity; tubules are capable of sensing bacterial challenge, and mounting an effective killing response by secretion of antimicrobial peptides, entirely independent of the fat body, the canonical immune tissue. The tubule has also proved to be a good model for some human renal disease, and to act as an organotypic 'testbed' for mammalian genes. The tubule can thus bask in a greatly enhanced reputation as a key tissue for an unexpectedly wide range of functions in the insect.
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Affiliation(s)
- Julian A T Dow
- Division of Molecular Genetics, University of Glasgow, Glasgow G11 6NU, UK.
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