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Xu Q, Xi Y, Wang L, Xu M, Ruan T, Du Z, Jiang C, Cao J, Zhu X, Wang X, Yang B, Liu J. In situ self-referenced intracellular two-electrode system for enhanced accuracy in single-cell analysis. Biosens Bioelectron 2024; 253:116173. [PMID: 38432075 DOI: 10.1016/j.bios.2024.116173] [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: 12/04/2023] [Revised: 02/19/2024] [Accepted: 02/26/2024] [Indexed: 03/05/2024]
Abstract
Since the emergence of single-cell electroanalysis, the two-electrode system has become the predominant electrochemical system for real-time behavioral analysis of single-cell and multicellular populations. However, due to the transmembrane placement of the two electrodes, cellular activities can be interrupted by the transmembrane potentials, and the test results are susceptible to influences from factors such as intracellular solution, membrane, and bulk solution. These limitations impede the advancement of single-cell analysis. Here, we propose a highly miniaturized and integrated in situ self-referenced intracellular two-electrode system (IS-SRITES), wherein both the working and reference electrodes are positioned inside the cell. Additionally, we demonstrated the stability (0.28 mV/h) of the solid-contact in situ Ag/AgCl reference electrode and the ability of the system to conduct standard electrochemical testing in a wide pH range (pH 6.0-8.0). Cell experiments confirmed the non-destructive performance of the electrode system towards cells and its capacity for real-time monitoring of intra- and extracellular pH values. Moreover, through equivalent circuits, finite element simulations, and drug delivery experiments, we illustrated that the IS-SRITES can yield more accurate test results and exhibit enhanced resistance to interference from the extracellular environment. Our proposed system holds the potential to enable the precise detection of intracellular substances and optimize the existing model of the electrode system for intracellular signal detection, thereby spearheading advancements in single-cell analysis.
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Affiliation(s)
- Qingda Xu
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Ye Xi
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Longchun Wang
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Mengfei Xu
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Tao Ruan
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zhiyuan Du
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Chunpeng Jiang
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jiawei Cao
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiantao Zhu
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiaolin Wang
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Bin Yang
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jingquan Liu
- National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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2
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Andersen MK, Roe AD, Liu Y, Musso AE, Fudlosid S, Haider F, Evenden ML, MacMillan HA. The freeze-avoiding mountain pine beetle (Dendroctonus ponderosae) survives prolonged exposure to stressful cold by mitigating ionoregulatory collapse. J Exp Biol 2024; 227:jeb247498. [PMID: 38682690 PMCID: PMC11128280 DOI: 10.1242/jeb.247498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 04/02/2024] [Indexed: 05/01/2024]
Abstract
Insect performance is linked to environmental temperature, and surviving through winter represents a key challenge for temperate, alpine and polar species. To overwinter, insects have adapted a range of strategies to become truly cold hardy. However, although the mechanisms underlying the ability to avoid or tolerate freezing have been well studied, little attention has been given to the challenge of maintaining ion homeostasis at frigid temperatures in these species, despite this limiting cold tolerance for insects susceptible to mild chilling. Here, we investigated how prolonged exposure to temperatures just above the supercooling point affects ion balance in freeze-avoidant mountain pine beetle (Dendroctonus ponderosae) larvae in autumn, mid-winter and spring, and related it to organismal recovery times and survival. Hemolymph ion balance was gradually disrupted during the first day of exposure, characterized by hyperkalemia and hyponatremia, after which a plateau was reached and maintained for the rest of the 7-day experiment. The degree of ionoregulatory collapse correlated strongly with recovery times, which followed a similar asymptotical progression. Mortality increased slightly during extensive cold exposures, where hemolymph K+ concentration was highest, and a sigmoidal relationship was found between survival and hyperkalemia. Thus, the cold tolerance of the freeze-avoiding larvae of D. ponderosae appears limited by the ability to prevent ionoregulatory collapse in a manner similar to that of chill-susceptible insects, albeit at much lower temperatures. Based on these results, we propose that a prerequisite for the evolution of insect freeze avoidance may be a convergent or ancestral ability to maintain ion homeostasis during extreme cold stress.
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Affiliation(s)
| | - Amanda Diane Roe
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, Sault Ste. Marie, ON, Canada, P6A 2E5
| | - Yuehong Liu
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, Sault Ste. Marie, ON, Canada, P6A 2E5
| | - Antonia E. Musso
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada, T6G 2E9
| | - Serita Fudlosid
- Department of Biology, Carleton University, Ottawa, ON, Canada, K1S 5B6
| | - Fouzia Haider
- Department of Biology, Carleton University, Ottawa, ON, Canada, K1S 5B6
| | - Maya L. Evenden
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada, T6G 2E9
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3
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Zhang Q, Wang X, Decker V, Meyerhoff ME. Plasticizer-Free Thin-Film Sodium-Selective Optodes Inkjet-Printed on Transparent Plastic for Sweat Analysis. ACS APPLIED MATERIALS & INTERFACES 2020; 12:25616-25624. [PMID: 32426973 DOI: 10.1021/acsami.0c05379] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A novel strategy to functionalize transparent flexible plastic films with an optical ion-sensing layer using an inkjet-printing technology is described. The hydrophobic sensing chemicals that include a sodium ionophore, a lipophilic proton chromoionophore, and a lipophilic ion-exchanger are co-deposited onto substrates such as transparent polyester film sheets in the absence of any plasticizer and/or hydrophobic polymer matrix. The inkjet-printing process enables the formation of optode films with nanoscale thickness/roughness that readily facilitate interfacing with aqueous samples. Using a smartphone detector, the colorimetric response of the optodes is shown to reach 95% of equilibrium values within 100 s in response to different concentrations of sodium ions, which is more rapid than traditional ion-selective optodes based on plasticized PVC films as the sensing layer. The new optodes also exhibit high selectivity to Na+ over interfering ions including K+, Ca2+, and Mg2+. Chemical leaching experiments show that the highly hydrophobic optode components remain in place on the plastic substrate surface. Hence, excellent sensor stability and fully reversible optical responses are obtained, which is essential for potential continuous monitoring applications. Further testing of the sensors with undiluted human sweat samples is shown to yield accurate values for sodium concentrations. Therefore, the use of plasticizer-free ion-selective optode nanolayers that enable highly selective ion sensing on a clear plastic support is likely to expand the range of available chemical sensors suited for preparing wearable real-time sweat analysis devices.
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Affiliation(s)
- Qi Zhang
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Xuewei Wang
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Vanessa Decker
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Mark E Meyerhoff
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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A highly-selective chloride microelectrode based on a mercuracarborand anion carrier. Sci Rep 2019; 9:18860. [PMID: 31827130 PMCID: PMC6906508 DOI: 10.1038/s41598-019-54885-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/20/2019] [Indexed: 11/08/2022] Open
Abstract
The chloride gradient plays an important role in regulating cell volume, membrane potential, pH, secretion, and the reversal potential of inhibitory glycine and GABAA receptors. Measurement of intracellular chloride activity, \documentclass[12pt]{minimal}
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\begin{document}$${{\boldsymbol{a}}}_{{\boldsymbol{Cl}}}^{{\boldsymbol{i}}}$$\end{document}aCli, using liquid membrane ion-selective microelectrodes (ISM), however, has been limited by the physiochemical properties of Cl− ionophores which have caused poor stability, drift, sluggish response times, and interference from other biologically relevant anions. Most importantly, intracellular \documentclass[12pt]{minimal}
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\begin{document}$${\bf{HC}}{{\bf{O}}}_{{\bf{3}}}^{-}$$\end{document}HCO3− may be up to 4 times more abundant than Cl− (e.g. skeletal muscle) which places severe constraints on the required selectivity of a Cl− – sensing ISM. Previously, a sensitive and highly-selective Cl− sensor was developed in a polymeric membrane electrode using a trinuclear Hg(II) complex containing carborane-based ligands, [9]-mercuracarborand-3, or MC3 for short. Here, we have adapted the use of the MC3 anion carrier in a liquid membrane ion-selective microelectrode and show the MC3-ISM has a linear Nernstian response over a wide range of aCl (0.1 mM to 100 mM), is highly selective for Cl− over other biological anions or inhibitors of Cl− transport, and has a 10% to 90% settling time of 3 sec. Importantly, over the physiological range of aCl (1 mM to 100 mM) the potentiometric response of the MC3-ISM is insensitive to \documentclass[12pt]{minimal}
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\begin{document}$${\bf{HC}}{{\bf{O}}}_{{\bf{3}}}^{-}$$\end{document}HCO3− or changes in pH. Finally, we demonstrate the biological application of an MC3-ISM by measuring intracellular aCl, and the response to an external Cl-free challenge, for an isolated skeletal muscle fiber.
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Morris C, O'Donnell M. Multiple functions of ion transport by the nuchal organ in embryos and neonates of the freshwater branchiopod crustacean Daphnia magna. ACTA ACUST UNITED AC 2019; 222:jeb.211128. [PMID: 31645374 DOI: 10.1242/jeb.211128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/18/2019] [Indexed: 01/07/2023]
Abstract
The nuchal organ, also referred to as the dorsal organ or neck organ, is a dorsal structure located posteriorly to the compound eye, between the bases of the second antennae of embryonic and neonate branchiopod crustaceans such as the water flea, Daphnia magna The ultrastructure of the nuchal organ is similar to ion-transporting tissues in other crustaceans, including abundant mitochondria and extensive amplification of apical and basal plasma membranes through microvilli and infoldings, but direct evidence for ion transport is lacking. We used the scanning ion-selective electrode technique to measure transport of Na+, K+, H+, Cl-, NH4 + and Ca2+ across the nuchal organ and body surface of embryos and neonates bathed in dechlorinated Hamilton tap water. Influx of Na+ and efflux of H+ and NH4 + was found to occur across the nuchal organ of both embryos and neonates. We propose that the efflux of K+ and Cl- across the nuchal organ in embryos is related to the expansion of the haemocoel and release of intracellular solutes into the extracellular space during development. K+ is taken up across the nuchal organ later during development, coincident with expansion of the intracellular compartment through the development of gills and other organs. Ca2+ influx across the nuchal organ and body surface of neonates but not embryos is presumably related to calcification of the exoskeleton. Increases in the levels of Na+ and Ca2+ in the water within the brood chamber suggest maternal provisioning of ions for uptake by the embryos. Our data thus support roles for the nuchal organ in ionoregulation, pH regulation and nitrogenous waste excretion.
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Affiliation(s)
- Carolyn Morris
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Michael O'Donnell
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
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6
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Messerli MA, Sarkar A. Advances in Electrochemistry for Monitoring Cellular Chemical Flux. Curr Med Chem 2019; 26:4984-5002. [PMID: 31057100 DOI: 10.2174/0929867326666190506111629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 03/06/2019] [Accepted: 03/12/2019] [Indexed: 11/22/2022]
Abstract
The transport of organic and inorganic molecules, along with inorganic ions across the plasma membrane results in chemical fluxes that reflect the cellular function in healthy and diseased states. Measurement of these chemical fluxes enables the characterization of protein function and transporter stoichiometry, characterization of a single cell and embryo viability prior to implantation, and screening of pharmaceutical agents. Electrochemical sensors emerge as sensitive and non-invasive tools for measuring chemical fluxes immediately outside the cells in the boundary layer, that are capable of monitoring a diverse range of transported analytes including inorganic ions, gases, neurotransmitters, hormones, and pharmaceutical agents. Used on their own or in combination with other methods, these sensors continue to expand our understanding of the function of rare cells and small tissues. Advances in sensor construction and detection strategies continue to improve sensitivity under physiological conditions, diversify analyte detection, and increase throughput. These advances will be discussed in the context of addressing technical challenges to measuring chemical flux in the boundary layer of cells and measuring the resultant changes to the chemical concentration in the bulk media.
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Affiliation(s)
- Mark A Messerli
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD. United States
| | - Anyesha Sarkar
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD. United States
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7
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Mousavi MPS, Abd El-Rahman MK, Mahmoud AM, Abdelsalam RM, Bühlmann P. In Situ Sensing of the Neurotransmitter Acetylcholine in a Dynamic Range of 1 nM to 1 mM. ACS Sens 2018; 3:2581-2589. [PMID: 30398333 DOI: 10.1021/acssensors.8b00950] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The neurotransmitter acetylcholine (ACh) plays a key role in the pathophysiology of brain disorders such as Alzheimer's disease. Understanding the dynamics of ACh concentration changes and kinetics of ACh degradation in the living brain is crucial to unravel the pathophysiology of such diseases and the rational design of therapeutics. In this work, an electrochemical sensor capable of dynamic, label-free, selective, and in situ detection of ACh in a range of 1 nM to 1 mM (with temporal resolution of less than one second) was developed. The sensor was employed for the direct detection of ACh in artificial cerebrospinal fluid and rat brain homogenate, without any prior separation steps. A potentiometric receptor-doped ion-selective electrode (ISE) with selectivity for ACh was designed by taking advantage of the positive charge of ACh. The dynamic range, limit of detection (LOD), and the selectivity of the sensor were optimized stepwise by (i) screening of hydrophobic biomimetic calixarenes to identify receptors that strongly bind to ACh based on shape-selective multitopic recognition, (ii) doping of the ISE sensing membrane with an ACh-binding hydrophobic calixarene to enable selective detection of ACh in complex matrices, (iii) utilizing a hydrophilic calixarene in the inner filling solution of the ISE to buffer the concentration of ACh and, thereby, lower the LOD of the sensor, and (iv) introducing a surface treatment step prior to the measurement by placing the sensor for ∼1 min in a solution of a hydrophilic calixarene to lower the LOD of the sensor even further.
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Affiliation(s)
- Maral P. S. Mousavi
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | | | | | | | - Philippe Bühlmann
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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8
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Yerushalmi GY, Misyura L, Donini A, MacMillan HA. Chronic dietary salt stress mitigates hyperkalemia and facilitates chill coma recovery in Drosophila melanogaster. JOURNAL OF INSECT PHYSIOLOGY 2016; 95:89-97. [PMID: 27642001 DOI: 10.1016/j.jinsphys.2016.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 06/06/2023]
Abstract
Chill susceptible insects like Drosophila lose the ability to regulate water and ion homeostasis at low temperatures. This loss of hemolymph ion and water balance drives a hyperkalemic state that depolarizes cells, causing cellular injury and death. The ability to maintain ion homeostasis at low temperatures and/or recover ion homeostasis upon rewarming is closely related to insect cold tolerance. We thus hypothesized that changes to organismal ion balance, which can be achieved in Drosophila through dietary salt loading, could alter whole animal cold tolerance phenotypes. We put Drosophila melanogaster in the presence of diets highly enriched in NaCl, KCl, xylitol (an osmotic control) or sucrose (a dietary supplement known to impact cold tolerance) for 24h and confirmed that they consumed the novel food. Independently of their osmotic effects, NaCl, KCl, and sucrose supplementation all improved the ability of flies to maintain K+ balance in the cold, which allowed for faster recovery from chill coma after 6h at 0°C. These supplements, however, also slightly increased the CTmin and had little impact on survival rates following chronic cold stress (24h at 0°C), suggesting that the effect of diet on cold tolerance depends on the measure of cold tolerance assessed. In contrast to prolonged salt stress, brief feeding (1.5h) on diets high in salt slowed coma recovery, suggesting that the long-term effects of NaCl and KCl on chilling tolerance result from phenotypic plasticity, induced in response to a salty diet, rather than simply the presence of the diet in the gut lumen.
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Affiliation(s)
- Gil Y Yerushalmi
- Department of Biology, York University, 4700 Keele St., Toronto M3J 1P3, Canada
| | - Lidiya Misyura
- Department of Biology, York University, 4700 Keele St., Toronto M3J 1P3, Canada
| | - Andrew Donini
- Department of Biology, York University, 4700 Keele St., Toronto M3J 1P3, Canada
| | - Heath A MacMillan
- Department of Biology, York University, 4700 Keele St., Toronto M3J 1P3, Canada.
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9
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The capacity to maintain ion and water homeostasis underlies interspecific variation in Drosophila cold tolerance. Sci Rep 2015; 5:18607. [PMID: 26678786 PMCID: PMC4683515 DOI: 10.1038/srep18607] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 11/19/2015] [Indexed: 02/02/2023] Open
Abstract
Many insects, including Drosophila, succumb to the physiological effects of chilling at temperatures well above those causing freezing. Low temperature causes a loss of extracellular ion and water homeostasis in such insects, and chill injuries accumulate. Using an integrative and comparative approach, we examined the role of ion and water balance in insect chilling susceptibility/ tolerance. The Malpighian tubules (MT), of chill susceptible Drosophila species lost [Na(+)] and [K(+)] selectivity at low temperatures, which contributed to a loss of Na(+) and water balance and a deleterious increase in extracellular [K(+)]. By contrast, the tubules of chill tolerant Drosophila species maintained their MT ion selectivity, maintained stable extracellular ion concentrations, and thereby avoided injury. The most tolerant species were able to modulate ion balance while in a cold-induced coma and this ongoing physiological acclimation process allowed some individuals of the tolerant species to recover from chill coma during low temperature exposure. Accordingly, differences in the ability to maintain homeostatic control of water and ion balance at low temperature may explain large parts of the wide intra- and interspecific variation in insect chilling tolerance.
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10
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Schellinger JN, Rodan AR. Use of the Ramsay Assay to Measure Fluid Secretion and Ion Flux Rates in the Drosophila melanogaster Malpighian Tubule. J Vis Exp 2015. [PMID: 26650886 DOI: 10.3791/53144] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Modulation of renal epithelial ion transport allows organisms to maintain ionic and osmotic homeostasis in the face of varying external conditions. The Drosophila melanogaster Malpighian (renal) tubule offers an unparalleled opportunity to study the molecular mechanisms of epithelial ion transport, due to the powerful genetics of this organism and the accessibility of its renal tubules to physiological study. Here, we describe the use of the Ramsay assay to measure fluid secretion rates from isolated fly renal tubules, with the use of ion-specific electrodes to measure sodium and potassium concentrations in the secreted fluid. This assay allows study of transepithelial fluid and ion fluxes of ~20 tubules at a time, without the need to transfer the secreted fluid to a separate apparatus to measure ion concentrations. Genetically distinct tubules can be analyzed to assess the role of specific genes in transport processes. Additionally, the bathing saline can be modified to examine the effects of its chemical characteristics, or drugs or hormones added. In summary, this technique allows the molecular characterization of basic mechanisms of epithelial ion transport in the Drosophila tubule, as well as regulation of these transport mechanisms.
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Affiliation(s)
| | - Aylin R Rodan
- Department of Internal Medicine, University of Texas Southwestern Medical Center;
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11
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O'Donnell MJ, Ruiz-Sanchez E. The rectal complex and Malpighian tubules of the cabbage looper (Trichoplusia ni): regional variations in Na+ and K+ transport and cation reabsorption by secondary cells. J Exp Biol 2015; 218:3206-14. [PMID: 26491192 DOI: 10.1242/jeb.128314] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
ABSTRACT
In larvae of most Lepidoptera the distal ends of the Malpighian tubules are closely applied to the rectal epithelia and are ensheathed within the perinephric membrane, thus forming the rectal complex. The cryptonephric Malpighian tubules within the rectal complex are bathed in fluid within a functional compartment, the perinephric space, which is separate from the haemolymph. In this study, the scanning ion-selective electrode technique (SIET) was used to measure transport of Na+ and K+ across the rectal complex and across multiple regions of the Malpighian tubules of larvae of the cabbage looper Trichoplusia ni. Measurements were made in an intact preparation in which connections of the tubules upstream to the rectal complex and downstream to the urinary bladder and gut remained intact. SIET measurements revealed reabsorption of Na+ and K+ across the intact rectal complex and into the bath (haemolymph), with K+ fluxes approximately twice as large as those of Na+. Analyses of fluxes in larvae with empty guts, found in recently moulted larvae, versus those with full guts highlighted differences in the rates of K+ or Na+ transport within tubule regions that appeared morphologically homogeneous, such as the rectal lead. The distal rectal lead of larvae with empty guts reabsorbed K+, whereas the same region secreted K+ in tubules of larvae with full guts. SIET measurements of the ileac plexus also indicated a novel role for secondary (type II) cells in cation reabsorption. Secondary cells reabsorb K+, whereas the adjacent principal (type I) cells secrete K+. Na+ is reabsorbed by both principal and secondary cells, but the rate of reabsorption by the secondary cells is approximately twice the rate in the adjacent principal cells.
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Affiliation(s)
- Michael J. O'Donnell
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1
| | - Esau Ruiz-Sanchez
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1
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12
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Mendecki L, Fayose T, Stockmal KA, Wei J, Granados-Focil S, McGraw CM, Radu A. Robust and Ultrasensitive Polymer Membrane-Based Carbonate-Selective Electrodes. Anal Chem 2015; 87:7515-8. [DOI: 10.1021/acs.analchem.5b01756] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lukasz Mendecki
- Lennard-Jones
Laboratories, Birchall Centre, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
| | - Tolulope Fayose
- Lennard-Jones
Laboratories, Birchall Centre, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
| | - Kelli A. Stockmal
- Sackler
Sciences Center, Department of Chemistry, Clark University, Worcester, Massachusetts 01610, United States
| | - Jia Wei
- Sackler
Sciences Center, Department of Chemistry, Clark University, Worcester, Massachusetts 01610, United States
| | - Sergio Granados-Focil
- Sackler
Sciences Center, Department of Chemistry, Clark University, Worcester, Massachusetts 01610, United States
| | - Christina M. McGraw
- School
of Science and Technology, University of New England, Armidale, 2351, New South Wales, Australia
| | - Aleksandar Radu
- Lennard-Jones
Laboratories, Birchall Centre, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
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13
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MacMillan HA, Andersen JL, Loeschcke V, Overgaard J. Sodium distribution predicts the chill tolerance of Drosophila melanogaster raised in different thermal conditions. Am J Physiol Regul Integr Comp Physiol 2015; 308:R823-31. [DOI: 10.1152/ajpregu.00465.2014] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 03/05/2015] [Indexed: 11/22/2022]
Abstract
Many insects, including the model holometabolous insect Drosophila melanogaster, display remarkable plasticity in chill tolerance in response to the thermal environment experienced during development or as adults. At low temperatures, many insects lose the ability to regulate Na+ balance, which is suggested to cause a secondary loss of hemolymph water to the tissues and gut lumen that concentrates the K+ remaining in the hemolymph. The resultant increase in extracellular [K+] inhibits neuromuscular excitability and is proposed to cause cellular apoptosis and injury. The present study investigates whether and how variation in chill tolerance induced through developmental and adult cold acclimation is associated with changes in Na+, water, and K+ balance. Developmental and adult cold acclimation improved the chilling tolerance of D. melanogaster in an additive manner. In agreement with the proposed model, these effects were intimately related to differences in Na+ distribution prior to cold exposure, such that chill-tolerant flies had low hemolymph [Na+], while intracellular [Na+] was similar among treatment groups. The low hemolymph Na+ of cold-acclimated flies allowed them to maintain hemolymph volume, prevent hyperkalemia, and avoid injury following chronic cold exposure. These findings extend earlier observations of hemolymph volume disruption during cold exposure to the most ubiquitous model insect ( D. melanogaster), highlight shared mechanisms of developmental and adult thermal plasticity and provide strong support for ionoregulatory failure as a central mechanism of insect chill susceptibility.
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Affiliation(s)
- Heath A. MacMillan
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus C, Denmark; and
| | - Jonas L. Andersen
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus C, Denmark; and
| | - Volker Loeschcke
- Genetics, Ecology and Evolution, Department of Bioscience, Aarhus University, Aarhus C, Denmark
| | - Johannes Overgaard
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus C, Denmark; and
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14
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MacMillan HA, Ferguson LV, Nicolai A, Donini A, Staples JF, Sinclair BJ. Parallel ionoregulatory adjustments underlie phenotypic plasticity and evolution of Drosophila cold tolerance. ACTA ACUST UNITED AC 2014; 218:423-32. [PMID: 25524989 DOI: 10.1242/jeb.115790] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Low temperature tolerance is the main predictor of variation in the global distribution and performance of insects, yet the molecular mechanisms underlying cold tolerance variation are poorly known, and it is unclear whether the mechanisms that improve cold tolerance within the lifetime of an individual insect are similar to those that underlie evolved differences among species. The accumulation of cold-induced injuries by hemimetabolous insects is associated with loss of Na(+) and K(+) homeostasis. Here we show that this model holds true for Drosophila; cold exposure increases haemolymph [K(+)] in D. melanogaster, and cold-acclimated flies maintain low haemolymph [Na(+)] and [K(+)], both at rest and during a cold exposure. This pattern holds across 24 species of the Drosophila phylogeny, where improvements in cold tolerance have been consistently paired with reductions in haemolymph [Na(+)] and [K(+)]. Cold-acclimated D. melanogaster have low activity of Na(+)/K(+)-ATPase, which may contribute to the maintenance of low haemolymph [Na(+)] and underlie improvements in cold tolerance. Modifications to ion balance are associated with both phenotypic plasticity within D. melanogaster and evolutionary differences in cold tolerance across the Drosophila phylogeny, which suggests that adaptation and acclimation of cold tolerance in insects may occur through similar mechanisms. Cold-tolerant flies maintain haemolymph osmolality despite low haemolymph [Na(+)] and [K(+)], possibly through modest accumulations of organic osmolytes. We propose that this could have served as an evolutionary route by which chill-susceptible insects developed more extreme cold tolerance strategies.
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Affiliation(s)
- Heath A MacMillan
- Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7
| | - Laura V Ferguson
- Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7
| | - Annegret Nicolai
- Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7
| | - Andrew Donini
- Department of Biology, York University, Toronto, ON, Canada M3J 1P3
| | - James F Staples
- Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7
| | - Brent J Sinclair
- Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7
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15
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Wu Y, Schellinger JN, Huang CL, Rodan AR. Hypotonicity stimulates potassium flux through the WNK-SPAK/OSR1 kinase cascade and the Ncc69 sodium-potassium-2-chloride cotransporter in the Drosophila renal tubule. J Biol Chem 2014; 289:26131-26142. [PMID: 25086033 DOI: 10.1074/jbc.m114.577767] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The ability to osmoregulate is fundamental to life. Adult Drosophila melanogaster maintain hemolymph osmolarity within a narrow range. Osmolarity modulates transepithelial ion and water flux in the Malpighian (renal) tubules of the fly, which are in direct contact with hemolymph in vivo, but the mechanisms causing increased transepithelial flux in response to hypotonicity are unknown. Fly renal tubules secrete a KCl-rich fluid. We have previously demonstrated a requirement for Ncc69, the fly sodium-potassium-2-chloride cotransporter (NKCC), in tubule K(+) secretion. Mammalian NKCCs are regulated by a kinase cascade consisting of the with-no-lysine (WNK) and Ste20-related proline/alanine-rich (SPAK)/oxidative stress response (OSR1) kinases. Here, we show that decreasing Drosophila WNK activity causes a reduction in K(+) flux. Similarly, knocking down the SPAK/OSR1 homolog fray also decreases K(+) flux. We demonstrate that a hierarchical WNK-Fray signaling cascade regulates K(+) flux through Ncc69, because (i) a constitutively active Fray mutant rescues the wnk knockdown phenotype, (ii) Fray directly phosphorylates Ncc69 in vitro, and (iii) the effect of wnk and fray knockdown is abolished in Ncc69 mutants. The stimulatory effect of hypotonicity on K(+) flux is absent in wnk, fray, or Ncc69 mutant tubules, suggesting that the Drosophila WNK-SPAK/OSR1-NKCC cascade is an essential molecular pathway for osmoregulation, through its effect on transepithelial ion flux and fluid generation by the renal tubule.
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Affiliation(s)
- Yipin Wu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8856
| | - Jeffrey N Schellinger
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8856
| | - Chou-Long Huang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8856
| | - Aylin R Rodan
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8856.
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16
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MacMillan HA, Hughson BN. A high-throughput method of hemolymph extraction from adult Drosophila without anesthesia. JOURNAL OF INSECT PHYSIOLOGY 2014; 63:27-31. [PMID: 24561358 DOI: 10.1016/j.jinsphys.2014.02.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/04/2014] [Accepted: 02/11/2014] [Indexed: 06/03/2023]
Abstract
A rapid and cost-effective method of sampling hemolymph from the model insect Drosophila melanogaster is needed for studies in several fields, including ionoregulatory physiology, metabolism, immunology and toxicology. Here, we describe the construction and use of a device that uses airflow and pressure to manipulate adult flies and extract high-volume hemolymph samples. This method is rapid and inexpensive, and does not require cold or CO2 anesthesia at any point in the sampling process, thus avoiding the possible confounding effects of these treatments on the biochemical properties of the hemolymph sampled. To demonstrate one use for this method, we measure active concentrations of Na(+) and K(+) in isolated hemolymph droplets from individual adult D. melanogaster using an ion-selective microelectrode technique.
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Affiliation(s)
- Heath A MacMillan
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada.
| | - Bryon N Hughson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
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17
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Pacey EK, O'Donnell MJ. Transport of H(+), Na(+) and K(+) across the posterior midgut of blood-fed mosquitoes (Aedes aegypti). JOURNAL OF INSECT PHYSIOLOGY 2014; 61:42-50. [PMID: 24406662 DOI: 10.1016/j.jinsphys.2013.12.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 12/03/2013] [Accepted: 12/28/2013] [Indexed: 06/03/2023]
Abstract
Following ingestion of a blood meal, the adult female mosquito undergoes a massive diuresis during which Na(+), Cl(-) and water are secreted at high rates by the Malpighian tubules. In the hours following completion of diuresis, digestion of the K(+)-rich blood cells provides a source of energy as well as amino acids for proteins in the developing eggs. Although the transport of inorganic ions by the Malpighian tubules of blood-fed mosquitoes has been extensively characterized, relatively little is known of the epithelial transport mechanisms responsible for movement of Na(+), H(+), and K(+) across the posterior midgut. In this paper we have used the Scanning Ion-selective Electrode Technique (SIET) to measure the basal (unstimulated) rates of transport of K(+), Na(+) and H(+) across the isolated posterior midgut at intervals after the blood meal. We have also measured luminal concentrations of Na(+) and K(+) and the transepithelial electrical potential at the same time points and have calculated the electrochemical potentials for Na(+), K(+) and H(+) across the midgut. SIET measurements reveal absorption (lumen to bath) of Na(+) and H(+) and secretion of K(+) for the first 2h after blood-feeding. By 24h after the meal, absorption of Na(+) and H(+) remains active while there is an electrochemical gradient favouring absorption of K(+). Inhibition by ouabain and Ba(2+) suggest a role for the Na(+)/K(+)-ATPase and K(+) channels in absorption of Na(+) and K(+), respectively. Inhibition of H(+) absorption by acetazolamide implicates carbonic anhydrase in transepithelial H(+) transport.
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Affiliation(s)
- Evan K Pacey
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton L8S 4K1, Canada
| | - Michael J O'Donnell
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton L8S 4K1, Canada.
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18
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The heterodimeric glycoprotein hormone, GPA2/GPB5, regulates ion transport across the hindgut of the adult mosquito, Aedes aegypti. PLoS One 2014; 9:e86386. [PMID: 24466069 PMCID: PMC3896475 DOI: 10.1371/journal.pone.0086386] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 12/06/2013] [Indexed: 11/30/2022] Open
Abstract
A family of evolutionarily old hormones is the glycoprotein cysteine knot-forming heterodimers consisting of alpha- (GPA) and beta-subunits (GPB), which assemble by noncovalent bonds. In mammals, a common glycoprotein hormone alpha-subunit (GPA1) pairs with unique beta-subunits that establish receptor specificity, forming thyroid stimulating hormone (GPA1/TSHβ) and the gonadotropins luteinizing hormone (GPA1/LHβ), follicle stimulating hormone (GPA1/FSHβ), choriogonadotropin (GPA1/CGβ). A novel glycoprotein heterodimer was identified in vertebrates by genome analysis, called thyrostimulin, composed of two novel subunits, GPA2 and GPB5, and homologs occur in arthropods, nematodes and cnidarians, implying that this neurohormone system existed prior to the emergence of bilateral metazoans. In order to discern possible physiological roles of this hormonal signaling system in mosquitoes, we have isolated the glycoprotein hormone genes producing the alpha- and beta-subunits (AedaeGPA2 and AedaeGPB5) and assessed their temporal expression profiles in the yellow and dengue-fever vector, Aedes aegypti. We have also isolated a putative receptor for this novel mosquito hormone, AedaeLGR1, which contains features conserved with other glycoprotein leucine-rich repeating containing G protein-coupled receptors. AedaeLGR1 is expressed in tissues of the alimentary canal such as the midgut, Malpighian tubules and hindgut, suggesting that this novel mosquito glycoprotein hormone may regulate ionic and osmotic balance. Focusing on the hindgut in adult stage A. aegypti, where AedaeLGR1 was highly enriched, we utilized the Scanning Ion-selective Electrode Technique (SIET) to determine if AedaeGPA2/GPB5 modulated cation transport across this epithelial tissue. Our results suggest that AedaeGPA2/GPB5 does indeed participate in ionic and osmotic balance, since it appears to inhibit natriuresis and promote kaliuresis. Taken together, our findings imply this hormone may play an important role in ionic balance when levels of Na+ are limited and levels of K+ are in excess – such as during the digestion and assimilation of erythrocytes following vertebrate blood-feeding by females.
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19
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Browne A, O'Donnell MJ. Ammonium secretion by Malpighian tubules of Drosophila melanogaster: application of a novel ammonium-selective microelectrode. ACTA ACUST UNITED AC 2013; 216:3818-27. [PMID: 23821719 DOI: 10.1242/jeb.091082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ammonia is a toxic nitrogenous waste product of amino acid metabolism that may accumulate to high levels in the medium ingested by larvae of the fruit fly Drosophila melanogaster. Here we report measurements of haemolymph NH4(+) concentration and the secretion of NH4(+) by the Malpighian (renal) tubules. Measurement of NH4(+) concentrations in secreted droplets is complicated either by the requirement for large sample volumes for enzymatic assays or by the inadequate selectivity of NH4(+)-selective microelectrodes based on nonactin. We have developed a novel liquid membrane NH4(+)-selective microelectrode based on a 19-membered crown compound (TD19C6), which has been used previously in ammonium-selective macroelectrodes. In conjunction with an improved technique for correcting for interference of potassium, NH4(+)-selective microelectrodes based on TD19C6 permit accurate measurement of ammonium concentration in haemolymph samples and nanolitre droplets of fluid secreted by the Malpighian tubules of D. melanogaster. The results indicate that active secretion of ammonium into the Malpighian tubule lumen is sufficient to maintain concentrations of ~1 mmol l(-1) ammonium in the haemolymph of larvae reared on diets containing 100 mmol l(-1) ammonium chloride.
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Affiliation(s)
- Austin Browne
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada, L8S 4K1
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20
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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: 40] [Impact Index Per Article: 3.3] [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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21
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Paluzzi JPV, Naikkhwah W, O'Donnell MJ. Natriuresis and diuretic hormone synergism in R. prolixus upper Malpighian tubules is inhibited by the anti-diuretic hormone, RhoprCAPA-α2. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:534-542. [PMID: 22154955 DOI: 10.1016/j.jinsphys.2011.11.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 11/22/2011] [Accepted: 11/28/2011] [Indexed: 05/31/2023]
Abstract
Insects contain an array of hormones that coordinate the actions of the excretory system to achieve osmotic and ionic balance. In the hematophagous insect, Rhodnius prolixus, two diuretic hormones have been identified, serotonin (5HT) and a corticotropin releasing factor-related peptide (RhoprDH), and both lead to an increase in fluid secretion by Malpighian tubules (MTs). However, only 5HT activates reabsorption by the lower MTs to recover K(+) and Cl(-). An anti-diuretic hormone (RhoprCAPA-α2) is believed to coordinate the cessation of the rapid diuresis following blood meal engorgement. However, the role of RhoprCAPA-α2 on fluid secretion by MTs stimulated by RhoprDH was previously unknown. Here we demonstrate that, unlike the inhibitory effect on 5HT-stimulated secretion by MTs, RhoprCAPA-α2 does not inhibit secretion stimulated by RhoprDH although it does abolish the synergism that occurs between the two diuretic hormones. In addition, we show that the natriuresis elicited by either diuretic hormone is reduced by RhoprCAPA-α2. Using electrophysiological tools, we investigate the possible mechanism by which this complex regulatory pathway is achieved. Analysis of the pH of secreted fluid as well as the triphasic response in transepithelial potential in MTs treated with diuretic hormones, suggests that RhoprCAPA-α2 does not inhibit the V-type H(+) ATPase. Taken together, these results indicate that RhoprCAPA-α2 functions to reduce the rapid diuresis following blood feeding, and in addition, it inhibits the natriuresis associated with diuretic hormone stimulated MTs. This may reflect an important regulatory mechanism related to the slow diuresis that occurs as the K(+)-rich blood cells are digested.
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Affiliation(s)
- Jean-Paul V Paluzzi
- Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1.
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22
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23
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Del Duca O, Nasirian A, Galperin V, Donini A. Pharmacological characterisation of apical Na+ and Cl- transport mechanisms of the anal papillae in the larval mosquito Aedes aegypti. ACTA ACUST UNITED AC 2012; 214:3992-9. [PMID: 22071191 DOI: 10.1242/jeb.063719] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The anal papillae of freshwater mosquito larvae are important sites of NaCl uptake, thereby acting to offset the dilution of the hemolymph by the dilute habitat. The ion-transport mechanisms in the anal papillae are not well understood. In this study, the scanning ion-selective electrode technique (SIET) was utilized to measure ion fluxes at the anal papillae, and pharmacological inhibitors of ion transport were utilized to identify ion-transport mechanisms. Na(+) uptake by the anal papillae was inhibited by bafilomycin and phenamil but not by HMA. Cl(-) uptake was inhibited by methazolamide, SITS and DIDS but not by bafilomycin. H(+) secretion was inhibited by bafilomycin and methazolamide. Ouabain and bumetanide had no effect on NaCl uptake or H(+) secretion. Together, the results suggest that Na(+) uptake at the apical membrane occurs through a Na(+) channel that is driven by a V-type H(+)-ATPase and that Cl(-) uptake occurs through a Cl(-)/HCO(3)(-) exchanger, with carbonic anhydrase providing H(+) and HCO(3)(-) to the V-type H(+)-ATPase and exchanger, respectively.
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24
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Naikkhwah W, O'Donnell MJ. Phenotypic plasticity in response to dietary salt stress: Na+ and K+ transport by the gut of Drosophila melanogaster larvae. J Exp Biol 2012; 215:461-70. [PMID: 22246255 DOI: 10.1242/jeb.064048] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
SUMMARY
Drosophila provides a useful model system for studies of the mechanisms involved in regulation of internal ion levels in response to variations in dietary salt load. This study assessed whether alterations in Na+ and K+ transport by the gut of larval D. melanogaster reared on salt-rich diets contribute to haemolymph ionoregulation. Na+ and K+ fluxes across the isolated guts of third instar larvae reared on control or salt-rich diets were measured using the scanning ion-selective electrode technique (SIET). K+ absorption across the anterior portion of the posterior midgut of larvae reared on diet in which the concentration of KCl was increased 0.4 mol l-1 above that in the control diet was reduced eightfold relative to the same gut segment of larvae reared on the control diet. There was also an increase in the magnitude and extent of K+ secretion across the posterior half of the posterior midgut. Na+ was absorbed across the ileum of larvae reared on the control diet, but was secreted across the ileum of larvae reared on diet in which the concentration of NaCl was increased 0.4 mol l-1 above that in the control diet. There was also a small reduction in the extent of Na+ absorption across the middle midgut of larvae reared on the NaCl-rich diet. The results indicate considerable phenotypic plasticity with respect to K+ and Na+ transport by the gut epithelia of larval D. melanogaster. SIET measurements of K+ and Na+ fluxes along the length of the gut show that ion transport mechanisms of the gut are reconfigured during salt stress so that there are reductions in K+ and Na+ absorption and increases in K+ and Na+ secretion. Together with previously described changes in salt secretion by the Malpighian tubules, these changes contribute to haemolymph ionoregulation.
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Affiliation(s)
- Wida Naikkhwah
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
| | - Michael J. O'Donnell
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
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25
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Naikkhwah W, O'Donnell MJ. Salt stress alters fluid and ion transport by Malpighian tubules of Drosophila melanogaster: evidence for phenotypic plasticity. ACTA ACUST UNITED AC 2012; 214:3443-54. [PMID: 21957108 DOI: 10.1242/jeb.057828] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Drosophila are tolerant of high levels of dietary salt and can provide a useful model for studies of the physiology of salt stress. The effects of NaCl- and KCl-rich diets on haemolymph ionoregulation and Malpighian tubule (MT) fluid secretion, Na(+) and K(+) secretion and transepithelial potential were examined in larval and adult Drosophila melanogaster. K(+) concentrations in the haemolymph of adults reared on the KCl-rich (0.4 mol l(-1)) diet did not differ from the values for insects reared on the control diet. In the haemolymph of larvae reared on the K-rich diet, K(+) concentrations increased from 23 to 75 mmol l(-1) after 6 h, then returned to the control value within 48 h. Na(+) concentrations in the haemolymph of adults or larvae reared for 1-7 days on the NaCl-rich (0.4 mol l(-1)) diet increased by ~50% relative to values for insects reared on the control diet. Rates of secretion of fluid, Na(+) and K(+) by MTs isolated from larvae reared on the Na-rich diet for >6 h and bathed in control saline containing 20 mmol l(-1) K(+) did not differ from the values for tubules of larvae reared on the control diet. Evidence of phenotypic plasticity was seen in the response of MTs isolated from larvae reared on the K-rich diet for >6 h and bathed in saline containing 60 mmol l(-1) K(+); secretion of fluid and K(+) increased by >50% relative to the values for tubules of larvae reared on the control diet. Secretion of fluid, Na(+) and K(+) increased when tubules were bathed in haemolymph collected from larvae reared on the Na- or K-rich diets. Secretion was further increased by addition of exogenous cAMP but not by addition of thapsigargin to the haemolymph. The results show that haemolymph ionoregulation in larvae reared on salt-rich diets involves both alterations in the basal secretion rates of Na(+) and/or K(+) as well as stimulatory effects of diuretic factors present in the haemolymph. The results suggest that such factors stimulate tubule fluid and ion secretion through increases in intracellular Ca(2+) in response to salt stress.
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Affiliation(s)
- Wida Naikkhwah
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
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26
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Jayakannan M, Babourina O, Rengel Z. Improved measurements of Na+ fluxes in plants using calixarene-based microelectrodes. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:1045-1051. [PMID: 21256620 DOI: 10.1016/j.jplph.2010.12.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 12/17/2010] [Accepted: 12/17/2010] [Indexed: 05/30/2023]
Abstract
Ion-selective microelectrodes are a powerful tool in studying adaptive responses of plant cells and tissues to various abiotic stresses. However, application of this technique in Na(+) flux measurements was limited due to poor selectivity for Na(+) ions of commercially available Na(+) cocktails. Often, these cocktails cannot discriminate between Na(+) and other interfering ions such as K(+) and Ca(2+), leading to inaccurate measurements of Na(+) concentration and, consequently, inaccurate Na(+) flux calculations. To overcome this problem, three Na(+)-selective cocktail mixtures were prepared using tetramethoxyethyl ester derivative of p-t-butyl calix[4]arene. These cocktail mixtures were compared with commercially available ETH 227-based Na(+) cocktail for selectivity for Na(+) ions over other ions (particularly K(+) and Ca(2+)). Among the three calixarene-based Na(+) cocktails tested, cocktail 2 [in % w/w: Na(+) ionophore (4-tert-butylcalix[4]arene-tetra acetic acid tetraethyl ester) 3.5, the plasticizer (2-nitrophenyl octyl ether) 95.9 and lipophilic anion (potassium tetrakis (4-chlorophenyl) borate) 0.6] showed the best selectivity for Na(+) ions over K(+) and Ca(2+) ions and was highly stable over time (up to 10h). Na(+) flux measurements under a wide range of NaCl concentrations (25-150 mM) using Na(+) cocktail 2 established a clear dose-response relationship between severity of salt stress and magnitude of Na(+) influx at the distal elongation and mature zones of Arabidopsis thaliana roots. Furthermore, Na(+) cocktail 2 was compared with commercially available ETH 227-based Na(+) cocktail by measuring Na(+) fluxes at the two Arabidopsis root zones in response to 100mM NaCl treatment. With calixarene-based Na(+) cocktail 2, a large decreasing Na(+) influx (0-15 min) followed by small Na(+) influx (15-45 min) was measured, whereas with ETH-based Na(+) cocktail Na(+) influx was short-lived (1-3 min) and was followed by Na(+) efflux (3-45 min) that might have been due to K(+) and Ca(2+) efflux measured together with Na(+) influx. In conclusion, Na(+)-selective calixarene-based microelectrodes have excellent potential to be used in real-time Na(+) flux measurements in plants.
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Affiliation(s)
- Maheswari Jayakannan
- School of Earth and Environment, The University of Western Australia, M087, Crawley, WA 6009, Perth, Australia.
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27
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Lew RR. Ion and oxygen fluxes in the unicellular alga Eremosphaera viridis. PLANT & CELL PHYSIOLOGY 2010; 51:1889-1899. [PMID: 20926416 DOI: 10.1093/pcp/pcq149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Plasma membrane fluxes of the large unicellular model algal cell Eremosphaera viridis (De Bary) were measured under various light regimes to explore the role of plasma membrane fluxes during photosynthesis and high light-induced chloroplast translocation. Plasma membrane fluxes were measured directly and non-invasively with self-referencing ion-selective (H(+), Ca(2+), K(+) and Cl(-)) potentiometric microelectrodes and oxygen amperometric microelectrodes. At light irradiances high enough to induce chloroplast migration from the cell periphery to its center, oxygen evolution declined to respiratory net O(2) uptake prior to any significant chloroplast translocation, while net K(+) and Cl(-) influx increased during the decline in photosynthetic activity (and the membrane potential depolarized). The results suggest that chloroplast translocation is not the cause of the cessation of O(2) evolution at high irradiance. Rather, the chloroplast translocation may play a protective role: shielding the centrally located nucleus from damaging light intensities. At both high and low light intensities (similar to ambient growth conditions), there was a strong inverse correlation between H(+) net fluxes and respiratory and photosynthetic net O(2) fluxes. A similar inverse relationship was also observed for Ca(2+) net fluxes, but only at higher light intensities. The net H(+) fluxes are small relative to the buffering capacity of the cell, but are clearly related to both photosynthetic and respiratory activity.
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Affiliation(s)
- Roger R Lew
- Department of Biology, York University, Toronto, Ontario Canada.
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28
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Smith PJS, Collis LP, Messerli MA. Windows to cell function and dysfunction: signatures written in the boundary layers. Bioessays 2010; 32:514-23. [PMID: 20486138 DOI: 10.1002/bies.200900173] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The medium surrounding cells either in culture or in tissues contains a chemical mix varying with cell state. As solutes move in and out of the cytoplasmic compartment they set up characteristic signatures in the cellular boundary layers. These layers are complex physical and chemical environments the profiles of which reflect cell physiology and provide conduits for intercellular messaging. Here we review some of the most relevant characteristics of the extracellular/intercellular space. Our initial focus is primarily on cultured cells but we extend our consideration to the far more complex environment of tissues, and discuss how chemical signatures in the boundary layer can or may affect cell function. Critical to the entire essay are the methods used, or being developed, to monitor chemical profiles in the boundary layers. We review recent developments in ultramicro electrochemical sensors and tailored optical reporters suitable for the task in hand.
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Affiliation(s)
- Peter J S Smith
- BioCurrents Research Center, Cellular Dynamics Program, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
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Herr JE, Winegard TM, O'Donnell MJ, Yancey PH, Fudge DS. Stabilization and swelling of hagfish slime mucin vesicles. ACTA ACUST UNITED AC 2010; 213:1092-9. [PMID: 20228345 DOI: 10.1242/jeb.038992] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
When agitated, Atlantic hagfish (Myxine glutinosa) produce large quantities of slime that consists of hydrated bundles of protein filaments and membrane-bound mucin vesicles from numerous slime glands. When the slime exudate contacts seawater, the thread bundles unravel and the mucin vesicles swell and rupture. Little is known about the mechanisms of vesicle rupture in seawater and stabilization within the gland, although it is believed that the vesicle membrane is permeable to most ions except polyvalent anions. We hypothesized that the most abundant compounds within the slime gland exudate have a stabilizing effect on the mucin vesicles. To test this hypothesis, we measured the chemical composition of the fluid component of hagfish slime exudate and conducted functional assays with these solutes to test their ability to keep the vesicles in a condensed state. We found K(+) concentrations that were elevated relative to plasma, and Na(+), Cl(-) and Ca(2+) concentrations that were considerably lower. Our analysis also revealed high levels of methylamines such as trimethylamine oxide (TMAO), betaine and dimethylglycine, which had a combined concentration of 388 mmol l(-1) in the glandular fluid. In vitro rupture assays demonstrated that both TMAO and betaine had a significant effect on rupture, but neither was capable of completely abolishing mucin swelling and rupture, even at high concentrations. This suggests that some other mechanism such as the chemical microenvironment within gland mucous cells, or hydrostatic pressure is responsible for stabilization of the vesicles within the gland.
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Affiliation(s)
- J E Herr
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G-2W1 Canada
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Dimeski G, Badrick T, John AS. Ion Selective Electrodes (ISEs) and interferences--a review. Clin Chim Acta 2009; 411:309-17. [PMID: 20004654 DOI: 10.1016/j.cca.2009.12.005] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 11/25/2009] [Accepted: 12/04/2009] [Indexed: 11/29/2022]
Abstract
Ion Selective Electrodes (ISEs) are used to measure some of the most critical analytes on clinical laboratory and point-of-care analysers. These analytes which include Na(+), K(+), Cl(-), Ca(2+), Mg(2+) and Li(+) are used for rapid patient care decisions. Although the electrodes are very selective, they are not free of interferences. It is important for laboratories to have an understanding of the type and extent of interferences in order to avoid incorrect clinical decisions and treatment.
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Affiliation(s)
- Goce Dimeski
- Department of Chemical Pathology, Pathology Queensland, Princess Alexandra Hospital, Brisbane, 4102, Australia.
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