51
|
Ruiz-Sanchez E, O'Donnell MJ. The insect excretory system as a target for novel pest control strategies. CURRENT OPINION IN INSECT SCIENCE 2015; 11:14-20. [PMID: 28285757 DOI: 10.1016/j.cois.2015.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 08/04/2015] [Accepted: 08/05/2015] [Indexed: 06/06/2023]
Abstract
The insect excretory system plays essential roles in osmoregulation, ionoregulation and toxin elimination. Understanding the mechanisms of fluid and ion transport by the epithelial cells of the excretory system provides a foundation for development of novel pest management strategies. In the present review, we focus on two such strategies: first, impairment of osmoregulation by manipulation of diuretic or antidiuretic signaling pathways and second, interference with toxin elimination by inhibition of toxin transport systems.
Collapse
Affiliation(s)
- Esau Ruiz-Sanchez
- Instituto Tecnologico de Conkal, Km. 16.3, Ex-Carretera Merida-Motul, Conkal , Yucatan C.P. 97345, Mexico
| | - Michael J O'Donnell
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.
| |
Collapse
|
52
|
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.
Collapse
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
| |
Collapse
|
53
|
Beyenbach KW, Yu Y, Piermarini PM, Denton J. Targeting renal epithelial channels for the control of insect vectors. Tissue Barriers 2015; 3:e1081861. [PMID: 26716074 DOI: 10.1080/21688370.2015.1081861] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/04/2015] [Accepted: 08/07/2015] [Indexed: 12/14/2022] Open
Abstract
Three small molecules were identified in high throughput screens that 1) block renal inward rectifier potassium (Kir) channels of Aedes aegypti expressed in HEK cells and Xenopus oocytes, 2) inhibit the secretion of KCl but not NaCl in isolated Malpighian tubules, and after injection into the hemolymph, 3) inhibit KCl excretion in vivo, and 4) render mosquitoes flightless or dead within 24h. Some mosquitoes had swollen abdomens at death consistent with renal failure. VU625, the most potent and promising small molecule for development as mosquitocide, inhibits AeKir1-mediated currents with an IC50 less than 100 nM. It is highly selective for AeKir1 over mammalian Kir channels, and it affects only 3 of 68 mammalian membrane proteins. These results document 1) renal failure as a new mode-of-action for mosquitocide development, 2) renal Kir channels as molecular target for inducing renal failure, and 3) the promise of the discovery and development of new species-specific insecticides.
Collapse
Affiliation(s)
- Klaus W Beyenbach
- Department of Biomedical Sciences; Cornell University ; Ithaca, NY USA
| | - Yasong Yu
- College of Medicine; SUNY Downstate Medical Center ; Brooklyn, NY USA
| | - Peter M Piermarini
- Department of Entomology; Ohio Agricultural Research and Development Center; The Ohio State University ; Wooster, OH USA
| | - Jerod Denton
- Department of Anesthesiology; Vanderbilt University School of Medicine ; Nashville, TN USA
| |
Collapse
|
54
|
Transport proteins NHA1 and NHA2 are essential for survival, but have distinct transport modalities. Proc Natl Acad Sci U S A 2015; 112:11720-5. [PMID: 26324901 DOI: 10.1073/pnas.1508031112] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The cation/proton antiporter (CPA) family includes the well-known sodium/proton exchanger (NHE; SLC9A) family of Na(+)/H(+) exchangers, and the more recently discovered and less well understood CPA2s (SLC9B), found widely in living organisms. In Drosophila, as in humans, they are represented by two genes, Nha1 (Slc9b1) and Nha2 (Slc9b2), which are enriched and functionally significant in renal tubules. The importance of their role in organismal survival has not been investigated in animals, however. Here we show that single RNAi knockdowns of either Nha1 or Nha2 reduce survival and in combination are lethal. Knockdown of either gene alone results in up-regulation of the other, suggesting functional complementation of the two genes. Under salt stress, knockdown of either gene decreases survival, demonstrating a key role for the CPA2 family in ion homeostasis. This is specific to Na(+) stress; survival on K(+) intoxication is not affected by sodium/hydrogen antiporter (NHA) knockdown. A direct functional assay in Xenopus oocytes shows that Nha2 acts as a Na(+)/H(+) exchanger. In contrast, Nha1 expressed in Xenopus oocytes shows strong Cl(-) conductance and acts as a H(+)-Cl(-) cotransporter. The activity of Nha1 is inhibited by chloride-binding competitors 4,4'-diiso-thiocyano-2,2'-disulfonic acid stilbene and 4,4'-dibenzamido-2,2'-stilbenedisulphonate. Salt stress induces a massive up-regulation of NHA gene expression not in the major osmoregulatory tissues of the alimentary canal, but in the crop, cuticle, and associated tissues. Thus, it is necessary to revise the classical view of the coordination of different tissues in the coordination of the response to osmoregulatory stress.
Collapse
|
55
|
Wu Y, Baum M, Huang CL, Rodan AR. Two inwardly rectifying potassium channels, Irk1 and Irk2, play redundant roles in Drosophila renal tubule function. Am J Physiol Regul Integr Comp Physiol 2015. [PMID: 26224687 DOI: 10.1152/ajpregu.00148.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Inwardly rectifying potassium channels play essential roles in renal physiology across phyla. Barium-sensitive K(+) conductances are found on the basolateral membrane of a variety of insect Malpighian (renal) tubules, including Drosophila melanogaster. We found that barium decreases the lumen-positive transepithelial potential difference in isolated perfused Drosophila tubules and decreases fluid secretion and transepithelial K(+) flux. In those insect species in which it has been studied, transcripts from multiple genes encoding inwardly rectifying K(+) channels are expressed in the renal (Malpighian) tubule. In Drosophila melanogaster, this includes transcripts of the Irk1, Irk2, and Irk3 genes. The role of each of these gene products in renal tubule function is unknown. We found that simultaneous knockdown of Irk1 and Irk2 in the principal cell of the fly tubule decreases transepithelial K(+) flux, with no additive effect of Irk3 knockdown, and decreases barium sensitivity of transepithelial K(+) flux by ∼50%. Knockdown of any of the three inwardly rectifying K(+) channels individually has no effect, nor does knocking down Irk3 simultaneously with Irk1 or Irk2. Irk1/Irk2 principal cell double-knockdown tubules remain sensitive to the kaliuretic effect of cAMP. Inhibition of the Na(+)/K(+)-ATPase with ouabain and Irk1/Irk2 double knockdown have additive effects on K(+) flux, and 75% of transepithelial K(+) transport is due to Irk1/Irk2 or ouabain-sensitive pathways. In conclusion, Irk1 and Irk2 play redundant roles in transepithelial ion transport in the Drosophila melanogaster renal tubule and are additive to Na(+)/K(+)-ATPase-dependent pathways.
Collapse
Affiliation(s)
- Yipin Wu
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Michel Baum
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas; and Department of Pediatrics, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Chou-Long Huang
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Aylin R Rodan
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas; and
| |
Collapse
|
56
|
McCann MC, Carpita NC. Biomass recalcitrance: a multi-scale, multi-factor, and conversion-specific property. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:4109-18. [PMID: 26060266 DOI: 10.1093/jxb/erv267] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Recalcitrance of plant biomass to enzymatic hydrolysis for biofuel production is thought to be a property conferred by lignin or lignin-carbohydrate complexes. However, chemical catalytic and thermochemical conversion pathways, either alone or in combination with biochemical and fermentative pathways, now provide avenues to utilize lignin and to expand the product range beyond ethanol or butanol. To capture all of the carbon in renewable biomass, both lignin-derived aromatics and polysaccharide-derived sugars need to be transformed by catalysts to liquid hydrocarbons and high-value co-products. We offer a new definition of recalcitrance as those features of biomass which disproportionately increase energy requirements in conversion processes, increase the cost and complexity of operations in the biorefinery, and/or reduce the recovery of biomass carbon into desired products. The application of novel processing technologies applied to biomass reveal new determinants of recalcitrance that comprise a broad range of molecular, nanoscale, and macroscale factors. Sampling natural genetic diversity within a species, transgenic approaches, and synthetic biology approaches are all strategies that can be used to select biomass for reduced recalcitrance in various pretreatments and conversion pathways.
Collapse
Affiliation(s)
- Maureen C McCann
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA
| | - Nicholas C Carpita
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-1392, USA
| |
Collapse
|
57
|
Tracing the evolutionary origins of insect renal function. Nat Commun 2015; 6:6800. [PMID: 25896425 PMCID: PMC4410669 DOI: 10.1038/ncomms7800] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/02/2015] [Indexed: 12/21/2022] Open
Abstract
Knowledge on neuropeptide receptor systems is integral to understanding animal physiology. Yet, obtaining general insight into neuropeptide signalling in a clade as biodiverse as the insects is problematic. Here we apply fluorescent analogues of three key insect neuropeptides to map renal tissue architecture across systematically chosen representatives of the major insect Orders, to provide an unprecedented overview of insect renal function and control. In endopterygote insects, such as Drosophila, two distinct transporting cell types receive separate neuropeptide signals, whereas in the ancestral exopterygotes, a single, general cell type mediates all signals. Intriguingly, the largest insect Order Coleoptera (beetles) has evolved a unique approach, in which only a small fraction of cells are targets for neuropeptide action. In addition to demonstrating a universal utility of this technology, our results reveal not only a generality of signalling by the evolutionarily ancient neuropeptide families but also a clear functional separation of the types of cells that mediate the signal. The evolution of neuropeptide signalling in insects is poorly understood. Here the authors map renal tissue architecture in the major insect Orders, and show that while the ancient neuropeptide families are involved in signalling in nearly all species, there is functional variation in the cell types that mediate the signal.
Collapse
|
58
|
Weihrauch D, O’Donnell MJ. Links between Osmoregulation and Nitrogen-Excretion in Insects and Crustaceans. Integr Comp Biol 2015; 55:816-29. [DOI: 10.1093/icb/icv013] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
|