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Hoogenboom JL, Anderson WG. Investigating nitrogen movement in North Pacific spiny dogfish (Squalus acanthias suckleyi), with focus on UT, Rhp2, and Rhbg mRNA abundance. J Comp Physiol B 2023:10.1007/s00360-023-01487-4. [PMID: 37162540 DOI: 10.1007/s00360-023-01487-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 03/15/2023] [Accepted: 04/14/2023] [Indexed: 05/11/2023]
Abstract
For ureosmotic marine elasmobranchs, the acquisition and retention of nitrogen is critical for the synthesis of urea. To better understand whole-body nitrogen homeostasis, we investigated mechanisms of nitrogen trafficking in North Pacific spiny dogfish (Squalus acanthias suckleyi). We hypothesized that the presence of nitrogen within the spiral valve lumen would affect both the transport of nitrogen and the mRNA abundance of a urea transporter (UT) and two ammonia transport proteins (Rhp2, Rhbg) within the intestinal epithelium. The in vitro preincubation of intestinal tissues in NH4Cl, intended to simulate dietary nitrogen availability, showed that increased ammonia concentrations did not significantly stimulate the net uptake of total urea or total methylamine. We also examined the mRNA abundance of UT, Rhp2, and Rhbg in the gills, kidney, liver, and spiral valve of fasted, fed, excess urea fed, and antibiotic-treated dogfish. After fasting, hepatic UT mRNA abundance was significantly lower, and Rhp2 mRNA in the gills was significantly higher than the other treatments. Feeding significantly increased Rhp2 mRNA levels in the kidney and mid spiral valve region. Both excess urea and antibiotics significantly reduced Rhbg mRNA levels along all three spiral valve regions. The antibiotic treatment also significantly diminished UT mRNA abundance levels in the anterior and mid spiral valve, and Rhbg mRNA levels in the kidney. In our study, no single treatment had significantly greater influence on the overall transcript abundance of the three transport proteins compared to another treatment, demonstrating the dynamic nature of nitrogen balance in these ancient fish.
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Affiliation(s)
- J Lisa Hoogenboom
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, V0R 1B0, Canada.
| | - W Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, V0R 1B0, Canada
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2
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Oka Y, Umatani C. Zoology of Fishes. Zoolog Sci 2023; 40:79-82. [PMID: 37042687 DOI: 10.2108/zsj.40.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
The Zoological Society of Japan is one of the longest-standing scientific societies in Japan, and it has been publishing a unique prestigious international journal in zoology, Zoological Science, for a long period of time since its foundation in 1984 as the continuation of Zoological Magazine (1888-1983) and Annotationes Zoologicae Japonenses (1897-1983). One of the most salient features of the Society and the Journal may be the variety of species of animals used in the studies by the members of the society and the authors of the journal. Among various animal species, fish may have contributed to almost all disciplines of presentations and publications, including behavioral biology, biochemistry, cell biology, developmental biology, diversity and evolution, ecology, endocrinology, genetics, immunology, morphology, neurobiology, phylogeny, reproductive biology, and taxonomy. Owing to the recent advancement of modern molecular genetic methods in biology, not a few fish species have contributed to various research disciplines in zoological science as model animals. The present Special Issue includes various kinds of such studies in zoological science by taking advantage of a variety of fish species, which are contributed by authors of various generations ranging from junior to senior zoologists.
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Affiliation(s)
- Yoshitaka Oka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan,
| | - Chie Umatani
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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Hoogenboom JL, Wong MKS, Hyodo S, Anderson WG. Nitrogen transporters along the intestinal spiral valve of cloudy catshark (Scyliorhinus torazame): Rhp2, Rhbg, UT. Comp Biochem Physiol A Mol Integr Physiol 2023; 280:111418. [PMID: 36965831 DOI: 10.1016/j.cbpa.2023.111418] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/16/2023] [Accepted: 03/21/2023] [Indexed: 03/27/2023]
Abstract
As part of their osmoregulatory strategy, marine elasmobranchs retain large quantities of urea to balance the osmotic pressure of the marine environment. The main source of nitrogen used to synthesize urea comes from the digestion and absorption of food across the gastrointestinal tract. In this study we investigated possible mechanisms of nitrogen movement across the spiral valve of the cloudy catshark (Scyliorhinus torazame) through the molecular identification of two Rhesus glycoprotein ammonia transporters (Rhp2 and Rhbg) and a urea transporter (UT). We used immunohistochemistry to determine the cellular localizations of Rhp2 and UT. Within the spiral valve, Rhp2 was expressed along the apical brush-border membrane, and UT was expressed along the basolateral membrane and the blood vessels. The mRNA abundance of Rhp2 was significantly higher in all regions of the spiral valve of fasted catsharks compared to fed catsharks. The mRNA abundance of UT was significantly higher in the anterior spiral valve of fasted catsharks compared to fed. The mRNA transcript of four ornithine urea cycle (OUC) enzymes were detected along the length of the spiral valve and in the renal tissue, indicating the synthesis of urea via the OUC occurs in these tissues. The presence of Rhp2, Rhbg, and UT along the length of the spiral valve highlights the importance of ammonia and urea movement across the intestinal tissues, and increases our understanding of the mechanisms involved in maintaining whole-body nitrogen homeostasis in the cloudy catshark.
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Affiliation(s)
- J Lisa Hoogenboom
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 0A8, Canada.
| | - Marty Kwok-Shing Wong
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba, Japan
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba, Japan
| | - W Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 0A8, Canada
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Horie T, Takagi W, Aburatani N, Yamazaki M, Inokuchi M, Tachizawa M, Okubo K, Ohtani-Kaneko R, Tokunaga K, Wong MKS, Hyodo S. Segment-Dependent Gene Expression Profiling of the Cartilaginous Fish Nephron Using Laser Microdissection for Functional Characterization of Nephron at Segment Levels. Zoolog Sci 2023; 40:91-104. [PMID: 37042689 DOI: 10.2108/zs220092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/21/2022] [Indexed: 01/18/2023]
Abstract
For adaptation to a high salinity marine environment, cartilaginous fishes have evolved a ureosmotic strategy. They have a highly elaborate "four-loop nephron" in the kidney, which is considered to be important for reabsorption of urea from the glomerular filtrate to maintain a high concentration of urea in the body. However, the function and regulation, generally, of the "four-loop nephron" are still largely unknown due to the complicated configuration of the nephron and its many subdivided segments. Laser microdissection (LMD) followed by RNA-sequencing (RNA-seq) analysis is a powerful technique to obtain segment-dependent gene expression profiles. In the present study, using the kidney of cloudy catshark, Scyliorhinus torazame, we tested several formaldehyde-free and formaldehyde-based fixatives to optimize the fixation methods. Fixation by 1% neutral buffered formalin for 15 min resulted in sufficient RNA and structural integrities, which allowed LMD clipping of specific nephron segments and subsequent RNA-seq analysis. RNA-seq from the LMD samples of the second-loop, the fourth-loop, and the five tubular segments in the bundle zone revealed a number of specific membrane transporter genes that can characterize each segment. Among them, we examined expressions of the Na + -coupled cotransporters abundantly expressed in the second loop samples. Although the proximal II segment of the second loop is known for the elimination of excess solutes, the present results imply that the PII segment is also crucial for reabsorption of valuable solutes. Looking ahead to future studies, the segment-dependent gene expression profiling will be a powerful technique for unraveling the renal mechanisms and regulation in euryhaline elasmobranchs.
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Affiliation(s)
- Takashi Horie
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Wataru Takagi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Naotaka Aburatani
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Manabu Yamazaki
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Mayu Inokuchi
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
| | - Masaya Tachizawa
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
| | - Kataaki Okubo
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
| | | | - Kotaro Tokunaga
- Ibaraki Prefectural Oarai Aquarium, Oarai, Ibaraki 311-1301, Japan
| | - Marty Kwok-Sing Wong
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
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Fujimori C, Umatani C, Chimura M, Ijiri S, Bando H, Hyodo S, Kanda S. In vitro and in vivo gene transfer in the cloudy catshark Scyliorhinus torazame. Dev Growth Differ 2022; 64:558-565. [PMID: 36376176 PMCID: PMC10099843 DOI: 10.1111/dgd.12824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/20/2022] [Accepted: 09/29/2022] [Indexed: 11/16/2022]
Abstract
Cartilaginous fishes have various unique physiological features such as a cartilaginous skeleton and a urea-based osmoregulation strategy for adaptation to their marine environment. Also, because they are a sister group of bony vertebrates, understanding their unique features is important from an evolutionary perspective. However, genetic engineering based on gene functions as well as cellular behavior has not been effectively utilized in cartilaginous fishes. This is partly because their reproductive strategy involves internal fertilization, which results in difficulty in microinjection into fertilized eggs at the early developmental stage. Here, to identify efficient gene transfer methods in cartilaginous fishes, we examined the effects of various methods both in vitro and in vivo using the cloudy catshark, a candidate model cartilaginous fish species. In all methods, green fluorescent protein (GFP) expression was used to evaluate exogenous gene transfer. First, we examined gene transfer into primary cultured cells from cloudy catshark embryos by lipofection, polyethylenimine (PEI) transfection, adenovirus infection, baculovirus infection, and electroporation. Among the methods tested, lipofection, electroporation, and baculovirus infection enabled the successful transfer of exogenous genes into primary cultured cells. We then attempted in vivo transfection into cloudy catshark embryos by electroporation and baculovirus infection. Although baculovirus-injected groups did not show GFP fluorescence, electroporation successfully introduced GFP into muscle cells. Furthermore, we succeeded in GFP transfer into adult tissues by electroporation. The in vitro and in vivo gene transfer methods that worked in this study may open ways for genetic manipulation including knockout experiments and cellular lineage analysis in cartilaginous fishes.
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Affiliation(s)
- Chika Fujimori
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Chie Umatani
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Misaki Chimura
- Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan
| | - Shigeho Ijiri
- Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan
| | - Hisanori Bando
- Division of Applied Bioscience, Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Susumu Hyodo
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Shinji Kanda
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
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Aburatani N, Takagi W, Wong MKS, Kuraku S, Tanegashima C, Kadota M, Saito K, Godo W, Sakamoto T, Hyodo S. Molecular and morphological investigations on the renal mechanisms enabling euryhalinity of red stingray Hemitrygon akajei. Front Physiol 2022; 13:953665. [PMID: 36017340 PMCID: PMC9396271 DOI: 10.3389/fphys.2022.953665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/04/2022] [Indexed: 11/24/2022] Open
Abstract
Most cartilaginous fishes live in seawater (SW), but a few exceptional elasmobranchs (sharks and rays) are euryhaline and can acclimate to freshwater (FW) environments. The plasma of elasmobranchs is high in NaCl and urea concentrations, which constrains osmotic water loss. However, these euryhaline elasmobranchs maintain high levels of plasma NaCl and urea even when acclimating to low salinity, resulting in a strong osmotic gradient from external environment to body fluid. The kidney consequently produces a large volume of dilute urine to cope with the water influx. In the present study, we investigated the molecular mechanisms of dilute urine production in the kidney of Japanese red stingray, Hemitrygon akajei, transferred from SW to low-salinity environments. We showed that red stingray maintained high plasma NaCl and urea levels by reabsorbing more osmolytes in the kidney when transferred to low salinity. RNA-seq and qPCR analyses were conducted to identify genes involved in NaCl and urea reabsorption under the low-salinity conditions, and the upregulated gene expressions of Na+-K+-Cl- cotransporter 2 (nkcc2) and Na+/K+-ATPase (nka) were found in the FW-acclimated individuals. These upregulations occurred in the early distal tubule (EDT) in the bundle zone of the kidney, which coils around the proximal and collecting tubules to form the highly convoluted structure of batoid nephron. Considering the previously proposed model for urea reabsorption, the upregulation of nkcc2 and nka not only causes the reabsorption of NaCl in the EDT, but potentially also supports enhanced urea reabsorption and eventually the production of dilute urine in FW-acclimated individuals. We propose advantageous characteristics of the batoid-type nephron that facilitate acclimation to a wide range of salinities, which might have allowed the batoids to expand their habitats.
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Affiliation(s)
- Naotaka Aburatani
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
- *Correspondence: Naotaka Aburatani, ; Wataru Takagi,
| | - Wataru Takagi
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
- *Correspondence: Naotaka Aburatani, ; Wataru Takagi,
| | - Marty Kwok-Shing Wong
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
- Department of Biomolecular Science, Toho University, Funabashi, Japan
| | - Shigehiro Kuraku
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Japan
- Department of Genetics, Sokendai (Graduate University for Advanced Studies), Mishima, Japan
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Chiharu Tanegashima
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Mitsutaka Kadota
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Kazuhiro Saito
- Ushimado Marine Institute, Faculty of Science, Okayama University, Setouchi, Japan
| | - Waichiro Godo
- Ushimado Marine Institute, Faculty of Science, Okayama University, Setouchi, Japan
| | - Tatsuya Sakamoto
- Ushimado Marine Institute, Faculty of Science, Okayama University, Setouchi, Japan
| | - Susumu Hyodo
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
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Kovarik JJ, Morisawa N, Wild J, Marton A, Takase‐Minegishi K, Minegishi S, Daub S, Sands JM, Klein JD, Bailey JL, Kovalik J, Rauh M, Karbach S, Hilgers KF, Luft F, Nishiyama A, Nakano D, Kitada K, Titze J. Adaptive physiological water conservation explains hypertension and muscle catabolism in experimental chronic renal failure. Acta Physiol (Oxf) 2021; 232:e13629. [PMID: 33590667 PMCID: PMC8244025 DOI: 10.1111/apha.13629] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 02/11/2021] [Accepted: 02/11/2021] [Indexed: 12/22/2022]
Abstract
Aim We have reported earlier that a high salt intake triggered an aestivation‐like natriuretic‐ureotelic body water conservation response that lowered muscle mass and increased blood pressure. Here, we tested the hypothesis that a similar adaptive water conservation response occurs in experimental chronic renal failure. Methods In four subsequent experiments in Sprague Dawley rats, we used surgical 5/6 renal mass reduction (5/6 Nx) to induce chronic renal failure. We studied solute and water excretion in 24‐hour metabolic cage experiments, chronic blood pressure by radiotelemetry, chronic metabolic adjustment in liver and skeletal muscle by metabolomics and selected enzyme activity measurements, body Na+, K+ and water by dry ashing, and acute transepidermal water loss in conjunction with skin blood flow and intra‐arterial blood pressure. Results 5/6 Nx rats were polyuric, because their kidneys could not sufficiently concentrate the urine. Physiological adaptation to this renal water loss included mobilization of nitrogen and energy from muscle for organic osmolyte production, elevated norepinephrine and copeptin levels with reduced skin blood flow, which by means of compensation reduced their transepidermal water loss. This complex physiologic‐metabolic adjustment across multiple organs allowed the rats to stabilize their body water content despite persisting renal water loss, albeit at the expense of hypertension and catabolic mobilization of muscle protein. Conclusion Physiological adaptation to body water loss, termed aestivation, is an evolutionary conserved survival strategy and an under‐studied research area in medical physiology, which besides hypertension and muscle mass loss in chronic renal failure may explain many otherwise unexplainable phenomena in medicine.
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Affiliation(s)
- Johannes J. Kovarik
- Programme in Cardiovascular and Metabolic DisordersDuke‐NUS Medical School Singapore Singapore
- Clinical Division of Nephrology and Dialysis Department of Internal Medicine III Medical University of Vienna Vienna Austria
| | - Norihiko Morisawa
- Department of Pharmacology Faculty of Medicine Kagawa University Kagawa Japan
| | - Johannes Wild
- Division for Cardiology 1 Centre for Cardiology Johannes Gutenberg‐University Mainz Mainz Germany
| | - Adriana Marton
- Programme in Cardiovascular and Metabolic DisordersDuke‐NUS Medical School Singapore Singapore
| | - Kaoru Takase‐Minegishi
- Programme in Cardiovascular and Metabolic DisordersDuke‐NUS Medical School Singapore Singapore
- Department of Stem Cell and Immune Regulation Yokohama City University Graduate School of Medicine Yokohama Japan
| | - Shintaro Minegishi
- Programme in Cardiovascular and Metabolic DisordersDuke‐NUS Medical School Singapore Singapore
- Department of Medical Science and Cardiorenal Medicine Yokohama City University Graduate School of Medicine Yokohama Japan
| | - Steffen Daub
- Division for Cardiology 1 Centre for Cardiology Johannes Gutenberg‐University Mainz Mainz Germany
| | - Jeff M. Sands
- Renal Division Department of Medicine Emory University Atlanta GA USA
| | - Janet D. Klein
- Renal Division Department of Medicine Emory University Atlanta GA USA
| | - James L. Bailey
- Renal Division Department of Medicine Emory University Atlanta GA USA
| | - Jean‐Paul Kovalik
- Programme in Cardiovascular and Metabolic DisordersDuke‐NUS Medical School Singapore Singapore
| | - Manfred Rauh
- Division of Paediatrics Research Laboratory Erlangen Germany
| | - Susanne Karbach
- Division for Cardiology 1 Centre for Cardiology Johannes Gutenberg‐University Mainz Mainz Germany
| | - Karl F. Hilgers
- Division of Nephrology and Hypertension University Clinic Erlangen Erlangen Germany
| | - Friedrich Luft
- Experimental and Clinical Research Center Max Delbrück Center for Molecular Medicine Berlin Germany
| | - Akira Nishiyama
- Department of Pharmacology Faculty of Medicine Kagawa University Kagawa Japan
| | - Daisuke Nakano
- Department of Pharmacology Faculty of Medicine Kagawa University Kagawa Japan
| | - Kento Kitada
- Programme in Cardiovascular and Metabolic DisordersDuke‐NUS Medical School Singapore Singapore
- JSPS Overseas Research Fellow Japan Society for the Promotion of Science Tokyo Japan
| | - Jens Titze
- Programme in Cardiovascular and Metabolic DisordersDuke‐NUS Medical School Singapore Singapore
- Division of Nephrology and Hypertension University Clinic Erlangen Erlangen Germany
- Division of Nephrology Duke University School of Medicine Durham NC USA
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Marton A, Kaneko T, Kovalik JP, Yasui A, Nishiyama A, Kitada K, Titze J. Organ protection by SGLT2 inhibitors: role of metabolic energy and water conservation. Nat Rev Nephrol 2020; 17:65-77. [PMID: 33005037 DOI: 10.1038/s41581-020-00350-x] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2020] [Indexed: 12/17/2022]
Abstract
Therapeutic inhibition of the sodium-glucose co-transporter 2 (SGLT2) leads to substantial loss of energy (in the form of glucose) and additional solutes (in the form of Na+ and its accompanying anions) in urine. However, despite the continuously elevated solute excretion, long-term osmotic diuresis does not occur in humans with SGLT2 inhibition. Rather, patients on SGLT2 inhibitor therapy adjust to the reduction in energy availability and conserve water. The metabolic adaptations that are induced by SGLT2 inhibition are similar to those observed in aestivation - an evolutionarily conserved survival strategy that enables physiological adaptation to energy and water shortage. Aestivators exploit amino acids from muscle to produce glucose and fatty acid fuels. This endogenous energy supply chain is coupled with nitrogen transfer for organic osmolyte production, which allows parallel water conservation. Moreover, this process is often accompanied by a reduction in metabolic rate. By comparing aestivation metabolism with the fuel switches that occur during therapeutic SGLT2 inhibition, we suggest that SGLT2 inhibitors induce aestivation-like metabolic patterns, which may contribute to the improvements in cardiac and renal function observed with this class of therapeutics.
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Affiliation(s)
- Adriana Marton
- Programme in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Tatsuroh Kaneko
- Medicine Division, Nippon Boehringer Ingelheim Co., Ltd, Tokyo, Japan
| | - Jean-Paul Kovalik
- Programme in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Atsutaka Yasui
- Medicine Division, Nippon Boehringer Ingelheim Co., Ltd, Tokyo, Japan
| | - Akira Nishiyama
- Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Kento Kitada
- Programme in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, Singapore.,Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Jens Titze
- Programme in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, Singapore. .,Division of Nephrology and Hypertension, University Clinic Erlangen, Erlangen, Germany. .,Division of Nephrology, Duke University Medical Center, Durham, NC, USA.
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Aburatani N, Takagi W, Wong MKS, Kadota M, Kuraku S, Tokunaga K, Kofuji K, Saito K, Godo W, Sakamoto T, Hyodo S. Facilitated NaCl Uptake in the Highly Developed Bundle of the Nephron in Japanese Red Stingray Hemitrygon akajei Revealed by Comparative Anatomy and Molecular Mapping. Zoolog Sci 2020; 37:458-466. [PMID: 32972087 DOI: 10.2108/zs200038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/08/2020] [Indexed: 11/17/2022]
Abstract
Batoidea (rays and skates) is a monophyletic subgroup of elasmobranchs that diverged from the common ancestor with Selachii (sharks) about 270 Mya. A larger number of batoids can adapt to low-salinity environments, in contrast to sharks, which are mostly stenohaline marine species. Among osmoregulatory organs of elasmobranchs, the kidney is known to be dedicated to urea retention in ureosmotic cartilaginous fishes. However, we know little regarding urea reabsorbing mechanisms in the kidney of batoids. Here, we performed physiological and histological investigations on the nephrons in the red stingray (Hemitrygon akajei) and two shark species. We found that the urine/plasma ratios of salt and urea concentrations in the stingray are significantly lower than those in cloudy catshark (Scyliorhinus torazame) under natural seawater, indicating that the kidney of stingray more strongly reabsorbs these osmolytes. By comparing the three-dimensional images of nephrons between stingray and banded houndshark (Triakis scyllium), we showed that the tubular bundle of stingray has a more compact configuration. In the compact tubular bundle of stingray kidney, the distal diluting tubule was highly developed and frequently coiled around the proximal and collecting tubules. Furthermore, co-expression of NKAα1 (Na+/K +-ATPase) and NKCC2 (Na+- K+-2Cl- cotransporter 2) mRNAs was prominent in the coiled diluting segment. These findings imply that NaCl reabsorption is greatly facilitated in the stingray kidney, resulting in a higher reabsorption rate of urea. Lowering the loss of osmolytes in the glomerular filtrate is likely favorable to the adaptability of batoids to a wide range of environmental salinity.
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Affiliation(s)
- Naotaka Aburatani
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa 277-8564, Japan,
| | - Wataru Takagi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa 277-8564, Japan,
| | - Marty Kwok-Sing Wong
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa 277-8564, Japan
| | - Mitsutaka Kadota
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics, Kobe 650-0047, Japan
| | - Shigehiro Kuraku
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics, Kobe 650-0047, Japan
| | | | - Kazuya Kofuji
- Ibaraki Prefectural Oarai Aquarium, Oarai 311-1301, Japan
| | - Kazuhiro Saito
- Ushimado Marine Institute, Faculty of Science,Okayama University, Ushimado 701-4303, Japan
| | - Waichiro Godo
- Ushimado Marine Institute, Faculty of Science,Okayama University, Ushimado 701-4303, Japan
| | - Tatsuya Sakamoto
- Ushimado Marine Institute, Faculty of Science,Okayama University, Ushimado 701-4303, Japan
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa 277-8564, Japan
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Honda Y, Takagi W, Wong MKS, Ogawa N, Tokunaga K, Kofuji K, Hyodo S. Morphological and functional development of the spiral intestine in cloudy catshark ( Scyliorhinus torazame). J Exp Biol 2020; 223:jeb225557. [PMID: 32527960 DOI: 10.1242/jeb.225557] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/27/2020] [Indexed: 12/17/2022]
Abstract
Cartilaginous fish have a comparatively short intestine known as the spiral intestine that consists of a helical spiral of intestinal mucosa. However, morphological and functional development of the spiral intestine has not been fully described. Unlike teleosts, cartilaginous fish are characterized by an extremely long developmental period in ovo or in utero; for example, in the oviparous cloudy catshark (Scyliorhinus torazame), the developing fish remains inside the egg capsule for up to 6 months, suggesting that the embryonic intestine may become functional prior to hatching. In the present study, we describe the morphological and functional development of the spiral intestine in the developing catshark embryo. Spiral formation of embryonic intestine was completed at the middle of stage 31, prior to 'pre-hatching', which is a developmental event characterized by the opening of the egg case at the end of the first third of development. Within 48 h of the pre-hatching event, egg yolk began to flow from the external yolk sac into the embryonic intestine via the yolk stalk. At the same time, there was a rapid increase in mRNA expression of the peptide transporter pept1 and neutral amino acid transporter slc6a19 Secondary folds in the intestinal mucosa and microvilli on the apical membrane appeared after pre-hatching, further supporting the onset of nutrient absorption in the developing intestine at this time. We demonstrate the acquisition of intestinal nutrient absorption at the pre-hatching stage of an oviparous elasmobranch.
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Affiliation(s)
- Yuki Honda
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Wataru Takagi
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Marty K S Wong
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Nobuhiro Ogawa
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Kotaro Tokunaga
- Ibaraki Prefectural Oarai Aquarium, Oarai, Ibaraki 311-1301, Japan
| | - Kazuya Kofuji
- Ibaraki Prefectural Oarai Aquarium, Oarai, Ibaraki 311-1301, Japan
| | - Susumu Hyodo
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
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Abstract
The number of fish as pets far exceeds the populations of any other companion animal. As our knowledge of aquatic animal species and aquatic animal medicine continues to expand, veterinary expertise is becoming more critical to the client, researcher, fisheries biologist, aquarist, farmer, and fish hobbyist. Similar to other vertebrates, fish are susceptible to infectious and noninfectious renal disease. This article compares vertebrate renal anatomy and physiology and highlights some renal disease examples.
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Imaseki I, Wakabayashi M, Hara Y, Watanabe T, Takabe S, Kakumura K, Honda Y, Ueda K, Murakumo K, Matsumoto R, Matsumoto Y, Nakamura M, Takagi W, Kuraku S, Hyodo S. Comprehensive analysis of genes contributing to euryhalinity in the bull shark, Carcharhinus leucas; Na +-Cl - co-transporter is one of the key renal factors upregulated in acclimation to low-salinity environment. ACTA ACUST UNITED AC 2019; 222:jeb.201780. [PMID: 31138636 DOI: 10.1242/jeb.201780] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/18/2019] [Indexed: 11/20/2022]
Abstract
Most cartilaginous fishes live principally in seawater (SW) environments, but a limited number of species including the bull shark, Carcharhinus leucas, inhabit both SW and freshwater (FW) environments during their life cycle. Euryhaline elasmobranchs maintain high internal urea and ion levels even in FW environments, but little is known about the osmoregulatory mechanisms that enable them to maintain internal homeostasis in hypoosmotic environments. In the present study, we focused on the kidney because this is the only organ that can excrete excess water from the body in a hypoosmotic environment. We conducted a transfer experiment of bull sharks from SW to FW and performed differential gene expression analysis between the two conditions using RNA-sequencing. A search for genes upregulated in the FW-acclimated bull shark kidney indicated that the expression of the Na+-Cl- cotransporter (NCC; Slc12a3) was 10 times higher in the FW-acclimated sharks compared with that in SW sharks. In the kidney, apically located NCC was observed in the late distal tubule and in the anterior half of the collecting tubule, where basolateral Na+/K+-ATPase was also expressed, implying that these segments contribute to NaCl reabsorption from the filtrate for diluting the urine. This expression pattern was not observed in the houndshark, Triakis scyllium, which had been transferred to 30% SW; this species cannot survive in FW environments. The salinity transfer experiment combined with a comprehensive gene screening approach demonstrates that NCC is a key renal protein that contributes to the remarkable euryhaline ability of the bull shark.
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Affiliation(s)
- Itaru Imaseki
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Midori Wakabayashi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Yuichiro Hara
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Taro Watanabe
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Souichirou Takabe
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Keigo Kakumura
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Yuki Honda
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Keiichi Ueda
- Okinawa Churaumi Aquarium, Motobu, Okinawa 905-0206, Japan
| | | | - Rui Matsumoto
- Okinawa Churaumi Aquarium, Motobu, Okinawa 905-0206, Japan
| | | | - Masaru Nakamura
- Okinawa Churashima Foundation, Motobu, Okinawa 905-0206, Japan
| | - Wataru Takagi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Shigehiro Kuraku
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
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Takagi W, Kajimura M, Tanaka H, Hasegawa K, Ogawa S, Hyodo S. Distributional shift of urea production site from the extraembryonic yolk sac membrane to the embryonic liver during the development of cloudy catshark ( Scyliorhinus torazame ). Comp Biochem Physiol A Mol Integr Physiol 2017; 211:7-16. [DOI: 10.1016/j.cbpa.2017.05.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 05/30/2017] [Accepted: 05/30/2017] [Indexed: 10/19/2022]
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Multi-tissue RNA-seq and transcriptome characterisation of the spiny dogfish shark (Squalus acanthias) provides a molecular tool for biological research and reveals new genes involved in osmoregulation. PLoS One 2017; 12:e0182756. [PMID: 28832628 PMCID: PMC5568229 DOI: 10.1371/journal.pone.0182756] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/24/2017] [Indexed: 12/29/2022] Open
Abstract
The spiny dogfish shark (Squalus acanthias) is one of the most commonly used cartilaginous fishes in biological research, especially in the fields of nitrogen metabolism, ion transporters and osmoregulation. Nonetheless, transcriptomic data for this organism is scarce. In the present study, a multi-tissue RNA-seq experiment and de novo transcriptome assembly was performed in four different spiny dogfish tissues (brain, liver, kidney and ovary), providing an annotated sequence resource. The characterization of the transcriptome greatly increases the scarce sequence information for shark species. Reads were assembled with the Trinity de novo assembler both within each tissue and across all tissues combined resulting in 362,690 transcripts in the combined assembly which represent 289,515 Trinity genes. BUSCO analysis determined a level of 87% completeness for the combined transcriptome. In total, 123,110 proteins were predicted of which 78,679 and 83,164 had significant hits against the SwissProt and Uniref90 protein databases, respectively. Additionally, 61,215 proteins aligned to known protein domains, 7,208 carried a signal peptide and 15,971 possessed at least one transmembrane region. Based on the annotation, 81,582 transcripts were assigned to gene ontology terms and 42,078 belong to known clusters of orthologous groups (eggNOG). To demonstrate the value of our molecular resource, we show that the improved transcriptome data enhances the current possibilities of osmoregulation research in spiny dogfish by utilizing the novel gene and protein annotations to investigate a set of genes involved in urea synthesis and urea, ammonia and water transport, all of them crucial in osmoregulation. We describe the presence of different gene copies and isoforms of key enzymes involved in this process, including arginases and transporters of urea and ammonia, for which sequence information is currently absent in the databases for this model species. The transcriptome assemblies and the derived annotations generated in this study will support the ongoing research for this particular animal model and provides a new molecular tool to assist biological research in cartilaginous fishes.
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Hasegawa K, Kato A, Watanabe T, Takagi W, Romero MF, Bell JD, Toop T, Donald JA, Hyodo S. Sulfate transporters involved in sulfate secretion in the kidney are localized in the renal proximal tubule II of the elephant fish (Callorhinchus milii). Am J Physiol Regul Integr Comp Physiol 2016; 311:R66-78. [PMID: 27122370 PMCID: PMC4967232 DOI: 10.1152/ajpregu.00477.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 03/22/2016] [Indexed: 11/22/2022]
Abstract
Most vertebrates, including cartilaginous fishes, maintain their plasma SO4 (2-) concentration ([SO4 (2-)]) within a narrow range of 0.2-1 mM. As seawater has a [SO4 (2-)] about 40 times higher than that of the plasma, SO4 (2-) excretion is the major role of kidneys in marine teleost fishes. It has been suggested that cartilaginous fishes also excrete excess SO4 (2-) via the kidney. However, little is known about the underlying mechanisms for SO4 (2-) transport in cartilaginous fish, largely due to the extraordinarily elaborate four-loop configuration of the nephron, which consists of at least 10 morphologically distinguishable segments. In the present study, we determined cDNA sequences from the kidney of holocephalan elephant fish (Callorhinchus milii) that encoded solute carrier family 26 member 1 (Slc26a1) and member 6 (Slc26a6), which are SO4 (2-) transporters that are expressed in mammalian and teleost kidneys. Elephant fish Slc26a1 (cmSlc26a1) and cmSlc26a6 mRNAs were coexpressed in the proximal II (PII) segment of the nephron, which comprises the second loop in the sinus zone. Functional analyses using Xenopus oocytes and the results of immunohistochemistry revealed that cmSlc26a1 is a basolaterally located electroneutral SO4 (2-) transporter, while cmSlc26a6 is an apically located, electrogenic Cl(-)/SO4 (2-) exchanger. In addition, we found that both cmSlc26a1 and cmSlc26a6 were abundantly expressed in the kidney of embryos; SO4 (2-) was concentrated in a bladder-like structure of elephant fish embryos. Our results demonstrated that the PII segment of the nephron contributes to the secretion of excess SO4 (2-) by the kidney of elephant fish. Possible mechanisms for SO4 (2-) secretion in the PII segment are discussed.
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Affiliation(s)
- Kumi Hasegawa
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan;
| | - Akira Kato
- Center for Biological Resources and Informatics and Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, Japan; Departments of Physiology and Biomedical Engineering, Nephrology, and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Taro Watanabe
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
| | - Wataru Takagi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan; Evolutionary Morphology Laboratory, RIKEN Center for Life Science and Technologies, Kobe, Japan
| | - Michael F Romero
- Departments of Physiology and Biomedical Engineering, Nephrology, and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Justin D Bell
- School of Life and Environmental Sciences, Deakin University, Geelong, Australia; and Institute for Marine and Antarctic Studies, The University of Tasmania, Taroona, Australia
| | - Tes Toop
- School of Life and Environmental Sciences, Deakin University, Geelong, Australia; and
| | - John A Donald
- School of Life and Environmental Sciences, Deakin University, Geelong, Australia; and
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
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