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Heimroth RD, Casadei E, Benedicenti O, Amemiya CT, Muñoz P, Salinas I. The lungfish cocoon is a living tissue with antimicrobial functions. SCIENCE ADVANCES 2021; 7:eabj0829. [PMID: 34788085 PMCID: PMC8597997 DOI: 10.1126/sciadv.abj0829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 09/29/2021] [Indexed: 06/13/2023]
Abstract
Terrestrialization is an extreme physiological adaptation by which African lungfish survive dry seasons. For months and up to several years, lungfish live inside a dry mucus cocoon that protects them from desiccation. Light and electron microscopy reveal that the lungfish cocoon is a living tissue that traps bacteria. Transcriptomic analyses identify a global state of inflammation in the terrestrialized lungfish skin characterized by granulocyte recruitment. Recruited granulocytes transmigrate into the cocoon where they release extracellular traps. In vivo DNase I surface spraying during terrestrialization results in dysbiosis, septicemia, skin wounds, and hemorrhages. Thus, lungfish have evolved unique immunological adaptations to protect their bodies from infection for extended periods of time while living on land. Trapping bacteria outside their bodies may benefit estivating vertebrates that undergo metabolic torpor.
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Affiliation(s)
- Ryan Darby Heimroth
- Center for Evolutionary and Theoretical Immunology, Biology Department, University of New Mexico, Albuquerque, NM, USA
| | - Elisa Casadei
- Center for Evolutionary and Theoretical Immunology, Biology Department, University of New Mexico, Albuquerque, NM, USA
| | - Ottavia Benedicenti
- Center for Evolutionary and Theoretical Immunology, Biology Department, University of New Mexico, Albuquerque, NM, USA
| | - Chris Tsuyoshi Amemiya
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, USA
| | - Pilar Muñoz
- Department of Animal Health, Campus de Espinardo, University of Murcia, 30100 Murcia, Spain
| | - Irene Salinas
- Center for Evolutionary and Theoretical Immunology, Biology Department, University of New Mexico, Albuquerque, NM, USA
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Abstract
During water-land transition, ancient fishes acquired the ability to breathe air, but air-breathing engendered problems in nitrogenous waste excretion. Nitrogen is a fundamental component of amino acids, proteins, and nucleic acids, and the degradation of these nitrogen-containing compounds releases ammonia. Ammonia is toxic and must be removed. Fishes in water excrete ammonia as the major nitrogenous waste through gills, but gills of air-breathing fishes are modified for air-breathing or largely replaced by air-breathing organs. Notably, fishes emerged from water can no longer excrete ammonia effectively because of a lack of water to flush the gills. Hence, ancient fishes that participated in water-land transition must have developed means to deal with ammonia toxicity. Extant air-breathing fishes, particularly amphibious ones, can serve as models to examine adaptations which might have facilitated the emergence of ancient fishes from water. Some of these fishes can actively emerge from water and display complex behaviors on land, while a few can burrow into mud and survive for years during drought. Many of them are equipped with mechanisms to ameliorate ammonia toxicity during emersion. In this review, the mechanisms adopted by air-breathing fishes to deal with ammonia toxicity during emersion were organized into seven disparate strategies. In addition, eight extant air-breathing fishes with distinctive terrestrial behaviors and peculiar natural habitats were selected to describe in detail how these seven strategies could be adopted in disparate combinations to ameliorate ammonia toxicity during emersion.
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Heimroth RD, Casadei E, Salinas I. Effects of Experimental Terrestrialization on the Skin Mucus Proteome of African Lungfish ( Protopterus dolloi). Front Immunol 2018; 9:1259. [PMID: 29915597 PMCID: PMC5994560 DOI: 10.3389/fimmu.2018.01259] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 05/18/2018] [Indexed: 11/13/2022] Open
Abstract
Animal mucosal barriers constantly interact with the external environment, and this interaction is markedly different in aquatic and terrestrial environments. Transitioning from water to land was a critical step in vertebrate evolution, but the immune adaptations that mucosal barriers such as the skin underwent during that process are essentially unknown. Vertebrate animals such as the African lungfish have a bimodal life, switching from freshwater to terrestrial habitats when environmental conditions are not favorable. African lungfish skin mucus secretions contribute to the terrestrialization process by forming a cocoon that surrounds and protects the lungfish body. The goal of this study was to characterize the skin mucus immunoproteome of African lungfish, Protopterus dolloi, before and during the induction phase of terrestrialization as well as the immunoproteome of the gill mucus during the terrestrialization induction phase. Using LC-MS/MS, we identified a total of 974 proteins using a lungfish Illumina RNA-seq database, 1,256 proteins from previously published lungfish sequence read archive and 880 proteins using a lungfish 454 RNA-seq database for annotation in the three samples analyzed (free-swimming skin mucus, terrestrialized skin mucus, and terrestrialized gill mucus). The terrestrialized skin mucus proteome was enriched in proteins with known antimicrobial functions such as histones and S100 proteins compared to free-swimming skin mucus. In support, gene ontology analyses showed that the terrestrialized skin mucus proteome has predicted functions in processes such as viral process, defense response to Gram-negative bacterium, and tumor necrosis factor-mediated signaling. Importantly, we observed a switch in immunoglobulin heavy chain secretion upon terrestrialization, with IgW1 long form (IgW1L) and IgM1 present in free-swimming skin mucus and IgW1L, IgM1, and IgM2 in terrestrialized skin mucus. Combined, these results indicate an increase in investment in the production of unique immune molecules in P. dolloi skin mucus in response to terrestrialization that likely better protects lungfish against external aggressors found in land.
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Affiliation(s)
| | | | - Irene Salinas
- Center for Evolutionary and Theoretical Immunology (CETI), Department of Biology, University of New Mexico, Albuquerque, NM, United States
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Chng YR, Ong JLY, Ching B, Chen XL, Hiong KC, Wong WP, Chew SF, Lam SH, Ip YK. Molecular characterization of three Rhesus glycoproteins from the gills of the African lungfish, Protopterus annectens, and effects of aestivation on their mRNA expression levels and protein abundance. PLoS One 2017; 12:e0185814. [PMID: 29073147 PMCID: PMC5657625 DOI: 10.1371/journal.pone.0185814] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 09/20/2017] [Indexed: 11/19/2022] Open
Abstract
African lungfishes are ammonotelic in water. They can aestivate for long periods on land during drought. During aestivation, the gills are covered with dried mucus and ammonia excretion ceases. In fishes, ammonia excretion through the gills involves Rhesus glycoproteins (RhGP/Rhgp). This study aimed to obtain the complete cDNA coding sequences of rhgp from the gills of Protopterus annectens, and to determine their branchial mRNA and protein expression levels during the induction, maintenance and arousal phases of aestivation. Three isoforms of rhgp (rhag, rhbg and rhcg) were obtained in the gills of P. annectens. Their complete cDNA coding sequences ranged between 1311 and 1398 bp, coding for 436 to 465 amino acids with estimated molecular masses between 46.8 and 50.9 kDa. Dendrogramic analyses indicated that Rhag was grouped closer to fishes, while Rhbg and Rhcg were grouped closer to tetrapods. During the induction phase, the protein abundance of Rhag, but not its transcript level, was down-regulated in the gills, suggesting that there could be a decrease in the release of ammonia from the erythrocytes to the plasma. Furthermore, the branchial transcript levels of rhbg and rhcg decreased significantly, in preparation for the subsequent shutdown of gill functions. During the maintenance phase, the branchial expression levels of rhag/Rhag, rhbg/Rhbg and rhcg/Rhcg decreased significantly, indicating that their transcription and translation were down-regulated. This could be part of an overall mechanism to shut down branchial functions and save metabolic energy used for transcription and translation. It could also be regarded as an adaptive response to stop ammonia excretion. During the arousal phase, it is essential for the lungfish to regain the ability to excrete ammonia. Indeed, the protein abundance of Rhag, Rhbg and Rhcg recovered to the corresponding control levels after 1 day or 3 days of recovery from 6 months of aestivation.
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Affiliation(s)
- You R. Chng
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Jasmine L. Y. Ong
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Biyun Ching
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Xiu L. Chen
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Kum C. Hiong
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore
| | - Siew H. Lam
- Department of Biological Sciences, National University of Singapore, Singapore
- NUS Environmental Research Institute, National University of Singapore, Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Singapore
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Ong JLY, Chng YR, Ching B, Chen XL, Hiong KC, Wong WP, Chew SF, Ip YK. Molecular characterization of myostatin from the skeletal muscle of the African lungfish, Protopterus annectens, and changes in its mRNA and protein expression levels during three phases of aestivation. J Comp Physiol B 2017; 187:575-589. [PMID: 28184997 DOI: 10.1007/s00360-017-1057-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Revised: 12/26/2016] [Accepted: 01/11/2017] [Indexed: 01/12/2023]
Affiliation(s)
- Jasmine L Y Ong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore, 117543, Singapore
| | - You R Chng
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore, 117543, Singapore
| | - Biyun Ching
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore, 117543, Singapore
| | - Xiu L Chen
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore, 117543, Singapore
| | - Kum C Hiong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore, 117543, Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore, 117543, Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore, 637616, Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore, 117543, Singapore.
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Chng YR, Ong JLY, Ching B, Chen XL, Hiong KC, Wong WP, Chew SF, Lam SH, Ip YK. Molecular Characterization of Aquaporin 1 and Aquaporin 3 from the Gills of the African Lungfish, Protopterus annectens, and Changes in Their Branchial mRNA Expression Levels and Protein Abundance during Three Phases of Aestivation. Front Physiol 2016; 7:532. [PMID: 27891097 PMCID: PMC5102888 DOI: 10.3389/fphys.2016.00532] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/25/2016] [Indexed: 01/07/2023] Open
Abstract
African lungfishes can undergo long periods of aestivation on land during drought. During aestivation, lungfishes are confronted with desiccation and dehydration, and their gills become non-functional and covered with a thick layer of dried mucus. Aquaporins (Aqps) are a superfamily of integral membrane proteins which generally facilitate the permeation of water through plasma membranes. This study aimed to obtain the complete cDNA coding sequences of aqp1 and aqp3 from the gills of Protopterus annectens, and to determine their branchial mRNA and protein expression levels during the induction, maintenance and arousal phases of aestivation. Dendrogramic analyses of the deduced Aqp1 and Aqp3 amino acid sequences of P. annectens revealed their close relationships with those of Latimeria chalumnae and tetrapods. During the induction phase, there were significant decreases in the transcript levels of aqp1 and aqp3 in the gills of P. annectens, but the branchial Aqp1 and Aqp3 protein abundance remained unchanged. As changes in transcription might precede changes in translation, this could be regarded as an adaptive response to decrease the protein abundance of Aqp1 and Aqp3 in the subsequent maintenance phase of aestivation. As expected, the branchial transcript levels and protein abundance of aqp1/Aqp1 and aqp3/Aqp3 were significantly down-regulated during the maintenance phase, probably attributable to the shutdown of branchial functions and the cessation of volume regulation of branchial epithelial cells. Additionally, these changes could reduce the loss of water through branchial epithelial surfaces, supplementing the anti-desiccating property of the dried mucus. Upon arousal, it was essential for the lungfish to restore branchial functions. Indeed, the protein abundance of Aqp1 recovered partially, with complete recovery of mRNA expression level and protein abundance of Aqp3, in the gills of P. annectens after 3 days of arousal. These results provide insights into how P. annectens regulates branchial Aqp expression to cope with desiccation and rehydration during different phases of aestivation.
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Affiliation(s)
- You R. Chng
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Jasmine L. Y. Ong
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Biyun Ching
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Xiu L. Chen
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Kum C. Hiong
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological UniversitySingapore, Singapore
| | - Siew H. Lam
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
- NUS Environmental Research Institute, National University of SingaporeSingapore, Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
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Ong JLY, Woo JM, Hiong KC, Ching B, Wong WP, Chew SF, Ip YK. Molecular characterization of betaine-homocysteine methyltransferase 1 from the liver, and effects of aestivation on its expressions and homocysteine concentrations in the liver, kidney and muscle, of the African lungfish, Protopterus annectens. Comp Biochem Physiol B Biochem Mol Biol 2015; 183:30-41. [PMID: 25575738 DOI: 10.1016/j.cbpb.2014.12.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 12/19/2014] [Accepted: 12/23/2014] [Indexed: 01/12/2023]
Abstract
Homocysteine accumulation has numerous deleterious effects, and betaine-homocysteine S-methyltransferase (BHMT) catalyses the synthesis of methionine from homocysteine and betaine. This study aimed to determine homocysteine concentrations, and mRNA expression levels and protein abundances of bhmt1/Bhmt1 in the liver, kidney and muscle of the African lungfish, Protopterus annectens, during the induction (6 days), maintenance (6 months) or arousal (3 days after arousal) phase of aestivation. The homocysteine concentration decreased significantly in the liver of P. annectens after 6 days or 6 months of aestivation, but it returned to the control level upon arousal. By contrast, homocysteine concentrations in the kidney and muscle remained unchanged during the three phases of aestivation. The complete coding cDNA sequence of bhmt1 from P. annectens consisted of 1236 bp, coding for 412 amino acids. The Bhmt1 from P. annectens had a close phylogenetic relationship with those from tetrapods and Callorhinchus milii. The expression of bhmt1 was detected in multiple organs/tissues of P. annectens, and this is the first report on the expression of bhmt1/Bhmt1 in animal skeletal muscle. The mRNA and protein expression levels of bhmt1/Bhmt1 were up-regulated in the liver of P. annectens during the induction and maintenance phases of aestivation, possibly to regulate the hepatic homocysteine concentration. The significant increase in hepatic Bhmt1 protein abundance during the arousal phase could be a response to increased cellular methylation for the purpose of tissue reconstruction. Unlike the liver, Bhmt1 expression in the kidney and muscle of P. annectens was regulated translationally, and its up-regulation could be crucial to prevent homocysteine accumulation.
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Affiliation(s)
- Jasmine L Y Ong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Jia M Woo
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Kum C Hiong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Biyun Ching
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore; The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore 119227, Republic of Singapore.
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Garofalo F, Amelio D, Icardo J, Chew S, Tota B, Cerra M, Ip Y. Signal molecule changes in the gills and lungs of the African lungfish Protopterus annectens, during the maintenance and arousal phases of aestivation. Nitric Oxide 2015; 44:71-80. [DOI: 10.1016/j.niox.2014.11.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 11/17/2014] [Accepted: 11/26/2014] [Indexed: 01/20/2023]
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Hiong KC, Tan XR, Boo MV, Wong WP, Chew SF, Ip YK. Aestivation induces changes in transcription and translation of coagulation factor II and fibrinogen gamma chain in the liver of the African lungfish, Protopterus annectens. J Exp Biol 2015; 218:3717-28. [DOI: 10.1242/jeb.125260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 09/17/2015] [Indexed: 11/20/2022]
Abstract
This study aimed to sequence and characterize two pro-coagulant genes, coagulation factor II (f2) and fibrinogen gamma chain (fgg), from the liver of the African lungfish Protopterus annectens, and to determine their hepatic mRNA expression levels during three phases of aestivation. The protein abundances of F2 and Fgg in the liver and plasma were determined by immunoblotting. Results indicated that F2 and Fgg of P. annectens were phylogenetically closer to those of amphibians than those of teleosts. Three days of aestivation resulted in an up-regulation in the hepatic fgg mRNA expression level, while 6 days of aestivation led to a significant increase (3-fold) in the protein abundance of Fgg in the plasma. Hence, there could be an increase in the blood clotting ability in P. annectens during the induction phase of aestivation. By contrast, the blood clotting ability in P. annectens might be reduced in response to decreased blood flow and increased possibility of thrombosis during the maintenance phase of aestivation, as 6 months of aestivation led to significant decreases in mRNA expression levels of f2 and fgg in the liver. There could also be a decrease in the export of F2 and Fgg from the liver to the plasma so as to avert thrombosis. Upon 3-6 days of arousal from 6 months of aestivation, the protein abundances of F2 and Fgg recovered partially in the plasma of P. annectens, and a complete recovery of the transcription and translation of f2/F2 in the liver might occur only after refeeding.
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Affiliation(s)
- Kum C. Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Xiang R. Tan
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Mel V. Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
- The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore 119227, Republic of Singapore
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Uchiyama M, Konno N, Shibuya S, Nogami S. Cloning and expression of the epithelial sodium channel and its role in osmoregulation of aquatic and estivating African lungfish Protopterus annectens. Comp Biochem Physiol A Mol Integr Physiol 2014; 183:1-8. [PMID: 25541184 DOI: 10.1016/j.cbpa.2014.12.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 12/12/2014] [Accepted: 12/12/2014] [Indexed: 11/18/2022]
Abstract
The epithelial sodium channel (ENaC) is a sodium (Na(+))-selective aldosterone-stimulated ion channel involved in Na(+) transport homeostasis of tetrapods. We examined full-length cDNA sequences and tissue distributions of ENaCα, ENaCβ, and ENaCγ subunits in the African lungfish Protopterus annectens. Protopterus ENaC (pENaC) comprises 3 subunits: pENaCα, pENaCβ, and pENaCγ. pENaCα, pENaCβ, and pENaCγ subunits are closely related to α, β, and γ subunits of the Australian lungfish Neoceratodus forsteri ENaC (nENaC), respectively. Three ENaC subunit mRNAs were highly expressed in the gills and moderately expressed in the kidney and rectum of P. annectens. During estivation for 2-4weeks and 2-3months, plasma Na(+) concentration was relatively stable, but plasma urea concentration significantly increased in comparison with the control fish kept in a freshwater environment. Plasma aldosterone concentration and mRNA expression of the ENaCα subunit gradually and significantly decreased in the gills and kidney after 2months of estivation. Thus, aldosterone-dependent Na(+) absorption via ENaC probably exists in the epithelial cells of osmoregulatory organs of lungfish kept in fresh water, whereas plasma Na(+) concentration may be maintained by a mechanism independent of aldosterone-ENaC axis during estivation in lungfish.
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Affiliation(s)
- Minoru Uchiyama
- Department of Life and Environmental Science, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan.
| | - Norifumi Konno
- Department of Life and Environmental Science, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Sachika Shibuya
- Department of Life and Environmental Science, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Satoshi Nogami
- Department of Life and Environmental Science, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
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Molecular characterization of argininosuccinate synthase and argininosuccinate lyase from the liver of the African lungfish Protopterus annectens, and their mRNA expression levels in the liver, kidney, brain and skeletal muscle during aestivation. J Comp Physiol B 2014; 184:835-53. [PMID: 25034132 DOI: 10.1007/s00360-014-0842-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 06/11/2014] [Accepted: 06/20/2014] [Indexed: 02/05/2023]
Abstract
Argininosuccinate synthase (Ass) and argininosuccinate lyase (Asl) are involved in arginine synthesis for various purposes. The complete cDNA coding sequences of ass and asl from the liver of Protopterus annectens consisted of 1,296 and 1,398 bp, respectively. Phylogenetic analyses revealed that the deduced Ass and Asl of P. annectens had close relationship with that of the cartilaginous fish Callorhinchus milii. Besides being strongly expressed in the liver, ass and asl expression were detectable in many tissues/organs. In the liver, mRNA expression levels of ass and asl increased significantly during the induction phase of aestivation, probably to increase arginine production to support increased urea synthesis. The increases in ass and asl mRNA expression levels during the prolonged maintenance phase and early arousal phase of aestivation could reflect increased demand on arginine for nitric oxide (NO) production in the liver. In the kidney, there was a significant decrease in ass mRNA expression level after 6 months of aestivation, indicating possible decreases in the synthesis and supply of arginine to other tissues/organs. In the brain, changes in ass and asl mRNA expression levels during the three phases of aestivation could be related to the supply of arginine for NO synthesis in response to conditions that resemble ischaemia and ischaemia-reperfusion during the maintenance and arousal phase of aestivation, respectively. The decrease in ass mRNA expression level, accompanied with decreases in the concentrations of arginine and NO, in the skeletal muscle of aestivating P. annectens might ameliorate the potential of disuse muscle atrophy.
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Lympho-granulocytic tissue associated with the wall of the spiral valve in the African lungfish Protopterus annectens. Cell Tissue Res 2013; 355:397-407. [PMID: 24253466 DOI: 10.1007/s00441-013-1746-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
We describe the structure of the lympho-granulocytic tissue associated with the wall of the spiral valve of the African lungfish Protopterus annectens. The study was performed under freshwater conditions and after 6 months of aestivation. The lympho-granulocytic tissue consists of nodes surrounded by reticular tissue. The nodes are formed by an outer and an inner component separated by a thin collagenous layer. The outer component is a reticular-like tissue that contains two types of granulocytes, developing and mature plasma cells and melanomacrophage centres (MMCs). The inner component, the parenchyma, contains a meshwork of trabeculae and vascular sinusoids and shows dark and pale areas. The dark areas contain diffuse lymphoid tissue, with a large number of mitoses and plasma cell clusters. The pale areas contain a small number of macrophages and lymphocytes. Macrophages and sinus endothelial cells are filled with haemosiderin granules and appear to form part of the reticuloendothelial system of the lungfish. The reticular tissue houses granulocytes, plasma cells and MMCs and might serve for the housing and maturation of cells of the white series. After aestivation, the nodes undergo lymphocyte depletion, the suppression of mitosis, granulocyte invasion and the occurrence of cell death. By contrast, few histological changes occur in the reticular tissue. Whereas the nodes appear to be involved in lymphocyte proliferation and plasma cell maturation, the function of the reticular tissue remains obscure.
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Hiong KC, Ip YK, Wong WP, Chew SF. Differential gene expression in the brain of the African lungfish, Protopterus annectens, after six days or six months of aestivation in air. PLoS One 2013; 8:e71205. [PMID: 23976998 PMCID: PMC3745453 DOI: 10.1371/journal.pone.0071205] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Accepted: 07/03/2013] [Indexed: 11/18/2022] Open
Abstract
The African lungfish, Protopterus annectens, can undergo aestivation during drought. Aestivation has three phases: induction, maintenance and arousal. The objective of this study was to examine the differential gene expression in the brain of P. annectens during the induction (6 days) and maintenance (6 months) phases of aestivation as compared with the freshwater control using suppression subtractive hybridization. During the induction phase of aestivation, the mRNA expression of prolactin (prl) and growth hormone were up-regulated in the brain of P. annectens, which indicate for the first time the possible induction role of these two hormones in aestivation. Also, the up-regulation of mRNA expression of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein γ polypeptide and the down-regulation of phosphatidylethanolamine binding protein, suggest that there could be a reduction in biological and neuronal activities in the brain. The mRNA expression of cold inducible RNA-binding protein and glucose regulated protein 58 were also up-regulated in the brain, probably to enhance their cytoprotective effects. Furthermore, the down-regulation of prothymosin α expression suggests that there could be a suppression of transcription and cell proliferation in preparation for the maintenance phase. In general, the induction phase appeared to be characterized by reduction in glycolytic capacity and metabolic activity, suppression of protein synthesis and degradation, and an increase in defense against ammonia toxicity. In contrast, there was a down-regulation in the mRNA expression of prl in the brain of P. annectens during the maintenance phase of aestivation. In addition, there could be an increase in oxidative defense capacity, and up-regulation of transcription, translation, and glycolytic capacities in preparation for arousal. Overall, our results signify the importance of reconstruction of protein structures and regulation of energy expenditure during the induction phase, and the needs to suppress protein degradation and conserve metabolic fuel stores during the maintenance phase of aestivation.
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Affiliation(s)
- Kum C. Hiong
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore
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The spleen of the African lungfish Protopterus annectens: freshwater and aestivation. Cell Tissue Res 2012; 350:143-56. [DOI: 10.1007/s00441-012-1462-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 05/31/2012] [Indexed: 10/28/2022]
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15
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Loong AM, Chng YR, Chew SF, Wong WP, Ip YK. Molecular characterization and mRNA expression of carbamoyl phosphate synthetase III in the liver of the African lungfish, Protopterus annectens, during aestivation or exposure to ammonia. J Comp Physiol B 2011; 182:367-79. [PMID: 22038021 DOI: 10.1007/s00360-011-0626-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 09/27/2011] [Accepted: 10/04/2011] [Indexed: 01/01/2023]
Abstract
This study aimed to obtain the full sequence of carbamoyl phosphate synthetase III (cps III) from, and to determine the mRNA expression of cps III in, the liver of P. annectens during aestivation in air, hypoxia or mud, or exposure to environmental ammonia (100 mmol l(-1) NH(4)Cl). The complete coding cDNA sequence of cps III from the liver of P. annectens consisted of 4530 bp, which coded for 1,510 amino acids with an estimated molecular mass of 166.1 kDa. The Cps III of P. annectens consisted of a mitochondrial targeting sequence of 44 amino acid residues, a GAT domain spanning from tyrosine 45 to isoleucine 414, and a methylglyoxal synthase-like domain spanning from valine 433 to arginine 1513. Two cysteine residues (cysteine 1337 and cysteine 1347) that are characteristic of N-acetylglutamate dependency were also present. The critical Cys-His-Glu catalytic triad (cysteine 301, histidine 385 and glutamate 387) together with methionine 302 and glutamine 305 affirmed that P. annectens expressed Cps III and not Cps I. A comparison of the translated amino acid sequence of Cps III from P. annectens with CPS sequences from other animals revealed that it shared the highest similarity with elasmobranch Cps III. A phylogenetic analysis indicates that P. annectens CPS III could have evolved from Cps III of elasmobranchs. Indeed, Cps III from P. annectens used mainly glutamine as the substrate, and its activity decreased significantly when glutamine and ammonia were included together in the assay system. There were significant increases (9- to 12-fold) in the mRNA expression of cps III in the liver of fish during the induction phase (days 3 and 6) of aestivation in air. Aestivation in hypoxia or in mud had a delayed effect on the increase in the mRNA expression of cps III, which extended beyond the induction phase of aestivation, reiterating the importance of differentiating effects that are intrinsic to aestivation from those intrinsic to hypoxia. Furthermore, results from this study confirmed that environmental ammonia exposure led to a significant increase in the mRNA expression of cps III in the liver of P. annectens, alluding to the important functional role of urea not only as a product of ammonia detoxification but also as a putative internal cue for aestivation.
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Affiliation(s)
- A M Loong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, 117543, Republic of Singapore
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