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Das S, Kar I, Patra AK. Cadmium induced bioaccumulation, histopathology, gene regulation in fish and its amelioration - A review. J Trace Elem Med Biol 2023; 79:127202. [PMID: 37263063 DOI: 10.1016/j.jtemb.2023.127202] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 05/03/2023] [Accepted: 05/14/2023] [Indexed: 06/03/2023]
Abstract
Different anthropogenic activities as well as natural sources contribute enormously towards various heavy metal contaminations in aquatic habitats. Cadmium (Cd) is one of most prevalent and toxic heavy metals with a long half life. Unlike terrestrial animals, exposure of Cd in fishes may happen not only through feeds but also from its habitat water. Bioaccumulation of Cd in fishes occurs in many tissues, but mainly in gill, liver, kidney, skin, and muscle. The concentrations of Cd in fish tissues depend upon the extent and duration of Cd exposure, species and age of fishes, dietary minerals and antioxidant concentrations, and habitat water quality. Specific histopathological observations in liver, kidney, and gill are useful to understand the effects of Cd, which could help to determine the ameliorating methods to be adopted. Exposure of Cd exerts several adverse effects on general growth and development, reproductive processes, osmoregulation, morphological and histological structures, stress tolerance, and endocrine system, mainly due to changes in biological functions induced by differential expressions of several genes related to oxidative stress, apoptosis, inflammation, immunosuppressions, genotoxicity, Cd chelation and carbohydrate metabolism. Chronic biomagnifications of Cd exceeding the permitted level may be harmful not only to the fishes itself but also to humans through food chains. Amelioration of such toxic heavy metal that has been categorized as a potent carcinogenic in humans is of utmost importance. Main modes of amelioration encompas reducing oxidative damages by promoting the antioxidative defenses, decreasing Cd absorption, increasing excretion through excretory system and improving the tolerance of fishes to Cd toxicity. Many amelioration measures such as use of minerals (for example, zinc, calcium, and iron), vitamins (vitamin C, A, and E), different herbs, probiotics and other agents (taurine, bentonite, chitosan, zeolite, and metallothionein) have been explored for their effective roles to reduce Cd bioaccumulation and toxicity symptoms in fishes. The present review discusses bioaccumulation of Cd, histopathological alterations, oxidative stress, synergism-antagonism, and gene regulation in different tissues, and its amelioration measures in fishes.
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Affiliation(s)
- Srinibas Das
- Department of Fish Nutrition, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India
| | - Indrajit Kar
- Department of Avian Sciences, West Bengal University of Animal and Fishery Sciences, Mohanpur, Nadia, West Bengal, India.
| | - Amlan Kumar Patra
- Department of Animal Nutrition, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India.
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Drp1 and RB interaction to mediate mitochondria-dependent necroptosis induced by cadmium in hepatocytes. Cell Death Dis 2019; 10:523. [PMID: 31285421 PMCID: PMC6614419 DOI: 10.1038/s41419-019-1730-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 06/04/2019] [Accepted: 06/07/2019] [Indexed: 12/22/2022]
Abstract
Mitochondrial quality control (MQC) is implicated in cell death induced by heavy metal pollutants. Dynamin-related protein 1 (Drp1) regulates mitochondrial fission, which is an important part of MQC. Retinoblastoma (RB) protein can regulate MQC in a transcription-independent manner. Necroptosis plays a critical role in hepatic pathologies such as inflammatory, infectious, and xenobiotics-induced injury and diseases. We aimed to explore the role and mechanism of Drp1 interaction with RB in hepatocyte's necroptosis caused by cadmium (Cd). CdCl2 was employed to expose to Institute of Cancer Research (ICR) mice and human hepatic L02 cells. CdCl2 exposure induced necroptosis and hepatic injury both in vivo and in vitro. Moreover, Drp1 and RB protein were up-regulated and translocated to mitochondria in CdCl2-exposed hepatocytes. Inhibition of Drp1 with siRNA (siDNM1L) or inhibitors not only suppressed the RB expression and its mitochondrial translocation, but also alleviated MQC disorder, necroptosis, and hepatotoxicity caused by CdCl2. Moreover, blocking Drp1 with metformin rescued necroptosis and hepatic injury triggered by CdCl2. RB was proved to directly interact with Drp1 at mitochondria to form a complex which then bound to receptor interaction protein kinase (RIPK3) and enhanced the formation of necrosome after CdCl2 exposure. In summary, we found a new molecular mechanism of regulated cell death that Drp1 interacted with RB and promoted them mitochondrial translocation to mediate necroptosis and hepatic injury in hepatocytes induced by Cd-exposure. The mitochondrial Drp1-RB axis would be a novel target for the protection cells from xenobiotics triggering hepatic injury and diseases involved in necroptosis.
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Le Croizier G, Lacroix C, Artigaud S, Le Floch S, Raffray J, Penicaud V, Coquillé V, Autier J, Rouget ML, Le Bayon N, Laë R, Tito De Morais L. Significance of metallothioneins in differential cadmium accumulation kinetics between two marine fish species. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 236:462-476. [PMID: 29414371 DOI: 10.1016/j.envpol.2018.01.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 12/26/2017] [Accepted: 01/02/2018] [Indexed: 06/08/2023]
Abstract
Impacted marine environments lead to metal accumulation in edible marine fish, ultimately impairing human health. Nevertheless, metal accumulation is highly variable among marine fish species. In addition to ecological features, differences in bioaccumulation can be attributed to species-related physiological processes, which were investigated in two marine fish present in the Canary Current Large Marine Ecosystem (CCLME), where natural and anthropogenic metal exposure occurs. The European sea bass Dicentrarchus labrax and Senegalese sole Solea senegalensis were exposed for two months to two environmentally realistic dietary cadmium (Cd) doses before a depuration period. Organotropism (i.e., Cd repartition between organs) was studied in two storage compartments (the liver and muscle) and in an excretion vector (bile). To better understand the importance of physiological factors, the significance of hepatic metallothionein (MT) concentrations in accumulation and elimination kinetics in the two species was explored. Accumulation was faster in the sea bass muscle and liver, as inferred by earlier Cd increase and a higher accumulation rate. The elimination efficiency was also higher in the sea bass liver compared to sole, as highlighted by greater biliary excretion. In the liver, no induction of MT synthesis was attributed to metal exposure, challenging the relevance of using MT concentration as a biomarker of metal contamination. However, the basal MT pools were always greater in the liver of sea bass than in sole. This species-specific characteristic might have enhanced Cd biliary elimination and relocation to other organs such as muscle through the formation of more Cd/MT complexes. Thus, MT basal concentrations seem to play a key role in the variability observed in terms of metal concentrations in marine fish species.
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Affiliation(s)
- Gaël Le Croizier
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, BP 70, 29280 Plouzané, France.
| | - Camille Lacroix
- Centre of Documentation, Research and Experimentation on Accidental Water Pollution (CEDRE), 715 rue Alain Colas, CS 41836, Brest 29218-Cedex 2, France
| | - Sébastien Artigaud
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, BP 70, 29280 Plouzané, France
| | - Stéphane Le Floch
- Centre of Documentation, Research and Experimentation on Accidental Water Pollution (CEDRE), 715 rue Alain Colas, CS 41836, Brest 29218-Cedex 2, France
| | - Jean Raffray
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, BP 70, 29280 Plouzané, France
| | - Virginie Penicaud
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, BP 70, 29280 Plouzané, France
| | - Valérie Coquillé
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, BP 70, 29280 Plouzané, France
| | - Julien Autier
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, BP 70, 29280 Plouzané, France
| | - Marie-Laure Rouget
- Institut Universitaire Européen de la Mer (IUEM), Université de Bretagne Occidentale (UBO), CNRS UMS 3113, 29280 Plouzané, France
| | - Nicolas Le Bayon
- Ifremer, Unité de Physiologie Fonctionnelle des Organismes Marins, LEMAR UMR 6539, Ifremer, Centre de Brest, Laboratoire PFOM/ARN, BP 70, 29280 Plouzané, France
| | - Raymond Laë
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, BP 70, 29280 Plouzané, France
| | - Luis Tito De Morais
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, BP 70, 29280 Plouzané, France
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Liu GD, Sheng Z, Hou CC, Ni J, Han YL, Wang YF, Zhou Y, Fu SY, Zhu JQ. Molecular cloning, characterization and expression analysis of metallothionein in the liver of the teleost Acrossocheilus fasciatus exposed to cadmium chloride. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2017; 53:1-9. [PMID: 28482255 DOI: 10.1016/j.etap.2017.03.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/26/2017] [Accepted: 03/28/2017] [Indexed: 06/07/2023]
Abstract
Metallothionein (MT) has a characteristic molecular structure with a cysteine-rich content. This unique structure provides metal-binding and redox capabilities and promoting metal homeostasis and detoxification in living animals. In order to evaluate the effects of cadmium (Cd) on hepatic MT expression in the liver of Acrossocheilus fasciatus, we obtained the complete cDNA of the A. fasciatus liver MT for the first time. The MT cDNA contains a 605-bp sequence, which codes for 60 amino acids. Protein alignment showed that the similarity between MT protein sequences of A. fasciatus and those of other vertebrates (especially teleosts) was very high and a cysteine residue structure was also conserved. MT was detected in the liver, kidney, gill, testis, muscle, spleen, heart and brain tissues of A. fasciatus by tissue-specific expression analysis. After Cd exposure, Cd/hemoglobin saturation assay, immunohistochemistry and reverse-transcription quantitative PCR (RT-qPCR) were used to describe MT expression in liver tissue. These techniques indicate a sensitive response by liver MT to Cd exposure. The results suggest that A. fasciatus MT may play an important role in the detoxification processes in the liver, and also would be a useful biomarker for monitoring metal pollution in aquatic environments. In addition, A. fasciatus could be regarded as one candidate for a model species for bony fishes in ecotoxicology.
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Affiliation(s)
- Guo-Di Liu
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - Zhang Sheng
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - Cong-Cong Hou
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - Jie Ni
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - Ying-Li Han
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - You-Fa Wang
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - Yang Zhou
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - Su-Yan Fu
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - Jun-Quan Zhu
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, PR China.
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Physiological relevance and contribution to metal balance of specific and non-specific Metallothionein isoforms in the garden snail, Cantareus aspersus. Biometals 2011; 24:1079-92. [PMID: 21625890 DOI: 10.1007/s10534-011-9466-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 05/17/2011] [Indexed: 10/18/2022]
Abstract
Variable environmental availability of metal ions represents a constant challenge for most organisms, so that during evolution, they have optimised physiological and molecular mechanisms to cope with this particular requirement. Metallothioneins (MTs) are proteins that play a major role in metal homeostasis and as a reservoir. The MT gene/protein systems of terrestrial helicid snails are an invaluable model for the study of metal-binding features and MT isoform-specific functionality of these proteins. In the present study, we characterised three paralogous MT isogenes and their expressed products in the escargot (Cantareus aspersus). The metal-dependent transcriptional activation of the three isogenes was assessed using quantitative Real Time PCR. The metal-binding capacities of the three isoforms were studied by characterising the purified native complexes. All the data were analysed in relation to the trace element status of the animals after metal feeding. Two of the three C. aspersus MT (CaMT) isoforms appeared to be metal-specific, (CaCdMT and CaCuMT, for cadmium and copper respectively). A third isoform (CaCd/CuMT) was non-specific, since it was natively recovered as a mixed Cd/Cu complex. A specific role in Cd detoxification for CaCdMT was revealed, with a 80-90% contribution to the Cd balance in snails exposed to this metal. Conclusive data were also obtained for the CaCuMT isoform, which is involved in Cu homeostasis, sharing about 30-50% of the Cu balance of C. aspersus. No apparent metal-related physiological function was found for the third isoform (CaCd/CuMT), so its contribution to the metal balance of the escargot may be, if at all, of only marginal significance, but may enclose a major interest in evolutionary studies.
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Doulaty Baneh H, Mohammadi SA, Labra M, Nazemieh A, De Mattia F, Mardi M. Chloroplast microsatellites markers to assess genetic diversity in wild and cultivated grapevines of Iran. Pak J Biol Sci 2009; 10:1855-9. [PMID: 19086550 DOI: 10.3923/pjbs.2007.1855.1859] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
To assess the haplotype diversity and genetic relationship between them, A set of 69 Iranian cultivated accessions, six European cultivars and an accession of Vitis labrusca along with 63 wild grapevine individuals were studied using chloroplast microsatellite markers. Results showed that among analyzed cpssr loci only ccmp 3 and ccmp10 were polymorphic within cultivars and only ccmp3 was polymorphic in wild grape individuals. The size variants of both loci combine in a total of 4 different haplotypes. All the 4 haplotype are displayed in the cultivars while only 2 are presented in wild grapes. Sultani or keshmeshi Bidane cultivar has the haplotype III that there is not this haplotype among the wild grapes of studied regions. Concerning to existence of both haplotypes I and II in the number of Iranian cultivated and wild grapes, it is possible to consider that the wild grapes are ancestor of some of our native cultivars.
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Jebali J, Banni M, Gerbej H, Boussetta H, López-Barea J, Alhama J. Metallothionein induction by Cu, Cd and Hg in Dicentrarchus labrax liver: assessment by RP-HPLC with fluorescence detection and spectrophotometry. MARINE ENVIRONMENTAL RESEARCH 2008; 65:358-363. [PMID: 18304627 DOI: 10.1016/j.marenvres.2008.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 01/08/2008] [Accepted: 01/09/2008] [Indexed: 05/26/2023]
Abstract
Metallothionein was quantified in sea bass Dicentrarchus labrax intraperitoneally (i.p.) injected with different Cu, Cd and Hg doses (50-250 microg kg(-1) wet wt) after 48 h exposure. A distinct peak with 16.8 min retention time was obtained by reversed-phase high performance liquid chromatography coupled to fluorescence detection (RP-HPLC-FD) with the three metals. Total metallothionein levels assayed in unheated liver extracts by RP-HPLC-FD were significantly higher (1.3-1.95-fold) than those obtained by the well-established spectrophotometric method. In the RP-HPLC-FD method, metallothionein increased linearly with Cu and Hg doses, being saturated beyond 100 mug kg(-1) Cd. Maximum induction was obtained at 100 microg kg(-1) Cd (5.3-fold), and 250 microg kg(-1) Cu or Hg (8- and 5.1-fold, respectively). At low doses no metallothionein induction was shown by the less sensitive spectrophotometric assay.
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Affiliation(s)
- Jamel Jebali
- Laboratoire de Biochimie et de Toxicologie Environmentale, Institut Supérieur d'Agronomie de Chott-Mariem, 4042 Sousse, Tunisia
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Ren H, Xu M, He P, Muto N, Itoh N, Tanaka K, Xing J, Chu M. Cloning of crucian carp (Carassius cuvieri) metallothionein-II gene and characterization of its gene promoter region. Biochem Biophys Res Commun 2006; 342:1297-304. [PMID: 16516146 DOI: 10.1016/j.bbrc.2006.02.082] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Accepted: 02/15/2006] [Indexed: 10/25/2022]
Abstract
The genomic DNA of crucian carp (Carassius cuvieri) metallothionein-II (ccMT-II), with its upstream region, was obtained. The sequence analysis of its upstream region revealed several putative cis-acting elements including seven metal regulatory elements (MREs), three activator protein 1 (AP1), two glucocorticoid response elements (GREs), etc. The seven MREs locate into two clusters, a distal cluster with four MREs within -800/-600bp from the translation start site and a proximal cluster with three MREs close to TATA box. In transient luciferase gene expression assays, both of the distal and proximal cluster MREs have significantly shown synergistic effects in the transcription of ccMT-II gene; the proximal cluster of MREs serves as the major elements in metal inducing activity; Zn(2+) and Cd(2+) served as much stronger inducers than Cu(2+) shown in ccMT-II expression. The two GRE homologous sequences in ccMT-II promoter showed not to be inductive in either HepG2 or HEK293.
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Affiliation(s)
- Hongwei Ren
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Peking University, Beijing 100871, China.
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Cho YS, Choi BN, Ha EM, Kim KH, Kim SK, Kim DS, Nam YK. Shark (Scyliorhinus torazame) metallothionein: cDNA cloning, genomic sequence, and expression analysis. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2005; 7:350-62. [PMID: 15976934 DOI: 10.1007/s10126-004-0043-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2004] [Accepted: 10/07/2004] [Indexed: 05/03/2023]
Abstract
Novel metallothionein (MT) complementary DNA and genomic sequences were isolated from a cartilaginous shark species, Scyliorhinus torazame. The full-length open reading frame (ORF) of shark MT cDNA encoded 68 amino acids with a high cysteine content (29%). The genomic ORF sequence (932 bp) of shark MT isolated by polymerase chain reaction (PCR) comprised 3 exons with 2 interventing introns. Shark MT sequence shared many conserved features with other vertebrate MTs: overall amino acid identities of shark MT ranged from 47% to 57% with fish MTs, and 41% to 62% with mammalian MTs. However, in addition to these conserved characteristics, shark MT sequence exhibited some unique characteristics. It contained 4 extra amino acids (Lys-Ala-Gly-Arg) at the end of the beta-domain, which have not been reported in any other vertebrate MTs. The last amino acid residue at the C-terminus was Ser, which also has not been reported in fish and mammalian MTs. The MT messenger RNA levels in shark liver and kidney, assessed by semiquantitative reverse transcriptase PCR and RNA blot hybridization, were significantly affected by experimental exposures to heavy metals (cadmium, copper, and zinc). Generally, the transcriptional activation of shark MT gene was dependent on the dose (0-10 mg/kg body weight for injection and 0-20 microM for immersion) and duration (1-10 days); zinc was a more potent inducer than copper and cadmium.
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Affiliation(s)
- Young Sun Cho
- Department of Aquaculture, Pukyong National University, Busan, 608-737, South Korea
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Lin CH, John JAC, Ou LW, Chen JC, Lin CH, Chang CY. Cloning and characterization of metallothionein gene in ayu Plecoglossus altivelis. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2004; 66:111-124. [PMID: 15036867 DOI: 10.1016/j.aquatox.2003.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2003] [Revised: 06/06/2003] [Accepted: 06/30/2003] [Indexed: 05/24/2023]
Abstract
Metallothionein (MT) has been used widely as a potential molecular marker to detect the deleterious effects of heavy metals in aquatic ecosystem. Here we exposed ayu, Plecoglossus altivelis, to zinc (Zn) and tested the distribution as well as the induction of MT in various tissues such as liver, kidney, intestine and stomach. MT induction was significant in liver tissue, followed by kidney and intestine, whereas no induction was detected in stomach. The gene encoding ayu MT was successfully cloned and characterized. Complete nucleotide sequencing and analysis of the 4.5 kb DNA fragment containing the ayu MT gene revealed that the gene has three exons interrupted by two introns, a 5'-flanking region of about 2.5 kb and about 1.6 kb of 3'-flanking region. In grouper heart and kidney cells, the 2.5 kb promoter containing eight metal responsive elements (MREs), two hepatic nuclear factor 5 responsive elements (HNF5REs) and one cAMP responsive element (CRE) had the highest reporter activity.
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Affiliation(s)
- Chih-Hung Lin
- Molecular Genetics Laboratory, 336, Institute of Zoology (44), Academia Sinica, 128, Academia Road Section 2, NanKang, Taipei 11529, Taiwan, ROC
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Van Cleef-Toedt KA, Kaplan LA, Crivello JF. Killifish metallothionein messenger RNA expression following temperature perturbation and cadmium exposure. Cell Stress Chaperones 2001; 6:351-9. [PMID: 11795472 PMCID: PMC434418 DOI: 10.1379/1466-1268(2001)006<0351:kmmref>2.0.co;2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2001] [Revised: 05/17/2001] [Accepted: 05/30/2001] [Indexed: 11/24/2022] Open
Abstract
Metallothionein (MT), a cysteine-rich metal binding protein, is considered to play an essential role in the regulation of intracellular metals. Induction of MT in mammalian and nonmammalian tissues following heavy metal exposure may serve as a defense mechanism and a biomarker of environmental exposure to chemical stressors such as toxic metals. In this study, MT messenger RNA (mRNA) expression was characterized in male and female nonspawning and spawning killifish (Fundulus heteroclitus) following an 8-day exposure to specific sublethal stressors, which included temperature perturbation (26 degrees C or 10 degrees C) and/or 6 ppb of waterborne cadmium chloride (CdCl2). Hepatic, gill, and intestinal MT mRNA, expressed as copy number per microgram of total RNA, was assessed by reverse transcriptase-polymerase chain reaction and electrochemiluminescence using winter flounder (Pleuronectes americanus) MT complementary DNA primers. Liver, gill, and intestine MT mRNA expression was significantly (P < 0.05) increased in nonspawning killifish exposed to 26 degrees C compared with those exposed to 19 degrees C (control). In addition, a significant (P < 0.05) increase in gill MT mRNA induction was observed in nonspawning killifish exposed to 6 ppb of waterborne CdCl2 compared with controls. The results of this study demonstrate significant MT mRNA induction in nonspawning killifish following short-term exposure to physiological and chemical stressors. Thus, further research may be necessary before the use of killifish MT mRNA induction as a biomarker of environmental chemical stress exposure alone.
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Affiliation(s)
- K A Van Cleef-Toedt
- Department of Physiology and Neurobiology, University of Connecticut, Storrs 06269, USA
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