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Kohl J, Schweikert M, Klaas N, Lemloh ML. Intracellular bioaccumulation of the rare earth element Gadolinium in ciliate cells resulting in biogenic particle formation and excretion. Sci Rep 2023; 13:5650. [PMID: 37024513 PMCID: PMC10079679 DOI: 10.1038/s41598-023-32596-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 03/29/2023] [Indexed: 04/08/2023] Open
Abstract
Ciliates are abundant unicellular organisms capable of resisting high concentrations of metal ions in the environment caused by various anthropogenic activities. Understanding the cellular pathways involved in resistance to and detoxification of elements is required to predict the impact of ciliates on environmental element cycles. Here, we investigated the so far unknown process of tolerance, cellular uptake and bioaccumulation of the emerging rare earth element gadolinium (Gd) in the common ciliate Tetrahymena pyriformis. Gd treatment results in the intracellular formation and excretion of biogenic Gd-containing particles. This cellular process effectively removes dissolved Gd from the organic growth medium by 53.37% within 72 h. Based on light and electron microscopic observations, we postulate a detoxification pathway: Cells take up toxic Gd3+ ions from the medium by endocytosis, process them into stable Gd-containing particles within food vacuoles, and exocytose them. Stable biogenic particles can be isolated, which are relatively homogeneous and have a diameter of about 3 µm. They consist of the elements Gd, C, O, P, Na, Mg, K, and Ca. These findings broaden the view of metal ion accumulation by protists and are of relevance to understand environmental elemental cycles and may inspire approaches for metal recovery or bioremediation.
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Affiliation(s)
- Jana Kohl
- Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, 70569, Stuttgart, Germany
| | - Michael Schweikert
- Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, 70569, Stuttgart, Germany
- SRF AMICA, University of Stuttgart, 70569, Stuttgart, Germany
| | - Norbert Klaas
- IWS, Research Facility for Subsurface Remediation (VEGAS), University of Stuttgart, 70569, Stuttgart, Germany
| | - Marie-Louise Lemloh
- SRF AMICA, University of Stuttgart, 70569, Stuttgart, Germany.
- Materials Testing Institute, University of Stuttgart, 70569, Stuttgart, Germany.
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2
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Narayanan M, Ma Y. Metal tolerance mechanisms in plants and microbe-mediated bioremediation. ENVIRONMENTAL RESEARCH 2023; 222:115413. [PMID: 36736758 DOI: 10.1016/j.envres.2023.115413] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/29/2023] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
The heavy metal contamination, which causes toxic effects on plants, has evolved into a significant constraint to plant quality and yield. This scenario has been exacerbated by booming population expansion and intrinsic food insecurity. Numerous studies have found that counteracting heavy metal tolerance and accumulation necessitates complex mechanisms at the biochemical, molecular, tissue, cellular and whole plant levels, which may demonstrate increased crop yields. Essential and non-essential elements have similar harmful impacts on plants including reduced biomass production, growth and photosynthesis inhibition, chlorosis, altered fluid balance and nutrient absorption, as well as senescence, all of which led to plant death. Notable biotechnological strategies for effective remediation require knowledge of metal stress and tolerance mechanisms in plants. Assimilation, cooperation and integration, of biotechnological improvements, are required for adequate environmental rehabilitation in the emerging area of bioremediation. This review emphasizes a deeper understanding of metal toxicity, stress, and potential tolerance mechanisms in plants exposed to metal stress. The microbe-mediated metal toxic effects and stress mitigation knowledge can be used to create a new strategic plan as feasible, sustainable, and environmentally friendly bioremediation techniques.
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Affiliation(s)
- Mathiyazhagan Narayanan
- Division of Research and Innovation, Department of Biotechnology, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Science, Chennai, Tamil Nadu, India
| | - Ying Ma
- College of Resources and Environment, Southwest University, Chongqing, 400716, China.
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3
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Balzano S, Sardo A. Bioinformatic prediction of putative metallothioneins in non-ciliate protists. Biol Lett 2022; 18:20220039. [PMID: 35414221 PMCID: PMC9006003 DOI: 10.1098/rsbl.2022.0039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Intracellular ligands that bind heavy metals (HMs) and thereby minimize their detrimental effects to cellular metabolism are attracting great interest for a number of applications including bioremediation and development of HM-biosensors. Metallothioneins (MTs) are short, cysteine-rich, genetically encoded proteins involved in intracellular metal-binding and play a key role in detoxification of HMs. We searched approximately 700 genomes and transcriptomes of non-ciliate protists for novel putative MTs by similarity and structural analyses and found 21 unique proteins playing a potential role as MTs. Most putative MTs derive from heterokonts and dinoflagellates and share common features such as (i) a putative metal-binding domain in proximity of the N-terminus, (ii) two putative MT-specific domains near the C-terminus and (iii) one to three CTCGXXCXCGXXCXCXXC patterns. Although the biological function of these proteins has not been experimentally proven, knowledge of their genetic sequences adds useful information on proteins that are potentially involved in HM-binding and can contribute to the design of future biomolecular assays on HM-microbe interactions and MT-based biosensors.
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Affiliation(s)
- Sergio Balzano
- Stazione Zoologica Anton Dohrn Napoli (SZN), Department of Ecosustainable Marine Biotechnology, via Ammiraglio Ferdinando Acton 55, 80133, Naples, Italy.,NIOZ Royal Netherlands Institute for Sea Research, 1790AB Den Burg, The Netherlands
| | - Angela Sardo
- Stazione Zoologica Anton Dohrn Napoli (SZN), Department of Ecosustainable Marine Biotechnology, via Ammiraglio Ferdinando Acton 55, 80133, Naples, Italy.,Istituto di Scienze Applicate e Sistemi Intelligenti - CNR, via Campi Flegrei 34, 80078 Pozzuoli, Naples, Italy
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4
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Ranjbar S, Malcata FX. Is Genetic Engineering a Route to Enhance Microalgae-Mediated Bioremediation of Heavy Metal-Containing Effluents? Molecules 2022; 27:1473. [PMID: 35268582 PMCID: PMC8911655 DOI: 10.3390/molecules27051473] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 12/19/2022] Open
Abstract
Contamination of the biosphere by heavy metals has been rising, due to accelerated anthropogenic activities, and is nowadays, a matter of serious global concern. Removal of such inorganic pollutants from aquatic environments via biological processes has earned great popularity, for its cost-effectiveness and high efficiency, compared to conventional physicochemical methods. Among candidate organisms, microalgae offer several competitive advantages; phycoremediation has even been claimed as the next generation of wastewater treatment technologies. Furthermore, integration of microalgae-mediated wastewater treatment and bioenergy production adds favorably to the economic feasibility of the former process-with energy security coming along with environmental sustainability. However, poor biomass productivity under abiotic stress conditions has hindered the large-scale deployment of microalgae. Recent advances encompassing molecular tools for genome editing, together with the advent of multiomics technologies and computational approaches, have permitted the design of tailor-made microalgal cell factories, which encompass multiple beneficial traits, while circumventing those associated with the bioaccumulation of unfavorable chemicals. Previous studies unfolded several routes through which genetic engineering-mediated improvements appear feasible (encompassing sequestration/uptake capacity and specificity for heavy metals); they can be categorized as metal transportation, chelation, or biotransformation, with regulation of metal- and oxidative stress response, as well as cell surface engineering playing a crucial role therein. This review covers the state-of-the-art metal stress mitigation mechanisms prevalent in microalgae, and discusses putative and tested metabolic engineering approaches, aimed at further improvement of those biological processes. Finally, current research gaps and future prospects arising from use of transgenic microalgae for heavy metal phycoremediation are reviewed.
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Affiliation(s)
- Saeed Ranjbar
- LEPABE—Laboratory for Process Engineering, Environment, Biotechnology and Energy, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal;
- Department of Chemical Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal
| | - Francisco Xavier Malcata
- LEPABE—Laboratory for Process Engineering, Environment, Biotechnology and Energy, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal;
- Department of Chemical Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal
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5
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Bio- and phytoremediation: plants and microbes to the rescue of heavy metal polluted soils. SN APPLIED SCIENCES 2022. [DOI: 10.1007/s42452-021-04911-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
AbstractBio- and phytoremediation, being encouraging terms implying the use of biological systems for cleansing purposes, have risen a worthy venture toward environmental restoration in discouraging scenarios, such as the augmentation of indestructible heavy metals. Hyperaccumulating plants and heavy metal resistant microbes own mechanisms embedded in their metabolism, proteins, and genes that confer them with “super characteristics” allowing them to assimilate heavy metals in order to amend polluted soils, and when combined in a symbiotic system, these super features could complement each other and be enhanced to overpower the exposure to toxic environments. Though xenobiotic pollution has been an object of concern for decades and physicochemical procedures are commonly carried out to offset this purpose, a “live” remediation is rather chosen and looked upon for promising results. A variety of benefits have been registered from symbiotic relationships, including plants teaming up with microbes to cope down with non-biodegradable elements such as heavy metals; but a carefully maneuvered interaction might signify a greater insight toward the application of bioremediation systems. These manipulations could consist of genetic engineering and/or additional supplementation of molecules and microbes. In the present study, a contemporary connection between plants and microbes involving their controlled management is summarized in a visionary display.
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6
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Kannappan S, Ramisetty BCM. Engineered Whole-Cell-Based Biosensors: Sensing Environmental Heavy Metal Pollutants in Water-a Review. Appl Biochem Biotechnol 2021; 194:1814-1840. [PMID: 34783990 DOI: 10.1007/s12010-021-03734-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 10/21/2021] [Indexed: 11/27/2022]
Abstract
The frequent exposure and accumulation of heavy metals in organisms cause serious health issues affecting a range of organs such as the brain, liver, and reproductive organs in adults, infants, and children. Several parts of the world have high levels of heavy metals affecting millions of people, costing millions of dollars for improving the potability of water and medical treatment of the affected. Hence, water quality assessment is required to monitor the degree of heavy metal contamination in potable water. In nature, organisms respond to various environmental pollutants such as heavy metals, allowing their survival in a diverse environmental niche. With the advent of recombinant DNA technology, it is now possible to manipulate these natural bioreporters into controlled systems which either turn on or off gene expression or activity of enzymes in the presence of specific heavy metals (compound-specific biosensors) otherwise termed as whole-cell biosensors (WCBs). WCBs provide an upper hand compared to other immunosensors, enzyme-based sensors, and DNA-based sensors since microbes can be relatively easily manipulated, scaled up with relative ease, and can detect only the bioavailable heavy metals. In this review, we summarize the current knowledge of the various mechanisms of toxicity elicited by various heavy metals, thence emphasizing the need to develop heavy metal sensing platforms. Following this, the biosensor-based platforms including WCBs for detecting heavy metals developed thus far have been briefly elaborated upon, emphasizing the challenges and solutions associated with WCBs.
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Affiliation(s)
- Shrute Kannappan
- Department of Precision Medicine, School of Medicine, Sungkyunkwan University (SKKU), Suwon, 16419, South Korea
- Research Center for Advanced Materials Technology, Sungkyunkwan University (SKKU), Suwon, 16419, South Korea
- School of Chemical and Biotechnology, SASTRA Deemed University, Thanjavur, India
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7
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Lv H, Xu J, Bo T, Wang W. Comparative transcriptome analysis uncovers roles of hydrogen sulfide for alleviating cadmium toxicity in Tetrahymena thermophila. BMC Genomics 2021; 22:21. [PMID: 33407108 PMCID: PMC7788932 DOI: 10.1186/s12864-020-07337-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 12/22/2020] [Indexed: 11/10/2022] Open
Abstract
Background Cadmium (Cd) is a nonessential heavy metal with potentially deleterious effects on different organisms. The organisms have evolved sophisticated defense system to alleviate heavy metal toxicity. Hydrogen sulfide (H2S) effectively alleviates heavy metal toxicity in plants and reduces oxidative stress in mammals. However, the function of H2S for alleviating heavy metal toxicity in aquatic organisms remains less clear. Tetrahymena thermophila is an important model organism to evaluate toxic contaminants in an aquatic environment. In this study, the molecular roles of exogenously H2S application were explored by RNA sequencing under Cd stress in T. thermophila. Results The exposure of 30 μM Cd resulted in T. thermophila growth inhibition, cell nigrescence, and malondialdehyde (MDA) content considerably increase. However, exogenous NaHS (donor of H2S, 70 μM) significantly alleviated the Cd-induced toxicity by inhibiting Cd absorbtion, promoting CdS nanoparticles formation and improving antioxidant system. Comparative transcriptome analysis showed that the expression levels of 9152 genes changed under Cd stress (4658 upregulated and 4494 downregulated). However, only 1359 genes were differentially expressed with NaHS treatment under Cd stress (1087 upregulated and 272 downregulated). The functional categories of the differentially expressed genes (DEGs) by gene ontology (GO) revealed that the transcripts involved in the oxidation–reduction process, oxidoreductase activity, glutathione peroxidase activity, and cell redox homeostasis were the considerable enrichments between Cd stress and NaHS treatment under Cd stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) indicated that the carbon metabolism, glutathione metabolism, metabolism of xenobiotics by cytochrome P450, and ABC transporters were significantly differentially expressed components between Cd stress and NaHS treatment under Cd stress in T. thermophila. The relative expression levels of six DEGs were further confirmed through quantitative real-time polymerase chain reaction (qRT-PCR). Conclusion NaHS alleviated Cd stress mainly through inhibiting Cd absorbtion, promoting CdS nanoparticles formation, increasing oxidation resistance, and regulation of transport in free-living unicellular T. thermophila. These findings will expand our understanding for H2S functions in the freshwater protozoa. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-020-07337-9.
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Affiliation(s)
- Hongrui Lv
- School of Life Science, Shanxi University, Taiyuan, 030006, China.,Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006, China
| | - Jing Xu
- School of Life Science, Shanxi University, Taiyuan, 030006, China.,Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006, China
| | - Tao Bo
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006, China
| | - Wei Wang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006, China.
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8
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Chatterjee S, Kumari S, Rath S, Priyadarshanee M, Das S. Diversity, structure and regulation of microbial metallothionein: metal resistance and possible applications in sequestration of toxic metals. Metallomics 2020; 12:1637-1655. [PMID: 32996528 DOI: 10.1039/d0mt00140f] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Metallothioneins (MTs) are a group of cysteine-rich, universal, low molecular weight proteins distributed widely in almost all major taxonomic groups ranging from tiny microbes to highly organized vertebrates. The primary function of this protein is storage, transportation and binding of metals, which enable microorganisms to detoxify heavy metals. In the microbial world, these peptides were first identified in a cyanobacterium Synechococcus as the SmtA protein which exhibits high affinity towards rising level of zinc and cadmium to preserve metal homeostasis in a cell. In yeast, MTs aid in reserving copper and confer protection against copper toxicity by chelating excess copper ions in a cell. Two MTs, CUP1 and Crs5, originating from Saccharomyces cerevisiae predominantly bind to copper though are capable of binding with zinc and cadmium ions. MT superfamily 7 is found in ciliated protozoa which show high affinity towards copper and cadmium. Several tools and techniques, such as western blot, capillary electrophoresis, inductively coupled plasma, atomic emission spectroscopy and high performance liquid chromatography, have been extensively utilized for the detection and quantification of microbial MTs which are utilized for the efficient remediation and sequestration of heavy metals from a contaminated environment.
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Affiliation(s)
- Shreosi Chatterjee
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela 769 008, Odisha, India.
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9
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Balzano S, Sardo A, Blasio M, Chahine TB, Dell’Anno F, Sansone C, Brunet C. Microalgal Metallothioneins and Phytochelatins and Their Potential Use in Bioremediation. Front Microbiol 2020; 11:517. [PMID: 32431671 PMCID: PMC7216689 DOI: 10.3389/fmicb.2020.00517] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/10/2020] [Indexed: 01/02/2023] Open
Abstract
The persistence of heavy metals (HMs) in the environment causes adverse effects to all living organisms; HMs accumulate along the food chain affecting different levels of biological organizations, from cells to tissues. HMs enter cells through transporter proteins and can bind to enzymes and nucleic acids interfering with their functioning. Strategies used by microalgae to minimize HM toxicity include the biosynthesis of metal-binding peptides that chelate metal cations inhibiting their activity. Metal-binding peptides include genetically encoded metallothioneins (MTs) and enzymatically produced phytochelatins (PCs). A number of techniques, including genetic engineering, focus on increasing the biosynthesis of MTs and PCs in microalgae. The present review reports the current knowledge on microalgal MTs and PCs and describes the state of art of their use for HM bioremediation and other putative biotechnological applications, also emphasizing on techniques aimed at increasing the cellular concentrations of MTs and PCs. In spite of the broad metabolic and chemical diversity of microalgae that are currently receiving increasing attention by biotechnological research, knowledge on MTs and PCs from these organisms is still limited to date.
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Affiliation(s)
- Sergio Balzano
- Stazione Zoologica Anton Dohrn Napoli (SZN), Naples, Italy
- NIOZ Royal Netherlands Institute for Sea Research, Den Burg, Netherlands
| | - Angela Sardo
- Stazione Zoologica Anton Dohrn Napoli (SZN), Naples, Italy
| | - Martina Blasio
- Stazione Zoologica Anton Dohrn Napoli (SZN), Naples, Italy
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10
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de Francisco P, Amaro F, Martín-González A, Gutiérrez JC. AP-1 (bZIP) Transcription Factors as Potential Regulators of Metallothionein Gene Expression in Tetrahymena thermophila. Front Genet 2018; 9:459. [PMID: 30405686 PMCID: PMC6205968 DOI: 10.3389/fgene.2018.00459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 09/19/2018] [Indexed: 12/31/2022] Open
Abstract
Metallothioneins (MT) are multi-stress proteins mainly involved in metal detoxification. MT gene expression is normally induced by a broad variety of stimulus and its gene expression regulation mainly occurs at a transcriptional level. Conserved motifs in the Tetrahymena thermophila MT promoters have been described. These motifs show a consensus sequence very similar to AP-1 sites, and bZIP type transcription factors might participate in the MT gene expression regulation. In this research work, we characterize four AP-1 transcription factors in each of four different analyzed Tetrahymena species, detecting a high conservation among them. Each AP-1 molecule has its counterpart in the other three Tetrahymena species. A comparative qRT-PCR analysis of these AP-1 genes have been carried out in different T. thermophila strains (including metal-adapted, knockout and/or knockdown strains among others), and under different metal-stress conditions (1 or 24 h Cd2+, Cu2+, or Pb2+ treatments). The possible interaction of these transcription factors with the conserved AP-1 motifs present in MT promoters has been corroborated by protein-DNA interaction experiments. Certain connection between the expression patterns of the bZIP and MT genes seems to exist. For the first time, and based on our findings, a possible gene expression regulation model including both AP-1 transcription factors and MT genes from the ciliate T. thermophila has been elaborated.
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Affiliation(s)
- Patricia de Francisco
- Departamento de Genética, Fisiología y Microbiología, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Madrid, Spain
| | - Francisco Amaro
- Departamento de Genética, Fisiología y Microbiología, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana Martín-González
- Departamento de Genética, Fisiología y Microbiología, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Madrid, Spain
| | - Juan Carlos Gutiérrez
- Departamento de Genética, Fisiología y Microbiología, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Madrid, Spain
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11
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J AJ, M I, A G, S A G, S SR, P SL, M A, N R K, K G, N A. Biomimetic strategies to design metallic proteins for detoxification of hazardous heavy metal. JOURNAL OF HAZARDOUS MATERIALS 2018; 358:92-100. [PMID: 29990822 DOI: 10.1016/j.jhazmat.2018.06.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 06/24/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
Discharge of hazardous heavy metals in to the environment poses a serious threat to the ecosystem owing to its non-degradability and indestructability. Physical and chemical techniques for the removal of heavy metals from industrial effluent is expensive and causes secondary pollution. On the other hand, biological processes using microorganisms play a vital role due to their large surface area to volume ratio, which increases the interactions with metal ions present in the environment. Here, we developed a third generation biological tool for the removal of heavy metal (copper) from the effluent through the biosynthesis of intracellular and surface displayed metallic proteins with novel metal co-ordination chemistry. We evaluated the cell viability for maximum heavy metal adsorption and metal tolerance of synthesized congener metallic proteins. Finally, to eliminate the cost associated with incorporation of metal binding aminoacid, we have introduced a genetic circuit in order to evolve a novel magnetotactic bacterium. The bioreactor studies of the consortia of metallic protein expressing cells immobilized on functionalized granular activated carbon revealed that 97% of copper was adsorbed from the industrial effluent. It is evident that the use of congener metallic proteins will be a futuristic approach for the treatment of wastewater facilitating environmental detoxification.
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Affiliation(s)
- Asuma Janeena J
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India; Academy of Scientific and Innovative Research, Ghaziabad, Uttar Pradesh, India
| | - Ilamaran M
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India
| | - George A
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India
| | - George S A
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India
| | - Sriram Raghavan S
- Department of Crystallography and Biophysics, Madras University, Chennai, India
| | - Surya Lakshmi P
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India
| | - Aarthy M
- CSIR-National Environmental Engineering Research Institute (NEERI), Chennai Zonal Laboratory, Chennai, India
| | - Kamini N R
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India
| | - Gunasekaran K
- Department of Crystallography and Biophysics, Madras University, Chennai, India
| | - Ayyadurai N
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India.
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12
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de Francisco P, Martín-González A, Turkewitz AP, Gutiérrez JC. Genome plasticity in response to stress in Tetrahymena thermophila: selective and reversible chromosome amplification and paralogous expansion of metallothionein genes. Environ Microbiol 2018; 20:2410-2421. [PMID: 29687579 DOI: 10.1111/1462-2920.14251] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 04/18/2018] [Indexed: 12/11/2022]
Abstract
Extreme stress situations can induce genetic variations including genome reorganization. In ciliates like Tetrahymena thermophila, the approximately 45-fold ploidy of the somatic macronucleus may enable adaptive responses that depend on genome plasticity. To identify potential genome-level adaptations related to metal toxicity, we isolated three Tetrahymena thermophila strains after an extended adaptation period to extreme metal concentrations (Cd2+ , Cu2+ or Pb2+ ). In the Cd-adapted strain, we found a approximately five-fold copy number increase of three genes located in the same macronuclear chromosome, including two metallothionein genes, MTT1 and MTT3. The apparent amplification of this macronuclear chromosome was reversible and reproducible, depending on the presence of environmental metal. We also analysed three knockout (KO) and/or knockdown (KD) strains for MTT1 and/or MTT5. In the MTT5KD strain, we found at least two new genes arising from paralogous expansion of MTT1, which encode truncated variants of MTT1. The expansion can be explained by a model based on somatic recombination between MTT1 genes on pairs of macronuclear chromosomes. At least two of the new paralogs are transcribed and upregulated in response to Cd2+ . Altogether, we have thus identified two distinct mechanisms, both involving genomic plasticity in the polyploid macronucleus that may represent adaptive responses to metal-related stress.
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Affiliation(s)
- Patricia de Francisco
- Departamento Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid (UCM). C/. Jose Antonio Nováis, 12. 28040 Madrid, Spain
| | - Ana Martín-González
- Departamento Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid (UCM). C/. Jose Antonio Nováis, 12. 28040 Madrid, Spain
| | - Aaron P Turkewitz
- Department of Molecular Genetics and Cell Biology, Cummings Life Science Center, University of Chicago. 920 East 58th Street, Chicago, IL 60637, USA
| | - Juan Carlos Gutiérrez
- Departamento Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid (UCM). C/. Jose Antonio Nováis, 12. 28040 Madrid, Spain
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13
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de Francisco P, Martín-González A, Turkewitz AP, Gutiérrez JC. Extreme metal adapted, knockout and knockdown strains reveal a coordinated gene expression among different Tetrahymena thermophila metallothionein isoforms. PLoS One 2017; 12:e0189076. [PMID: 29206858 PMCID: PMC5716537 DOI: 10.1371/journal.pone.0189076] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 11/17/2017] [Indexed: 01/01/2023] Open
Abstract
Metallothioneins (MT) constitute a superfamily of small cytosolic proteins that are able to bind metal cations through numerous cysteine (Cys) residues. Like other organisms the ciliate Tetrahymena thermophila presents several MT isoforms, which have been classified into two subfamilies (Cd- and Cu-metallothioneins). The main aim of this study was to examine the specific functions and transcriptional regulation of the five MT isoforms present in T. thermophila, by using several strains of this ciliate. After a laboratory evolution experiment over more than two years, three different T. thermophila strains adapted to extreme metal stress (Cd2+, Cu2+ or Pb2+) were obtained. In addition, three knockout and/or knockdown strains for different metallothionein (MT) genes were generated. These strains were then analyzed for expression of the individual MT isoforms. Our results provide a strong basis for assigning differential roles to the set of MT isoforms. MTT1 appears to have a key role in adaptation to Cd. In contrast, MTT2/4 are crucial for Cu-adaptation and MTT5 appears to be important for Pb-adaptation and might be considered as an “alarm” MT gene for responding to metal stress. Moreover, results indicate that likely a coordinated transcriptional regulation exists between the MT genes, particularly among MTT1, MTT5 and MTT2/4. MTT5 appears to be an essential gene, a first such report in any organism of an essential MT gene.
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Affiliation(s)
- Patricia de Francisco
- Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense de Madrid (UCM), Madrid, Spain
| | - Ana Martín-González
- Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense de Madrid (UCM), Madrid, Spain
| | - Aaron P. Turkewitz
- Department of Molecular Genetics and Cell Biology, Cummings Life Sciences Center, University of Chicago, Chicago, Illinois, United States of America
| | - Juan Carlos Gutiérrez
- Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense de Madrid (UCM), Madrid, Spain
- * E-mail:
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14
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Chasapis CT, Andreini C, Georgiopolou AK, Stefanidou ME, Vlamis-Gardikas A. Identification of the zinc, copper and cadmium metalloproteome of the protozoon Tetrahymena thermophila by systematic bioinformatics. Arch Microbiol 2017; 199:1141-1149. [DOI: 10.1007/s00203-017-1385-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/24/2017] [Accepted: 05/02/2017] [Indexed: 11/30/2022]
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15
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Ziller A, Yadav RK, Capdevila M, Reddy MS, Vallon L, Marmeisse R, Atrian S, Palacios Ò, Fraissinet-Tachet L. Metagenomics analysis reveals a new metallothionein family: Sequence and metal-binding features of new environmental cysteine-rich proteins. J Inorg Biochem 2016; 167:1-11. [PMID: 27886631 DOI: 10.1016/j.jinorgbio.2016.11.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/28/2016] [Accepted: 11/11/2016] [Indexed: 11/18/2022]
Abstract
Metallothioneins are cysteine-rich proteins, which function as (i) metal carriers in basal cell metabolism and (ii) protective metal chelators in conditions of metal excess. Metallothioneins have been characterized from different eukaryotic model and cultivable species. Presently, they are categorized in 15 families but evolutionary relationships between these metallothionein families remain unresolved. Several cysteine-rich protein encoding genes that conferred Cd-tolerance in Cd-sensitive yeast mutants have previously been isolated from soil eukaryotic metatranscriptomes. They were called CRPs for "cysteine-rich proteins". These proteins, of unknown taxonomic origins, share conserved cysteine motifs and could be considered as metallothioneins. In the present work, we analyzed these CRPs with respect to their amino acid sequence features and their metal-binding abilities towards Cd, Zn and Cu metal ions. Sequence analysis revealed that they share common features with different known metallothionein families, but also exhibit unique specific features. Noticeably, CRPs display two separate cysteine-rich domains which, when expressed separately in yeast, confer Cd-tolerance. The N-terminal domain contains some conserved atypical Cys motifs, such as one CCC and two CXCC ones. Five CRPs were expressed and purified as recombinant proteins and their metal-binding characteristics were studied. All these CRPs chelated Cd(II), Zn(II) and Cu(I), although displaying a better capacity for Zn(II) coordination. All CRPs are able to confer Cd-tolerance, and four of them confer Zn-tolerance in the Zn-sensitive zrc1Δ yeast mutant. We designated these CRPs as environmental metallothioneins belonging to a new formerly undescribed metallothionein family.
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Affiliation(s)
- Antoine Ziller
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France
| | - Rajiv Kumar Yadav
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France
| | - Mercè Capdevila
- Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Barcelona, Spain
| | | | - Laurent Vallon
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France
| | - Roland Marmeisse
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France
| | - Silvia Atrian
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, E-08028 Barcelona, Spain
| | - Òscar Palacios
- Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Barcelona, Spain
| | - Laurence Fraissinet-Tachet
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France.
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16
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de Francisco P, Melgar LM, Díaz S, Martín-González A, Gutiérrez JC. The Tetrahymena metallothionein gene family: twenty-one new cDNAs, molecular characterization, phylogenetic study and comparative analysis of the gene expression under different abiotic stressors. BMC Genomics 2016; 17:346. [PMID: 27165301 PMCID: PMC4862169 DOI: 10.1186/s12864-016-2658-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 04/22/2016] [Indexed: 01/22/2023] Open
Abstract
Background Ciliate metallothioneins (MTs) are included in family 7 of the MT superfamily. This family has been divided into two main subfamilies: 7a or CdMTs and 7b or CuMTs. All ciliate MTs reported have been isolated from different Tetrahymena species and present unique features with regard to standard MTs. Likewise, an expression analysis has been carried out on some of MT genes under metal stress, corroborating their classification into two subfamilies. Results We isolated 21 new cDNAs from different Tetrahymena species to obtain a wider view of the biodiversity of these conserved genes. Structural analysis (cysteine patterns) and an updated phylogenetic study both corroborated the previous classification into two subfamilies. A new CuMT from a Tetrahymena-related species Ichthyophthirius multifiliis was also included in this general analysis. We detected a certain tendency towards the presentation of a CdMT tri-modular structure in Borealis group species with respect to Australis group. We report for the first time a semi-complete paralog duplication of a CdMT gene originating a new CdMT gene isoform in T. malaccensis. An asymmetry of the codon usage for glutamine residues was detected between Cd- and CuMTs, and the phylogenetic implications are discussed. A comparative gene expression analysis of several MT genes by qRT-PCR revealed differential behavior among them under different abiotic stressors in the same Tetrahymena species. Conclusions The Tetrahymena metallothionein family represents a quite conserved protein structure group with unique features with respect to standard MTs. Both Cd- and CuMT subfamilies present very defined and differentiated characteristics at several levels: cysteine patterns, modular structure, glutamine codon usage and gene expression under metal stress, among others. Gene duplication through evolution seems to be the major genetic mechanism for creating new MT gene isoforms and increasing their functional diversity. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2658-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Patricia de Francisco
- Departamento Microbiología-III, Facultad de Biología. C/José Antonio Novais, 12, Universidad Complutense de Madrid (UCM), 28040, Madrid, Spain
| | - Laura María Melgar
- Universidad Castilla-La Mancha, Campus Tecnológico de la fábrica de armas, Edificio Sabatini. Av. Carlos III, s/n. 45071, Toledo, Spain
| | - Silvia Díaz
- Departamento Microbiología-III, Facultad de Biología. C/José Antonio Novais, 12, Universidad Complutense de Madrid (UCM), 28040, Madrid, Spain
| | - Ana Martín-González
- Departamento Microbiología-III, Facultad de Biología. C/José Antonio Novais, 12, Universidad Complutense de Madrid (UCM), 28040, Madrid, Spain
| | - Juan Carlos Gutiérrez
- Departamento Microbiología-III, Facultad de Biología. C/José Antonio Novais, 12, Universidad Complutense de Madrid (UCM), 28040, Madrid, Spain.
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17
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Fierros-Romero G, Gómez-Ramírez M, Arenas-Isaac GE, Pless RC, Rojas-Avelizapa NG. Identification of Bacillus megaterium and Microbacterium liquefaciens genes involved in metal resistance and metal removal. Can J Microbiol 2016; 62:505-13. [PMID: 27210016 DOI: 10.1139/cjm-2015-0507] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bacillus megaterium MNSH1-9K-1 and Microbacterium liquefaciens MNSH2-PHGII-2, 2 nickel- and vanadium-resistant bacteria from mine tailings located in Guanajuato, Mexico, are shown to have the ability to remove 33.1% and 17.8% of Ni, respectively, and 50.8% and 14.0% of V, respectively, from spent petrochemical catalysts containing 428 ± 30 mg·kg(-1) Ni and 2165 ± 77 mg·kg(-1) V. In these strains, several Ni resistance determinants were detected by conventional PCR. The nccA (nickel-cobalt-cadmium resistance) was found for the first time in B. megaterium. In M. liquefaciens, the above gene as well as the czcD gene (cobalt-zinc-cadmium resistance) and a high-affinity nickel transporter were detected for the first time. This study characterizes the resistance of M. liquefaciens and B. megaterium to Ni through the expression of genes conferring metal resistance.
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Affiliation(s)
- Grisel Fierros-Romero
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
| | - Marlenne Gómez-Ramírez
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
| | - Ginesa E Arenas-Isaac
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
| | - Reynaldo C Pless
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
| | - Norma G Rojas-Avelizapa
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
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18
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Zahid MT, Shakoori FR, Zulifqar S, Ahmed I, Al-Ghanim K, Mehboob S, Shakoori AR. Molecular Characterization of a Copper Metallothionein Gene From a Ciliate Tetrahymena farahensis. J Cell Biochem 2016; 117:1843-54. [PMID: 26754785 DOI: 10.1002/jcb.25484] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 01/06/2016] [Indexed: 11/06/2022]
Abstract
A new copper metallothionein (TfCuMT) gene has been identified from a locally isolated ciliate Tetrahymena farahensis. It contains 327 nucleotides encoding a peptide chain of 108 amino acids and belongs to class MTT2 and subfamily 7b. Amplification from both gDNA and mRNA confirmed the intronless nature of this gene. Like most of the metallohtioneins, cysteine residues contribute nearly 30% content with the specific CKC motifs. Structural repeats present in peptide sequence of TfCuMT indicate internal duplication of gene at some stage of gene evolution. The predicted model of copper metallothionein protein showed that copper ions are mainly chelated by thiol sulfur of cysteine residues and are embedded in the folds of polypeptide chain. For in vivo expression of TfCuMT in Escherichia coli host cells the classical stop codons, which coded for glutamine in the ciliate were mutated to CAA and CAG through site directed mutagenesis. The mutated gene showed higher expression in pET28a expression vector compared with pET21a. Optimum expression was obtained after 6-8 h of 0.1 mM IPTG induction. Stability of His tagged TfCuMT in 5% SDS was low, with half-life of about 104 min. Presence of 1.0 μM copper increased the expression level by 1.65-fold. Presence of 100 μM Cysteine in culture medium caused 2.4-fold increase in expression level. His tagged TfCuMT was purified through affinity chromatography using NTN-His binding resin in the presence of 0.1 M imidazole and NaCl. The modeled structure of the TfCuMT showed a cleft for Cu binding with correct orientation of Cys residues in the motif CKC. J. Cell. Biochem. 117: 1843-1854, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Muhammad Tariq Zahid
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan.,Departmenmt of Zoology, GC University, Katchery Road, Lahore, Pakistan
| | - Farah Rauf Shakoori
- Departmenmt of Zoology, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
| | - Soumble Zulifqar
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
| | - Ishtiaq Ahmed
- Institute of Industrial Biotechnology, GC University, Katchery Road, Lahore, Pakistan
| | - Khalid Al-Ghanim
- Department of Zoology, College of Science, King Saud University, PO Box 24555, Riyadh 11451, Kingdom of Saudi Arabia
| | - Shahid Mehboob
- Department of Zoology, College of Science, King Saud University, PO Box 24555, Riyadh 11451, Kingdom of Saudi Arabia
| | - Abdul Rauf Shakoori
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan.,Department of Zoology, College of Science, King Saud University, PO Box 24555, Riyadh 11451, Kingdom of Saudi Arabia
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19
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Espart A, Marín M, Gil-Moreno S, Palacios Ò, Amaro F, Martín-González A, Gutiérrez JC, Capdevila M, Atrian S. Hints for metal-preference protein sequence determinants: different metal binding features of the five tetrahymena thermophila metallothioneins. Int J Biol Sci 2015; 11:456-71. [PMID: 25798065 PMCID: PMC4366644 DOI: 10.7150/ijbs.11060] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 01/21/2015] [Indexed: 11/12/2022] Open
Abstract
The metal binding preference of metallothioneins (MTs) groups them in two extreme subsets, the Zn/Cd- and the Cu-thioneins. Ciliates harbor the largest MT gene/protein family reported so far, including 5 paralogs that exhibit relatively low sequence similarity, excepting MTT2 and MTT4. In Tetrahymena thermophila, three MTs (MTT1, MTT3 and MTT5) were considered Cd-thioneins and two (MTT2 and MTT4) Cu-thioneins, according to gene expression inducibility and phylogenetic analysis. In this study, the metal-binding abilities of the five MTT proteins were characterized, to obtain information about the folding and stability of their cognate- and non-cognate metal complexes, and to characterize the T. thermophila MT system at protein level. Hence, the five MTTs were recombinantly synthesized as Zn2+-, Cd2+- or Cu+-complexes, which were analyzed by electrospray mass spectrometry (ESI-MS), circular dichroism (CD), and UV-vis spectrophotometry. Among the Cd-thioneins, MTT1 and MTT5 were optimal for Cd2+ coordination, yielding unique Cd17- and Cd8- complexes, respectively. When binding Zn2+, they rendered a mixture of Zn-species. Only MTT5 was capable to coordinate Cu+, although yielding heteronuclear Zn-, Cu-species or highly unstable Cu-homometallic species. MTT3 exhibited poor binding abilities both for Cd2+ and for Cu+, and although not optimally, it yielded the best result when coordinating Zn2+. The two Cu-thioneins, MTT2 and MTT4 isoforms formed homometallic Cu-complexes (major Cu20-MTT) upon synthesis in Cu-supplemented hosts. Contrarily, they were unable to fold into stable Cd-complexes, while Zn-MTT species were only recovered for MTT4 (major Zn10-MTT4). Thus, the metal binding preferences of the five T. thermophila MTs correlate well with their previous classification as Cd- and Cu-thioneins, and globally, they can be classified from Zn/Cd- to Cu-thioneins according to the gradation: MTT1>MTT5>MTT3>MTT4>MTT2. The main mechanisms underlying the evolution and specialization of the MTT metal binding preferences may have been internal tandem duplications, presence of doublet and triplet Cys patterns in Zn/Cd-thioneins, and optimization of site specific amino acid determinants (Lys for Zn/Cd- and Asn for Cu-coordination).
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Affiliation(s)
- Anna Espart
- 1. Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Maribel Marín
- 2. Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193-Cerdanyola del Vallès (Barcelona), Spain
| | - Selene Gil-Moreno
- 2. Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193-Cerdanyola del Vallès (Barcelona), Spain
| | - Òscar Palacios
- 2. Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193-Cerdanyola del Vallès (Barcelona), Spain
| | - Francisco Amaro
- 3. Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense, 28040-Madrid, Spain
| | - Ana Martín-González
- 3. Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense, 28040-Madrid, Spain
| | - Juan C Gutiérrez
- 3. Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense, 28040-Madrid, Spain
| | - Mercè Capdevila
- 2. Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193-Cerdanyola del Vallès (Barcelona), Spain
| | - Sílvia Atrian
- 1. Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, 08028-Barcelona, Spain
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20
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Chang Y, Liu G, Guo L, Liu H, Yuan D, Xiong J, Ning Y, Fu C, Miao W. Cd-metallothioneins in three additional tetrahymena species: intragenic repeat patterns and induction by metal ions. J Eukaryot Microbiol 2014; 61:333-42. [PMID: 24628663 DOI: 10.1111/jeu.12112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 01/12/2014] [Accepted: 01/26/2014] [Indexed: 01/07/2023]
Abstract
Ciliate metallothioneins (MTs) possess many unique features compared to the "classic" MTs in other organisms, but they have only been studied in a small number of species. In this study, we investigated cDNAs encoding subfamily 7a metallothioneins (CdMTs) in three Tetrahymena species (T. hegewischi, T. malaccensis, and T. mobilis). Four CdMT genes (ThegMT1, ThegMT2, TmalMT1, and TmobMT1) were cloned and characterized. They share high sequence similarity to previously identified subfamily 7a MT members. Tetrahymena CdMTs exhibit a remarkably regular intragenic repeat homology. The CdMT sequences were divided into two main types of modules, which had been previously described, and which we name "A" and "B". ThegMT2 was identified as the first MT isoform solely composed of module "B". A phylogenetic analysis of individual modules of every characterized Tetrahymena CdMT rigorously documents the conclusion that modules are important units of CdMT evolution, which have undergone frequent and rapid gain/loss and shuffling. The transcriptional activity of the four newly identified genes was measured under different heavy metal exposure (Cd, Cu, Zn, Pb) using real-time quantitative PCR. The results showed that these genes were differentially induced after short (1 h) or long (24 h) metal exposure. The evolutionary diversity of Tetrahymena CdMTs is further discussed with regard to their induction by metal ions.
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Affiliation(s)
- Yue Chang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China; Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
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21
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Amaro F, Turkewitz AP, Martín-González A, Gutiérrez JC. Functional GFP-metallothionein fusion protein from Tetrahymena thermophila: a potential whole-cell biosensor for monitoring heavy metal pollution and a cell model to study metallothionein overproduction effects. Biometals 2014; 27:195-205. [PMID: 24430977 PMCID: PMC4707044 DOI: 10.1007/s10534-014-9704-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 12/31/2013] [Indexed: 11/26/2022]
Abstract
The significance of metal(oid)s as environmental pollutants has made them a priority in ecotoxicology, with the aim of minimizing exposure to animals or humans. Therefore, it is necessary to develop sensitive and inexpensive methods that can efficiently detect and monitor these pollutants in the environment. Conventional analytical techniques suffer from the disadvantages of high cost and complexity. Alternatively, prokaryotic or eukaryotic whole-cell biosensors (WCB) are one of the newest molecular tools employed in environmental monitoring that use the cell as an integrated reporter incorporating a reporter gene fused to a heavy metal responsive promoter. In the present paper, we report results from expressing, in the ciliate Tetrahymena thermophila, constructs consisting of the reporter gfp gene fused to the complete MTT1 or MTT5 protein coding regions under the transcriptional control of the MTT1 metallothionein promoter, which plays a critical role in heavy metal stress in this ciliate. When exposed to Cd(2+), such cells overexpress both the GFP reporter transgene and the linked metallothionein gene. We report that, for the GFPMTT5 strain, this metallothionein overexpression results in marked resistance to cadmium toxicity (24 h LC50 ~15 μM of Cd(2+)), compared to wild type cells (24 h LC50 ~1.73 μM of Cd(2+)). These results provide the first experimental evidence that ciliate metallothioneins, like in other organisms, function to protect the cell against toxic metal ions. Because these strains may have novel advantages as WCBs, we have compared their properties to those of other previously reported Tetrahymena WCBs.
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Affiliation(s)
- Francisco Amaro
- Departamento de Microbiología-III, Facultad de Biología, C/. José Antonio Novais 12, Universidad Complutense (UCM), 28040 Madrid, Spain
| | - Aaron P. Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Cummings Life Science Center, 920 East 58th Street, Chicago, IL. 60637, USA
| | - Ana Martín-González
- Departamento de Microbiología-III, Facultad de Biología, C/. José Antonio Novais 12, Universidad Complutense (UCM), 28040 Madrid, Spain
| | - Juan Carlos Gutiérrez
- Departamento de Microbiología-III, Facultad de Biología, C/. José Antonio Novais 12, Universidad Complutense (UCM), 28040 Madrid, Spain
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22
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Assessing the resistance and bioremediation ability of selected bacterial and protozoan species to heavy metals in metal-rich industrial wastewater. BMC Microbiol 2013; 13:28. [PMID: 23387904 PMCID: PMC3575345 DOI: 10.1186/1471-2180-13-28] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 01/31/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Heavy-metals exert considerable stress on the environment worldwide. This study assessed the resistance to and bioremediation of heavy-metals by selected protozoan and bacterial species in highly polluted industrial-wastewater. Specific variables (i.e. chemical oxygen demand, pH, dissolved oxygen) and the growth/die-off-rates of test organisms were measured using standard methods. Heavy-metal removals were determined in biomass and supernatant by the Inductively Couple Plasma Optical Emission Spectrometer. A parallel experiment was performed with dead microbial cells to assess the biosorption ability of test isolates. RESULTS The results revealed that the industrial-wastewater samples were highly polluted with heavy-metal concentrations exceeding by far the maximum limits (in mg/l) of 0.05-Co, 0.2-Ni, 0.1-Mn, 0.1-V, 0.01-Pb, 0.01-Cu, 0.1-Zn and 0.005-Cd, prescribed by the UN-FAO. Industrial-wastewater had no major effects on Pseudomonas putida, Bacillus licheniformis and Peranema sp. (growth rates up to 1.81, 1.45 and 1.43 d-1, respectively) compared to other test isolates. This was also revealed with significant COD increases (p < 0.05) in culture media inoculated with living bacterial isolates (over 100%) compared to protozoan isolates (up to 24% increase). Living Pseudomonas putida demonstrated the highest removal rates of heavy metals (Co-71%, Ni-51%, Mn-45%, V-83%, Pb-96%, Ti-100% and Cu-49%) followed by Bacillus licheniformis (Al-23% and Zn-53%) and Peranema sp. (Cd-42%). None of the dead cells were able to remove more than 25% of the heavy metals. Bacterial isolates contained the genes copC, chrB, cnrA3 and nccA encoding the resistance to Cu, Cr, Co-Ni and Cd-Ni-Co, respectively. Protozoan isolates contained only the genes encoding Cu and Cr resistance (copC and chrB genes). Peranema sp. was the only protozoan isolate which had an additional resistant gene cnrA3 encoding Co-Ni resistance. CONCLUSION Significant differences (p < 0.05) observed between dead and living microbial cells for metal-removal and the presence of certain metal-resistant genes indicated that the selected microbial isolates used both passive (biosorptive) and active (bioaccumulation) mechanisms to remove heavy metals from industrial wastewater. This study advocates the use of Peranema sp. as a potential candidate for the bioremediation of heavy-metals in wastewater treatment, in addition to Pseudomonas putida and Bacillus licheniformis.
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Capdevila M, Bofill R, Palacios Ò, Atrian S. State-of-the-art of metallothioneins at the beginning of the 21st century. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2011.07.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Koster S, Boobis AR, Cubberley R, Hollnagel HM, Richling E, Wildemann T, Würtzen G, Galli CL. Application of the TTC concept to unknown substances found in analysis of foods. Food Chem Toxicol 2011; 49:1643-60. [DOI: 10.1016/j.fct.2011.03.049] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 03/21/2011] [Accepted: 03/25/2011] [Indexed: 11/29/2022]
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Ciliate metallothioneins: unique microbial eukaryotic heavy-metal-binder molecules. J Biol Inorg Chem 2011; 16:1025-34. [DOI: 10.1007/s00775-011-0820-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 07/11/2011] [Indexed: 11/27/2022]
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Amaro F, Turkewitz AP, Martín-González A, Gutiérrez JC. Whole-cell biosensors for detection of heavy metal ions in environmental samples based on metallothionein promoters from Tetrahymena thermophila. Microb Biotechnol 2011; 4:513-22. [PMID: 21366892 PMCID: PMC3815263 DOI: 10.1111/j.1751-7915.2011.00252.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Heavy metals are among the most serious pollutants, and thus there is a need to develop sensitive and rapid biomonitoring methods for heavy metals in the environment. Critical parameters such as bioavailability, toxicity and genotoxicity cannot be tested using chemical analysis, but only can be assayed using living cells. A whole‐cell biosensor uses the whole cell as a single reporter incorporating both bioreceptor and transducer elements. In the present paper, we report results with two gene constructs using the Tetrahymena thermophila MTT1 and MTT5 metallothionein promoters linked with the eukaryotic luciferase gene as a reporter. This is the first report of a ciliated protozoan used as a heavy metal whole‐cell biosensor. T. thermophila transformed strains were created as heavy metal whole‐cell biosensors, and turn on bioassays were designed to detect, in about 2 h, the bioavailable heavy metals in polluted soil or aquatic samples. Validation of these whole‐cell biosensors was carried out using both artificial and natural samples, including methods for detecting false positives and negatives. Comparison with other published cell biosensors indicates that the Tetrahymena metallothionein promoter‐based biosensors appear to be the most sensitive eukaryotic metal biosensors and compare favourably with some prokaryotic biosensors as well.
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Affiliation(s)
- Francisco Amaro
- Departamento de Microbiología-III, Facultad de Biología, C/. José Antonio Novais 2, Universidad Complutense, Madrid, Spain
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Chaudhry R, Shakoori AR. Isolation and characterization of a novel copper-inducible metallothionein gene of a ciliate, Tetrahymena tropicalis lahorensis. J Cell Biochem 2010; 110:630-44. [PMID: 20512924 DOI: 10.1002/jcb.22573] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The two isoforms of copper metallothionein (CuMT) gene of a copper resistant ciliate, Tetrahymena tropicalis lahorensis (Ttl), have been isolated and characterized. The molecular cloning and nucleotide sequencing of cDNAs coding for the two CuMT isoforms revealed that TtlCuMT1 gene has 300, while TtlCuMT2 has 327 nucleotides, both with ATG as the initiation codon and TGA as the translational termination codon. TAG codes for glutamine in TtlCuMT2 gene which is peculiar to Tetrahymena. The deduced or translated TtlCuMT1 and TtlCuMT2 peptide sequences contain 100 and 108 amino acid residues including 28 and 32 cysteine residues, respectively. The amino acid sequences of TtlCuMT1 and TtlCuMT2 have special features of two and three CXCXXCXCXXCXC intragenic tandem repeats with a conserved structural pattern of cysteine, respectively. The predicted tertiary structures of these two isoforms indicate two domains. Domain I and the initial part of domain II showed >98% homology with other Tetrahymena CuMT. On the basis of the differences in the domain II, the metallothionein subfamily 7b can be divided into two groups, one (TtlCuMT1) comprising >100 amino acids and the other (TtlCuMT2) comprising <100 amino acids. This is a novel finding of the present study as no such report on this type of classification exists at the moment. TtlCuMT1 has 95%, while TtlCuMT2 has 97% resemblance with the previously reported CuMT genes of Tetrahymena spp. SDS-PAGE analysis using fluorescent probe as well as coomassie brilliant blue staining also confirmed the presence of metallothionein.
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Affiliation(s)
- Raheela Chaudhry
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
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Haferburg G, Kothe E. Metallomics: lessons for metalliferous soil remediation. Appl Microbiol Biotechnol 2010; 87:1271-80. [PMID: 20532755 DOI: 10.1007/s00253-010-2695-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 05/19/2010] [Accepted: 05/19/2010] [Indexed: 10/19/2022]
Abstract
The term metallomics has been established for the investigation of transcriptome, proteome, and metabolome changes induced by metals. The mechanisms allowing the organisms to cope with metals in the environment, metal resistance factors, will in turn change biogeochemical cycles of metals in soil, coupling the metal pool with the root system of plants. This makes microorganisms key players in introducing metals into food webs, as well as for bioremediation strategies. Research on physiological and metabolic responses of microorganisms on metal stress in soil is thus essential for the selection of optimized consortia applicable in bioremediation strategies such as bioaugmentation or microbially enhanced phytoextraction. The results of metallomics studies will help to develop applications including identification of biomarkers for ecotoxicological studies, bioleaching, in situ soil regeneration, and microbially assisted phytoremediation of contaminated land. This review will therefore focus on the molecular understanding of metal resistance in bacteria and fungi, as can be derived from metallomics studies.
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Affiliation(s)
- Götz Haferburg
- Institute of Microbiology, Friedrich Schiller University, Neugasse 25, 07743 Jena, Germany.
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Capdevila M, González-Bellavista A, Muñoz M, Atrian S, Fàbregas E. The first isoform-selective protein biosensor: a metallothionein potentiometric electrode. Chem Commun (Camb) 2010; 46:2040-2. [DOI: 10.1039/b922284g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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