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Aguinaga OE, White KN, Dean AP, Pittman JK. Addition of organic acids to acid mine drainage polluted wetland sediment leads to microbial community structure and functional changes and improved water quality. Environ Pollut 2021; 290:118064. [PMID: 34481302 DOI: 10.1016/j.envpol.2021.118064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/24/2021] [Accepted: 08/26/2021] [Indexed: 06/13/2023]
Abstract
Acid mine drainage (AMD) is a serious environmental problem worldwide that requires efficient and sustainable remediation technologies including the use of biological mechanisms. A key challenge for AMD bioremediation is to provide optimal conditions for microbial-mediated immobilisation of trace metals. Although organic carbon and oxygen can enhance treatment efficiency, the effect on microbial communities is unclear. In this study, surface sediments from a natural wetland with proven efficiency for AMD bioremediation were artificially exposed to oxygen (by aeration) and/or organic carbon (in the form of mixed organic acids) and incubated under laboratory conditions. In addition to measuring changes in water chemistry, a metagenomics approach was used to determine changes in sediment bacterial, archaeal and fungal community structure, and functional gene abundance. The addition of organic carbon produced major changes in the abundance of microorganisms related to iron and sulfur metabolism (including Geobacter and Pelobacter) and increased levels of particulate metals via sulfate reduction. Aeration resulted in an increase in Sideroxydans abundance but no significant changes in metal chemistry were observed. The study concludes that the utilisation of organic carbon by microorganisms is more important for achieving efficient AMD treatment than the availability of oxygen, yet the combination of oxygen with organic carbon addition did not inhibit the improvements to water quality.
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Affiliation(s)
- Oscar E Aguinaga
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK; Departamento de Ingeniería, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Keith N White
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Andrew P Dean
- Department of Natural Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Oxford Road, Manchester, M1 5GD, UK
| | - Jon K Pittman
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK.
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2
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Ainerua MO, Tinwell J, Murphy R, Galli GLJ, van Dongen BE, White KN, Shiels HA. Prolonged phenanthrene exposure reduces cardiac function but fails to mount a significant oxidative stress response in the signal crayfish (Pacifastacus leniusculus). Chemosphere 2021; 268:129297. [PMID: 33359987 DOI: 10.1016/j.chemosphere.2020.129297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/08/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
Crustaceans are important ecosystem bio-indicators but their response to pollutants such as polyaromatic hydrocarbons (PAHs) remains understudied, particularly in freshwater habitats. Here we investigated the effect of phenanthrene (at 0.5, 1.0 and 1.5 mg L-1), a 3-ringed PAH associated with petroleum-based aquatic pollution on survival, in vivo and in situ cardiac performance, the oxidative stress response and the tissue burden in the signal crayfish (Pacifastacus leniusculus). Non-invasive sensors were used to monitor heart rate during exposure. Phenanthrene reduced maximum attainable heart rate in the latter half (days 8-15) of the exposure period but had no impact on routine heart rate. At the end of the 15-day exposure period, the electrical activity of the semi-isolated in situ crayfish heart was assessed and significant prolongation of the QT interval of the electrocardiogram was observed. Enzyme pathways associated with oxidative stress (superoxide dismutase and total oxyradical scavenging capacity) were also assessed after 15 days of phenanthrene exposure in gill, hepatopancreas and skeletal muscle; the results suggest limited induction of protective antioxidant pathways. Lastly, we report that 15 days exposure caused a dose-dependent increase in phenanthrene in hepatopancreas and heart tissues which was associated with reduced survivability. To our knowledge, this study is the first to provide such a thorough understanding of the impact of phenanthrene on a crustacean.
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Affiliation(s)
- Martins Oshioriamhe Ainerua
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom; Department of Animal and Environmental Biology, Faculty of Life Sciences, University of Benin, PMB, 1154, Benin City, Nigeria
| | - Jake Tinwell
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom
| | - Rory Murphy
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom
| | - Gina L J Galli
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom
| | - Bart E van Dongen
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering and Williamson Research Centre for Molecular Science. University of Manchester, Williamson Building, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Keith N White
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9GB, United Kingdom
| | - Holly A Shiels
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom.
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Ainerua MO, Tinwell J, Kompella SN, Sørhus E, White KN, van Dongen BE, Shiels HA. Understanding the cardiac toxicity of the anthropogenic pollutant phenanthrene on the freshwater indicator species, the brown trout (Salmo trutta): From whole heart to cardiomyocytes. Chemosphere 2020; 239:124608. [PMID: 31499312 PMCID: PMC6857438 DOI: 10.1016/j.chemosphere.2019.124608] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 08/15/2019] [Accepted: 08/17/2019] [Indexed: 05/05/2023]
Abstract
Freshwater systems are faced with a myriad of stressors including geomorphological alterations, nutrient overloading and pollution. Previous studies in marine fish showed polyaromatic hydrocarbons (PAHs) to be cardiotoxic. However, the cardiotoxicity of anthropogenic pollutants in freshwater fishes is unclear and has not been examined across multiple levels of cardiac organization. Here we investigated the effect of phenanthrene (Phe), a pervasive anthropogenic pollutant on a sentinel freshwater species, the brown trout (Salmo trutta). We first examined the electrical activity of the whole heart and found prolongation (∼8.6%) of the QT interval (time between ventricular depolarization and repolarization) of the electrocardiogram (ECG) and prolongation (∼13.2%) of the monophasic action potential duration (MAPD) following ascending doses of Phe. At the tissue level, Phe significantly reduced trabecular force generation by ∼24% at concentration 15 μM and above, suggesting Phe reduces cellular calcium cycling. This finding was supported by florescent microscopy showing a reduction (∼39%) in the intracellular calcium transient amplitude following Phe exposure in isolated brown trout ventricular myocytes. Single-cell electrophysiology was used to reveal the mechanism underlying contractile and electrical dysfunction following Phe exposure. A Phe-dependent reduction (∼38%) in the L-type Ca2+ current accounts, at least in part, for the lowered Ca2+ transient and force production. Prolongation of the MAPD and QT interval was explained by a reduction (∼70%) in the repolarising delayed rectifier K+ current following Phe exposure. Taken together, our study shows a direct impact of Phe across multiple levels of cardiac organization in a key freshwater salmonid.
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Affiliation(s)
- Martins Oshioriamhe Ainerua
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom; Department of Animal and Environmental Biology, Faculty of Life Sciences, University of Benin, PMB 1154, Benin City, Nigeria
| | - Jake Tinwell
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom
| | - Shiva Nag Kompella
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom
| | - Elin Sørhus
- Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817, Bergen, Norway
| | - Keith N White
- School of Earth Atmospheric and Environmental Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9GB, United Kingdom
| | - Bart E van Dongen
- School of Earth Atmospheric and Environmental Sciences, Williamson Research Centre for Molecular Science, University of Manchester, Williamson Building, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Holly A Shiels
- Cardiovascular Division, School of Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility Building, Manchester, M13 9NT, United Kingdom.
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Chalkley R, Child F, Al-Thaqafi K, Dean AP, White KN, Pittman JK. Macroalgae as spatial and temporal bioindicators of coastal metal pollution following remediation and diversion of acid mine drainage. Ecotoxicol Environ Saf 2019; 182:109458. [PMID: 31398784 DOI: 10.1016/j.ecoenv.2019.109458] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 07/12/2019] [Accepted: 07/18/2019] [Indexed: 05/27/2023]
Abstract
Acid mine drainage (AMD) is a significant contributor of metal pollution leading to ecosystem damage. Bioindicator organisms such as intertidal brown macroalgae have an important role in quantifying the risks of metal bioaccumulation in coastal locations exposed to AMD contamination. Measurement of As, Cd, Cu, Fe, Pb, and Zn accumulation was performed in Fucus serratus, Fucus vesiculosus and Ascophyllum nodosum sampled from two marine locations near to an abandoned Cu mine in Anglesey, Wales, UK. Transect samples were taken from a coastal location (Amlwch) that has seen a substantial increase in AMD contamination over 15 years, in comparison to a nearby estuarine location (Dulas Estuary leading to Dulas Bay) with a historic legacy of pollution. These were compared with samples from the same sites taken 30 years earlier. Some of the Dulas macroalgae samples had Cd, Cu and Zn concentrations that were above background but in general indicated a non-polluted estuary in comparison to substantial pollution over previous decades. In contrast, Fucus samples collected from directly below an AMD outflow at Amlwch showed extremely elevated metal bioaccumulation (>250 mg Fe g-1, >6 mg Cu g-1, >2 mg Zn g-1, >190 μg As g-1) and evidence of macroalgae toxicity, indicating severe pollution at this site. However, the pollution dispersed within 200 m of the outflow source. This study has demonstrated the efficiency of three brown macroalgae species as indicators for metal bioavailability at high spatial resolution and over time.
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Affiliation(s)
- Richard Chalkley
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Frederick Child
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Khalil Al-Thaqafi
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Andrew P Dean
- Department of Natural Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Oxford Road, Manchester, M1 5GD, UK
| | - Keith N White
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK.
| | - Jon K Pittman
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK.
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Aguinaga OE, Wakelin JFT, White KN, Dean AP, Pittman JK. The association of microbial activity with Fe, S and trace element distribution in sediment cores within a natural wetland polluted by acid mine drainage. Chemosphere 2019; 231:432-441. [PMID: 31146135 DOI: 10.1016/j.chemosphere.2019.05.157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 05/14/2019] [Accepted: 05/18/2019] [Indexed: 06/09/2023]
Abstract
Natural recovery and remediation of acid mine drainage (AMD) reduces the generation of acidity and transport of trace elements in the runoff. A natural wetland that receives and remediates AMD from an abandoned copper mine at Parys Mountain (Anglesey, UK) was investigated for better understanding of the remediation mechanisms. Water column concentrations of dissolved Fe and S species, trace metal (loid)s and acidity decreased markedly as the mine drainage stream passed through the wetland. The metal (loid)s were removed from the water column by deposition into the sediment. Fe typically accumulated to higher concentrations in the surface layers of sediment while S and trace metal (loid)s were deposited at higher concentration within deeper (20-50 cm) sediments. High resolution X-ray fluorescence scans of sediment cores taken at three sites along the wetland indicates co-immobilization of Zn, Cu and S with sediment depth as each element showed a similar core profile. To examine the role of bacteria in sediment elemental deposition, marker genes for Fe and S metabolism were quantified. Increased expression of marker genes for S and Fe oxidation was detected at the same location within the middle of the wetland where significant decrease in SO42- and Fe2+ was observed and where generation of particulate Fe occurs. This suggests that the distribution and speciation of Fe and S that mediates the immobilization and deposition of trace elements within the natural wetland sediments is mediated in part by bacterial activity.
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Affiliation(s)
- Oscar E Aguinaga
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK; Departamento de Ingeniería, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - James F T Wakelin
- School of Environment, Education and Development, Faculty of Humanities, The University of Manchester, Arthur Lewis Building, Oxford Road, Manchester M13 9PL, UK
| | - Keith N White
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Andrew P Dean
- Department of Natural Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Oxford Road, Manchester M1 5GD, UK
| | - Jon K Pittman
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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Dean AP, Hartley A, McIntosh OA, Smith A, Feord HK, Holmberg NH, King T, Yardley E, White KN, Pittman JK. Metabolic adaptation of a Chlamydomonas acidophila strain isolated from acid mine drainage ponds with low eukaryotic diversity. Sci Total Environ 2019; 647:75-87. [PMID: 30077857 DOI: 10.1016/j.scitotenv.2018.07.445] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/30/2018] [Accepted: 07/30/2018] [Indexed: 06/08/2023]
Abstract
The diversity and biological characteristics of eukaryotic communities within acid mine drainage (AMD) sites is less well studied than for prokaryotic communities. Furthermore, for many eukaryotic extremophiles the potential mechanisms of adaptation are unclear. This study describes an evaluation of eight highly acidic (pH 1.6-3.1) and one moderately acidic (pH 5.6) metal-rich acid mine drainage ponds at a disused copper mine. The severity of AMD pollution on eukaryote biodiversity was examined, and while the most species-rich site was less acidic, biodiversity did not only correlate with pH but also with the concentration of dissolved and particulate metals. Acid-tolerant microalgae were present in all ponds, including the species Chlamydomonas acidophila, abundance of which was high in one very metal-rich and highly acidic (pH 1.6) pond, which had a particularly high PO4-P concentration. The C. acidophila strain named PM01 had a broad-range pH tolerance and tolerance to high concentrations of Cd, Cu and Zn, with bioaccumulation of these metals within the cell. Comparison of metal tolerance between the isolated strain and other C. acidophila strains previously isolated from different acidic environments found that the new strain exhibited much higher Cu tolerance, suggesting adaptation by C. acidophila PM01 to excess Cu. An analysis of the metabolic profile of the strains in response to increasing concentrations of Cu suggests that this tolerance by PM01 is in part due to metabolic adaptation and changes in protein content and secondary structure.
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Affiliation(s)
- Andrew P Dean
- School of Science and the Environment, Manchester Metropolitan University, Oxford Road, Manchester M1 5GD, UK
| | - Antoni Hartley
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Owen A McIntosh
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Alyssa Smith
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Helen K Feord
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Nicolas H Holmberg
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Thomas King
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Ellen Yardley
- Department of Geography, University of Sheffield, Sheffield S10 2TN, UK
| | - Keith N White
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK; School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Jon K Pittman
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK; School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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Aguinaga OE, McMahon A, White KN, Dean AP, Pittman JK. Microbial Community Shifts in Response to Acid Mine Drainage Pollution Within a Natural Wetland Ecosystem. Front Microbiol 2018; 9:1445. [PMID: 30013541 PMCID: PMC6036317 DOI: 10.3389/fmicb.2018.01445] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 06/11/2018] [Indexed: 01/03/2023] Open
Abstract
Natural wetlands are known to play an important role in pollutant remediation, such as remediating acid mine drainage (AMD) from abandoned mine sites. However, many aspects of the microbiological mechanisms underlying AMD remediation within wetlands are poorly understood, including the role and composition of associated microbial communities. We have utilized an AMD-polluted river-wetland system to perform rRNA sequence analysis of microbial communities that play a role in biogeochemical activities that are linked to water quality improvement. Next-generation sequencing of bacterial 16S rRNA gene amplicons from river and wetland sediment samples identified variation in bacterial community structure and diversity on the basis of dissolved and particulate metal concentrations, sediment metal concentrations and other water chemistry parameters (pH and conductivity), and wetland plant presence. Metabolic reconstruction analysis allowed prediction of relative abundance of microbial metabolic pathways and revealed differences between samples that cluster on the basis of the severity of AMD pollution. Global metabolic activity was predicted to be significantly higher in unpolluted and wetland sediments in contrast to polluted river sediments, indicating a metabolic stress response to AMD pollution. This is one of the first studies to explore microbial community structure dynamics within a natural wetland exposed to AMD and our findings indicate that wetland ecosystems play critical roles in maintaining diversity and metabolic structure of sediment microbial communities subject to high levels of acidity and metal pollution. Moreover, these microbial communities are predicted to be important for the remediation action of the wetland.
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Affiliation(s)
- Oscar E. Aguinaga
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom
| | - Anna McMahon
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom
| | - Keith N. White
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom
| | - Andrew P. Dean
- School of Science and the Environment, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, United Kingdom
| | - Jon K. Pittman
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom
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Michailova P, Ilkova J, Dean AP, White KN. Cytogenetic index and functional genome alterations in Chironomus piger Strenzke (Diptera, Chironomidae) in the assessment of sediment pollution: a case study of Bulgarian and UK rivers. Ecotoxicol Environ Saf 2015; 111:220-227. [PMID: 25450937 DOI: 10.1016/j.ecoenv.2014.10.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/09/2014] [Accepted: 10/10/2014] [Indexed: 06/04/2023]
Abstract
The genotoxicity of trace metals in the sediments from a number of polluted sites on UK and Bulgarian rivers to Chironomus piger was assessed by an examination of genome instability as demonstrated by structural and functional changes to the salivary glands chromosomes. Based on the metal assays, the sediments were characterized to range from 'extremely' to 'strongly contaminated'. The cytogenetic index calculated on the basis of somatic structural chromosome alterations in the polytene chromosomes indicates a high level of pollution (0.07-0.06 in Bulgarian and 0.10-0.13 in UK stations). Exposure of C. piger to contaminated sediments resulted in a high level of chromosome damage as indicated by a somatic index of between 1.96 and 4.0. The transcription mechanism of the Balbiani rings and nucleolar organizer was damaged as their activity was either partially or completely suppressed. We have demonstrated that the C. piger genome is a sensitive sublethal indicator of sediment contamination, and is a highly suitable candidate for ecotoxicological monitoring of running waters.
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Affiliation(s)
- P Michailova
- Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, boulv. Tzar Osvoboditel 1, Sofia 1000, Bulgaria.
| | - J Ilkova
- Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, boulv. Tzar Osvoboditel 1, Sofia 1000, Bulgaria
| | - A P Dean
- Department of Geography, The University of Sheffield, Sheffield S10 2TN, UK
| | - K N White
- Faculty of Life Sciences, University of Manchester, Oxford Road, M13 9PT Manchester, UK
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Dean AP, Lynch S, Rowland P, Toft BD, Pittman JK, White KN. Natural wetlands are efficient at providing long-term metal remediation of freshwater systems polluted by acid mine drainage. Environ Sci Technol 2013; 47:12029-12036. [PMID: 24088022 DOI: 10.1021/es4025904] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study describes the first long-term (14-year) evaluation of the efficacy of an established (>100 years) natural wetland to remediate highly acidic mine drainage (AMD). Although natural wetlands are highly valued for their biodiversity, this study demonstrates that they also provide important ecosystem service functions through their ability to consistently and reliably improve water quality by mitigating AMD. The Afon Goch river flows from Parys Mountain copper mine via a natural wetland, and was the major source of Zn and Cu contamination to the Irish Sea. Prior to 2003 the wetland received severe acidic metal contamination and retained a large proportion of the contamination (55, 64, and 37% in dissolved Fe, Zn, and Cu) leading to a greatly reduced metal flow to the Irish Sea. Reduced wetland loadings midway through the sampling period led to a reduction of metals by 83-94% and a pH increase from 2.7 to 5.5, resulting in long-term improvements in the downstream benthic invertebrate community. High root metal accumulation by the dominant wetland plant species and the association of acidophilic bacteria in the wetland rhizosphere indicate that multiple interacting processes provide an efficient and self-sustaining system to remediate AMD.
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Affiliation(s)
- Andrew P Dean
- Faculty of Life Sciences, University of Manchester , Michael Smith Building, Oxford Road, Manchester M13 9PT, U.K
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McTeer J, Dean AP, White KN, Pittman JK. Bioaccumulation of silver nanoparticles intoDaphnia magnafrom a freshwater algal diet and the impact of phosphate availability. Nanotoxicology 2013; 8:305-16. [DOI: 10.3109/17435390.2013.778346] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
Aluminium (Al) is highly abundant in the environment and can elicit a variety of toxic responses in biological systems. Here we characterize the effects of Al on Caenorhabditis elegans by identifying phenotypic abnormalities and disruption in whole-body metal homeostasis (metallostasis) following Al exposure in food. Widespread changes to the elemental content of adult nematodes were observed when chronically exposed to Al from the first larval stage (L1). Specifically, we saw increased barium, chromium, copper and iron content, and a reduction in calcium levels. Lifespan was decreased in worms exposed to low levels of Al, but unexpectedly increased when the Al concentration reached higher levels (4.8 mM). This bi-phasic phenotype was only observed when Al exposure occurred during development, as lifespan was unaffected by Al exposure during adulthood. Lower levels of Al slowed C. elegans developmental progression, and reduced hermaphrodite self-fertility and adult body size. Significant developmental delay was observed even when Al exposure was restricted to embryogenesis. Similar changes in Al have been noted in association with Al toxicity in humans and other mammals, suggesting that C. elegans may be of use as a model for understanding the mechanisms of Al toxicity in mammalian systems.
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Affiliation(s)
- Kathryn E Page
- The Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA
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Papathanasiou G, White KN, Walton R, Boult S. Toxicity of aluminium in natural waters controlled by type rather than quantity of natural organic matter. Sci Total Environ 2011; 409:5277-5283. [PMID: 21937086 DOI: 10.1016/j.scitotenv.2011.08.064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 08/22/2011] [Accepted: 08/25/2011] [Indexed: 05/31/2023]
Abstract
Extension of the conditions under which Al toxicity is tested is required. Environmentally representative preparation of waters is used in investigating roles of alginate (AA) and humic acids (HA) in partitioning of Al (0.5 mg L(-1)), subsequent uptake and accumulation by and toxicity to Lymnaea stagnalis. HA and AA did not alter precipitation of Al(OH)3, but altered subsequent behaviour of Al. High (40 mg L(-1)) HA concentrations, and to a lesser extent AA, prevented settling and availability for benthic grazing but made deposited Al more likely to be ingested. HA detoxified but AA increased toxicity relative to Al alone. Low concentration (4 mg L(-1)) AA and HA do not change partitioning but increase uptake; they both detoxify, but AA less than HA. The study shows OC:Al ratio is critical in predicting Al behaviour in natural waters, also uptake is mediated by snail behaviour, not solely a function of concentration and form of Al. Therefore, predicting Al behaviour will be subject to errors in determining relevant water composition and response of biota to the new speciation. However, with respect to toxicity, rather than other aspects of Al behaviour, different ratios of HA and Al are insignificant compared to whether AA is present rather than HA.
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Walton RC, McCrohan CR, Livens F, White KN. Trophic transfer of aluminium through an aquatic grazer-omnivore food chain. Aquat Toxicol 2010; 99:93-99. [PMID: 20451262 DOI: 10.1016/j.aquatox.2010.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 03/24/2010] [Accepted: 04/02/2010] [Indexed: 05/29/2023]
Abstract
The potential for trophic transfer of aluminium (Al) was investigated using a grazing detritivore, the freshwater snail Lymnaea stagnalis, and a predator, the signal crayfish Pacifastacus leniusculus. Snails were exposed to either aqueous Al (500 microg l(-1)) in the presence or absence of an inorganic ligand (phosphate (+P); 500 microg l(-1)) for 30 days, or kept as unexposed controls. Subcellular partitioning of Al in the snail tissues was characterised using ultracentrifugation. Al content in the soft tissues and the subcellular fractions was measured using inductively coupled plasma atomic emission spectroscopy. Exposed and control snails were fed to individually housed crayfish (n=6 per group) over 40 days. Water samples, uneaten snail tissue and faeces were collected throughout the experiment in order to assess the fate of Al. Behavioural toxicity to the crayfish was assessed at four time points, and tissue accumulation of Al in soft tissues was measured following a 2-day depuration period. Snails exposed to Al+P accumulated more Al per snail than those exposed to Al only (291 microg vs 206 microg), and also contained a higher proportion of detoxified Al (in inorganic granules and associated with heat stable proteins) (39% vs 26%). There were no significant differences in behavioural activity between the different groups of crayfish at any time point. Crayfish fed snails exposed to only Al accumulated significant levels of Al in their total soft tissues, compared to controls; crayfish fed Al+P-exposed snails did not, even though concentrations of Al in these snails were higher. The highest concentrations of Al were found in the green gland in both crayfish feeding groups, and the gut and hepatopancreas in crayfish fed Al only exposed snails; all of these were significantly higher than in crayfish fed control snails. There was no significant accumulation of Al in the gills or flexor muscle in any group. At least 17% of trophically available Al in the snail tissues was accumulated by the crayfish. This proportion was similar in both feeding groups but, as the proportion of trophically available Al in the snails exposed to Al+P was lower, this led to lower accumulation in the Al+P crayfish feeding group. This study indicates that in comparison to vertebrates, aquatic invertebrates accumulate a higher proportion of Al via oral ingestion but it does not accumulate in tissues that may pose a threat to human consumers.
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Affiliation(s)
- Rachel C Walton
- Faculty of Life Sciences, The University of Manchester, Manchester M13 9PT, UK.
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Walton RC, White KN, Livens F, McCrohan CR. The suitability of gallium as a substitute for aluminum in tracing experiments. Biometals 2009; 23:221-30. [DOI: 10.1007/s10534-009-9280-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Accepted: 11/18/2009] [Indexed: 10/20/2022]
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Walton RC, McCrohan CR, Livens FR, White KN. Tissue accumulation of aluminium is not a predictor of toxicity in the freshwater snail, Lymnaea stagnalis. Environ Pollut 2009; 157:2142-2146. [PMID: 19285770 DOI: 10.1016/j.envpol.2009.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 02/03/2009] [Accepted: 02/08/2009] [Indexed: 05/27/2023]
Abstract
The amount of toxic metal accumulated by an organism is often taken as an indicator of potential toxicity. We investigated this relationship in the freshwater snail, Lymnaea stagnalis, exposed to 500 microg l(-1) Al over 30 days, either alone or in the presence of phosphate (500 microg l(-1) P) or a fulvic acid surrogate (FAS; 10 mg l(-1) C). Behavioural activity was assessed and tissue accumulation of Al quantified. Lability of Al within the water column was a good predictor of toxicity. FAS increased both Al lability and behavioural dysfunction, whereas phosphate reduced Al lability, and completely abolished Al-induced behavioural toxicity. Tissue accumulation of Al was not linked to toxicity. Higher levels of Al were accumulated in snails exposed to Al + P, compared to those exposed to Al alone, whereas FAS reduced Al accumulation. These findings demonstrate that the degree of tissue accumulation of a metal can be independent of toxicity.
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Affiliation(s)
- Rachel C Walton
- Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester M13 9PT, UK.
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16
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Abstract
In a well mixed-stream, in which the iron/organic carbon (OC) ratio varied from 0.333 to 0.05 with sampling point and discharge, 40-70% of the Fe load was found to be present as lightly bound Fe(II). In laboratory simulations of streamwater, after 24 h of aeration at pH 6.5, and with an Fe/OC concentration ratio of 0.417, 97% of Fe(II) was converted to Fe(III) (hydr)oxides, while at a ratio of 0.083, 87% of Fe(ll) remained unoxidized. The particle size distribution of Fe contained < 0.2 microm fractions only when OC was present and comparison of Fe and OC size distributions suggested that there was more than one mechanism by which colloidal Fe was produced. At high Fe/ OC ratios, < 0.2 microm fractions may be predominantly Fe(III) (hydr)oxides stabilized by OC, but at low ratios, they must consist of otherwise soluble Fe(ll) attached to < 0.2 microm OC. The recognition in the field of the consequences of processes demonstrated in the laboratory suggests that OC may be a predominant control of both size and oxidation state of Fe in many natural waters.
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Affiliation(s)
- John W Gaffney
- School of Earth, Atmospheric, and Environmental Sciences, University of Manchester, Manchester M13 9PL, United Kingdom
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White KN, Ejim AI, Walton RC, Brown AP, Jugdaohsingh R, Powell JJ, McCrohan CR. Avoidance of aluminum toxicity in freshwater snails involves intracellular silicon-aluminum biointeraction. Environ Sci Technol 2008; 42:2189-2194. [PMID: 18409657 DOI: 10.1021/es7028608] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Silicon (Si) ameliorates aluminum (Al) toxicity to a range of organisms, but in almost all cases this is due to ex vivo Si-Al interactions forming inert hydroxyaluminosilicates (HAS). We hypothesized a Si-specific intracellular mechanism for Al detoxification in aquatic snails, involving regulation of orthosilicic acid [Si(OH)4]. However, the possibility of ex vivo formation and uptake of soluble HAS could not be ruled out Here we provide unequivocal evidence for Si-Al interaction in vivo, including their intracellular colocalization. In snails preloaded with Si(0H)4, behavioral toxicity in response to subsequent exposure to Al was abolished. Similarly, recovery from Al-induced toxicity was faster when Si(OH)4 was provided, together with rapid loss of Al from the major detoxificatory organ (digestive gland). Temporal separation of Al and Si exposure excluded the possibility of their interaction ex vivo. Elemental mapping using analytical transmission electron microscopy revealed nanometre-scale colocalization of Si and Al within excretory granules in the digestive gland, consistent with recruitment of Si(OH)4, followed by high-affinity Al binding to form particles similarto allophane, an amorphous HAS. Given the environmental abundance of both elements, we anticipate this to be a widespread phenomenon, providing a cellular defense against the profoundly toxic Al(III) ion.
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Affiliation(s)
- Keith N White
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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Ward RJS, McCrohan CR, White KN. Influence of aqueous aluminium on the immune system of the freshwater crayfish Pacifasticus leniusculus. Aquat Toxicol 2006; 77:222-8. [PMID: 16436302 DOI: 10.1016/j.aquatox.2005.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 12/01/2005] [Accepted: 12/05/2005] [Indexed: 05/06/2023]
Abstract
Little is known of the effects of aluminium (Al) on invertebrate immunity despite the ubiquitous nature of the metal and its toxicity to aquatic organisms. Here we examine the effect of Al at neutral pH on the immune system of the freshwater crayfish Pacifasticus leniusculus. Heat-killed bacteria were injected at intervals into the haemolymph of crayfish continuously exposed to a sub-lethal concentration (500 microg l(-1)) of Al over 40 days. Circulating haemocyte and bacterial numbers were monitored for 16 days post-injection at each time interval. In the absence of bacterial challenge, the number of circulating haemocytes increased in Al-exposed crayfish compared to unexposed controls. Aluminium exposure initially reduced the crayfish's ability to clear bacteria from the circulation and decreased the rate of recovery in haemocyte numbers following bacterial challenge. These effects on bacterial and haemocyte numbers were abolished after prolonged exposure (>10 days) to Al, indicating adaptation to the metal. Aqueous Al impairs gill function in P. leniusculus by inducing hypersecretion of mucus and we suggest that the decrease in immunocompetence is due to haemolymph hypoxia. We conclude that exposure to episodic pulses of aqueous Al over the short term (<10 days) increases the risk of infection in the crayfish by impairing the ability of haemocytes to recognise and/or remove bacteria from the circulation.
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Dobranskyte A, Jugdaohsingh R, McCrohan CR, Stuchlik E, Powell JJ, White KN. Effect of humic acid on water chemistry, bioavailability and toxicity of aluminium in the freshwater snail, Lymnaea stagnalis, at neutral pH. Environ Pollut 2006; 140:340-7. [PMID: 16242225 DOI: 10.1016/j.envpol.2005.06.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Accepted: 06/30/2005] [Indexed: 05/05/2023]
Abstract
The influence of humic acid on the water chemistry of environmentally relevant concentrations of Al at neutral pH was studied, together with its effect on the bioavailability and toxicity of Al in Lymnaea stagnalis. Humic acid significantly reduced the loss of Al from the water and increased the fraction of filterable Al, although this was a relatively small fraction of total Al. Filterable Al concentration in the presence or absence of humic acid was independent of initial Al concentration. Humic acid only partly reduced toxicity, as observed by a reduction in behavioural suppression, and had no effect on the level of Al accumulated in tissues. These results suggest that humic acid maintains Al in a colloidal form that is bioavailable to L. stagnalis. However, these colloidal Al-humic acid species were less toxic since behavioural toxicity was reduced. Humic acid may play an important role in limiting the toxicity of Al to freshwater organisms.
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Affiliation(s)
- A Dobranskyte
- Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester M13 9PT, UK
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Tien CJ, Sigee DC, White KN. Characterization of surface sugars on algal cells with fluorescein isothiocyanate-conjugated lectins. Protoplasma 2005; 225:225-33. [PMID: 16228900 DOI: 10.1007/s00709-005-0092-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Accepted: 10/26/2004] [Indexed: 05/04/2023]
Abstract
We used qualitative and quantitative fluorescence microscopy of the fluorescein isothiocyanate-conjugated lectins Concanavalin A, phytohaemagglutinin-erythroagglutinin, pokeweed mitogen, and peanut agglutinin to examine sugar composition on the cell surface and cell-associated mucilage (where present) in a number of cultured and environmental algae. Lectin-binding activity was markedly different between laboratory-cultured and environmental samples of the same species. Sugar composition of the cyanobacterium Anabaena cylindrica varied with growth cycle, although no clear pattern of change was observed. Akinetes typically showed lectin-binding activity higher than that of the vegetative cells or heterocysts throughout the growth cycle. Algae with mucilage showed greater lectin binding, indicating that mucilage contained more surface sugars accessible to the lectin probe compared with the cell wall surface. A low level of galactose and N-acetyl galactosamine (detected by peanut agglutinin) was associated with the surface mucilage of most algal species. Relatively high amounts of mannose, glucose, and N-acetyl glucosamine (detected by Concanavalin A, phytohaemagglutinin, and pokeweed mitogen) were also present. Lectin binding was shown to be a highly specific and sensitive approach to the examination of cell surface chemistry of both cultured and environmental algae and to the study of biodiversity in phytoplankton.
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Affiliation(s)
- C-J Tien
- Department of Industrial Safety and Hygiene, Chung Hwa College of Medical Technology, Jen-Te Hsiang
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Dobranskyte A, Jugdaohsingh R, Stuchlik E, Powell JJ, White KN, McCrohan CR. Role of exogenous and endogenous silicon in ameliorating behavioural responses to aluminium in a freshwater snail. Environ Pollut 2004; 132:427-433. [PMID: 15325458 DOI: 10.1016/j.envpol.2004.05.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Accepted: 05/21/2004] [Indexed: 05/24/2023]
Abstract
Aluminium accumulation by the freshwater snail Lymnaea stagnalis is correlated with behavioural depression which is ameliorated by addition of orthosilicic acid. We hypothesised that Si is relocated to the digestive gland in response to Al, leading to the formation of non-toxic hydroxyaluminosilicates (HAS). Exposure to 500 microg l(-1) Al for 30 days was associated with an initial period of behavioural depression, followed by apparent tolerance and subsequent depression, suggesting saturation of the cellular detoxification pathway during prolonged exposure. Exogenous Si (7.77 mg l(-1)) completely ameliorated all behavioural effects of Al but did not prevent its accumulation. In the presence of added Al, significantly more of this Si was accumulated by the tissues, compared to controls and snails exposed to Si alone. In snails exposed to Al plus Si, Al and Si concentrations were significantly correlated, with a ratio around 3:1 Al:Si, consistent with the presence of the non-toxic HAS protoimogolite.
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Affiliation(s)
- A Dobranskyte
- School of Biological Sciences, University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester M13 9PT, UK
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Du M, Wu XJ, Ding J, Hu ZB, White KN, Branford-White CJ. Astragaloside IV and polysaccharide production by hairy roots of Astragalus membranaceus in bioreactors. Biotechnol Lett 2004; 25:1853-6. [PMID: 14677711 DOI: 10.1023/a:1026233728375] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Hairy roots of Astragalus membranaceus were grown in bioreactors up to 30 l for 20 d. Cultures from a 30 l airlift bioreactor gave 11.5 g l dry wt with 1.4 mg g(-1) astragaloside IV, similar to cultures from 250 ml and 1 l flasks, but greater than yields from a 10 l bioreactor (dry wt 9.4 g l(-1), astragaloside IV 0.9 mg g(-1)). Polysaccharide yields were similar amongst the different bioreactors (range 25-32 mg g(-1)). The active constituent content of the cells approached that of plant extracts, indicating that large scale hairy root cultures of A. membranaceus has the potential to provide an alternative to plant crops without compromising yield or pharmacological potential.
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Affiliation(s)
- M Du
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Box 67, No. 530 Lingling Road, Shanghai 200032, PR China.
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Ballance S, Howard M, White KN, McCrohan CR, Thornton DJ, Sheehan JK. Partial characterisation of high-molecular weight glycoconjugates in the trail mucus of the freshwater pond snail Lymnaea stagnalis. Comp Biochem Physiol B Biochem Mol Biol 2004; 137:475-86. [PMID: 15081999 DOI: 10.1016/j.cbpc.2004.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2003] [Revised: 01/04/2004] [Accepted: 02/06/2004] [Indexed: 11/26/2022]
Abstract
We have studied the glycoconjugates in trail mucus of the pond snail Lymnaea stagnalis. The mucus was dissolved with 6 M guanidinium hydrochloride (GuHCl) and the major component was comprised of very high-M(r) glycoconjugates that were eluted in the void volume of a Sepharose CL-4B gel-filtration column. This high-M(r) material was pooled and thereafter subjected to density gradient centrifugation first in 4 M GuHCl/CsCl and subsequently 0.2 M GuHCl/CsCl to further remove non-glycosylated proteins and DNA. The harvested glycoconjugate pool chromatographed in the void volume of Sepharose CL-2B. However, reduction of disulfide bonds lowered the molecular size of approximately 80% of the void material yielding a major fragment and some minor smaller fragments in gel chromatography. The reduced glycoconjugates were digested with papain and yielded high molecular weight, proteinase-resistant glycopeptides. This fragmentation pattern is similar to that found for oligomeric gel-forming mucins in mammals and the amino acid composition (60% Ser/Thr) and sugar analysis of the glycopeptides is consistent with mucin-like molecules, there being no significant amounts of xylose or uronic acids. The residual 20% of the preparation, which apparently resisted reduction and protease digestion, had a similar amino acid composition to the bulk, but was somewhat different in sugar composition, containing some xylose and a significant amount of glucuronic acid. The two groups of molecules had very different morphologies in the electron microscope. Taken together, these data suggest that trail mucus is a complex mixture of at least two families of protein-glycoconjugate molecules based upon the gel-forming mucin and proteoglycan families, though we cannot rule out that polysaccharides may also be present.
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Affiliation(s)
- Simon Ballance
- School of Biological Sciences, University of Manchester, Manchester M13 9PL, UK.
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Alexopoulos E, McCrohan CR, Powell JJ, Jugdaohsingh R, White KN. Bioavailability and toxicity of freshly neutralized aluminium to the freshwater crayfish Pacifastacus leniusculus. Arch Environ Contam Toxicol 2003; 45:509-514. [PMID: 14708667 DOI: 10.1007/s00244-003-0228-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Freshly neutralized aluminium (Al) is toxic to a variety of freshwater organisms despite its insolubility at circumneutral pH. Insoluble Al acts exogenously--for example, on the fish gill--thereby impairing respiratory function, and endogenously in grazing and filter-feeding invertebrates following ingestion during drinking and feeding. This paper examines the bioavailability and behavioral toxicity of freshly neutralized Al to the freshwater crayfish Pacifastacus leniusculus exposed to 500 microg L(-1) added Al for 20 days under controlled conditions. We test the hypothesis that aqueous Al is toxic to the crayfish and that this is largely due to the metal's association with the gill rather than following accumulation in the body. Little Al was accumulated in the digestive gland (hepatopancreas) or flexor muscle, but large amounts were associated with the gills, resulting in concentration factors of up to 1 x 10(4). Histochemistry showed that much of this metal was extracellular to the gill epithelium and associated with the mucus layer. Behavioral dysfunction was observed following exposure to Al for five days. Reduction in the amount of Al in the water column, due to binding to snail trail mucus attached to the substrate, reduced the amount of Al associated with the gill and delayed the onset of behavioral dysfunction. We conclude that freshly neutralized Al is toxic to the crayfish and that main site of Al action is the gill.
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Affiliation(s)
- E Alexopoulos
- School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
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Desouky MM, McCrohan CR, Jugdaohsingh R, Powell JJ, White KN. Effect of orthosilicic acid on the accumulation of trace metals by the pond snail Lymnaea stagnalis. Aquat Toxicol 2003; 64:63-71. [PMID: 12763676 DOI: 10.1016/s0166-445x(03)00027-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Silicon (Si) has a marked affinity for aluminium (Al(III)), but not other trace metals such as cadmium (Cd(II)) and zinc (Zn(II)). Exogenous orthosilicic acid (Si(OH)(4)) ameliorates the toxicity of Al(III) to the pond snail Lymnaea stagnalis, but its mechanism of action is unclear. Here, studies were conducted to ascertain whether interaction between orthosilicic acid and Al(III) occurs in the water column to prevent Al(III) uptake, or in the tissues to reduce the toxicity of accumulated metal. Silicon did not reduce the accumulation of Al(III) by the digestive gland (the main "sink" for trace metals in L. stagnalis) following exposure of the snail for 30 days to 500 microg l(-1) added Al(III) and 13-fold molar excess of orthosilicic acid. However, Si concentrations correlated well with Al(III) levels in the digestive gland (R(2)=0.77), giving a ratio of 2.5:1 (Al(III):Si). Exposure to Zn(II) or Cd(II) and 13-fold molar excess of orthosilicic acid did not prevent uptake of these metals, or result in a correlation between metal and Si concentrations of the snail digestive gland. These data show that aquated orthosilicic acid does not prevent Al(III) accumulation by L. stagnalis. However, following exposure, the ratio of Al(III) to Si in the digestive gland is suggestive of the early formation of hydroxyaluminosilicates, probably proto-imogolites (2-3:1 Al(III):Si). Whether hydroxyaluminates are formed ex vivo in the water column and taken up by snails into the digestive gland, or formed in situ within the digestive gland remains to be established. Either way, orthosilicic acid clearly prevents the in vivo toxicity of Al(III) rather than reducing its uptake. Silicon appears to have an important role in the handling Al(III) by the pond snail which may also have wider relevance in understanding the role of Si in ameliorating Al(III) toxicity.
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Kádár E, Salánki J, Powell J, White KN, McCrohan CR. Effect of sub-lethal concentrations of aluminium on the filtration activity of the freshwater mussel Anodonta cygnea L. at neutral pH. Acta Biol Hung 2003; 53:485-93. [PMID: 12501933 DOI: 10.1556/abiol.53.2002.4.9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Significant amounts of aluminium (Al) are commonly present in rivers and lakes, largely in particulate form in neutral waters. Freshwater bivalves, as filter feeders are therefore exposed to both particulate and dissolved metal and are potentially vulnerable to Al. The effect of Al on filtering behaviour of the freshwater mussel Anodonta cygnea L. was investigated during short (1 hour) and long-term (15 days) exposure to environmentally relevant concentrations (250 and 500 microg l(-1)) at neutral pH. Water flow through the outflow siphon was monitored as an indicator of pumping capacity. Short-term (1 hour) exposure to 500 microg l(-1) added Al produced an irreversible decrease in the duration of filtering periods, presumably as an avoidance response to the toxicant. One-hour exposure 250 microg l(-1) Al had no detectable effect. When mussels were exposed to 250 or 500 microg l(-1) added Al for 15 days, siphon activity measured in days 11-15 of exposure was inhibited by 50% and 65%, respectively, compared to pre-exposure levels. Recovery occurred following transfer of mussels to uncontaminated water. Interaction between Al and freshwater bivalves at neutral pH may affect both the performance of the mussels and the chemical speciation of the metal in the natural environment.
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Affiliation(s)
- Eniko Kádár
- School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK.
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Michailova P, Ilkova J, White KN. Functional and structural rearrangements of salivary gland polytene chromosomes of Chironomus riparius Mg. (Diptera,Chironomidae) in response to freshly neutralized aluminium. Environ Pollut 2003; 123:193-207. [PMID: 12628199 DOI: 10.1016/s0269-7491(02)00405-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Although recent work has shown that environmentally relevant concentrations of freshly neutralized aluminium (AI) are bioavailable and toxic to freshwater invertebrates, the genotoxicity of Al has not been examined. Here we show that freshly neutralized Al affects structure and function of the salivary gland polytene chromosomes of the ubiquitous chironomid larva Chironomus riparius over three generations. Exposure to 500 microg l-1 added Al for 24-25 days resulted in a significantly higher frequency of numerous somatic aberrations, while no structural aberrations were found in F1 controls and few in the second and third generation. Aberrations also included deletions of sections of chromosome G of C. riparius larvae as well as deletions of one or more Balbiani rings. Changes in functional activity included decreased activity of the Balbiani rings (BR), and an increase in the number of decondensed centromeres. The activity of the nucleolar organizer (NOR) significantly decreased in F1 chironomids exposed to Al, while in the F2 and F3 generations the NOR showed normal (high) activity. First generation chironomids were generally more susceptible to Al although no clear evidence of tolerance was apparent over three generations. The possible use of alterations in chironomid polytene chromosomes as biomarkers of trace metal pollution is discussed.
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Affiliation(s)
- P Michailova
- Institute of Zoology, Bulgarian Academy of Sciences, 1 Tzar Osvoboditel Boulevard. Sofia 1000, Bulgaria
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Desouky MM, Powell JJ, Jugdaohsingh R, White KN, McCrohan CR. Influence of oligomeric silicic and humic acids on aluminum accumulation in a freshwater grazing invertebrate. Ecotoxicol Environ Saf 2002; 53:382-387. [PMID: 12485582 DOI: 10.1016/s0147-6513(02)00015-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This study examined the influence of oligomeric silicic acid and humic acid on aluminum in the water column and its accumulation in the freshwater snail Lymnaea stagnalis. Forty-eight hours after addition of Al (500 microg L(-1)), 83% of the metal was lost from the water column. This loss was reduced by oligomeric silica (20 mg L(-1)) and by humic acid (10 mg L(-1)). Aluminum accumulated in the digestive gland and, to a lesser extent, in the remaining soft tissues, and this accumulation was reduced by oligomeric silica. In the presence of humic acid, Al accumulation in the digestive gland was unaffected, though less was accumulated in the remaining tissues. Snails accumulated Si preferentially in the digestive gland and this accumulation was increased in the presence of added Al. Thus, both oligomeric silica and humic acid influence Al bioavailability and Si is upregulated in the digestive gland in the presence of Al.
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Affiliation(s)
- M M Desouky
- School of Biological Sciences, University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester, UK
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Abstract
This study examined the interaction of mollusc trail mucus, and its biochemical constituents, with environmentally relevant concentrations of freshly neutralised aluminium (Al) in freshwater. Upon neutralisation Al starts to polymerise. In the presence of mucus the metal is rapidly localised into the hydrated mucus gel resulting in a likely reduction of its overall degree of polymerisation. A simple Al binding assay identified large-M(r) glycoconjugates as major Al-complexing molecules in mucus. Subsequent isolation and purification of these mucus glycoconjugates showed the metal readily bound to the carbohydrate portion and, in particular, to acidic components such as those containing carboxyl functionality. It is suggested gel-forming extracellular glycoconjugates play a crucial role in preventing the diffusion of Al into biological systems and thus serve to maintain metabolic homeostasis.
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Affiliation(s)
- Simon Ballance
- School of Biological Sciences, University of Manchester, Oxford Rd., Manchester, UK
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30
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Abstract
Cellular iron homoeostasis is maintained by iron sensor proteins known as iron-regulatory proteins (IRPs), which act post-transcriptionally by binding RNA stem-loop structures, termed iron-responsive elements (IREs), present on the mRNAs of proteins involved in iron storage, utilization and transport. IRP1 is a bifunctional protein that can act either as a cytoplasmic aconitase or as an IRE-binding protein. The RNA-binding activity of IRP1 is regulated post-translationally by the insertion or extrusion of a 4Fe-4S cluster, without changes in the levels of protein. In hereditary haemochromatosis (HH) accumulation of iron in parenchymal tissues, including the liver, occurs, possibly through dysfunctional IRP1. Investigation of IRP1 expression in liver biopsies from HH patients showed that the protein is completely absent or markedly reduced in heavily iron-loaded HH patients. Real-time PCR was then conducted in an attempt to investigate the mRNA levels and establish the underlying mechanism behind the disappearing act of IRP1. The two possibilities are: transcriptional regulation (through the inhibition of transcription) or post-transcriptional regulation (either through increased turnover of protein or inhibition of translation) of IRP1. Preliminary data suggest that transcription of IRP1 is not affected by chronic iron overload, and down-regulation may be attributable instead to degradation of the protein.
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Affiliation(s)
- M Neonaki
- Institute of Liver Studies, Guy's, King's and St Thomas' School of Medicine, King's College Hospital, Bessemer Road, London SE5 9PJ, UK.
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31
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Desouky M, Jugdaohsingh R, McCrohan CR, White KN, Powell JJ. Aluminum-dependent regulation of intracellular silicon in the aquatic invertebrate Lymnaea stagnalis. Proc Natl Acad Sci U S A 2002; 99:3394-9. [PMID: 11891333 PMCID: PMC122534 DOI: 10.1073/pnas.062478699] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Silicon is essential for some plants, diatoms, and sponges but, in higher animals, its endogenous regulation has not been demonstrated. Silicate ions may be natural ligands for aluminum and here we show that, in the freshwater snail (Lymnaea stagnalis), intracellular silicon seems specifically up-regulated in response to sublethal aluminum exposure. X-ray microanalysis showed that exposure of snails to low levels of aluminum led to its accumulation in lysosomal granules, accompanied by marked up-regulation of silicon. Increased lysosomal levels of silicon were a specific response to aluminum because cadmium and zinc had no such effect. Furthermore, intra-lysosomal sulfur from metallothionein and other sulfur-containing ligands was increased after exposure to cadmium and zinc but not aluminum. To ensure that these findings indicated a specific in vivo response, and not ex vivo formation of hydroxy-aluminosilicates (HAS) from added aluminum (555 microg/liter) and water-borne silicon (43 microg/liter), two further studies were undertaken. In a ligand competition assay the lability of aluminum (527 microg/liter) was completely unaffected by the presence of silicon (46 microg/liter), suggesting the absence of HAS. In addition, exogenous silicon (6.5 mg/liter), added to the water column to promote formation of HAS, caused a decrease in lysosomal aluminum accumulation, showing that uptake of HAS would not explain the loading of aluminum into lysosomal granules. These findings, and arguments on the stability, lability, and kinetics of aluminum-silicate interactions, suggest that a silicon-specific mechanism exists for the in vivo detoxification of aluminum, which provides regulatory evidence of silicon in a multicellular organism.
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Affiliation(s)
- Mahmoud Desouky
- School of Biological Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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32
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Kádár E, Salánki J, Jugdaohsingh R, Powell JJ, McCrohan CR, White KN. Avoidance responses to aluminium in the freshwater bivalve Anodonta cygnea. Aquat Toxicol 2001; 55:137-148. [PMID: 11595304 DOI: 10.1016/s0166-445x(01)00183-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This study examined the effect of aluminium (Al) on the filtering behaviour (shell opening or gape) of the freshwater bivalve Anodonta cygnea L in neutral fresh water. Parallel measurements of Al concentration in the soft tissues were made to examine the relationship between changes in behaviour and accumulation of Al. The number of lysosomal granules in the gill, kidney and digestive gland were counted, as lysosomes are known to be involved in the excretion and detoxification of trace metals. The bivalves were exposed to two environmentally relevant concentrations of added Al i.e. 250 and 500 microg l(-1) (9.25 and 18.5 microM l(-1)) at neutral pH for 15 days and shell movement monitored continuously. Aluminium affected the mussels' filtering activity, producing an avoidance reaction whose magnitude was concentration-dependent; 250 microg l(-1) added Al produced no detectable change, while 500 microg l(-1) Al reduced mean duration of shell opening by 50%. This effect was irreversible over a 15 day recovery period. Tissue levels of Al after 15 days exposure were an order of magnitude higher in animals exposed to 250 microg l(-1) added Al than in those exposed to 500 microg l(-1). This was consistent with the inhibition of filtering activity due to valve closure at the higher concentration, which may have prevented uptake of Al. In addition, probable different chemical speciation of Al in the water column (soluble for 250 and colloidal for 500 microg l(-1)) may lead to marked differences in tissue uptake. The kidney and digestive gland were the main sites of accumulation of Al and concentrations remained significantly elevated 15 days after transfer of animals to clean water. It is suggested that mucus plays a role in the exclusion of Al as elevated concentrations were measured in the pseudofaeces of animals during and after exposure. Lysosomal granules may be involved in the intracellular handling and detoxification of Al as numbers increased significantly in all organs during exposure and continued to increase after the animals were transferred to clean water. The present study provides evidence for the bioavailability and toxicity of Al to mussels at neutral pH and at concentrations which are known to enter neutral freshwaters when mobilised by natural or anthropogenic acidity. The changes in behaviour and uptake of Al in the mussel observed in this investigation are, therefore, likely to be reflected in the natural environment and the degree to which Al affects the 'fitness' of the mussel populations and the transfer of Al through the food chain merit investigation.
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Affiliation(s)
- E Kádár
- School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK
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33
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Jugdaohsingh R, Salim N, McCrohan CR, White KN, Thompson RP, Powell JJ. Rapid non-equilibrium aluminium-ligand interactions: studies on the precipitation of aluminium by laser light scattering, ultrafiltration and centrifugation. J Inorg Biochem 2001; 87:29-35. [PMID: 11709210 DOI: 10.1016/s0162-0134(01)00311-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The study aimed to develop simple assays to study aluminium-ligand interactions in natural/biological systems where equilibrium is rarely reached and thus where the initial seconds or hours of interactions are important. The immediate and non-equilibrium precipitation of aluminium hydroxide, in aqueous solution at neutral pH, was therefore studied by laser light scattering (diffraction), ultrafiltration and centrifugation. The interaction of weak ligands, present in the gastrointestinal lumen, on the precipitation of aluminium hydroxide was also investigated. The initial kinetics and particle sizes of precipitated aluminium hydroxide were sensitive to a number of external factors, including the presence of weak ligand (bicarbonate), sheer force (stirring), electrolyte concentration and initial (i.e. added) aluminium concentration. However, after a few seconds (no weak ligand), or several hundred seconds (with weak ligand), the subsequent observed changes to the solid phase were of small magnitude and occurred slowly. Thus, a 25-min window, within 5 and 30 min of pH adjustment, can be used to study the interactions of aluminium-ligand. This may approximate better to most natural systems where unperturbed aluminium-ligand equilibrium must rarely exist.
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Affiliation(s)
- R Jugdaohsingh
- Gastrointestinal Laboratory, Rayne Institute, St. Thomas' Hospital, London SE1 7EH, UK
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34
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Bloor BK, Jelvagharan M, White KN, Odell EW. Characterization of CD44 splicing patterns in normal keratinocytes, dysplastic and squamous carcinoma cell lines. Int J Oncol 2001; 18:1053-9. [PMID: 11295056 DOI: 10.3892/ijo.18.5.1053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The CD44 glycoprotein is spliced from a complex gene of 10 constitutive and 10 variant exons. In this study, CD44 splicing patterns and intron 9 retention were investigated by exon-specific RT-PCR for variant exons v1-v10 and intron 9 in normal, immortalized, dysplastic and malignant keratinocytes. Expression of product was determined immunohistochemically for some of the exons. Normal keratinocytes showed one major transcript including exons v2-v10 and 3 minor transcripts. No lines showed a normal CD44 splicing pattern but rather a variety of truncated transcripts of contiguous variant exons which overall correlated with expression. Squamous cell carcinoma (SCC)-4 and SCC-9 lines showed relatively normal transcripts although protein was expressed only by SCC-9. SCC-12B2, SCC-15, SCC-25 and SCC-27 showed a series of shorter overlapping transcripts, with loss of exons v8-v10 in the major transcripts. Intron 9 was not retained in normal keratinocytes or cell lines. Despite the fact that keratinocytes constitutively express all variant exons, splicing patterns are distinctly abnormal and merit investigation as potential markers for epidermal and oral squamous malignancy.
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Affiliation(s)
- B K Bloor
- Head & Neck Cancer Research Program, Guy's, King's & St. Thomas' Dental Institute, King's College London, UK
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35
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McCrohan CR, Campbell MM, Jugdaohsingh R, Ballance S, Powell JJ, White KN. Bioaccumulation and toxicity of aluminium in the pond snail at neutral pH. Acta Biol Hung 2001; 51:309-16. [PMID: 11034154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The low solubility of aluminium (Al) at neutral pH means that it largely exists as colloidal particulates in aquatic systems. However, the pond snail Lymnaea stagnalis accumulates significant amounts of Al following exposure to water containing added Al (up to 500 microg l(-1)) at pH 7. This is accompanied by depression of behavioural activity (locomotion, feeding) which subsequently recovers, suggesting tolerance to the metal. The presence of silica ameliorates behavioural toxicity of Al, but does not prevent uptake of the metal. In vitro studies using the isolated central nervous system demonstrate toxicity at the cellular level. Extracellular application of Al (100 microM) led to membrane depolarisation, bursts of action potentials and action potential broadening. The chemical form in which Al is applied influences the extent of bioaccumulation and toxicity. Detailed knowledge of its solution chemistry is therefore essential.
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Affiliation(s)
- C R McCrohan
- School of Biological Sciences, University of Manchester, UK.
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36
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Abstract
BACKGROUND Given that 90% of hip fractures result from a fall, individuals who fall frequently are more likely to be at greater risk for fracture than one-time fallers. Our aim was to determine whether performance variables associated with injurious falls could be used to distinguish frequent fallers from both one-time fallers and nonfallers. METHODS A total of 157 men and women (77.4-5.4 years) were recruited and categorized into one of the following three groups based on falls status over the previous 12 months: nonfallers (n = 48), one-time fallers (n = 56), and frequent fallers (more than one fall) (n = 53). All subjects were evaluated on functional mobility and lower extremity strength and power. RESULTS Using multivariate analysis of covariance with height as a covariate, nonfallers were significantly faster than both one-time and frequent fallers during the Get Up and Go (a test involving lower extremity strength and power, and mobility) and faster than one-time fallers on the Tandem Gait (p < .01). There were no significant differences between groups for other mobility variables or for laboratory measures of strength and power. Because one-time and frequent fallers were similar on all measures. they were grouped as "fallers" in discriminant analysis. The Get Up and Go discriminated between the fallers and nonfallers with a final Wilks's Lambda of .900 (p < .001) and correctly classified 72.4% of fallers and nonfallers before crossvalidation and 71.2% of the cases after validation. CONCLUSIONS Given that the Get Up and Go discriminates between fallers and nonfallers and is associated with lower extremity strength and power, fall prevention strategies should focus on improving both functional mobility and lower extremity strength and power.
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Affiliation(s)
- K B Gunter
- Bone Research Laboratory, Oregon State University, Corvallis 97330, USA
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37
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Abstract
This article examines the development of general practice in the latter half of the 20th century, documenting the issues of concern to both the profession and the state. General practice developed hand in hand with the welfare state in Australia. As the structural changes associated with restructuring of the welfare state have advanced, so have the fortunes of general practice declined, despite significant attempts in the 1970s and 1980s to "save" general practice by both the profession and the state. These structural changes have operated on two fronts, the economic and the cultural. On the economic, changes to the employment of general practitioners clearly indicate ongoing proletarianization, particularly in a changing environment of labor-capital relations. At the cultural level, development of the self-help and the women's movements and the elective affinity of these groups with the individualism of the new right are leading to deprofessionalization. The author advances this argument in a review of general practice over the last 40 years and in a case study of community health services. Theoretically he argues for a combination of the proletarianization and the deprofessionalization theses.
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Affiliation(s)
- K N White
- Department of Sociology, Faculty of Arts, Australian National University, Acton, ACT, Australia
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38
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Campbell MM, Jugdaohsingh R, White KN, Powell JJ, McCrohan CR. Aluminum toxicity in a molluscan neuron: effects of counterions. J Toxicol Environ Health A 2000; 59:253-270. [PMID: 10706033 DOI: 10.1080/009841000156925] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Previous studies using the freshwater snail Lymnaea stagnalis have indicated significant accumulation of aluminum (Al) from simple salts (chloride or nitrate) or Al lactate [Al(lactate)3 preparations, but not from the Al maltol complex [Al(maltol)3]. This is in contrast to findings in mammalian systems, where uptake and neurotoxicity are greatest for the soluble and lipophilic Al(maltol)3 complex. This study was undertaken to investigate the direct effects of extracellular Al (100 microM) from three Al preparations [AlCl3, Al(lactate)3 and Al(maltol)3] on electrophysiological parameters of an identified neuron, the right parietal dorsal 1 (RPD1) neuron, of L. stagnalis in vitro. The effects of the corresponding counterion/ligand on the solubility and availability of Al in solution were also examined. Significant effects of Al on electrical properties, including membrane depolarization, increased firing activity, and abnormal firing patterns, were seen in the presence of AlCl3 and Al(lactate)3, which formed polyhydroxy and labile Al species in aqueous solution, but not with Al(maltol)3, which remained as the soluble monomeric complex. Qualitative differences were also observed between the response to AlCl3 and Al(lactate)3, despite their similar chemistry. The extent of action potential broadening was greater with Al(lactate)3, suggesting some interaction between Al and lactate in their cellular uptake and/or toxicity. It is suggested that polyhydroxy Al species are toxic to molluscan neurons, possibly via disruption of intracellular Ca2+ homeostasis.
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Affiliation(s)
- M M Campbell
- School of Biological Sciences, University of Manchester, United Kingdom
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39
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Elangovan R, McCrohan CR, Ballance S, Powell JJ, White KN. Localization and fate of aluminium in the digestive gland of the freshwater snail Lymnaea stagnalis. Tissue Cell 2000; 32:79-87. [PMID: 10798321 DOI: 10.1054/tice.1999.0089] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The digestive gland of the freshwater snail Lymnaea stagnalis, exposed to water containing an elevated concentration of aluminium at neutral pH for up to 30 days, followed by a 20 day recovery period, was examined by light and electron microscopy and X-ray microanalysis. Aluminium was localized in the yellow granules present in the digestive and excretory cells and in the green and small granules present in the digestive cells. More aluminium, silicon, phosphorus and sulphur were present in all three granule types from aluminium exposed snails. The number of yellow and green granules from the digestive gland of aluminium exposed snails showed a progressive increase over the experimental period compared to controls. The number and aluminium content of the granules is likely to reflect the role of the digestive gland as a 'sink' for accumulated aluminium. We propose that intracellular monomeric silica is involved in the detoxification of aqueous aluminium which at neutral pH is largely in the form of an insoluble polyhydroxide. The increased amounts of sulphur and phosphorus in the granules are likely to be part of a broad response to metal loading but probably do not play a significant role in the storage and detoxification of aluminium.
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Affiliation(s)
- R Elangovan
- School of Biological Sciences, University of Manchester, UK
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40
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Elangovan R, Ballance S, White KN, McCrohan CR, Powell JJ. Accumulation of aluminium by the freshwater crustacean Asellus aquaticus in neutral water. Environ Pollut 1999; 106:257-263. [PMID: 15093021 DOI: 10.1016/s0269-7491(99)00117-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/1998] [Accepted: 05/04/1999] [Indexed: 05/24/2023]
Abstract
This study examined the accumulation of aluminium (Al), mostly as the insoluble (Al(OH)(3)) species, by the freshwater crustacean Asellus aquaticus at neutral pH. Animals were exposed to a range of Al concentrations (5-356 microg l(-1)) in three experiments. The first two were of 30 and 50 days duration, respectively, followed by transfer of the A. aquaticus to water containing no Al for 20 days. The third used live and dead animals in order to investigate the contribution made by surface adsorption of Al to the total accumulated. Significant accumulation of Al in the whole tissues occurred by day 10 in all animals in the 30- and 50- day experiment. Peak concentrations of Al were measured in animals between days 10 and 20 with high concentration factors ranging from 1.4 x 10(4) to 5.5 x 10(3). By day 30, accumulated Al had fallen but was still significantly greater than the control in the 50- day exposure experiment. This 30- day increase followed by decreased accumulation of Al was repeated over the remaining exposure period (i.e. 30-50 days) although rates of uptake and loss and peak tissue levels of Al were higher. Proportionality between environmental (water) and tissue concentrations of Al occurred at day 20 but not at day 45. Significantly more Al was accumulated by dead animals than live animals at all Al exposure concentrations. These results suggest that Al is available to the crustacean at neutral pH and that the cuticle may provide an important site of uptake.
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Affiliation(s)
- R Elangovan
- School of Biological Sciences, 1.124 Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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41
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White KN. Negotiating science and liberalism: medicine in nineteenth-century South Australia. Med Hist 1999; 43:173-191. [PMID: 10885138 PMCID: PMC1044731 DOI: 10.1017/s0025727300065078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- K N White
- Department of Sociology, Australian National University, Acton, Australia
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42
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Barsyte D, White KN, Lovejoy DA. Cloning and characterization of metallothionein cDNAs in the mussel Mytilus edulis L. digestive gland. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 1999; 122:287-96. [PMID: 10190057 DOI: 10.1016/s0742-8413(98)10126-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Metallothioneins are small metal-binding proteins found in all species of animals and are transcriptionally-induced by heavy metal ions, oxidative stresses, and inflammation. In the blue sea mussel, Mytilus edulis, several apparent subtypes of each isoform have been purified and biochemically sequenced. To determine whether the high number of metallothionein forms present in M. edulis were specific to the digestive gland, and to understand how these proteins evolved, we cloned five variants of metallothionein from M. edulis. MT10 and MT20 isoform fragments were amplified by PCR, and used as radiolabelled probes to screen digestive gland cDNA libraries. The MT10 transcripts were 321-353 nucleotides long and the MT20 transcripts, 513-555 nucleotides. Previously identified primary structures of MT10 subtypes were confirmed and, in addition, a novel subtype was identified. Expression of MT10 and MT20 isoforms shown by clonal representation and Northern blot analysis indicated that the MT10 message was more prevalent than the MT20 message. Only the MT20 II transcript could be identified among the MT20 clones. The high degree of untranslated region similarity between each isoform indicates that these additional forms are recent gene duplication events in the Mytilus lineage. Exposure of 0.4 mg l-1 of cadmium to the mussels resulted in a marked increase in both mRNAs suggesting that the MT20 isoform represents a primarily inducible metallothionein not highly expressed under basal conditions.
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Affiliation(s)
- D Barsyte
- Institute of Ecology, Akademijos 2, Vilnius, Lithuania.
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43
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Abstract
Keratins are a family of highly homologous proteins expressed as pairs of acidic and basic forms which make intermediate filaments in epithelial cells. Keratin 13 (K13) is the major acidic keratin, which together with K4, its basic partner, is expressed in the suprabasal layers of non-cornified stratified epithelia. The mechanism which allows mucosal-specific expression of this keratin remains unknown. To provide insight into the tissue-specific expression, we have isolated the human K13 gene by screening a chromosome 17 library with a specific K13 cRNA probe. Sequence analysis of unidirectional deletions produced by transposon Tn3 has revealed that the gene is 4601 nucleotides long and contains seven introns and eight exons. When driven by the CMV promoter, the gene produced K13 protein in MCF-7 cells, which normally do not express this protein. Two transcription-start sites were identified, the major being at 61 and the minor at 63 nucleotides upstream of ATG. The upstream sequence contained a TATA box and several other putative transcription factor binding sites. A single copy of the K13 gene was detected in the human genome by Southern hybridisation and polymerase chain reaction. K13 mRNA shows differential expression in cultured keratinocytes, and in A431 cells the RNA levels remained independent of calcium concentrations in the culture medium. Characterisation of the human K13 gene will facilitate elucidation of the molecular mechanism regulating K13 expression in mucosal tissues.
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Affiliation(s)
- A Waseem
- Department of Craniofacial Development, Guy's Dental School, Floor 28, Guy's Tower, London Bridge, London, SE1 9RT, UK.
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44
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Abstract
The temporal variation of Polonium-210 (210Po) was examined in coastal sea water, the mussel Mytilus edulis, the winkle Littorina littorea and green alga Ulva lactuca in order to investigate the entry of 210Po into the marine food chain. More than 99% of 210Po in the water column occurred in the particulate phase. Dissolved 210Po concentrations peaked during the spring phytoplankton bloom and it is suggested this is related to preferential scavenging of 210Po by the increased numbers of bacteria, viruses and small dissolved particulates. Changes in L. littorea 210Po specific activity are thought not to be related to food, but to a drop in body weight following spawning. Much of the 210Po accumulated by M. edulis was located in the digestive gland. The specific activity of 210Po in the digestive gland of M. edulis was shown to be strongly correlated with changes in sea water suspended particulate specific activity. Examination of other trace metal (Ag, Al, As, Ca, Cd, Cr, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Sb, Se, Sn and Zn) variations in the digestive gland revealed that class B and borderline metals had a strong positive correlation with 210Po. On-going work is investigating whether the accumulation and loss of 210Po is affected by the presence of metallothioneins.
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Affiliation(s)
- M A Wildgust
- School of Biological Sciences, University of Manchester, UK.
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45
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Abstract
Using in situ hybridisation to detect the intracellular localisation of mRNAs we have found that mRNAs expressed from intronless cDNAs of normally intronic genes are expressed well but largely retained in nuclei. The degree of nuclear retention is quite variable but in all cases addition of splicing signals to the expression cassette are required for efficient export of the mRNAs from nucleus to cytoplasm. In contrast mRNAs expressed from the intronless genes of hamster beta-adrenergic receptor and human serotonin receptor type 1A showed very little nuclear accumulation and strong expression in the cytoplasm independently of splicing signals. The data demonstrate a link between splicing and export and dissemble from the idea that splicing enhances mRNA expression by protecting nascent nuclear mRNAs from degradation.
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MESH Headings
- Animals
- COS Cells
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Ceruloplasmin/genetics
- Ceruloplasmin/metabolism
- Cricetinae
- Cytokines/genetics
- Cytokines/metabolism
- Cytoplasm/genetics
- Cytoplasm/metabolism
- DNA, Complementary
- Genetic Vectors
- Humans
- In Situ Hybridization/methods
- Introns
- Keratins/genetics
- Keratins/metabolism
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- RNA Splicing
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Adrenergic, beta/genetics
- Receptors, Adrenergic, beta/metabolism
- Receptors, Serotonin/genetics
- Receptors, Serotonin/metabolism
- Receptors, Serotonin, 5-HT1
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Transferrin/genetics
- Transferrin/metabolism
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Affiliation(s)
- L Fu
- Division of Biochemistry and Molecular Biology, United Medical School, Guy's Hospital, London, U.K
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46
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Rafiq M, Suen CK, Choudhury N, Joannou CL, White KN, Evans RW. Expression of recombinant human ceruloplasmin--an absolute requirement for splicing signals in the expression cassette. FEBS Lett 1997; 407:132-6. [PMID: 9166886 DOI: 10.1016/s0014-5793(97)00325-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We report the successful expression of recombinant human ceruloplasmin which was made possible by inclusion of splicing signals in the expression vector. Ceruloplasmin cDNA expressed from the vector pNUT in baby hamster kidney cells gave protein yields of 0.03 mg/l which increased to 15 mg/l with splicing signals present. The defect in expression from the intronless cDNA is due to complete retention of ceruloplasmin mRNA in cell nuclei. The block to cytoplasmic export is alleviated by splicing signals, allowing full expression of the mRNA.
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Affiliation(s)
- M Rafiq
- Division of Biochemistry and Molecular Biology, United Medical and Dental Schools of Guy's Hospital, London, UK
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47
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Elangovan R, White KN, McCrohan CR. Bioaccumulation of aluminium in the freshwater snail Lymnaea stagnalis at neutral pH. Environ Pollut 1997; 96:29-33. [PMID: 15093429 DOI: 10.1016/s0269-7491(97)00009-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/1996] [Accepted: 12/12/1996] [Indexed: 05/24/2023]
Abstract
This study examined the accumulation of aluminium (Al) by the freshwater snail Lymnaea stagnalis at neutral pH, when most Al would be predicted to be in an insoluble form (Al(OH)(3)). Snails were exposed to a range of Al concentrations (38-285 microg l(-1)) for 30 days, followed by 20 days in clean water. Aluminium was measured using atomic absorption spectroscopy. Significant accumulation of Al occurred in the whole soft tissues, gut, digestive gland and kidney at the latest by day 10. High concentration factors were observed, ranging from 4.5 x 10(3) in the whole soft tissues to 6.3 x 10(4) in the kidney, corresponding to actual concentrations of 800 to 7500 microg g(-1), respectively. Proportionality between environmental (water) and tissue concentrations of Al was observed in the gut but not in the other tissues. Following transfer to clean water, rapid loss of Al from the whole soft tissues and gut was seen over the first 10 days. Loss of Al from the digestive gland was much less as a proportion of the total, with approximately 90% of the Al remaining in the tissue. In contrast, significant loss of Al from the kidney occurred between days 20 and 30, even in the continued presence of Al; little further loss occurred following transfer to clean water. Aluminium is clearly available to the snail at neutral pH, the most likely route of entry being the gut. This could facilitate entry of the metal into the food chain. The possible roles of the digestive gland and kidney in the handling of Al are discussed.
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Affiliation(s)
- R Elangovan
- School of Biological Sciences, University of Manchester, Manchester, M13 9PT, UK
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Fu L, White KN. Enhancement of nucleocytoplasmic export of HTLV-1 Rex mRNA through cis and trans interactions of the mRNA with the complex of Rex protein and Rex-responsive element. FEBS Lett 1996; 396:47-52. [PMID: 8906864 DOI: 10.1016/0014-5793(96)01062-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
p27 rex of HTLV-1 promotes nucleocytoplasmic export of viral mRNAs through binding of the Rex-response element (RexRE) present at the 3' end of the viral transcripts in cis with respect to the ORFs of the viral mRNAs. We have found that expression of the RexRE in trans, as a separate RNA, still allows Rex protein to promote export of viral mRNAs lacking the RexRE. The data suggest the formation of a ternary complex between Rex protein, RexRE and upstream elements of viral mRNA and hence the existence of secondary sites of interaction between Rex protein and viral RNAs.
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Affiliation(s)
- L Fu
- Division of Biochemistry and Molecular Biology, United Medical and Dental Schools of Guy's and St. Thomas's Hospitals, London, UK
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Fu L, Suen CK, White KN. Variation of intracellular distribution of mRNAs expressed from transfected cDNAs--a study by FISH. Biochem Soc Trans 1995; 23:588S. [PMID: 8654773 DOI: 10.1042/bst023588s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
MESH Headings
- Animals
- Cell Line
- Cell Nucleus/metabolism
- Cytoplasm/metabolism
- DNA, Complementary/genetics
- DNA, Complementary/metabolism
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Gene Products, rex/genetics
- Human T-lymphotropic virus 1/genetics
- In Situ Hybridization, Fluorescence
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Transfection
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Affiliation(s)
- L Fu
- Division of Biochemistry and Molecular Biology, UMDS, Guy's Hospital, London, U.K
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50
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White KN, Vale VL, Hope DB. Identification of common forms of salicylate esterases in guinea-pig tissues similar to the microsomal aspirinases of liver. Biochem Soc Trans 1994; 22:220S. [PMID: 7958282 DOI: 10.1042/bst022220s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- K N White
- University Department of Pharmacology, Oxford, U.K
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