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Goh KC, Sim ZY, Te SH, He Y, Gin KYH. Microcystis genotypes in a tropical freshwater lake: Discovery of novel MIB-producing Microcystis with potentially unique synthesis pathway. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169249. [PMID: 38081424 DOI: 10.1016/j.scitotenv.2023.169249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 12/05/2023] [Accepted: 12/07/2023] [Indexed: 12/21/2023]
Abstract
Harmful algal blooms (HABs) are a threat to freshwater systems over the world due to the production of hepatotoxins like microcystin (MC), and nuisance taste and odour (T&O) compounds like 2-methylisoborneol (MIB). While MCs are known to cause detrimental effects to both water quality and human health, MIB is only reported to cause aesthetical problems. In this study, we investigated a tropical, urban lake that was experiencing persistent MC and MIB events. Although it was dominated by Microcystis blooms, analysis revealed that the toxigenic Microcystis were not the only species driving the MC concentrations. Additionally, there was also a lack of causative species for the MIB events. Through isolation, we have identified three toxigenic Microcystis found to produce four different variants of MCs, and two novel non-toxigenic Microcystis that were capable of producing MIB. The ability to produce MIB had never been previously reported for this species. Compared to other major producers such as Planktothricoides sp. and Streptomyces sp., the MIB synthase genes of our Microcystis sp. strains were partial, illustrating the possibility of unique synthesis pathways. The Microcystis sp. strains were found to produce about 2.77-5.22 fg MIB cell-1, with a majority of the contents (70-80 %) existing in the extracellular phase. Correlation analysis of field study indicated that phosphorus limitation may have an indirect effect on non-toxigenic Microcystis abundance and proportion by influencing the toxigenic genotype, suggesting that current measures to control HABs may favour the proliferation of the non-toxigenic Microcystis. The potential for Microcystis sp. to produce MIB through unique synthesis pathway, coupled with the potential dominance of non-toxigenic genotypes in Microcystis blooms, signals the possibility that non-toxigenic Microcystis should be monitored as well.
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Affiliation(s)
- Kwan Chien Goh
- National University of Singapore Environmental Research Institute, National University of Singapore, 1 Create Way, #15-02, Singapore 138602, Singapore
| | - Zhi Yang Sim
- National University of Singapore Environmental Research Institute, National University of Singapore, 1 Create Way, #15-02, Singapore 138602, Singapore
| | - Shu Harn Te
- National University of Singapore Environmental Research Institute, National University of Singapore, 1 Create Way, #15-02, Singapore 138602, Singapore
| | - Yiliang He
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Karina Yew-Hoong Gin
- National University of Singapore Environmental Research Institute, National University of Singapore, 1 Create Way, #15-02, Singapore 138602, Singapore; Department of Civil and Environmental Engineering, National University of Singapore, Blk E1A-07-03, 1 Engineering Drive 2, Singapore 117576, Singapore.
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2
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Heinzelmann D, Lindner B, Renner B, Fischer S, Schulz P, Schmidt M. Droplet digital PCR: A comprehensive tool for genetic analysis and prediction of bispecific antibody assembly during cell line development. N Biotechnol 2023; 78:42-51. [PMID: 37797917 DOI: 10.1016/j.nbt.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/15/2023] [Accepted: 10/01/2023] [Indexed: 10/07/2023]
Abstract
Molecular biological methods have emerged as inevitable tools to accompany the process of cell line development for the generation of stable and highly productive manufacturing cell lines in the biopharmaceutical industry. PCR-based methods are especially useful for screening and characterization of cell lines due to their low cost, scalability, precision and propensity for multidimensional read-outs. In this study, the diverse applications of droplet digital PCR (ddPCR) as a molecular biological tool for cell line development are demonstrated. Specifically, it is shown that ddPCR can be used to enable precise, sensitive and reproducible absolute quantification of genomically integrated transgene copies during cell line development and cell bank characterization. Additionally, an amplitude multiplexing approach is applied to simultaneously run multiple assays on different genetic targets in a single reaction and advance clonal screening by measuring gene expression profiles to predict the assembly and homogeneity of difficult-to-express (DTE) proteins. The implementation of ddPCR-based assays during cell line development allows for early screening at a transcriptional level, particularly for complex, multidomain proteins, where balanced polypeptide chain ratios are of primary importance. Moreover, it is demonstrated that ddPCR-based genomic characterization improves the robustness, efficiency and comparability of absolute transgene copy number quantification, an essential genetic parameter that must be demonstrated to regulatory authorities during clinical trial and market authorization application submissions to support genetic stability and consistency of the selected cell substrate.
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Affiliation(s)
- Daniel Heinzelmann
- Bioprocess Development Biologicals, Cell Line Development, Boehringer Ingelheim GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach, Germany.
| | - Benjamin Lindner
- Bioprocess Development Biologicals, Cell Line Development, Boehringer Ingelheim GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach, Germany
| | - Benjamin Renner
- Bioprocess Development Biologicals, Cell Line Development, Boehringer Ingelheim GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach, Germany
| | - Simon Fischer
- Bioprocess Development Biologicals, Cell Line Development, Boehringer Ingelheim GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach, Germany
| | - Patrick Schulz
- Bioprocess Development Biologicals, Cell Line Development, Boehringer Ingelheim GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach, Germany
| | - Moritz Schmidt
- Bioprocess Development Biologicals, Cell Line Development, Boehringer Ingelheim GmbH & Co. KG, Birkendorfer Strasse 65, 88397 Biberach, Germany
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3
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Potvin M, Gauthier J, Langevin C, Mohit V, da Costa NB, Deschênes T, Pomerleau M, Kukavica-Ibrulj I, Verreault D, Comte J, Levesque RC. Rapid on-site detection of harmful algal blooms: real-time cyanobacteria identification using Oxford Nanopore sequencing. Front Microbiol 2023; 14:1267652. [PMID: 38029199 PMCID: PMC10646836 DOI: 10.3389/fmicb.2023.1267652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/10/2023] [Indexed: 12/01/2023] Open
Abstract
With the increasing occurrence and severity of cyanobacterial harmful algal blooms (cHAB) at the global scale, there is an urgent need for rapid, accurate, accessible, and cost-effective detection tools. Here, we detail the RosHAB workflow, an innovative, in-the-field applicable genomics approach for real-time, early detection of cHAB outbreaks. We present how the proposed workflow offers consistent taxonomic identification of water samples in comparison to traditional microscopic analyses in a few hours and discuss how the generated data can be used to deepen our understanding on cyanobacteria ecology and forecast HABs events. In parallel, processed water samples will be used to iteratively build the International cyanobacterial toxin database (ICYATOX; http://icyatox.ibis.ulaval.ca) containing the analysis of novel cyanobacterial genomes, including phenomics and genomics metadata. Ultimately, RosHAB will (1) improve the accuracy of on-site rapid diagnostics, (2) standardize genomic procedures in the field, (3) facilitate these genomics procedures for non-scientific personnel, and (4) identify prognostic markers for evidence-based decisions in HABs surveillance.
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Affiliation(s)
- Marianne Potvin
- Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, QC, Canada
| | - Jeff Gauthier
- Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, QC, Canada
| | - Christophe Langevin
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Centre Eau Terre Environnement, Québec, QC, Canada
- Groupe de recherche interuniversitaire en limnologie (GRIL), Montréal, QC, Canada
| | - Vani Mohit
- Direction générale de la coordination scientifique et du Centre d’expertise en analyse environnementale du Québec (CEAEQ), Ministère de l’Environnement et de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP), Québec, QC, Canada
| | - Naíla Barbosa da Costa
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Centre Eau Terre Environnement, Québec, QC, Canada
- Groupe de recherche interuniversitaire en limnologie (GRIL), Montréal, QC, Canada
| | - Thomas Deschênes
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Centre Eau Terre Environnement, Québec, QC, Canada
| | - Maude Pomerleau
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Centre Eau Terre Environnement, Québec, QC, Canada
| | - Irena Kukavica-Ibrulj
- Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, QC, Canada
| | - Daniel Verreault
- Direction générale de la coordination scientifique et du Centre d’expertise en analyse environnementale du Québec (CEAEQ), Ministère de l’Environnement et de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP), Québec, QC, Canada
| | - Jérôme Comte
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Centre Eau Terre Environnement, Québec, QC, Canada
- Groupe de recherche interuniversitaire en limnologie (GRIL), Montréal, QC, Canada
| | - Roger C. Levesque
- Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, QC, Canada
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Kinoo A, Caye-Eude A, Vial Y, Cavé H, Arfeuille C. Partitioning for Easy Multiplexing: A Versatile Droplet PCR Application for Clone Monitoring in Tumors. J Mol Diagn 2023; 25:592-601. [PMID: 37302461 DOI: 10.1016/j.jmoldx.2023.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/04/2023] [Accepted: 04/10/2023] [Indexed: 06/13/2023] Open
Abstract
Clinical genome-wide next-generation sequencing (NGS) has brought new challenges to genetic laboratories. The identification of numerous patient-specific variants that may require to be screened for on multiple other samples poses an issue when striving for time and cost-effectiveness. Here, we propose d-multiSeq, a straightforward method utilizing the advantages of droplet PCR for multiplexing combined with amplicon-based NGS. By comparing d-multiSeq with a standard multiplex amplicon-based NGS, it was shown that partitioning prevents the amplification competition seen when multiplexing and leads to a homogeneous representation of each target in the total read count for up to a 40-target multiplex without the need for prior adjustment. Variant allele frequency was reliably evaluated with a sensitivity of 97.6% for variant allele frequency up to 1%. The applicability of d-multiSeq was also tested on cell-free DNA with the successful amplification of an eight-target multiplex panel. Preliminary application of the technique to assess the clonal evolution in a childhood leukemia harboring high interpatient variability in its somatic variants is shown. d-multiSeq represents a turnkey solution for analyzing large sets of patient-specific variants on low DNA amounts and cell-free DNA.
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Affiliation(s)
- Alexia Kinoo
- Molecular Genetics Unit, Genetics Department, Assistance Publique des Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Aurélie Caye-Eude
- Molecular Genetics Unit, Genetics Department, Assistance Publique des Hôpitaux de Paris, Hôpital Robert Debré, Paris, France; INSERM Unité Mixte de Recherche (UMR)_S1131, Institut de Recherche Saint-Louis, Université de Paris-Cité, Paris, France
| | - Yoann Vial
- Molecular Genetics Unit, Genetics Department, Assistance Publique des Hôpitaux de Paris, Hôpital Robert Debré, Paris, France; INSERM Unité Mixte de Recherche (UMR)_S1131, Institut de Recherche Saint-Louis, Université de Paris-Cité, Paris, France
| | - Hélène Cavé
- Molecular Genetics Unit, Genetics Department, Assistance Publique des Hôpitaux de Paris, Hôpital Robert Debré, Paris, France; INSERM Unité Mixte de Recherche (UMR)_S1131, Institut de Recherche Saint-Louis, Université de Paris-Cité, Paris, France
| | - Chloé Arfeuille
- Molecular Genetics Unit, Genetics Department, Assistance Publique des Hôpitaux de Paris, Hôpital Robert Debré, Paris, France; INSERM Unité Mixte de Recherche (UMR)_S1131, Institut de Recherche Saint-Louis, Université de Paris-Cité, Paris, France.
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5
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Hart JJ, Jamison MN, McNair JN, Woznicki SA, Jordan B, Rediske RR. Using watershed characteristics to enhance fecal source identification. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 336:117642. [PMID: 36907065 DOI: 10.1016/j.jenvman.2023.117642] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/17/2022] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Fecal pollution is one of the most prevalent forms of pollution affecting waterbodies worldwide, threatening public health and negatively impacting aquatic environments. Microbial source tracking (MST) applies polymerase chain reaction (PCR) technology to help identify the source of fecal pollution. In this study, we combine spatial data for two watersheds with general and host-associated MST markers to target human (HF183/BacR287), bovine (CowM2), and general ruminant (Rum2Bac) sources. Concentrations of MST markers in samples were determined with droplet digital PCR (ddPCR). The three MST markers were detected at all sites (n = 25), but bovine and general ruminant markers were significantly associated with watershed characteristics. MST results, combined with watershed characteristics, suggest that streams draining areas with low-infiltration soil groups and high agricultural land use are at an increased risk for fecal contamination. Microbial source tracking has been applied in numerous studies to aid in identifying the sources of fecal contamination, but these studies usually lack information on the involvement of watershed characteristics. Our study combined watershed characteristics with MST results to provide more comprehensive insight into the factors that influence fecal contamination in order to implement the most effective best management practices.
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Affiliation(s)
- John J Hart
- Robert B. Annis Water Resources Institute, 740 West Shoreline Dr, Muskegon, MI, 49441, USA.
| | - Megan N Jamison
- Oakland University, Department of Chemistry, 146 Library Dr., Rochester, MI, 48309, USA.
| | - James N McNair
- Robert B. Annis Water Resources Institute, 740 West Shoreline Dr, Muskegon, MI, 49441, USA.
| | - Sean A Woznicki
- Oakland University, Department of Chemistry, 146 Library Dr., Rochester, MI, 48309, USA.
| | - Ben Jordan
- Ottawa Conservation District, 16731 Ferris St, Grand Haven, MI, 49417, USA.
| | - Richard R Rediske
- Robert B. Annis Water Resources Institute, 740 West Shoreline Dr, Muskegon, MI, 49441, USA.
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6
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Barney RE, Huang G, Gallagher TL, Tischbein M, DeWitt J, Martindale R, LaRochelle EMP, Tsongalis GJ, Stommel EW. Validation of a Droplet Digital PCR (ddPCR) Assay to Detect Cyanobacterial 16S rDNA in Human Lung Tissue. TOXICS 2023; 11:531. [PMID: 37368631 DOI: 10.3390/toxics11060531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/02/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023]
Abstract
Cyanobacteria produce a variety of secondary metabolites, including toxins that may contribute to the development of disease. Previous work was able to detect the presence of a cyanobacterial marker in human nasal and broncoalveolar lavage samples; however, it was not able to determine the quantification of the marker. To further research the relationship between cyanobacteria and human health, we validated a droplet digital polymerase chain reaction (ddPCR) assay to simultaneously detect the cyanobacterial 16S marker and a human housekeeping gene in human lung tissue samples. The ability to detect cyanobacteria in human samples will allow further research into the role cyanobacteria plays in human health and disease.
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Affiliation(s)
- Rachael E Barney
- Dartmouth-Hitchcock Medical Center, Department of Pathology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Guohong Huang
- Dartmouth-Hitchcock Medical Center, Department of Pathology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Torrey L Gallagher
- Dartmouth-Hitchcock Medical Center, Department of Pathology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Maeve Tischbein
- Dartmouth-Hitchcock Medical Center, Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - John DeWitt
- Department of Pathology, University of Vermont, Burlington, VT 05405, USA
| | - Rachel Martindale
- Department of Pathology, University of Vermont, Burlington, VT 05405, USA
| | - Ethan M P LaRochelle
- Dartmouth-Hitchcock Medical Center, Department of Pathology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Gregory J Tsongalis
- Dartmouth-Hitchcock Medical Center, Department of Pathology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Elijah W Stommel
- Dartmouth-Hitchcock Medical Center, Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
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7
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Saleem F, Jiang JL, Atrache R, Paschos A, Edge TA, Schellhorn HE. Cyanobacterial Algal Bloom Monitoring: Molecular Methods and Technologies for Freshwater Ecosystems. Microorganisms 2023; 11:851. [PMID: 37110273 PMCID: PMC10144707 DOI: 10.3390/microorganisms11040851] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/15/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023] Open
Abstract
Cyanobacteria (blue-green algae) can accumulate to form harmful algal blooms (HABs) on the surface of freshwater ecosystems under eutrophic conditions. Extensive HAB events can threaten local wildlife, public health, and the utilization of recreational waters. For the detection/quantification of cyanobacteria and cyanotoxins, both the United States Environmental Protection Agency (USEPA) and Health Canada increasingly indicate that molecular methods can be useful. However, each molecular detection method has specific advantages and limitations for monitoring HABs in recreational water ecosystems. Rapidly developing modern technologies, including satellite imaging, biosensors, and machine learning/artificial intelligence, can be integrated with standard/conventional methods to overcome the limitations associated with traditional cyanobacterial detection methodology. We examine advances in cyanobacterial cell lysis methodology and conventional/modern molecular detection methods, including imaging techniques, polymerase chain reaction (PCR)/DNA sequencing, enzyme-linked immunosorbent assays (ELISA), mass spectrometry, remote sensing, and machine learning/AI-based prediction models. This review focuses specifically on methodologies likely to be employed for recreational water ecosystems, especially in the Great Lakes region of North America.
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Affiliation(s)
| | | | | | | | | | - Herb E. Schellhorn
- Department of Biology, McMaster University, Hamilton, ON L8S 4L8, Canada
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8
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Çiftçi O, Wagemaker CAM, Mertens A, van Bodegom P, Pirovano W, Gravendeel B. Genotyping by sequencing for estimating relative abundances of diatom taxa in mock communities. BMC Ecol Evol 2023; 23:4. [PMID: 36747145 PMCID: PMC9903628 DOI: 10.1186/s12862-023-02104-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 01/13/2023] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Diatoms are present in all waters and are highly sensitive to pollution gradients. Therefore, they are ideal bioindicators for water quality assessment. Current indices used in these applications are based on identifying diatom species and counting their abundances using traditional light microscopy. Several molecular techniques have been developed to help automate different steps of this process, but obtaining reliable estimates of diatom community composition and species abundance remains challenging. RESULTS Here, we evaluated a recently developed quantification method based on Genotyping by Sequencing (GBS) for the first time in diatoms to estimate the relative abundances within a species complex. For this purpose, a reference database comprised of thousands of genomic DNA clusters was generated from cultures of Nitzschia palea. The sequencing reads from calibration and mock samples were mapped against this database for parallel quantification. We sequenced 25 mock diatom communities containing up to five taxa per sample in different abundances. Taxon abundances in these communities were also quantified by a diatom expert using manual counting of cells on light microscopic slides. The relative abundances of strains across mock samples were over- or under-estimated by the manual counting method, and a majority of mock samples had stronger correlations using GBS. Moreover, one previously recognized putative hybrid had the largest number of false positive detections demonstrating the limitation of the manual counting method when morphologically similar and/or phylogenetically close taxa are analyzed. CONCLUSIONS Our results suggest that GBS is a reliable method to estimate the relative abundances of the N. palea taxa analyzed in this study and outperformed traditional light microscopy in terms of accuracy. GBS provides increased taxonomic resolution compared to currently available quantitative molecular approaches, and it is more scalable in the number of species that can be analyzed in a single run. Hence, this is a significant step forward in developing automated, high-throughput molecular methods specifically designed for the quantification of [diatom] communities for freshwater quality assessments.
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Affiliation(s)
- Ozan Çiftçi
- Institute of Environmental Sciences (CML), Leiden University, P.O. Box 9518, 2300 RA, Leiden, The Netherlands. .,Naturalis Biodiversity Center, Darwinweg 2, 2333 CR, Leiden, The Netherlands. .,BaseClear B.V., Sylviusweg 74, 2333 BE, Leiden, The Netherlands. .,German Research Center for Geosciences, GFZ, 14473, Potsdam, Germany.
| | - Cornelis A. M. Wagemaker
- Radboud Institute for Biological and Environmental Sciences, Heyendaalseweg 135, 6500 GL Nijmegen, The Netherlands
| | - Adrienne Mertens
- Diatomella, IJkelaarstraat 3, 6611 KN Overasselt, The Netherlands
| | - Peter van Bodegom
- grid.5132.50000 0001 2312 1970Institute of Environmental Sciences (CML), Leiden University, P.O. Box 9518, 2300 RA Leiden, The Netherlands
| | - Walter Pirovano
- BaseClear B.V., Sylviusweg 74, 2333 BE Leiden, The Netherlands
| | - Barbara Gravendeel
- grid.425948.60000 0001 2159 802XNaturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, The Netherlands ,Radboud Institute for Biological and Environmental Sciences, Heyendaalseweg 135, 6500 GL Nijmegen, The Netherlands
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9
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Li H, Te SH, Tavakoli Y, Zhang J, Yew-Hoong Gin K, He Y. Rapid detection methods and modelling simulations provide new insights into cyanobacteria detection and bloom management in a tropical reservoir. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 326:116730. [PMID: 36399808 DOI: 10.1016/j.jenvman.2022.116730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 09/18/2022] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
The increasing occurrence of cyanobacteria blooms is of global concern, and is often associated with environmental and socio-economic problems, such as degenerated ecosystems and aquaculture impairment. The diazotrophic cyanobacterium Raphidiopsis raciborskii (R. raciborskii) grows rapidly in the tropics, and produces the toxin, cylindrospermopsin (CYN), which has harmful effects on aquatic organisms. Thus, to protect water quality and ecosystem, it is essential to have rapid and reliable methods for cyanobacteria and R. raciborskii detection and prediction so that early warning can be provided for management. Molecular assays, such as PCR, real-time quantitative PCR (qPCR), two-step PCR assays are accurate and widely used, but still require several hours from sample preparation to data analysis. In this study, insulated isothermal PCR (iiPCR) assays in conjunction with fast DNA extraction method, were developed and verified as a rapid detection assay in detecting cyanobacteria and R. raciborskii within 50 min, and also with high detection accuracy (98.8%) and the overall high agreement level (98.8%, k = 97.5%)) comparing to conventional qPCR assay. However, the limitation of the iiPCR assay is that it only generates qualitative results. Therefore, the quantified iiPCR assay, named as A-iiPCR, by coupling iiPCR device with fluorescence signal catching and interpretation instrument (Andor spectrometer with Solis spectroscopy software) was developed and verified with in situ environmental samples. The fluorescence intensity decreased accordingly with the drop of DNA concentration until reaching 1.32 ng/μL. Also, Delft 3D modelling was established to simulate R. raciborskii change in predicting spatial and temporal variabilities for reservoir management, as the simulated R. raciborskii concentration was the highest at sampling site 1, as well as temporally highest in April and October, posing as the most high-risk location and time periods for R. raciborskii bloom-forming requiring corresponding governance measures.
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Affiliation(s)
- Han Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China; NUS Environmental Research Institute (E2S2-CREATE), National University of Singapore, Singapore
| | - Shu Harn Te
- NUS Environmental Research Institute (E2S2-CREATE), National University of Singapore, Singapore
| | - Yasaman Tavakoli
- NUS Environmental Research Institute (E2S2-CREATE), National University of Singapore, Singapore
| | - Jingjie Zhang
- NUS Environmental Research Institute (NERI), National University of Singapore, Singapore
| | - Karina Yew-Hoong Gin
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore; NUS Environmental Research Institute (E2S2-CREATE), National University of Singapore, Singapore.
| | - Yiliang He
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China.
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10
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Tiwari A, Ahmed W, Oikarinen S, Sherchan SP, Heikinheimo A, Jiang G, Simpson SL, Greaves J, Bivins A. Application of digital PCR for public health-related water quality monitoring. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 837:155663. [PMID: 35523326 DOI: 10.1016/j.scitotenv.2022.155663] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 05/25/2023]
Abstract
Digital polymerase chain reaction (dPCR) is emerging as a reliable platform for quantifying microorganisms in the field of water microbiology. This paper reviews the fundamental principles of dPCR and its application for health-related water microbiology. The relevant literature indicates increasing adoption of dPCR for measuring fecal indicator bacteria, microbial source tracking marker genes, and pathogens in various aquatic environments. The adoption of dPCR has accelerated recently due to increasing use for wastewater surveillance of Severe Acute Respiratory Coronavirus 2 (SARS-CoV-2) - the virus that causes Coronavirus Disease 2019 (COVID-19). The collective experience in the scientific literature indicates that well-optimized dPCR assays can quantify genetic material from microorganisms without the need for a calibration curve and often with superior analytical performance (i.e., greater sensitivity, precision, and reproducibility) than quantitative polymerase chain reaction (qPCR). Nonetheless, dPCR should not be viewed as a panacea for the fundamental uncertainties and limitations associated with measuring microorganisms in water microbiology. With dPCR platforms, the sample analysis cost and processing time are typically greater than qPCR. However, if improved analytical performance (i.e., sensitivity and accuracy) is critical, dPCR can be an alternative option for quantifying microorganisms, including pathogens, in aquatic environments.
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Affiliation(s)
- Ananda Tiwari
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Finland
| | - Warish Ahmed
- CSIRO Land and Water, Ecosciences Precinct, Queensland, Australia
| | - Sami Oikarinen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Samendra P Sherchan
- Department of Environmental Health Sciences, Tulane University, New Orleans, LA, USA; Department of Biology, Morgan State University, Baltimore, MD 21251, USA; BioEnvironmental Science Program, Department of Biology, Morgan State University, Baltimore, MD 21251, USA
| | - Annamari Heikinheimo
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Finland; Finnish Food Authority, Seinäjoki, Finland
| | - Guangming Jiang
- School of Civil, Mining and Environmental Engineering, University of Wollongong, Australia; Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, Australia
| | | | - Justin Greaves
- School of Environmental Sustainability, Loyola University Chicago, 6364 N. Sheridan Rd, Chicago, IL 60660, USA
| | - Aaron Bivins
- Department of Civil & Environmental Engineering, Louisiana State University, LA, USA.
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11
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Li J, Xiao X, Guo L, Chen H, Feng M, Yu X. A novel qPCR-based method to quantify seven phyla of common algae in freshwater and its application in water sources. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 823:153340. [PMID: 35085638 DOI: 10.1016/j.scitotenv.2022.153340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/27/2021] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
The light microscope is widely used to count algae, however, there are some disadvantages associated with this method, such as time consuming and laborious. In this study, a qPCR-based method was established for quantifying seven phyla of common algae in freshwater, including Cyanophyta, Chlorophyta, Euglenophyta, Bacillariophyta, Dinophyta, Cryptophyta, and Chrysophyta. The accuracy of qPCR in estimating algal cells was confirmed by comparing it with the microscopic counting. The qPCR was used to detect the cell concentration of seven phyla of algae in Longhu Reservoir, showing that green algal blooms occurred during the monitoring period. The intensity of algal blooms was further evaluated according to the classification standard, which suggested that the grade of this bloom was mild. An early warning system was proposed to early warn the occurrence of algal blooms in two water sources, Longhu Reservoir and Dongzhang Reservoir. The qPCR method developed in this study could be a useful tool in the monitoring of algae. The early warning system reported here will have important implications for the effective warning of algal blooms.
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Affiliation(s)
- Jingjing Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinyan Xiao
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Lizheng Guo
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hui Chen
- Fujian Provincial Investigation, Design & Research Institute of Water Conservancy & Hydropower, No.158 Dongda Road, Gulou District, Fuzhou 350001, China
| | - Mingbao Feng
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Xin Yu
- College of the Environment & Ecology, Xiamen University, Xiamen 361102, China.
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12
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Feist SM, Lance RF. Genetic detection of freshwater harmful algal blooms: A review focused on the use of environmental DNA (eDNA) in Microcystis aeruginosa and Prymnesium parvum. HARMFUL ALGAE 2021; 110:102124. [PMID: 34887004 DOI: 10.1016/j.hal.2021.102124] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
Recurrence and severity of harmful algal blooms (HABs) are increasing due to a number of factors, including human practices and climate change. Sensitive and robust methods that allow for early and expedited HAB detection across large landscape scales are needed. Among the suite of HAB detection tools available, a powerful option exists in genetics-based approaches utilizing environmental sampling, also termed environmental DNA (eDNA). Here we provide a detailed methodological review of three HAB eDNA approaches (quantitative PCR, high throughput sequencing, and isothermal amplification). We then summarize and synthesize recently published eDNA applications covering a variety of HAB surveillance and research objectives, all with a specific emphasis in the detection of two widely problematic freshwater species, Microcystis aeruginosa and Prymnesium parvum. In our summary and conclusion we build on this literature by discussing ways in which eDNA methods could be advanced to improve HAB detection. We also discuss ways in which eDNA data could be used to potentially provide novel insight into the ecology, mitigation, and prediction of HABs.
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Affiliation(s)
- Sheena M Feist
- Environmental Lab, United States Army Corps of Engineers Research and Development Center, Vicksburg, MS, 39180, United States.
| | - Richard F Lance
- Environmental Lab, United States Army Corps of Engineers Research and Development Center, Vicksburg, MS, 39180, United States
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13
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Tan F, Xiao P, Yang JR, Chen H, Jin L, Yang Y, Lin TF, Willis A, Yang J. Precision early detection of invasive and toxic cyanobacteria: A case study of Raphidiopsis raciborskii. HARMFUL ALGAE 2021; 110:102125. [PMID: 34887005 DOI: 10.1016/j.hal.2021.102125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 10/13/2021] [Accepted: 10/16/2021] [Indexed: 06/13/2023]
Abstract
Blooms of the toxic cyanobacterium, Raphidiopsis raciborskii (basionym Cylindrospermopsis raciborskii), are becoming a major environmental issue in freshwater ecosystems globally. Our precision prevention and early detection of R. raciborskii blooms rely upon the accuracy and speed of the monitoring method. A duplex digital PCR (dPCR) monitoring approach was developed and validated to detect the abundance and toxin-producing potential of R. raciborskii simultaneously in both laboratory spiked and environmental samples. Results of dPCR were strongly correlated with traditional real time quantitative PCR (qPCR) and microscopy for both laboratory and environmental samples. However, discrepancies between methods were observed when measuring R. raciborskii at low abundance (1 - 105 cells L - 1), with dPCR showing a higher precision compared to qPCR at low cell concentration. Furthermore, the dPCR assay had the highest detection rate for over two hundred environmental samples especially under low abundance conditions, followed by microscopy and qPCR. dPCR assay had the advantages of simple operation, time-saving, high sensitivity and excellent reproducibility. Therefore, dPCR would be a fast and precise monitoring method for the early warning of toxic bloom-forming cyanobacterial species and assessment of water quality risks, which can improve prediction and prevention of the impacts of harmful cyanobacterial bloom events in inland waters.
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Affiliation(s)
- Fengjiao Tan
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Xiao
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Jun R Yang
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Engineering Research Center of Ecology and Agricultural Use of Wetland (Ministry of Education), College of Agriculture, Yangtze University, Jingzhou 434025, China
| | - Huihuang Chen
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Jin
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yigang Yang
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tsair-Fuh Lin
- Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - Anusuya Willis
- Australian National Algae Culture Collection, CSIRO, Hobart 7000, Tasmania, Australia
| | - Jun Yang
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
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14
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Emerging methods for and novel insights gained by absolute quantification of mitochondrial DNA copy number and its clinical applications. Pharmacol Ther 2021; 232:107995. [PMID: 34592204 DOI: 10.1016/j.pharmthera.2021.107995] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 08/26/2021] [Accepted: 09/01/2021] [Indexed: 02/07/2023]
Abstract
The past thirty years have seen a surge in interest in pathophysiological roles of mitochondria, and the accurate quantification of mitochondrial DNA copy number (mCN) in cells and tissue samples is a fundamental aspect of assessing changes in mitochondrial health and biogenesis. Quantification of mCN between studies is surprisingly variable due to a combination of physiological variability and diverse protocols being used to measure this endpoint. The advent of novel methods to quantify nucleic acids like digital polymerase chain reaction (dPCR) and high throughput sequencing offer the ability to measure absolute values of mCN. We conducted an in-depth survey of articles published between 1969 -- 2020 to create an overview of mCN values, to assess consensus values of tissue-specific mCN, and to evaluate consistency between methods of assessing mCN. We identify best practices for methods used to assess mCN, and we address the impact of using specific loci on the mitochondrial genome to determine mCN. Current data suggest that clinical measurement of mCN can provide diagnostic and prognostic value in a range of diseases and health conditions, with emphasis on cancer and cardiovascular disease, and the advent of means to measure absolute mCN should improve future clinical applications of mCN measurements.
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15
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Weli SC, Bernhardt LV, Qviller L, Dale OB, Lillehaug A. Infectious Salmon Anemia Virus Shedding from Infected Atlantic Salmon ( Salmo salar L.)-Application of a Droplet Digital PCR Assay for Virus Quantification in Seawater. Viruses 2021; 13:v13091770. [PMID: 34578351 PMCID: PMC8471646 DOI: 10.3390/v13091770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/25/2021] [Accepted: 09/01/2021] [Indexed: 12/18/2022] Open
Abstract
Infectious salmon anemia virus (ISAV) infection is currently detected by fish sampling for PCR and immunohistochemistry analysis. As an alternative to sampling fish, we evaluated two different membrane filters in combination with four buffers for elution, concentration, and detection of ISAV in seawater, during a bath challenge of Atlantic salmon (Salmo salar L.) post-smolts with high and low concentrations of ISAV. Transmission of ISAV in the bath challenge was confirmed by a high mortality, clinical signs associated with ISA disease, and detection of ISAV RNA in organ tissues and seawater samples. The electronegatively charged filter, combined with lysis buffer, gave significantly higher ISAV RNA detection by droplet digital PCR from seawater (5.6 × 104 ISAV RNA copies/L; p < 0.001). Viral shedding in seawater was first detected at two days post-challenge and peaked on day 11 post-challenge, one day before mortalities started in fish challenged with high dose ISAV, demonstrating that a large viral shedding event occurs before death. These data provide important information for ISAV shedding that is relevant for the development of improved surveillance tools based on water samples, transmission models, and management of ISA.
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16
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Short communication: Evaluation of charged membrane filters and buffers for concentration and recovery of infectious salmon anaemia virus in seawater. PLoS One 2021; 16:e0253297. [PMID: 34133472 PMCID: PMC8208535 DOI: 10.1371/journal.pone.0253297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 06/02/2021] [Indexed: 11/19/2022] Open
Abstract
Infectious salmon anaemia virus (ISAV) is the cause of an important waterborne disease of farmed Atlantic salmon. Detection of virus in water samples may constitute an alternative method to sacrificing fish for surveillance of fish populations for the presence of ISA-virus. We aimed to evaluate different membrane filters and buffers for concentration and recovery of ISAV in seawater, prior to molecular detection. One litre each of artificial and natural seawater was spiked with ISAV, followed by concentration with different filters and subsequent elution with different buffers. The negatively charged MF hydrophilic membrane filter, combined with NucliSENS® lysis buffer, presented the highest ISAV recovery percentages with 12.5 ± 1.3% by RT-qPCR and 31.7 ± 10.7% by RT-ddPCR. For the positively charged 1 MDS Zeta Plus® Virosorb® membrane filter, combined with NucliSENS® lysis buffer, the ISAV recovery percentages were 3.4 ± 0.1% by RT-qPCR and 10.8 ± 14.2% by RT-ddPCR. The limits of quantification (LOQ) were estimated to be 2.2 x 103 ISAV copies/L of natural seawater for both RT-qPCR and RT-ddPCR. The ISAV concentration method was more efficient in natural seawater.
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17
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Yarimizu K, Sildever S, Hamamoto Y, Tazawa S, Oikawa H, Yamaguchi H, Basti L, Mardones JI, Paredes-Mella J, Nagai S. Development of an absolute quantification method for ribosomal RNA gene copy numbers per eukaryotic single cell by digital PCR. HARMFUL ALGAE 2021; 103:102008. [PMID: 33980448 DOI: 10.1016/j.hal.2021.102008] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 06/12/2023]
Abstract
Recent increase of Harmful Algal Blooms (HAB) causes world-wide ecological, economical, and health issues, and more attention is paid to frequent coastal monitoring for the early detection of HAB species to prevent or reduce such impacts. Use of molecular tools in addition to traditional microscopy-based observation has become one of the promising methodologies for coastal monitoring. However, as ribosomal RNA (rRNA) genes are commonly targeted in molecular studies, variability in the rRNA gene copy number within and between species must be considered to provide quantitative information in quantitative PCR (qPCR), digital PCR (dPCR), and metabarcoding analyses. Currently, this information is only available for a limited number of species. The present study utilized a dPCR technology to quantify copy numbers of rRNA genes per single cell in 16 phytoplankton species, the majority of which are toxin-producers, using a newly developed universal primer set accompanied by a labeled probe with a fluorophore and a double-quencher. In silico PCR using the newly developed primers allowed the detection of taxa from 8 supergroups, demonstrating universality and broad coverage of the primer set. Chelex buffer was found to be suitable for DNA extraction to obtain DNA fragments with suitable size to avoid underestimation of the copy numbers. The study successfully demonstrated the first comparison of absolute quantification of 18S rRNA copy numbers per cell from 16 phytoplankton species by the dPCR technology.
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Affiliation(s)
- Kyoko Yarimizu
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan; Office of Industry-Academia-Government and Community Collaboration, Hiroshima University, 1-3-2 22 Kagamiyama, Higashi-Hiroshima City, Hiroshima 739-8511, Japan
| | - Sirje Sildever
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan; Department of Marine Systems, Tallinn University of Technology, Akadeemia tee 15A, 12618 Tallinn, Estonia
| | - Yoko Hamamoto
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan
| | - Satoshi Tazawa
- AXIOHELIX Co. Ltd, 12-17 Kandaizumicho, Chiyoda-ku, Tokyo 101-0024, Japan
| | - Hiroshi Oikawa
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan
| | - Haruo Yamaguchi
- Faculty of Agriculture and Marine Sciences, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Leila Basti
- Department of Ocean Sciences, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, Japan
| | - Jorge I Mardones
- Instituto de Fomento Pesquero, Centro de Estudios de Algas Nocivas (IFOP-CREAN), Padre Harter 574, Puerto Montt 5501679, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia, Chile
| | - Javier Paredes-Mella
- Instituto de Fomento Pesquero, Centro de Estudios de Algas Nocivas (IFOP-CREAN), Padre Harter 574, Puerto Montt 5501679, Chile
| | - Satoshi Nagai
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan.
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18
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Devi A, Chiu YT, Hsueh HT, Lin TF. Quantitative PCR based detection system for cyanobacterial geosmin/2-methylisoborneol (2-MIB) events in drinking water sources: Current status and challenges. WATER RESEARCH 2021; 188:116478. [PMID: 33045635 DOI: 10.1016/j.watres.2020.116478] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 09/14/2020] [Accepted: 09/27/2020] [Indexed: 06/11/2023]
Abstract
Taste and odor (T&O) are an important issue in drinking water, aquaculture, recreation and a few other associated industries, and cyanobacteria-relevant geosmin and 2-methylisoborneol (2-MIB) are the two most commonly detected T&O compounds worldwide. A rise in the cyanobacterial blooms and associated geosmin/2-MIB episodes due to anthropogenic activities as well as climate change has led to global concerns for drinking water quality. The increasing awareness for the safe drinking, aquaculture or recreational water systems has boost the demand for rapid, robust, on-site early detection and monitoring system for cyanobacterial geosmin/2-MIB events. In past years, research has indicated quantitative PCR (qPCR) as one of the promising tools for detection of geosmin/2-MIB episodes. It offers advantages of detecting the source organism even at very low concentrations, distinction of odor-producing cyanobacterial strains from non-producers and evaluation of odor producing potential of the cyanobacteria at much faster rates compared to conventional techniques.The present review aims at examining the current status of developed qPCR primers and probes in identifying and detecting the cyanobacterial blooms along with geosmin/2-MIB events. Among the more than 100 articles about cyanobacteria associated geosmin/2-MIB in drinking water systems published after 1990, limited reports (approx. 10 each for geosmin and 2-MIB) focused on qPCR detection and its application in the field. Based on the review of literature, a comprehensive open access global cyanobacterial geosmin/2-MIB events database (CyanoGM Explorer) is curated. It acts as a single platform to access updated information related to origin and geographical distribution of geosmin/2-MIB events, cyanobacterial producers, frequency, and techniques associated with the monitoring of the events. Although a total of 132 cyanobacterial strains from 21 genera and 72 cyanobacterial strains from 13 genera have been reported for geosmin and 2-MIB production, respectively, only 58 geosmin and 28 2-MIB synthesis regions have been assembled in the NCBI database. Based on the identity, geosmin sequences were found to be more diverse in the geosmin synthase conserved/primer design region, compared to 2-MIB synthesis region, hindering the design of universal primers/probes. Emerging technologies such as the bioelectronic nose, Surface Enhanced Raman Scattering (SERS), and nanopore sequencing are discussed for future applications in early on-site detection of geosmin/2-MIB and producers. In the end, the paper also highlights various challenges in applying qPCR as a universal system of monitoring and development of response system for geosmin/2-MIB episodes.
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Affiliation(s)
- Apramita Devi
- Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan ROC
| | - Yi-Ting Chiu
- Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan ROC
| | - Hsin-Ta Hsueh
- Sustainable Environment Research Laboratories, National Cheng Kung University, Tainan 70101, Taiwan ROC
| | - Tsair-Fuh Lin
- Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan ROC.
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19
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Romanis CS, Pearson LA, Neilan BA. Cyanobacterial blooms in wastewater treatment facilities: Significance and emerging monitoring strategies. J Microbiol Methods 2020; 180:106123. [PMID: 33316292 DOI: 10.1016/j.mimet.2020.106123] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 12/06/2020] [Accepted: 12/08/2020] [Indexed: 12/30/2022]
Abstract
Municipal wastewater treatment facilities (WWTFs) are prone to the proliferation of cyanobacterial species which thrive in stable, nutrient-rich environments. Dense cyanobacterial blooms frequently disrupt treatment processes and the supply of recycled water due to their production of extracellular polymeric substances, which hinder microfiltration, and toxins, which pose a health risk to end-users. A variety of methods are employed by water utilities for the identification and monitoring of cyanobacteria and their toxins in WWTFs, including microscopy, flow cytometry, ELISA, chemoanalytical methods, and more recently, molecular methods. Here we review the literature on the occurrence and significance of cyanobacterial blooms in WWTFs and discuss the pros and cons of the various strategies for monitoring these potentially hazardous events. Particular focus is directed towards next-generation metagenomic sequencing technologies for the development of site-specific cyanobacterial bloom management strategies. Long-term multi-omic observations will enable the identification of indicator species and the development of site-specific bloom dynamics models for the mitigation and management of cyanobacterial blooms in WWTFs. While emerging metagenomic tools could potentially provide deep insight into the diversity and flux of problematic cyanobacterial species in these systems, they should be considered a complement to, rather than a replacement of, quantitative chemoanalytical approaches.
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Affiliation(s)
- Caitlin S Romanis
- School of Environmental and Life Sciences, University of Newcastle, Newcastle 2308, Australia
| | - Leanne A Pearson
- School of Environmental and Life Sciences, University of Newcastle, Newcastle 2308, Australia
| | - Brett A Neilan
- School of Environmental and Life Sciences, University of Newcastle, Newcastle 2308, Australia.
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20
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Multiplex droplet digital PCR assay for detection of Flavobacterium psychrophilum and Yersinia ruckeri in Norwegian aquaculture. J Microbiol Methods 2020; 177:106044. [DOI: 10.1016/j.mimet.2020.106044] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 08/28/2020] [Accepted: 08/28/2020] [Indexed: 11/21/2022]
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21
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Voegel TM, Larrabee MM, Nelson LM. Development of droplet digital PCR assays to quantify genes involved in nitrification and denitrification, comparison with quantitative real-time PCR and validation of assays in vineyard soil. Can J Microbiol 2020; 67:174-187. [PMID: 32910858 DOI: 10.1139/cjm-2020-0033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Quantifying genes in soil is important to relate the abundance of soil bacteria to biogeochemical cycles. Quantitative real-time PCR is widely used for quantification, but its use with environmental samples is limited by poor reaction efficiencies or by PCR inhibition through co-purified soil substances. Droplet digital PCR (ddPCR) is a technology for absolute, sensitive quantification of genes. This study optimized eight ddPCR assays to quantify total bacteria and archaea as well as the nitrification (bacterial and archaeal amoA) and denitrification (nirS, nirK, nosZI, nosZII) genes involved in the generation or reduction of the greenhouse gas nitrous oxide. Detection and quantification thresholds were compared with those of quantitative real-time PCR and were equal to, or improved, in ddPCR. To validate the assays using environmental samples, soil DNA was isolated from two vineyards in the Okanagan valley in British Columbia, Canada, over the 2017 growing season. Soil properties related to the observed gene abundances were determined. Total bacteria, nirK, and nosZII increased with time and the soil C/N ratio and NH4+-N concentration affected total archaea and archaeal amoA negatively. The results, compared with those of other studies, showed that ddPCR is a valid alternative to qPCR to quantify genes involved in nitrification or denitrification.
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Affiliation(s)
- Tanja M Voegel
- Irving K. Barber Faculty of Science, Department of Biology, University of British Columbia Okanagan, 1177 Research Road, Kelowna, BC V1V 1V7, Canada.,Irving K. Barber Faculty of Science, Department of Biology, University of British Columbia Okanagan, 1177 Research Road, Kelowna, BC V1V 1V7, Canada
| | - Melissa M Larrabee
- Irving K. Barber Faculty of Science, Department of Biology, University of British Columbia Okanagan, 1177 Research Road, Kelowna, BC V1V 1V7, Canada.,Irving K. Barber Faculty of Science, Department of Biology, University of British Columbia Okanagan, 1177 Research Road, Kelowna, BC V1V 1V7, Canada
| | - Louise M Nelson
- Irving K. Barber Faculty of Science, Department of Biology, University of British Columbia Okanagan, 1177 Research Road, Kelowna, BC V1V 1V7, Canada.,Irving K. Barber Faculty of Science, Department of Biology, University of British Columbia Okanagan, 1177 Research Road, Kelowna, BC V1V 1V7, Canada
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22
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Cao Y, Yu M, Dong G, Chen B, Zhang B. Digital PCR as an Emerging Tool for Monitoring of Microbial Biodegradation. Molecules 2020; 25:E706. [PMID: 32041334 PMCID: PMC7037809 DOI: 10.3390/molecules25030706] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 11/16/2022] Open
Abstract
Biodegradation of contaminants is extremely complicated due to unpredictable microbial behaviors. Monitoring of microbial biodegradation drives us to determine (1) the amounts of specific degrading microbes, (2) the abundance, and (3) expression level of relevant functional genes. To this endeavor, the cultivation independent polymerase chain reaction (PCR)-based monitoring technique develops from endpoint PCR, real-time quantitative PCR, and then into novel digital PCR. In this review, we introduce these three categories of PCR techniques and summarize the timely applications of digital PCR and its superiorities than qPCR for biodegradation monitoring. Digital PCR technique, emerging as the most accurately absolute quantification method, can serve as the most promising and robust tool for monitoring of microbial biodegradation.
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Affiliation(s)
| | | | | | - Bing Chen
- The Northern Region Persistent Organic Pollution (NRPOP) Control Laboratory, Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL A1B 3X5, Canada; (Y.C.); (M.Y.); (G.D.)
| | - Baiyu Zhang
- The Northern Region Persistent Organic Pollution (NRPOP) Control Laboratory, Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL A1B 3X5, Canada; (Y.C.); (M.Y.); (G.D.)
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23
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Dyer SW, Needoba JA. Use of High-Resolution Pressure Nephelometry To Measure Gas Vesicle Collapse as a Means of Determining Growth and Turgor Changes in Planktonic Cyanobacteria. Appl Environ Microbiol 2020; 86:e01790-19. [PMID: 31676479 PMCID: PMC6952233 DOI: 10.1128/aem.01790-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 10/27/2019] [Indexed: 01/10/2023] Open
Abstract
Previous work has demonstrated that the physical properties of intracellular bacterial gas vesicles (GVs) can be analyzed in vivo using pressure nephelometry. In analyzing the buoyant state of GV-containing cyanobacteria, hydrostatic pressure within a sample cell is increased in a stepwise manner, where the concomitant collapse of GVs due to pressure and the resultant decrease in suspended cells are detected by changes in nephelometric scattering. As the relative pressure at which GVs collapse is a function of turgor pressure and cellular osmotic gradients, pressure nephelometry is a powerful tool for assaying changes in metabolism that affect turgor, such as photosynthetic and osmoregulatory processes. We have developed an updated and automated pressure nephelometer that utilizes visible-infrared (Vis-IR) spectra to accurately quantify GV critical collapse pressure, critical collapse pressure distribution, and cell turgor pressure. Here, using the updated pressure nephelometer and axenic cultures of Microcystis aeruginosa PCC7806, we demonstrate that GV critical collapse pressure is stable during mid-exponential growth phase, introduce pressure-sensitive turbidity as a robust metric for the abundance of gas-vacuolate cyanobacteria, and demonstrate that pressure-sensitive turbidity is a more accurate proxy for abundance and growth than photopigment fluorescence. As cyanobacterium-dominated harmful algal bloom (cyanoHAB) formation is dependent on the constituent cells possessing gas vesicles, characterization of environmental cyanobacteria populations via pressure nephelometry is identified as an underutilized monitoring method. Applications of this instrument focus on physiological and ecological studies of cyanobacteria, for example, cyanoHAB dynamics and the drivers associated with cyanotoxin production in aquatic ecosystems.IMPORTANCE The increased prevalence of bloom-forming cyanobacteria and associated risk of exposure to cyanobacterial toxins through drinking water utilities and recreational waterways are growing public health concerns. Cost-effective, early-detection methodologies specific to cyanobacteria are crucial for mitigating these risks, with a gas vesicle-specific signal offering a number of benefits over photopigment fluorescence, including improved detection limits and discrimination against non-gas-vacuolate phototrophs. Here, we present a multiplexed instrument capable of quantifying the relative abundance of cyanobacteria based on the signal generated from the presence of intracellular gas vesicles specific to bloom-forming cyanobacteria. Additionally, as cell turgor can be measured in vivo via pressure nephelometry, the measurement furnishes information about the internal osmotic pressure of gas-vacuolate cyanobacteria, which relates to the metabolic state of the cell. Together these advances may improve routine waterway monitoring and the mitigation of human health threats due to cyanobacterial blooms.
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Affiliation(s)
- Stuart W Dyer
- Oregon Health and Science University, Institute of Environmental Health, Portland, Oregon, USA
- Oregon Health and Science University-Portland State University, School of Public Health, Portland, Oregon, USA
| | - Joseph A Needoba
- Oregon Health and Science University, Institute of Environmental Health, Portland, Oregon, USA
- Oregon Health and Science University-Portland State University, School of Public Health, Portland, Oregon, USA
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Draft Genome Sequences of Three Filamentous Cyanobacterial Strains, Dolichospermum planctonicum NIES-80, Planktothrix agardhii NIES-905, and Sphaerospermopsis reniformis NIES-1949. Microbiol Resour Announc 2019; 8:8/43/e00605-19. [PMID: 31649090 PMCID: PMC6813379 DOI: 10.1128/mra.00605-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Three freshwater planktonic filamentous cyanobacterial strains, Dolichospermum planctonicum NIES-80, Planktothrix agardhii NIES-905, and Sphaerospermopsis reniformis NIES-1949, were sequenced. The genome sizes of NIES-80, NIES-905, and NIES-1949 were 4,571,002 bp, 5,512,454 bp, and 6,025,023 bp, and the number of protein-coding genes in each genome was 4,009, 4,925, and 5,408, respectively. Three freshwater planktonic filamentous cyanobacterial strains, Dolichospermum planctonicum NIES-80, Planktothrix agardhii NIES-905, and Sphaerospermopsis reniformis NIES-1949, were sequenced. The genome sizes of NIES-80, NIES-905, and NIES-1949 were 4,571,002 bp, 5,512,454 bp, and 6,025,023 bp, and the number of protein-coding genes in each genome was 4,009, 4,925, and 5,408, respectively.
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Wood SA, Pochon X, Laroche O, Ammon U, Adamson J, Zaiko A. A comparison of droplet digital polymerase chain reaction (PCR), quantitative PCR and metabarcoding for species‐specific detection in environmental DNA. Mol Ecol Resour 2019; 19:1407-1419. [DOI: 10.1111/1755-0998.13055] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/07/2019] [Accepted: 06/10/2019] [Indexed: 12/01/2022]
Affiliation(s)
- Susanna A. Wood
- Coastal and Freshwater Group Cawthron Institute Nelson New Zealand
| | - Xavier Pochon
- Coastal and Freshwater Group Cawthron Institute Nelson New Zealand
- Institute of Marine Science University of Auckland Auckland New Zealand
| | - Olivier Laroche
- Coastal and Freshwater Group Cawthron Institute Nelson New Zealand
- Department of Oceanography, School of Ocean and Earth Science and Technology University of Hawaii at Manoa Honolulu HI USA
| | - Ulla Ammon
- Coastal and Freshwater Group Cawthron Institute Nelson New Zealand
- Institute of Marine Science University of Auckland Auckland New Zealand
| | - Janet Adamson
- Coastal and Freshwater Group Cawthron Institute Nelson New Zealand
| | - Anastasija Zaiko
- Coastal and Freshwater Group Cawthron Institute Nelson New Zealand
- Institute of Marine Science University of Auckland Auckland New Zealand
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Nshimyimana JP, Cruz MC, Wuertz S, Thompson JR. Variably improved microbial source tracking with digital droplet PCR. WATER RESEARCH 2019; 159:192-202. [PMID: 31096066 DOI: 10.1016/j.watres.2019.04.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 04/24/2019] [Accepted: 04/29/2019] [Indexed: 05/05/2023]
Abstract
This study addressed whether digital droplet PCR (ddPCR) could improve sensitivity and specificity of human-associated Bacteroidales genetic markers, BacHum and B. theta, and their quantification in environmental and fecal composite samples. Human markers were quantified by qPCR and ddPCR platforms obtained from the same manufacturer. A total of 180 samples were evaluated by each platform including human and animal feces, sewage, and environmental water. The sensitivity of ddPCR and qPCR marker assays in sewage and human stool was 0.85-1.00 with marginal reduction in human stool by ddPCR relative to qPCR (<10%). The prevalence and distribution of markers across complex sample types was similar (74-100% agreement) by both platforms with qPCR showing higher sensitivity for markers in environmental and composite samples and ddPCR showing greater reproducibility for marker detection in fecal composites. Determination of BacHum prevalence in fecal samples by ddPCR increased specificity relative to qPCR (from 0.58 to 0.88) and accuracy (from 0.77 to 0.94), while the B. theta assay performed similarly on both platforms (specificity = 0.98). In silico analysis indicated higher specificity of ddPCR for BacHum was not solely attributed to reduced sensitivity relative to qPCR. Marker concentrations measured by ddPCR for all sample types were consistently lower than those measured by qPCR, by a factor of 2.6 ± 2.8 for B. theta and 18.7 ± 10.0 for BacHum. We suggest that differences in assay performance on ddPCR and qPCR platforms may be linked to the characteristics of the assay targets (that is, genes with multiple versus single copies and encoding proteins versus ribosomal RNA) however further work is needed to validate these ideas. We conclude that ddPCR is a suitable tool for microbial source tracking, however, other factors such as cost-effectiveness and assay-specific performance should be considered.
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Affiliation(s)
- Jean Pierre Nshimyimana
- School of Civil and Environmental Engineering, Nanyang Technological University (NTU), 50 Nanyang Avenue, Singapore, 639798, Singapore; Singapore Centre for Environmental Life Sciences Engineering, NTU, 60 Nanyang Dr., Singapore, 637551, Singapore; Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - Mercedes C Cruz
- Singapore Centre for Environmental Life Sciences Engineering, NTU, 60 Nanyang Dr., Singapore, 637551, Singapore
| | - Stefan Wuertz
- School of Civil and Environmental Engineering, Nanyang Technological University (NTU), 50 Nanyang Avenue, Singapore, 639798, Singapore; Singapore Centre for Environmental Life Sciences Engineering, NTU, 60 Nanyang Dr., Singapore, 637551, Singapore
| | - Janelle R Thompson
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), 77 Massachusetts Avenue, Cambridge, MA, 02139, USA; Centre for Environmental Sensing and Modeling, Singapore-MIT Alliance for Research and Technology, 1 Create Way, Singapore, 138602, Singapore.
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Ding CYG, Pang LM, Liang ZX, Goh KKK, Glukhov E, Gerwick WH, Tan LT. MS/MS-Based Molecular Networking Approach for the Detection of Aplysiatoxin-Related Compounds in Environmental Marine Cyanobacteria. Mar Drugs 2018; 16:md16120505. [PMID: 30551660 PMCID: PMC6315786 DOI: 10.3390/md16120505] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 12/05/2018] [Accepted: 12/10/2018] [Indexed: 12/20/2022] Open
Abstract
Certain strains of cyanobacteria produce a wide array of cyanotoxins, such as microcystins, lyngbyatoxins and aplysiatoxins, that are associated with public health issues. In this pilot study, an approach combining LC-MS/MS and molecular networking was employed as a rapid analytical method to detect aplysiatoxins present in four environmental marine cyanobacterial samples collected from intertidal areas in Singapore. Based on 16S-ITS rRNA gene sequences, these filamentous cyanobacterial samples collected from Pulau Hantu were determined as Trichodesmium erythraeum, Oscillatoria sp. PAB-2 and Okeania sp. PNG05-4. Organic extracts were prepared and analyzed on LC-HRMS/MS and Global Natural Product Social Molecular Networking (GNPS) for the presence of aplysiatoxin-related molecules. From the molecular networking, six known compounds, debromoaplysiatoxin (1), anhydrodebromoaplysiatoxin (2), 3-methoxydebromoaplysiatoxin (3), aplysiatoxin (4), oscillatoxin A (5) and 31-noroscillatoxin B (6), as well as potential new analogues, were detected in these samples. In addition, differences and similarities in molecular networking clusters related to the aplysiatoxin molecular family were observed in extracts of Trichodesmium erythraeum collected from two different locations and from different cyanobacterial species found at Pulau Hantu, respectively.
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Affiliation(s)
- Chi Ying Gary Ding
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore 637616, Singapore.
| | - Li Mei Pang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore.
| | - Zhao-Xun Liang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore.
| | - Kau Kiat Kelvin Goh
- Singapore Phenome Centre, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, (K.K.K.G.).
| | - Evgenia Glukhov
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093, USA.
| | - William H Gerwick
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093, USA.
| | - Lik Tong Tan
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore 637616, Singapore.
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Wood SA, Pochon X, Ming W, von Ammon U, Woods C, Carter M, Smith M, Inglis G, Zaiko A. Considerations for incorporating real-time PCR assays into routine marine biosecurity surveillance programmes: a case study targeting the Mediterranean fanworm ( Sabella spallanzanii) and club tunicate ( Styela clava) 1. Genome 2018; 62:137-146. [PMID: 30278148 DOI: 10.1139/gen-2018-0021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Molecular techniques may provide effective tools to enhance marine biosecurity surveillance. Prior to routine implementation, evidence-based consideration of their benefits and limitations is needed. In this study, we assessed the efficiency and practicality of visual diver surveys and real-time PCR assays (targeting DNA and RNA) for detecting two marine invasive species whose infestation levels varied between species and location: Sabella spallanzanii and Styela clava. Filtered water samples (n = 171) were collected in parallel with dive surveys at two locations as part of the New Zealand Marine High Risk Site Surveillance programme: Nelson Harbour (27 sites) and Waitemata Harbour (30 sites). Diver surveys resulted in a greater number of detections compared to real-time PCR: S. clava - 21 versus 5 sites in Nelson, 6 versus 1 in Auckland; S. spallanzanii - 18 versus 10 in Auckland, no detections in Nelson. Occupancy modelling derived detection probabilities for the real-time PCR for S. clava were low (14%), compared to S. spallanzanii (66%). This could be related to abundances, or species-specific differences in DNA shedding. Only one RNA sample was positive, suggesting that most detections were from extracellular DNA or non-viable fragments. While molecular methods cannot yet replace visual observations, this study shows they provide useful complementary information.
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Affiliation(s)
- Susanna A Wood
- a Coastal and Freshwater Group, Cawthron Institute, Nelson, New Zealand
| | - Xavier Pochon
- a Coastal and Freshwater Group, Cawthron Institute, Nelson, New Zealand.,c Institute of Marine Science, University of Auckland, Auckland, New Zealand
| | - Witold Ming
- a Coastal and Freshwater Group, Cawthron Institute, Nelson, New Zealand
| | - Ulla von Ammon
- a Coastal and Freshwater Group, Cawthron Institute, Nelson, New Zealand.,b School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Chris Woods
- d National Institute of Water & Atmospheric Research Ltd., New Zealand
| | - Megan Carter
- d National Institute of Water & Atmospheric Research Ltd., New Zealand
| | - Matt Smith
- d National Institute of Water & Atmospheric Research Ltd., New Zealand
| | - Graeme Inglis
- d National Institute of Water & Atmospheric Research Ltd., New Zealand
| | - Anastasija Zaiko
- a Coastal and Freshwater Group, Cawthron Institute, Nelson, New Zealand.,b School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Vynck M, Thas O. Reducing Bias in Digital PCR Quantification Experiments: The Importance of Appropriately Modeling Volume Variability. Anal Chem 2018; 90:6540-6547. [DOI: 10.1021/acs.analchem.8b00115] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthijs Vynck
- Department of Data Analysis and Mathematical Modelling, Ghent University, Ghent 9000, Belgium
| | - Olivier Thas
- Department of Data Analysis and Mathematical Modelling, Ghent University, Ghent 9000, Belgium
- National Institute for Applied Statistics Research Australia (NIASRA), University of Wollongong, Wollongong, NSW 2522, Australia
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30
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Gobert G, Cotillard A, Fourmestraux C, Pruvost L, Miguet J, Boyer M. Droplet digital PCR improves absolute quantification of viable lactic acid bacteria in faecal samples. J Microbiol Methods 2018; 148:64-73. [DOI: 10.1016/j.mimet.2018.03.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/12/2018] [Accepted: 03/12/2018] [Indexed: 02/06/2023]
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31
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Niu C, Xu Y, Zhang C, Zhu P, Huang K, Luo Y, Xu W. Ultrasensitive Single Fluorescence-Labeled Probe-Mediated Single Universal Primer-Multiplex-Droplet Digital Polymerase Chain Reaction for High-Throughput Genetically Modified Organism Screening. Anal Chem 2018; 90:5586-5593. [PMID: 29652133 DOI: 10.1021/acs.analchem.7b03974] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
As genetically modified (GM) technology develops and genetically modified organisms (GMOs) become more available, GMOs face increasing regulations and pressure to adhere to strict labeling guidelines. A singleplex detection method cannot perform the high-throughput analysis necessary for optimal GMO detection. Combining the advantages of multiplex detection and droplet digital polymerase chain reaction (ddPCR), a single universal primer-multiplex-ddPCR (SUP-M-ddPCR) strategy was proposed for accurate broad-spectrum screening and quantification. The SUP increases efficiency of the primers in PCR and plays an important role in establishing a high-throughput, multiplex detection method. Emerging ddPCR technology has been used for accurate quantification of nucleic acid molecules without a standard curve. Using maize as a reference point, four heterologous sequences ( 35S, NOS, NPTII, and PAT) were selected to evaluate the feasibility and applicability of this strategy. Surprisingly, these four genes cover more than 93% of the transgenic maize lines and serve as preliminary screening sequences. All screening probes were labeled with FAM fluorescence, which allows the signals from the samples with GMO content and those without to be easily differentiated. This fiveplex screening method is a new development in GMO screening. Utilizing an optimal amplification assay, the specificity, limit of detection (LOD), and limit of quantitation (LOQ) were validated. The LOD and LOQ of this GMO screening method were 0.1% and 0.01%, respectively, with a relative standard deviation (RSD) < 25%. This method could serve as an important tool for the detection of GM maize from different processed, commercially available products. Further, this screening method could be applied to other fields that require reliable and sensitive detection of DNA targets.
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Affiliation(s)
- Chenqi Niu
- Laboratory of Food Safety, College of Food Science and Nutritional Engineering , China Agricultural University , Beijing 100083 , China
| | - Yuancong Xu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering , China Agricultural University , Beijing 100083 , China.,Laboratory of Food Safety, College of Food Science and Nutritional Engineering , China Agricultural University , Beijing 100083 , China
| | - Chao Zhang
- Laboratory of Food Safety, College of Food Science and Nutritional Engineering , China Agricultural University , Beijing 100083 , China
| | - Pengyu Zhu
- The Institute of Plant Quarantine , Chinese Academy of Inspection and Quarantine , Beijing 100029 , China
| | - Kunlun Huang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering , China Agricultural University , Beijing 100083 , China.,Laboratory of Food Safety, College of Food Science and Nutritional Engineering , China Agricultural University , Beijing 100083 , China.,Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety) , Ministry of Agriculture , Beijing 100083 , China
| | - Yunbo Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering , China Agricultural University , Beijing 100083 , China.,Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety) , Ministry of Agriculture , Beijing 100083 , China
| | - Wentao Xu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering , China Agricultural University , Beijing 100083 , China.,Laboratory of Food Safety, College of Food Science and Nutritional Engineering , China Agricultural University , Beijing 100083 , China.,Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety) , Ministry of Agriculture , Beijing 100083 , China
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32
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Cunha F, Jeon SJ, Daetz R, Vieira-Neto A, Laporta J, Jeong KC, Barbet AF, Risco CA, Galvão KN. Quantifying known and emerging uterine pathogens, and evaluating their association with metritis and fever in dairy cows. Theriogenology 2018; 114:25-33. [PMID: 29574306 DOI: 10.1016/j.theriogenology.2018.03.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/13/2018] [Indexed: 02/07/2023]
Abstract
Metritis is caused by polymicrobial infection; however, recent metagenomic work challenges the importance of known pathogens such as Escherichia coli and Trueperella pyogenes while identifying potential new pathogens such as Bacteroides pyogenes, Porphyromonas levii and Helcococcus ovis. This study aims to quantify known and emerging uterine pathogens, and to evaluate their association with metritis and fever in dairy cows. Metritis was diagnosed at 6 ± 2 days postpartum, a uterine swab was collected and rectal temperature was measured. 39 cows were classified into three groups: Healthy (n = 14), Metritis without fever (MNoFever; n = 12), and Metritis with fever (MFever; n = 13). Absolute copy number was determined for total bacteria and for 8 potentially pathogenic bacteria using droplet digital PCR. Both MNoFever and MFever cows had higher copy number of total bacteria, Fusobacterium necrophorum, Prevotella melaninogenica, Bacteroides pyogenes, Porphyromonas levii, and Helcococcus ovis than Healthy cows. MNoFever and MFever groups were similar. There was no difference among groups in copy number of Escherichia coli, Trueperella pyogenes, and Bacteroides heparinolyticus, and they all had low copy numbers. Our work confirms the importance of some bacteria identified by culture-based studies in the pathogenesis of metritis such as Fusobacterium necrophorum and Prevotella melaninogenica; however, it challenges the importance of others such as Escherichia coli and Trueperella pyogenes at the time of metritis diagnosis. Additionally, Bacteroides pyogenes, Porphyromonas levii, and Helcococcus ovis were recognized as emerging pathogens involved in the etiology of metritis. Furthermore, fever was not associated with the total bacterial load or specific bacteria.
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Affiliation(s)
- Federico Cunha
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Soo Jin Jeon
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Rodolfo Daetz
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Achilles Vieira-Neto
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; D. H. Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, FL 32610, USA
| | - Jimena Laporta
- Department of Animal Sciences, University of Florida, Gainesville, FL, USA
| | - K Casey Jeong
- Department of Animal Sciences, University of Florida, Gainesville, FL, USA; Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Anthony F Barbet
- Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Carlos A Risco
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Klibs N Galvão
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; D. H. Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, FL 32610, USA.
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The Abundance of Toxic Genotypes Is a Key Contributor to Anatoxin Variability in Phormidium-Dominated Benthic Mats. Mar Drugs 2017; 15:md15100307. [PMID: 29019928 PMCID: PMC5666415 DOI: 10.3390/md15100307] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 09/10/2017] [Accepted: 10/04/2017] [Indexed: 12/31/2022] Open
Abstract
The prevalence of benthic proliferations of the anatoxin-producing cyanobacterium Phormidium are increasing in cobble-bed rivers worldwide. Studies to date have shown high spatial and temporal variability in anatoxin concentrations among mats. In this study we determined anatoxin quotas (toxins per cell) in field samples and compared these results to the conventionally-used concentrations (assessed per dry weight of mat). Three mats were selected at sites in two rivers and were sampled every 2–3 h for 24–26 h. The samples were lyophilized and ground to a fine homogenous powder. Two aliquots of known weights were analyzed for anatoxin congeners using liquid chromatography-mass spectrometry, or digital droplet PCR with Phormidium-specific anaC primers to measure absolute quantities of gene copies. Anatoxin concentrations in the mats varied 59- and 303-fold in the two rivers over the study periods. A similar pattern was observed among gene copies (53- and 2828-fold). When converted to anatoxin quotas there was markedly less variability (42- and 16-fold), but significantly higher anatoxin quotas were observed in mats from the second river (p < 0.001, Student’s t-test). There were no obvious temporal patterns with high and low anatoxin concentrations or quotas measured at each sampling time and across the study period. These results demonstrate that variability in anatoxin concentrations among mats is primarily due to the abundance of toxic genotypes. No consistent modulation in anatoxin production was observed during the study, although significant differences in anatoxin quotas among rivers suggest that site-specific physiochemical or biological factors may influence anatoxin production.
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Sefrioui D, Beaussire L, Clatot F, Delacour J, Perdrix A, Frebourg T, Michel P, Di Fiore F, Sarafan-Vasseur N. Heparinase enables reliable quantification of circulating tumor DNA from heparinized plasma samples by droplet digital PCR. Clin Chim Acta 2017; 472:75-79. [PMID: 28729136 DOI: 10.1016/j.cca.2017.07.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/15/2017] [Indexed: 01/26/2023]
Abstract
BACKGROUND Heparin is often used as a blood anticoagulant for tumor marker analysis but results in the inhibition of PCR detection of circulating tumor DNA (ctDNA), which has been deemed a potential "liquid biopsy". We aimed to evaluate the impact of heparinase addition on heparinized plasma samples to allow ctDNA analysis. METHODS Plasma samples were collected in heparinized (n=194) and EDTA (n=8) tubes from hormone receptor-positive metastatic breast cancer (HR+MBC) (n=144) and pancreatic adenocarcinoma (PA) patients (n=50). Circulating ESR1 and KRAS mutations were detected with or without heparinase by digital PCR in HR+MBC and PA patients, respectively. Patients were classified into 2 subgroups i) inhibition, I+ and ii) no inhibition, I- based on a threshold of 200copies/μL for PCR inhibition by heparin. RESULTS In the I+ subgroup (91/144 HR+MBC and 26/50 PA), heparinase treatment significantly improved PCR efficacy, enabling ctDNA detection in 22/91 and 13/26 patients. Moreover, comparable results for ctDNA detection (4/8) were obtained with heparinized and EDTA PA samples. In the I- subgroup, heparinase addition did not quantitatively and qualitatively alter ctDNA detection. CONCLUSION Heparinase addition removes the heparin inhibition and allows accurate ctDNA detection in heparinized samples. These findings could make the samples from heparinized blood suitable for ctDNA analysis.
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Affiliation(s)
- David Sefrioui
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine and Digestive Oncology Unit, F 76000 Rouen, France
| | - Ludivine Beaussire
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine, F 76000 Rouen, France
| | - Florian Clatot
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine and Department of Medical Oncology, Henri Becquerel Centre, F 76000 Rouen, France
| | - Julien Delacour
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine, F 76000 Rouen, France
| | - Anne Perdrix
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine and Department of Biopathology, Henri Becquerel Centre, F 76000 Rouen, France
| | - Thierry Frebourg
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine, F 76000 Rouen, France
| | - Pierre Michel
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine and Digestive Oncology Unit, F 76000 Rouen, France
| | - Frédéric Di Fiore
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine, Digestive Oncology Unit and Department of Medical Oncology, Henri Becquerel Centre, F 76000 Rouen, France
| | - Nasrin Sarafan-Vasseur
- Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine, F 76000 Rouen, France.
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Schwarzenberger A, Keith NR, Jackson CE, Von Elert E. Copy number variation of a protease gene of Daphnia
: Its role in population tolerance. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:119-126. [DOI: 10.1002/jez.2077] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/16/2017] [Accepted: 05/18/2017] [Indexed: 12/30/2022]
Affiliation(s)
- Anke Schwarzenberger
- Cologne Biocenter, Aquatic Chemical Ecology, University of Cologne; Cologne Germany
- School of Public and Environmental Affairs (SPEA), Indiana University; Bloomington Indiana
- Limnological Institute, Konstanz University; Konstanz Germany
| | - Nathan R. Keith
- School of Public and Environmental Affairs (SPEA), Indiana University; Bloomington Indiana
| | - Craig E. Jackson
- School of Public and Environmental Affairs (SPEA), Indiana University; Bloomington Indiana
| | - Eric Von Elert
- Cologne Biocenter, Aquatic Chemical Ecology, University of Cologne; Cologne Germany
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Molecular Techniques for the Detection of Organisms in Aquatic Environments, with Emphasis on Harmful Algal Bloom Species. SENSORS 2017; 17:s17051184. [PMID: 28531156 PMCID: PMC5470929 DOI: 10.3390/s17051184] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 05/18/2017] [Accepted: 05/20/2017] [Indexed: 02/08/2023]
Abstract
Molecular techniques to detect organisms in aquatic ecosystems are being gradually considered as an attractive alternative to standard laboratory methods. They offer faster and more accurate means of detecting and monitoring species, with respect to their traditional homologues based on culture and microscopic counting. Molecular techniques are particularly attractive when multiple species need to be detected and/or are in very low abundance. This paper reviews molecular techniques based on whole cells, such as microscope-based enumeration and Fluorescence In-Situ Hybridization (FISH) and molecular cell-free formats, such as sandwich hybridization assay (SHA), biosensors, microarrays, quantitative polymerase chain reaction (qPCR) and real time PCR (RT-PCR). Those that combine one or several laboratory functions into a single integrated system (lab-on-a-chip) and techniques that generate a much higher throughput data, such as next-generation systems (NGS), were also reviewed. We also included some other approaches that enhance the performance of molecular techniques. For instance, nano-bioengineered probes and platforms, pre-concentration and magnetic separation systems, and solid-phase hybridization offer highly pre-concentration capabilities. Isothermal amplification and hybridization chain reaction (HCR) improve hybridization and amplification techniques. Finally, we presented a study case of field remote sensing of harmful algal blooms (HABs), the only example of real time monitoring, and close the discussion with future directions and concluding remarks.
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A qPCR-Based Tool to Diagnose the Presence of Harmful Cyanobacteria and Cyanotoxins in Drinking Water Sources. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:ijerph14050547. [PMID: 28531121 PMCID: PMC5451997 DOI: 10.3390/ijerph14050547] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/14/2017] [Accepted: 05/17/2017] [Indexed: 11/30/2022]
Abstract
Harmful cyanobacteria have been an important concern for drinking water quality for quite some time, as they may produce cyanotoxins and odorants. Microcystis and Cylindrospermopsis are two common harmful cyanobacterial genera detected in freshwater lakes and reservoirs, with microcystins (MCs) and cylindrospermopsin (CYN) as their important metabolites, respectively. In this study, two sets of duplex qPCR systems were developed, one for quantifying potentially-toxigenic Microcystis and Microcystis, and the other one for cylindrospermopsin-producing cyanobacteria and Cylindrospermopsis. The duplex qPCR systems were developed and validated in the laboratory by using 338 samples collected from 29 reservoirs in Taiwan and her offshore islands. Results show that cell numbers of Microcystis and Cylindorspermopsis enumerated with microscopy, and MCs and CYN concentrations measured with the enzyme-linked immuno-sorbent assay method, correlated well with their corresponding gene copies determined with the qPCR systems (range of coefficients of determination R2 = 0.392−0.740). The developed qPCR approach may serve as a useful tool for the water industry to diagnose the presence of harmful cyanobacteria and the potential presence of cyanotoxins in source waters.
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Four human Plasmodium species quantification using droplet digital PCR. PLoS One 2017; 12:e0175771. [PMID: 28423028 PMCID: PMC5396971 DOI: 10.1371/journal.pone.0175771] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 03/30/2017] [Indexed: 02/06/2023] Open
Abstract
Droplet digital polymerase chain reaction (ddPCR) is a partial PCR based on water-oil emulsion droplet technology. It is a highly sensitive method for detecting and delineating minor alleles from complex backgrounds and provides absolute quantification of DNA targets. The ddPCR technology has been applied for detection of many pathogens. Here the sensitive assay utilizing ddPCR for detection and quantification of Plasmodium species was investigated. The assay was developed for two levels of detection, genus specific for all Plasmodium species and for specific Plasmodium species detection. The ddPCR assay was developed based on primers and probes specific to the Plasmodium genus 18S rRNA gene. Using ddPCR for ultra-sensitive P. falciparum assessment, the lower level of detection from concentrated DNA obtained from a high volume (1 mL) blood sample was 11 parasites/mL. For species identification, in particular for samples with mixed infections, a duplex reaction was developed for detection and quantification P. falciparum/ P. vivax and P. malariae/ P. ovale. Amplification of each Plasmodium species in the duplex reaction showed equal sensitivity to singleplex single species detection. The duplex ddPCR assay had higher sensitivity to identify minor species in 32 subpatent parasitaemia samples from Cambodia, and performed better than real-time PCR. The ddPCR assay shows high sensitivity to assess very low parasitaemia of all human Plasmodium species. This provides a useful research tool for studying the role of the asymptomatic parasite reservoir for transmission in regions aiming for malaria elimination.
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Te SH, Tan BF, Thompson JR, Gin KYH. Relationship of Microbiota and Cyanobacterial Secondary Metabolites in Planktothricoides-Dominated Bloom. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:4199-4209. [PMID: 28345890 DOI: 10.1021/acs.est.6b05767] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The identification of phytoplankton species and microbial biodiversity is necessary to assess water ecosystem health and the quality of water resources. We investigated the short-term (2 days) vertical and diel variations in bacterial community structure and microbially derived secondary metabolites during a cyanobacterial bloom that emerged in a highly urbanized tropical reservoir. The waterbody was largely dominated by the cyanobacteria Planktothricoides spp., together with the Synechococcus, Pseudanabaena, Prochlorothrix, and Limnothrix. Spatial differences (i.e., water depth) rather than temporal differences (i.e., day versus night) better-explained the short-term variability in water quality parameters and bacterial community composition. Difference in bacterial structure suggested a resource-driven distribution pattern for the community. We found that the freshwater bacterial community associated with cyanobacterial blooms is largely conserved at the phylum level, with Proteobacteria (β-proteobateria), Bacteroidetes, and Actinobacteria as the main taxa despite the cyanobacterial species present and geographical (Asia, Europe, Australia, and North America) or climatic distinctions. Through multivariate statistical analyses of the bacterial community, environmental parameters, and secondary metabolite concentrations, we observed positive relationships between the occurrences of cyanobacterial groups and off-flavor compounds (2-methyisoborneol and β-ionone), suggesting a cyanobacterial origin. This study demonstrates the potential of 16S rRNA gene amplicon sequencing as a supporting tool in algal bloom monitoring or water-resource management.
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Affiliation(s)
- Shu Harn Te
- NUS Environmental Research Institute, National University of Singapore , 5A Engineering Drive 1, No. 02-01 T-Lab Building, Singapore 117411
| | - Boon Fei Tan
- Centre for Environmental Sensing and Modelling, Singapore-MIT Alliance for Research and Technology Centre , 1 CREATE Way, #09-03 CREATE Tower, Singapore 138602
| | - Janelle R Thompson
- Centre for Environmental Sensing and Modelling, Singapore-MIT Alliance for Research and Technology Centre , 1 CREATE Way, #09-03 CREATE Tower, Singapore 138602
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Karina Yew-Hoong Gin
- NUS Environmental Research Institute, National University of Singapore , 5A Engineering Drive 1, No. 02-01 T-Lab Building, Singapore 117411
- Department of Civil and Environmental Engineering, National University of Singapore , 1 Engineering Drive 2, E1A 07-03, Singapore 117576
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Jia P, Purcell MK, Pan G, Wang J, Kan S, Liu Y, Zheng X, Shi X, He J, Yu L, Hua Q, Lu T, Lan W, Winton JR, Jin N, Liu H. Analytical validation of a reverse transcriptase droplet digital PCR (RT-ddPCR) for quantitative detection of infectious hematopoietic necrosis virus. J Virol Methods 2017; 245:73-80. [PMID: 28347708 DOI: 10.1016/j.jviromet.2017.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 03/23/2017] [Accepted: 03/23/2017] [Indexed: 12/14/2022]
Abstract
Infectious hematopoietic necrosis virus (IHNV) is an important pathogen of salmonid fishes. A validated universal reverse transcriptase quantitative PCR (RT-qPCR) assay that can quantify levels of IHNV in fish tissues has been previously reported. In the present study, we adapted the published set of IHNV primers and probe for use in a reverse-transcriptase droplet digital PCR (RT-ddPCR) assay for quantification of the virus in fish tissue samples. The RT-ddPCR and RT-qPCR assays detected 13 phylogenetically diverse IHNV strains, but neither assay produced detectable amplification when RNA from other fish viruses was used. The RT-ddPCR assay had a limit of detection (LOD) equating to 2.2 plaque forming units (PFU)/μl while the LOD for the RT-qPCR was 0.2 PFU/μl. Good agreement (69.4-100%) between assays was observed when used to detect IHNV RNA in cell culture supernatant and tissues from IHNV infected rainbow trout (Oncorhynchus mykiss) and arctic char (Salvelinus alpinus). Estimates of RNA copy number produced by the two assays were significantly correlated but the RT-qPCR consistently produced higher estimates than the RT-ddPCR. The analytical properties of the N gene RT-ddPCR test indicated that this method may be useful to assess IHNV RNA copy number for research and diagnostic purposes. Future work is needed to establish the within and between laboratory diagnostic performance of the RT-ddPCR assay.
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Affiliation(s)
- Peng Jia
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China; Institute of Military Veterinary Medicine, Academy of Military Medical Sciences of PLA, Jilin, 130117, People's Republic of China
| | - Maureen K Purcell
- US Geological Survey, Western Fisheries Research Center, 6505 Northeast 65th Street, Seattle, WA 98115, USA
| | - Guang Pan
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Jinjin Wang
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Shifu Kan
- Shenzhen Supervision and Testing Center for Quality and Safety of Agri-products, Shenzhen, 518005, People's Republic of China
| | - Yin Liu
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Xiaocong Zheng
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Xiujie Shi
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Junqiang He
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Li Yu
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Qunyi Hua
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Tikang Lu
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - Wensheng Lan
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China
| | - James R Winton
- US Geological Survey, Western Fisheries Research Center, 6505 Northeast 65th Street, Seattle, WA 98115, USA
| | - Ningyi Jin
- Institute of Military Veterinary Medicine, Academy of Military Medical Sciences of PLA, Jilin, 130117, People's Republic of China
| | - Hong Liu
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China.
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Cavé L, Brothier E, Abrouk D, Bouda PS, Hien E, Nazaret S. Efficiency and sensitivity of the digital droplet PCR for the quantification of antibiotic resistance genes in soils and organic residues. Appl Microbiol Biotechnol 2016; 100:10597-10608. [DOI: 10.1007/s00253-016-7950-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/12/2016] [Accepted: 10/20/2016] [Indexed: 11/28/2022]
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Lin CTM, Leibovitch EC, Almira-Suarez MI, Jacobson S. Human herpesvirus multiplex ddPCR detection in brain tissue from low- and high-grade astrocytoma cases and controls. Infect Agent Cancer 2016; 11:32. [PMID: 27462365 PMCID: PMC4960850 DOI: 10.1186/s13027-016-0081-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/25/2016] [Indexed: 11/19/2022] Open
Abstract
Background Glioblastoma (GBM) is a fatal CNS malignancy, representing 50 % of all gliomas with approximately 12–18 months survival time after initial diagnosis. Recently, the human herpesvirus cytomegalovirus (CMV) has been suggested to have an oncogenic role, yet this association remains controversial. In addition, human herpesvirus 6 (HHV-6) and Epstein-Barr virus (EBV) have also been associated with low-grade gliomas, but few studies have examined HHV-6 and EBV in glioblastomas. Droplet digital PCR (ddPCR) is a highly precise diagnostic tool that enables the absolute quantification of target DNA. This study examines the association between multiple human herpesviruses and astrocytomas. Methods This study analyzed 112 brain tissue specimens, including 45 glioblastoma, 12 astrocytoma grade III, 2 astrocytoma grade II, 4 astrocytoma grade I, and 49 controls. All brain tissue samples were de-identified and pathologically confirmed. Each tissue block was sectioned for DNA extraction and CMV, EBV, HHV-6A and HHV-6B, and a cellular housekeeping gene were amplified by ddPCR. Results Neither CMV nor HHV-6A were detected in any of the astrocytoma samples. However, HHV-6B (p = 0.147) and EBV (p = 0.049) had a higher positivity frequency in the GBM compared to the controls. Conclusion The undetectable CMV DNA in the astrocytoma cohort does not support the observation of an increased prevalence of CMV DNA in GBM, as reported in other studies. EBV has a significantly higher positivity in the GBM cohort compared to the controls, while HHV-6B has a higher but not statistically significant positivity in the case cohort. Whether these viruses play an oncogenic role in GBM remains to be further investigated.
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Affiliation(s)
- Cheng-Te Major Lin
- The National Institute of Neurological Disorders and Stroke, National Institutes of Health, BG 10 RM 5C103 10 Center Dr., Bethesda, MD 20892 USA ; School of Medicine and Health Sciences, The George Washington University, Ross Hall 2300 Eye Street, NW, Washington, DC 20037 USA
| | - Emily C Leibovitch
- The National Institute of Neurological Disorders and Stroke, National Institutes of Health, BG 10 RM 5C103 10 Center Dr., Bethesda, MD 20892 USA ; School of Medicine and Health Sciences, The George Washington University, Ross Hall 2300 Eye Street, NW, Washington, DC 20037 USA
| | - M Isabel Almira-Suarez
- School of Medicine and Health Sciences, The George Washington University, Ross Hall 2300 Eye Street, NW, Washington, DC 20037 USA
| | - Steven Jacobson
- The National Institute of Neurological Disorders and Stroke, National Institutes of Health, BG 10 RM 5C103 10 Center Dr., Bethesda, MD 20892 USA
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Kaminski TS, Scheler O, Garstecki P. Droplet microfluidics for microbiology: techniques, applications and challenges. LAB ON A CHIP 2016; 16:2168-87. [PMID: 27212581 DOI: 10.1039/c6lc00367b] [Citation(s) in RCA: 245] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Droplet microfluidics has rapidly emerged as one of the key technologies opening up new experimental possibilities in microbiology. The ability to generate, manipulate and monitor droplets carrying single cells or small populations of bacteria in a highly parallel and high throughput manner creates new approaches for solving problems in diagnostics and for research on bacterial evolution. This review presents applications of droplet microfluidics in various fields of microbiology: i) detection and identification of pathogens, ii) antibiotic susceptibility testing, iii) studies of microbial physiology and iv) biotechnological selection and improvement of strains. We also list the challenges in the dynamically developing field and new potential uses of droplets in microbiology.
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Affiliation(s)
- Tomasz S Kaminski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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Pacheco ABF, Guedes IA, Azevedo SMFO. Is qPCR a Reliable Indicator of Cyanotoxin Risk in Freshwater? Toxins (Basel) 2016; 8:toxins8060172. [PMID: 27338471 PMCID: PMC4926139 DOI: 10.3390/toxins8060172] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/23/2016] [Accepted: 05/24/2016] [Indexed: 01/06/2023] Open
Abstract
The wide distribution of cyanobacteria in aquatic environments leads to the risk of water contamination by cyanotoxins, which generate environmental and public health issues. Measurements of cell densities or pigment contents allow both the early detection of cellular growth and bloom monitoring, but these methods are not sufficiently accurate to predict actual cyanobacterial risk. To quantify cyanotoxins, analytical methods are considered the gold standards, but they are laborious, expensive, time-consuming and available in a limited number of laboratories. In cyanobacterial species with toxic potential, cyanotoxin production is restricted to some strains, and blooms can contain varying proportions of both toxic and non-toxic cells, which are morphologically indistinguishable. The sequencing of cyanobacterial genomes led to the description of gene clusters responsible for cyanotoxin production, which paved the way for the use of these genes as targets for PCR and then quantitative PCR (qPCR). Thus, the quantification of cyanotoxin genes appeared as a new method for estimating the potential toxicity of blooms. This raises a question concerning whether qPCR-based methods would be a reliable indicator of toxin concentration in the environment. Here, we review studies that report the parallel detection of microcystin genes and microcystin concentrations in natural populations and also a smaller number of studies dedicated to cylindrospermopsin and saxitoxin. We discuss the possible issues associated with the contradictory findings reported to date, present methodological limitations and consider the use of qPCR as an indicator of cyanotoxin risk.
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Affiliation(s)
- Ana Beatriz F Pacheco
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21949-902, Brazil.
| | - Iame A Guedes
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21949-902, Brazil.
| | - Sandra M F O Azevedo
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21949-902, Brazil.
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Olsson M, Kierczak M, Karlsson Å, Jabłońska J, Leegwater P, Koltookian M, Abadie J, De Citres CD, Thomas A, Hedhammar Å, Tintle L, Lindblad-Toh K, Meadows JRS. Absolute quantification reveals the stable transmission of a high copy number variant linked to autoinflammatory disease. BMC Genomics 2016; 17:299. [PMID: 27107962 PMCID: PMC4841964 DOI: 10.1186/s12864-016-2619-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/13/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dissecting the role copy number variants (CNVs) play in disease pathogenesis is directly reliant on accurate methods for quantification. The Shar-Pei dog breed is predisposed to a complex autoinflammatory disease with numerous clinical manifestations. One such sign, recurrent fever, was previously shown to be significantly associated with a novel, but unstable CNV (CNV_16.1). Droplet digital PCR (ddPCR) offers a new mechanism for CNV detection via absolute quantification with the promise of added precision and reliability. The aim of this study was to evaluate ddPCR in relation to quantitative PCR (qPCR) and to assess the suitability of the favoured method as a genetic test for Shar-Pei Autoinflammatory Disease (SPAID). RESULTS One hundred and ninety-six individuals were assayed using both PCR methods at two CNV positions (CNV_14.3 and CNV_16.1). The digital method revealed a striking result. The CNVs did not follow a continuum of alleles as previously reported, rather the alleles were stable and pedigree analysis showed they adhered to Mendelian segregation. Subsequent analysis of ddPCR case/control data confirmed that both CNVs remained significantly associated with the subphenotype of fever, but also to the encompassing SPAID complex (p < 0.001). In addition, harbouring CNV_16.1 allele five (CNV_16.1|5) resulted in a four-fold increase in the odds for SPAID (p < 0.001). The inclusion of a genetic marker for CNV_16.1 in a genome-wide association test revealed that this variant explained 9.7 % of genetic variance and 25.8 % of the additive genetic heritability of this autoinflammatory disease. CONCLUSIONS This data shows the utility of the ddPCR method to resolve cryptic copy number inheritance patterns and so open avenues of genetic testing. In its current form, the ddPCR test presented here could be used in canine breeding to reduce the number of homozygote CNV_16.1|5 individuals and thereby to reduce the prevalence of disease in this breed.
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Affiliation(s)
- M Olsson
- Department of Medicine, Rheumatology Unit, Karolinska Institute, Stockholm, Sweden
| | - M Kierczak
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Å Karlsson
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - J Jabłońska
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - P Leegwater
- Department of Clinical Sciences of Companion Animals, Utrecht University, Utrecht, Netherlands
| | - M Koltookian
- Broad Institute of MIT and Harvard, Boston, MA, USA
| | - J Abadie
- LUNAM University, Oniris, AMaROC Unit, Nantes, F-44307, France
| | | | - A Thomas
- ANTAGENE Animal Genetics Laboratory, La Tour de Salvagny, Lyon, 69, France
| | - Å Hedhammar
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - L Tintle
- Wurtsboro Veterinary Clinic, Wurtsboro, New York, USA
| | - K Lindblad-Toh
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.,Broad Institute of MIT and Harvard, Boston, MA, USA
| | - J R S Meadows
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
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Cámara E, Albiol J, Ferrer P. Droplet digital PCR-aided screening and characterization of Pichia pastoris multiple gene copy strains. Biotechnol Bioeng 2016; 113:1542-51. [PMID: 26704939 DOI: 10.1002/bit.25916] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/18/2015] [Accepted: 12/21/2015] [Indexed: 01/25/2023]
Abstract
Pichia (syn. Komagataella) pastoris is a widely used yeast platform for heterologous protein production. Expression cassettes are usually stably integrated into the genome of this host via homologous recombination. Although increasing gene dosage is a powerful strategy to improve recombinant protein production, an excess in the number of gene copies often leads to decreased product yields and increased metabolic burden, particularly for secreted proteins. We have constructed a series of strains harboring different copy numbers of a Rhizopus oryzae lipase gene (ROL), aiming to find the optimum gene dosage for secreted Rol production. In order to accurately determine ROL gene dosage, we implemented a novel protocol based on droplet digital PCR (ddPCR), and cross validated it with conventional real-time PCR. Gene copy number determination based on ddPCR allowed for an accurate ranking of transformants according to their ROL gene dosage. Results indicated that ddPCR was particularly superior at lower gene dosages (one to five copies) over quantitative real-time PCR (qPCR). This facilitated the determination of the optimal ROL gene dosage as low as two copies. The ranking of ROL gene dosage versus Rol yield was consistent at both small scale and bioreactor chemostat cultures, thereby easing clone characterization in terms of gene dosage dependent physiological effects, which could be discriminated even among strains differing by only one ROL copy. A selected two-copy strain showed twofold increase in Rol specific production in a chemostat culture over the single copy strain. Conversely, strains harboring more than two copies of the ROL gene showed decreased product and biomass yields, as well as altered substrate consumption specific rates, compared to the reference (one-copy) strain. Biotechnol. Bioeng. 2016;113: 1542-1551. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Elena Cámara
- Department of Chemical, Biological, and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, Bellaterra, 08193, Catalonia, Spain
| | - Joan Albiol
- Department of Chemical, Biological, and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, Bellaterra, 08193, Catalonia, Spain
| | - Pau Ferrer
- Department of Chemical, Biological, and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, Bellaterra, 08193, Catalonia, Spain.
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Assessment of the real-time PCR and different digital PCR platforms for DNA quantification. Anal Bioanal Chem 2015; 408:107-21. [PMID: 26521179 PMCID: PMC4706846 DOI: 10.1007/s00216-015-9107-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/02/2015] [Accepted: 10/08/2015] [Indexed: 12/31/2022]
Abstract
Digital PCR (dPCR) is beginning to supersede real-time PCR (qPCR) for quantification of nucleic acids in many different applications. Several analytical properties of the two most commonly used dPCR platforms, namely the QX100 system (Bio-Rad) and the 12.765 array of the Biomark system (Fluidigm), have already been evaluated and compared with those of qPCR. However, to the best of our knowledge, direct comparison between the three of these platforms using the same DNA material has not been done, and the 37 K array on the Biomark system has also not been evaluated in terms of linearity, analytical sensitivity and limit of quantification. Here, a first assessment of qPCR, the QX100 system and both arrays of the Biomark system was performed with plasmid and genomic DNA from human cytomegalovirus. With use of PCR components that alter the efficiency of qPCR, each dPCR platform demonstrated consistent copy-number estimations, which indicates the high resilience of dPCR. Two approaches, one considering the total reaction volume and the other considering the effective reaction size, were used to assess linearity, analytical sensitivity and variability. When the total reaction volume was considered, the best performance was observed with qPCR, followed by the QX100 system and the Biomark system. In contrast, when the effective reaction size was considered, all three platforms showed almost equal limits of detection and variability. Although dPCR might not always be more appropriate than qPCR for quantification of low copy numbers, dPCR is a suitable method for robust and reproducible quantification of viral DNA, and a promising technology for the higher-order reference measurement method.
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