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Chan DK, Dykema K, Fatima M, Harvey H, Qaderi I, Burrows LL. Nutrient Limitation Sensitizes Pseudomonas aeruginosa to Vancomycin. ACS Infect Dis 2023; 9:1408-1423. [PMID: 37279282 PMCID: PMC10353551 DOI: 10.1021/acsinfecdis.3c00167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Indexed: 06/08/2023]
Abstract
Traditional antibacterial screens rely on growing bacteria in nutrient-replete conditions which are not representative of the natural environment or sites of infection. Instead, screening in more physiologically relevant conditions may reveal novel activity for existing antibiotics. Here, we screened a panel of antibiotics reported to lack activity against the opportunistic Gram-negative bacterium, Pseudomonas aeruginosa, under low-nutrient and low-iron conditions, and discovered that the glycopeptide vancomycin inhibited the growth of P. aeruginosa at low micromolar concentrations through its canonical mechanism of action, disruption of peptidoglycan crosslinking. Spontaneous vancomycin-resistant mutants underwent activating mutations in the sensor kinase of the two-component CpxSR system, which induced cross-resistance to almost all classes of β-lactams, including the siderophore antibiotic cefiderocol. Other mutations that conferred vancomycin resistance mapped to WapR, an α-1,3-rhamnosyltransferase involved in lipopolysaccharide core biosynthesis. A WapR P164T mutant had a modified LPS profile compared to wild type that was accompanied by increased susceptibility to select bacteriophages. We conclude that screening in nutrient-limited conditions can reveal novel activity for existing antibiotics and lead to discovery of new and impactful resistance mechanisms.
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Affiliation(s)
- Derek
C. K. Chan
- David Braley Center for Antibiotic
Discovery, Michael G. DeGroote Institute for Infectious Disease Research,
Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Katherine Dykema
- David Braley Center for Antibiotic
Discovery, Michael G. DeGroote Institute for Infectious Disease Research,
Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Mahrukh Fatima
- David Braley Center for Antibiotic
Discovery, Michael G. DeGroote Institute for Infectious Disease Research,
Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Hanjeong Harvey
- David Braley Center for Antibiotic
Discovery, Michael G. DeGroote Institute for Infectious Disease Research,
Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Ikram Qaderi
- David Braley Center for Antibiotic
Discovery, Michael G. DeGroote Institute for Infectious Disease Research,
Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Lori L. Burrows
- David Braley Center for Antibiotic
Discovery, Michael G. DeGroote Institute for Infectious Disease Research,
Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
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2
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Yin Q, Wu S, Wu L, Wang Z, Mu Y, Zhang R, Dong C, Zhou B, Zhao B, Zheng J, Sun Y, Cheng X, Yang L. A novel in silico antimicrobial peptide DP7 combats MDR Pseudomonas aeruginosa and related biofilm infections. J Antimicrob Chemother 2020; 75:3248-3259. [PMID: 32737484 DOI: 10.1093/jac/dkaa308] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 06/11/2020] [Indexed: 02/06/2023] Open
Abstract
Abstract
Background
Antimicrobial peptides are promising alternative antimicrobial agents to combat MDR. DP7, an antimicrobial peptide designed in silico, possesses broad-spectrum antimicrobial activities and immunomodulatory effects. However, the effects of DP7 against Pseudomonas aeruginosa and biofilm infection remain largely unexplored.
Objectives
To assess (i) the antimicrobial activity of DP7 against MDR P. aeruginosa; and (ii) the antibiofilm activity against biofilm infection. Also, to preliminarily investigate the possible antimicrobial mode of action.
Methods
The MICs of DP7 for 104 clinical P. aeruginosa strains (including 57 MDR strains) and the antibiofilm activity were determined. RNA-Seq, genome sequencing and cell morphology were conducted. Both acute and chronic biofilm infection mouse models were established. Two mutants, resulting from point mutations associated with LPS and biofilms, were constructed to investigate the potential mode of action.
Results
DP7, at 8–32 mg/L, inhibited the growth of clinical P. aeruginosa strains and, at 64 mg/L, reduced biofilm formation by 43% to 68% in vitro. In acute lung infection, 0.5 mg/kg DP7 exhibited a 70% protection rate and reduced bacterial colonization by 50% in chronic infection. DP7 mainly suppressed gene expression involving LPS and outer membrane proteins and disrupted cell wall structure. Genome sequencing of the DP7-resistant strain DP7R revealed four SNPs controlling LPS and biofilm production. gshA44 and wbpJ139 mutants displayed LPS reduction and motility deficiency, conferring the reduction of LPS and biofilm biomass of strain DP7R and indicating that LPS was a potential target of DP7.
Conclusions
These results demonstrate that DP7 may hold potential as an effective antimicrobial agent against MDR P. aeruginosa and related infections.
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Affiliation(s)
- Qi Yin
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, 3688 Nanhai Avenue, Nanshan Section, Shenzhen 518060, People’s Republic of China
| | - Siwen Wu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Lei Wu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Zhenling Wang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Yandong Mu
- Stomatology Department, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu 611731, People’s Republic of China
| | - Rui Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Chunyan Dong
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Bailing Zhou
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Binyan Zhao
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Jiajun Zheng
- Stomatology Department, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu 611731, People’s Republic of China
| | - Ying Sun
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Xingjun Cheng
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
| | - Li Yang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No. 17, Section 3, South Renmin Road, Chengdu, Sichuan 610041, People’s Republic of China
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Polymyxin Susceptibility in Pseudomonas aeruginosa Linked to the MexXY-OprM Multidrug Efflux System. Antimicrob Agents Chemother 2015; 59:7276-89. [PMID: 26369970 DOI: 10.1128/aac.01785-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 09/04/2015] [Indexed: 12/21/2022] Open
Abstract
The ribosome-targeting antimicrobial, spectinomycin (SPC), strongly induced the mexXY genes of the MexXY-OprM multidrug efflux system in Pseudomonas aeruginosa and increased susceptibility to the polycationic antimicrobials polymyxin B and polymyxin E, concomitant with a decrease in expression of the polymyxin resistance-promoting lipopolysaccharide (LPS) modification loci, arnBCADTEF and PA4773-74. Consistent with the SPC-promoted reduction in arn and PA4773-74 expression being linked to mexXY, expression of these LPS modification loci was moderated in a mutant constitutively expressing mexXY and enhanced in a mutant lacking the efflux genes. Still, the SPC-mediated increase in polymyxin susceptibility was retained in mutants lacking arnB and/or PA4773-74, an indication that their reduced expression in SPC-treated cells does not explain the enhanced polymyxin susceptibility. That the polymyxin susceptibility of a mutant strain lacking mexXY was unaffected by SPC exposure, however, was an indication that the unknown polymyxin resistance 'mechanism' is also influenced by the MexXY status of the cell. In agreement with SPC and MexXY influencing polymyxin susceptibility as a result of changes in the LPS target of these agents, SPC treatment yielded a decline in common polysaccharide antigen (CPA) synthesis in wild-type P. aeruginosa but not in the ΔmexXY mutant. A mutant lacking CPA still showed the SPC-mediated decline in polymyxin MICs, however, indicating that the loss of CPA did not explain the SPC-mediated MexXY-dependent increase in polymyxin susceptibility. It is possible, therefore, that some additional change in LPS promoted by SPC-induced mexXY expression impacted CPA synthesis or its incorporation into LPS and that this was responsible for the observed changes in polymyxin susceptibility.
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Visualizing and quantifying Pseudomonas aeruginosa infection in the hindbrain ventricle of zebrafish using confocal laser scanning microscopy. J Microbiol Methods 2015; 117:85-94. [PMID: 26188283 DOI: 10.1016/j.mimet.2015.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/08/2015] [Accepted: 07/09/2015] [Indexed: 02/06/2023]
Abstract
Pseudomonas aeruginosa colonizes surfaces using a stepwise process that involves several phases, including attachment, production of exopolysaccharides, formation of microcolonies and the eventual development of biofilms. This process has been extensively characterized in vitro using both light and electron microscopic techniques. However, our ability to visualize this process in situ at the site of infection has been limited by the nature of the vertebrate models available. The optically clear zebrafish (Danio rerio) is an emerging model well suited for imaging bacterial infections. In this study, we infected the hindbrain ventricle of 54 h post-fertilization zebrafish with P. aeruginosa PAO1 and visualized and quantified microcolony formation using confocal laser scanning microscopy and image analyses. In comparison to wildtype PAO1, infection with a P. aeruginosa mutant deficient in the ability to produce the exopolysaccharide Psl caused less zebrafish mortality and fewer, smaller microcolonies per zebrafish at both 18 h and 29 h post-infection. The work presented here demonstrates reproducible in situ visualization and quantification methods for determining the extent of P. aeruginosa infection in a vertebrate model. We demonstrate how this model system can be manipulated to understand the effect of virulence factors on pathogenicity. Furthermore, this model can be adapted to study biofilm formation in situ, thereby extending our understanding of how bacterial persistence leads to chronic infections.
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Single-Nucleotide Polymorphisms Found in the migA and wbpX Glycosyltransferase Genes Account for the Intrinsic Lipopolysaccharide Defects Exhibited by Pseudomonas aeruginosa PA14. J Bacteriol 2015; 197:2780-91. [PMID: 26078447 DOI: 10.1128/jb.00337-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/09/2015] [Indexed: 01/31/2023] Open
Abstract
UNLABELLED Pseudomonas aeruginosa PA14 is widely used by researchers in many laboratories because of its enhanced virulence over strain PAO1 in a wide range of hosts. Although lipopolysaccharide (LPS) is an important virulence factor of all P. aeruginosa strains, the LPS of PA14 has not been characterized fully. A recent study showed that the structure of its O-specific antigen (OSA) belongs to serotype O19. We found that the OSA gene cluster of PA14 shares ∼99% identity with those of the O10/O19 group. These two serotypes share the same O-unit structure, except for an O-acetyl substitution in one of the sugars in O10. Here we showed that both PA14 and O19 LPS cross-reacted with the O10-specific monoclonal antibody MF76-2 in Western blots. Analysis by SDS-PAGE and silver staining showed that PA14 LPS exhibited modal chain lengths that were different from those of O19 LPS, in that only "very long" and "short" chain lengths were observed, while "medium" and "long" chain lengths were not detected. Two other novel observations included the lack of the uncapped core oligosaccharide epitope and of common polysaccharide antigen (CPA) LPS. The lack of the uncapped core oligosaccharide was caused by point mutations in the glycosyltransferase gene migA, while the CPA-negative phenotype was correlated with a single amino acid substitution, G20R, in the glycosyltransferase WbpX. Additionally, we showed that restoring CPA biosynthesis in PA14 significantly stimulated mature biofilm formation after 72 h, while outer membrane vesicle production was not affected. IMPORTANCE P. aeruginosa PA14 is a clinical isolate that has become an important reference strain used by many researchers worldwide. LPS of PA14 has not been characterized fully, and hence, confusion about its phenotype exists in the literature. In the present study, we set out to characterize the O-specific antigen (OSA), the common polysaccharide antigen (CPA), and the core oligosaccharide produced by PA14. We present evidence that PA14 produces an LPS consisting of "very-long-chain" and some "short-chain" OSA belonging to the O19 serotype but is devoid of CPA and the uncapped core oligosaccharide epitope. These intrinsic defects in PA14 LPS were due to single-nucleotide polymorphisms (SNPs) in the genes that encode glycosyltransferases in the corresponding biosynthesis pathways. Since sugars in CPA and the uncapped core are receptors for different bacteriocins and pyocins, the lack of CPA and an intact core may contribute to the increased virulence of PA14. Restoring CPA production in PA14 was found to stimulate mature biofilm formation.
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Ruhal R, Antti H, Rzhepishevska O, Boulanger N, Barbero DR, Wai SN, Uhlin BE, Ramstedt M. A multivariate approach to correlate bacterial surface properties to biofilm formation by lipopolysaccharide mutants of Pseudomonas aeruginosa. Colloids Surf B Biointerfaces 2015; 127:182-91. [PMID: 25679490 DOI: 10.1016/j.colsurfb.2015.01.030] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 12/19/2014] [Accepted: 01/19/2015] [Indexed: 11/15/2022]
Abstract
Bacterial biofilms are involved in various medical infections and for this reason it is of great importance to better understand the process of biofilm formation in order to eradicate or mitigate it. It is a very complex process and a large range of variables have been suggested to influence biofilm formation. However, their internal importance is still not well understood. In the present study, a range of surface properties of Pseudomonas aeruginosa lipopolysaccharide mutants were studied in relation to biofilm formation measured in different kinds of multi-well plates and growth conditions in order to better understand the complexity of biofilm formation. Multivariate analysis was used to simultaneously evaluate the role of a range of physiochemical parameters under different conditions. Our results suggest the presence of serum inhibited biofilm formation due to changes in twitching motility. From the multivariate analysis it was observed that the most important parameters, positively correlated to biofilm formation on two types of plates, were high hydrophobicity, near neutral zeta potential and motility. Negative correlation was observed with cell aggregation, as well as formation of outer membrane vesicles and exopolysaccharides. This work shows that the complexity of biofilm formation can be better understood using a multivariate approach that can interpret and rank the importance of different factors being present simultaneously under several different environmental conditions, enabling a better understanding of this complex process.
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Affiliation(s)
- Rohit Ruhal
- Department of Chemistry, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Henrik Antti
- Department of Chemistry, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Olena Rzhepishevska
- Department of Chemistry, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | | | | | - Sun Nyunt Wai
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Madeleine Ramstedt
- Department of Chemistry, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
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Kocíncová D, Lam JS. A deletion in the wapB promoter in many serotypes of Pseudomonas aeruginosa accounts for the lack of a terminal glucose residue in the core oligosaccharide and resistance to killing by R3-pyocin. Mol Microbiol 2013; 89:464-78. [PMID: 23750877 DOI: 10.1111/mmi.12289] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2013] [Indexed: 01/16/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen producing a variety of virulence factors. One of them is lipopolysaccharide, consisting of endotoxic lipid A and long-chain O-antigen polysaccharide, which are connected together through a short linker region, called core oligosaccharide. Chemical structures of the core oligosaccharide are well conserved, with one exception, in that certain strains of P. aeruginosa add a terminal glucose residue (Glc(IV) ) to core by a transferase reaction, due to the activity of a glucosyltransferase, WapB. Here, we investigated the regulation of wapB expression. Our results showed that while the majority of analysed genomes of P. aeruginosa contain wapB, many of these have a conserved identical 5-nucleotide deletion in the upstream region that inactivated the promoter. This deletion is within the -10 hexamer that is recognized by a principle sigma factor (RpoD, or σ70) as proven by data from an electromobility shift assay. These results provide the molecular basis of why LPS core of many P. aeruginosa strains is lacking Glc(IV) . In addition, we show that absence of Glc(IV) due to an inactive wapB promoter confers resistance to killing by R3-pyocin, a phage tail-like bacteriocin of P. aeruginosa.
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Affiliation(s)
- Dana Kocíncová
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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Rhamnosyltransferase genes migA and wapR are regulated in a differential manner to modulate the quantities of core oligosaccharide glycoforms produced by Pseudomonas aeruginosa. J Bacteriol 2012; 194:4295-300. [PMID: 22685285 DOI: 10.1128/jb.05741-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
migA and wapR are rhamnosyltransferase genes involved in the biosynthesis of Pseudomonas aeruginosa lipopolysaccharide core oligosaccharide. Here, we show that preferential expression of migA and wapR correlated with the levels of uncapped and O polysaccharide-capped core, respectively. wapR is negatively regulated, while migA is positively regulated by RhlR/RhlI quorum sensing.
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Lam JS, Taylor VL, Islam ST, Hao Y, Kocíncová D. Genetic and Functional Diversity of Pseudomonas aeruginosa Lipopolysaccharide. Front Microbiol 2011; 2:118. [PMID: 21687428 PMCID: PMC3108286 DOI: 10.3389/fmicb.2011.00118] [Citation(s) in RCA: 184] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 05/12/2011] [Indexed: 12/13/2022] Open
Abstract
Lipopolysccharide (LPS) is an integral component of the Pseudomonas aeruginosa cell envelope, occupying the outer leaflet of the outer membrane in this Gram-negative opportunistic pathogen. It is important for bacterium-host interactions and has been shown to be a major virulence factor for this organism. Structurally, P. aeruginosa LPS is composed of three domains, namely, lipid A, core oligosaccharide, and the distal O antigen (O-Ag). Most P. aeruginosa strains produce two distinct forms of O-Ag, one a homopolymer of D-rhamnose that is a common polysaccharide antigen (CPA, formerly termed A band), and the other a heteropolymer of three to five distinct (and often unique dideoxy) sugars in its repeat units, known as O-specific antigen (OSA, formerly termed B band). Compositional differences in the O units among the OSA from different strains form the basis of the International Antigenic Typing Scheme for classification via serotyping of different strains of P. aeruginosa. The focus of this review is to provide state-of-the-art knowledge on the genetic and resultant functional diversity of LPS produced by P. aeruginosa. The underlying factors contributing to this diversity will be thoroughly discussed and presented in the context of its contributions to host-pathogen interactions and the control/prevention of infection.
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Affiliation(s)
- Joseph S. Lam
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Véronique L. Taylor
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Salim T. Islam
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Youai Hao
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Dana Kocíncová
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
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