Current understanding of potential toxicity of engineered nanomaterials to aquatic microorganisms is limited for risk assessment and management. Here we evaluate if the MetPLATE™ test can be used as an effective and rapid screening tool to test for potential aquatic toxicity of various metal-based nanoparticles (NPs). The MetPLATE bioassay is a heavy metal sensitive test based on β-galactosidase activity in Escherichia coli. Five different types of metal-based NPs were screened for toxicity: (1) citrate coated nAg (Citrate-nanosilver), (2) polyvinylpyrrolidone coated nAg (PVP-nAg), (3) uncoated nZnO, (4) uncoated nTiO2 and (5) 1-Octadecylamine coated CdSe Quantum Dots (CdSe QDs); and compared with their corresponding ionic salt toxicity. Citrate-nAg was further fractionated into clean Citrate-nAg, unclean Citrate-nAg and permeate using a tangential flow filtration (TFF) system to eliminate residual ions and impurities from the stock Citrate-nAg suspension and also to differentiate between ionic- versus nano-specific toxicity. Our results showed that nAg, nZnO and CdSe QDs were less toxic than their corresponding ionic salts tested, while nano- or ionic form of TiO2 was not toxic as high as 2.5 g L− 1 to the MetPLATE™ bacteria. Although coating-dependent toxicity was noticeable between two types of Ag NPs evaluated, particle size and surface charge were not adequate to explain the observed toxicity; hence, the toxicity appeared to be material-specific. Overall, the toxicity followed the trend: CdCl2 > AgNO3 > PVP-nAg > unclean Citrate-nAg > clean Citrate-nAg > ZnSO4 > nZnO > CdSe QDs > nTiO2/TiO2. These results indicate that an evaluation of β-galactosidase inhibition in MetPLATE™ E. coli can be an important consideration for rapid screening of metal-based NP toxicity, and should facilitate ecological risk assessment of these emerging contaminants.

Immunofluorescence assays are capable of both detecting the amount of a protein and the location of the protein within a cell or tissue section. Unfortunately, the traditional technique is not capable of detecting concentrations on the nanoscale. Also, the technique suffers from non-specific attachment, which can cause false-positives, as well as photobleaching when detecting lower concentrations is attempted. There is also a time constraint problem since the technique can take from many hours to a few days in some cases. In this work, metal-enhanced fluorescence (MEF) is used to lower the detection limit and reduce photobleaching. Unfortunately, MEF also increases the intensity of non-specifically bound proteins (NSBPs). Therefore, a surface acoustic wave (SAW) device is used to remove the more weakly bound NSBPs. Previously, this has been shown on lithium niobate, but it is used with a quartz substrate in this work. The SAW device is also used to cause micro-mixing which speeds the process up significantly. In this research, it was found that silver nanocubes can lower the detection limit down to below 1 ng/mL. Quartz SAW devices are shown to remove NSBPs at a power of 10 mW applied for five minutes. Micro-mixing is shown to be improved by a factor of six at 10 mW for 10 minutes by saturating the antibody used in this research, which takes 1 hour without micro-mixing. Finally, all three components are combined. In this work, the whole device is used to detect 50 ng/mL. After micro-mixing, the intensity is the same as with MEF, and, after removal, it has been lowered by 7 a.u.

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Typecript Includes bibliographical references

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<p>The genus <i>Arnica</i> (Asteraceae) was investigated for phylogenetic relationships and sesquiterpene lactone (STL) content with the aims to trace the evolutionary history of the genus and to investigate possible congruencies between DNA sequence data, secondary chemistry, and biological activity. </p><p>Complex evolutionary patterns in <i>Arnica</i> are evident from phylogenetic analyses of chloroplast regions (the <i>rpl16</i> and <i>rps16</i> introns and the <i>psbA–trnH</i>, <i>ycf4–cemA</i>, and <i>trnT–L</i> spacers), nuclear ribosomal regions (the internal and external transcribed spacers) and the nuclear low-copy DNA region coding for the second largest subunit of RNA polymerase II (<i>RPB2</i>) between exons 17 and 23. Polymorphism was detected in nuclear ribosomal and low-copy regions<i>,</i> likely caused by polyploidy and agamospermy. Lineage sorting and/or hybridization is a possible explanation for incongruencies between topologies of the different DNA regions. None of the five subgenera in <i>Arnica</i> constitute a monophyletic group according to any of our analyses. </p><p>Sesquiterpene lactone profiles were compared to nuclear ribosomal DNA data using phylogenetic inference and principal component analysis for 33 accessions of 16 species. Clusters supported by both STL chemistry and ribosomal DNA sequence data consist of multiple accessions of the same species (e.g.<i> A montana </i>and<i> A. longifolia</i>), indicating that these species are well defined both genetically and chemically, based on our sampling. Support for subspecies classification of <i>A. chamissonis</i> and <i>A. parryi</i> was found in chemical data. For the first time STLs are reported from subtribe Madiinae, sister to Arniciinae.</p><p>Anti-inflammatory properties, as measured by inhibition of human neutrophil elastase release from neutrophils and inhibition of the binding of transcription factor NF-κB to DNA, were investigated for extracts of 12 <i>Arnica</i> species. <i>Arnica montana</i>, <i>A. chamissonis</i> and <i>A. longifolia</i> accessions show high inhibitory effects in both bioassays. Generally, species with a more diverse STL chemistry also possess the strongest inhibitory activity in the bioassays.</p>

The genus Arnica (Asteraceae) was investigated for phylogenetic relationships and sesquiterpene lactone (STL) content with the aims to trace the evolutionary history of the genus and to investigate possible congruencies between DNA sequence data, secondary chemistry, and biological activity. Complex evolutionary patterns in Arnica are evident from phylogenetic analyses of chloroplast regions (the rpl16 and rps16 introns and the psbA–trnH, ycf4–cemA, and trnT–L spacers), nuclear ribosomal regions (the internal and external transcribed spacers) and the nuclear low-copy DNA region coding for the second largest subunit of RNA polymerase II (RPB2) between exons 17 and 23. Polymorphism was detected in nuclear ribosomal and low-copy regions, likely caused by polyploidy and agamospermy. Lineage sorting and/or hybridization is a possible explanation for incongruencies between topologies of the different DNA regions. None of the five subgenera in Arnica constitute a monophyletic group according to any of our analyses. Sesquiterpene lactone profiles were compared to nuclear ribosomal DNA data using phylogenetic inference and principal component analysis for 33 accessions of 16 species. Clusters supported by both STL chemistry and ribosomal DNA sequence data consist of multiple accessions of the same species (e.g. A montana and A. longifolia), indicating that these species are well defined both genetically and chemically, based on our sampling. Support for subspecies classification of A. chamissonis and A. parryi was found in chemical data. For the first time STLs are reported from subtribe Madiinae, sister to Arniciinae. Anti-inflammatory properties, as measured by inhibition of human neutrophil elastase release from neutrophils and inhibition of the binding of transcription factor NF-κB to DNA, were investigated for extracts of 12 Arnica species. Arnica montana, A. chamissonis and A. longifolia accessions show high inhibitory effects in both bioassays. Generally, species with a more diverse STL chemistry also possess the strongest inhibitory activity in the bioassays.

The objective of this study was to determine if the presence of two ALS inhibiting herbicide residues in three Saskatchewan soils would result in an additive, synergistic, or antagonistic interaction. This was determined through field trials where herbicides were applied sequentially over the course of two years and through dose-response modelling. The herbicides examined in these experiments were imazamethabenz, flucarbazone-sodium, sulfosulfuron, and florasulam, each in combination with imazamox/imazethapyr. The phytotoxicity and persistence of the herbicides in soil was assessed using an Oriental mustard root inhibition bioassay. The determination of herbicide interaction was made through the comparison of the experimentally observed values to theoretically expected values derived from a mathematical equation.<p>The dose response curves created by placing incremental concentrations of these herbicides in soil were compared using the I50 parameter, which is the concentration resulting in a 50% reduction in root length. It appeared that soil organic matter followed by soil pH had the greatest effect in reducing herbicide residue phytotoxicity in the tested soils. Based on the bioassay analysis of sequentially applied ALS inhibiting herbicides, it is proposed that the phytotoxic effect of herbicide residues in soil result in additive injury effects rather than synergistic or antagonistic interactions.

The overall objective of the work described in this thesis was to examine the effects of both waterborne and dietary routes of exposure to fathead minnow (Pimephales promelas) when exposed to complex metal mining mixtures. This was conducted using a 21-day, multi-trophic, short-term fathead minnow (FHM) reproductive bioassay. The endpoints that were measured were used to assess the effects on multiple levels of biological organization (sub-organismal to population endpoints). The first phase of this research was conducted in situ using environmentally realistic concentrations of 3 separate metal mining effluents [20% surface water effluent (SWE), 30% mine water effluent (MWE), 45% process water effluent (PWE)] from Sudbury, Ontario, Canada. Metals were analyzed in several media (water, sediments) and tissues (biofilm, Chironomus dilutus, female fathead minnow carcass, ovaries, liver and gills). The incorporation of the biofilm (primary producers) into the bioassay also added another level of organization that was novel to this study. Significant increases in metal concentrations were observed in the water and biofilm tissues in all treatments [SWE, MWE, PWE], compared to reference. Cobalt and nickel increased significantly in C. dilutus tissues in SWE (1.4-fold and 1.5-fold respectively), and copper and selenium in PWE (5.2-fold and 3.3-fold respectively), however no significant increases occurred in MWE compared to reference. There were no significant increases in metal concentrations in female FHM tissues (carcass, liver, gonads, gills) in any of the treatments, suggesting that metal bioavailability was reduced. Cumulative number of eggs per female per day increased significantly (+127%) after exposure to SWE and decreased significantly (-33%) after exposure to PWE when compared to the reference fish. Mean total number of days to hatch was also reduced in PWE compared to reference. In order to gain a better understanding of the routes of exposure causing toxicity in FHM, the second phase of this research examined the effects of exposure through diet, through water or through both using a fully factorial food exposure design in a laboratory setting. In this experiment we pre-exposed C. dilutus to both 45% PWE and laboratory control water until they reached the 3rd-4th instar stage of development (approximately 21 days) where they were collected and frozen until the start of the FHM reproductive bioassay. We further examined the role of food quality on fish toxicity by assessing differences between multi trophic (where fish were fed both a live and frozen diet of C. dilutus) in the laboratory. This research was conducted at the Toxicology Centre in Saskatoon, Saskatchewan, Canada. The results showed that significant effects were observed when fish were fed a live diet versus a frozen diet. Condition factor and body weight increased, although inconsistent effects were observed for liver somatic index (LSI) in fathead minnows in both experiments when exposed to one or both routes of exposure. Cumulative total egg production and cumulative spawning events were both significantly affected by both waterborne and dietborne exposures with the greatest effects seen in the multi-trophic streams and particularly when fish were fed a live diet. This significance of this research has demonstrated the importance of including both routes of exposure when assessing effects of mine effluent. This research also shows that the artificial stream technology is a useful tool in isolating the effects of a particular point source input (metal mining mixtures) when a system is highly confounded. The results suggest that under environmentally relevant exposure conditions, trophic transfer and live diet may lead to greater reproductive effects and increased fish toxicity. This also suggests that trophic transfer is an important route of exposure that is virtually impossible to attain using typical laboratory bioassay techniques (food-borne study using artificial diets or waterborne exposures only).