Browsing by Author "Lanctôt, CM"

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    Application of nuclear techniques to environmental plastics research
    (Elsevier, 2018-12) Lanctôt, CM; Al-Sid-Cheikh, M; Catarino, AI; Cresswell, T; Danis, B; Karapanagioti, HK; Mincer, T; Oberhänsli, F; Swarzenski, PW; Tolosa, I; Metian, M
    Plastic pollution is ubiquitous in aquatic environments and its potential impacts to wildlife and humans present a growing global concern. Despite recent efforts in understanding environmental impacts associated with plastic pollution, considerable uncertainties still exist regarding the true risks of nano- and micro-sized plastics (<5 mm). The challenges faced in this field largely relate to the methodological and analytical limitations associated with studying plastic debris at low (environmentally relevant) concentrations. The present paper highlights how radiotracing techniques that are commonly applied to trace the fate and behaviour of chemicals and particles in various systems, can contribute towards addressing several important and outstanding questions in environmental plastic pollution research. Specifically, we discuss the use of radiolabeled microplastics and/or chemicals for 1) determining sorption/desorption kinetics of a range of contaminants to different types of plastics under varying conditions, 2) understanding the influence of microplastics on contaminant and nutrient bioaccumulation in aquatic organisms, and 3) assessing biokinetics, biodistribution, trophic transfer and potential biological impacts of microplastic at realistic concentrations. Radiotracer techniques are uniquely suited for this research because of their sensitivity, accuracy and capacity to measure relevant parameters over time. Obtaining precise and timely information on the fate of plastic particles and co-contaminants in wildlife has widespread applications towards effective monitoring programmes and environmental management strategies. © 2018 Elsevier Ltd
  • No Thumbnail Available
    Item
    Bioaccumulation and biodistribution of selenium in metamorphosing tadpoles
    (American Chemical Society, 2017-04-19) Lanctôt, CM; Cresswell, T; Callaghan, PD; Melvin, SD
    Selenium is an important macronutrient with a very narrow margin between essentiality and toxicity. Amphibians are hypothesized to be particularly sensitive due to the potential for metamorphosis-driven mobilization, which could transfer or concentrate contaminant burdens within specific organs. We explored the potential role of tissue degeneration and remodeling during anuran metamorphosis as a mechanism for altering tissue-specific Se burdens. Limnodynastes peronii tadpoles were exposed to dissolved 75Se (as selenite) for 7 days and depurated until completion of metamorphosis. Bioaccumulation and retention kinetics were assessed in whole tadpoles and excised tissues using gamma spectroscopy, and temporal changes in biodistribution were assessed using autoradiography. Tadpoles retained Se throughout metamorphosis, and partitioned the element predominantly within digestive and excretory tissues, including livers > mesonephros > guts > gallbladder. Importantly, our results demonstrate that Se biodistribution varies significantly throughout development. This is indicative of tissue transference, and particularly in tissues developing de novo after depuration. To the best of our knowledge, this is the first study demonstrating Se transference during metamorphic tissue remodelling. Further research is warranted to explore the fate and metabolism of Se (and other metal and metalloids) during anuran development and the implications of transference for influencing toxicity. © 2017 American Chemical Society
  • No Thumbnail Available
    Item
    Fate and sublethal effects of metals during amphibian metamorphosis: a systematic review
    (Taylor & Francis, 2021-11-11) Hill, D; Cresswell, T; Bennett, WW; Lanctôt, CM
    Amphibians provide essential ecosystem services and are facing global decline. Exposure to contaminants is a contributing factor to this decline, with permeable skin and early aquatic life likely increasing amphibian susceptibility. Their vulnerability may also be increased through metamorphosis, which involves degeneration of tissues and high energy expenditure. Exposure to metal contaminants may also result in delays to metamorphosis or reduced growth. Understanding how metal burdens change during metamorphosis and the effects metals have on postmetamorphic amphibians is essential to ensure water quality guidelines offer sufficient protection. A systematic review of the literature was conducted to identify the changes in whole-body metal burden and biodistribution pre and postmetamorphosis and the effects of metal exposures on the timing of metamorphosis and size of animals postmetamorphosis. Premetamorphic amphibians were found to have higher metal concentrations than postmetamorphic, suggesting these metals can be largely excreted prior to or during metamorphosis. Only two articles were identified that compared changes in metal biodistribution during metamorphosis, with both reporting decreasing concentrations in the gut from pre to postmetamorphosis. No laboratory studies identified significant effects relating to metamorphosis at concentrations below USEPA chronic water quality criteria. However, delays to timing or growth were observed in field studies where all analyzed metals were below criteria. Many articles did not meet the suggested minimum reporting standards, particularly for the reporting of metal exposure concentrations and physico-chemical conditions of exposure solutions. © 2021 Informa UK Limited
  • Thumbnail Image
    Item
    Selenium speciation influences bioaccumulation in Limnodynastes peronii tadpoles
    (Elsevier, 2017-06) Lanctôt, CM; Melvin, SD; Cresswell, T
    Despite being essential for animal health and fitness, Se has a relatively narrow range between deficiency and toxicity, and excess Se can cause a variety of adverse effects in aquatic organisms. Amphibians are particularly vulnerable to contaminants during larval aquatic life stage, because they can accumulate toxic ions through various routes including skin, gills, lungs and digestive tract. Few attempts have been made to understand the tissue-specific accumulation of trace elements, including the impacts of chemical speciation in developing amphibian larvae. We used radiolabelled 75Se to explore the biokinetics and tissue distributions of the two dominant forms occurring in surface waters, selenite (SeIV) and selenate (SeVI). Tadpoles of the native Australian frog Limnodynastes peronii were exposed to Se in both forms, and live-animal gamma spectroscopy was used to track accumulation and retention over time. Tissue biodistributions were also quantified at the end of the uptake and depuration phases. Results showed the bioconcentration of SeIV to be 3 times greater compared to SeVI, but rates of elimination were similar for both forms. This suggests a change of Se speciation within the organism prior to excretion. Depuration kinetics were best described by a one-phase exponential decay model, and tadpoles retained approximately 19% of the accumulated Se after 12 days of depuration in clean water. Selenium bioaccumulation was greatest in digestive and excretory organs, as well as the eye, which may directly relate to previously reported Se-induced impairments. Results demonstrate how the use of radiotracing techniques can significantly improve our understanding of trace element toxicokinetics and tissue distributions in developing amphibians. From an environmental monitoring perspective, the findings highlight the importance of considering chemical speciation as this could influence the accuracy of risk assessment. Crown Copyright © 2017 Published by Elsevier B.V.
  • No Thumbnail Available
    Item
    Synchrotron-based imaging reveals the fate of selenium in striped marsh frog tadpoles
    (American Chemical Society, 2021-08-12) Lanctôt, CM; Cresswell, T; Lombi, E; Bennett, WW
    Synchrotron-based X-ray fluorescence microscopy (XFM) coupled with X-ray absorption near-edge structure (XANES) imaging was used to study selenium (Se) biodistribution and speciation in Limnodynastes peronii tadpoles. Tadpoles were exposed to dissolved Se (30 μg/L) as selenite (SeIV) or selenate (SeVI) for 7 days followed by 3 days of depuration. High-resolution elemental maps revealed that Se partitioned primarily in the eyes (specifically the eye lens, iris, and retinal pigmented epithelium), digestive and excretory organs of SeIV-exposed tadpoles. Speciation analysis confirmed that the majority of accumulated Se was converted to organo-Se. Multielement analyses provided new information on Se colocalization and its impact on trace element homeostasis. New insights into the fate of Se on a whole organism scale contribute to our understanding of the mechanisms and risks associated with Se pollution. © 2021 American Chemical Society
  • No Thumbnail Available
    Item
    Uptake and tissue distributions of cadmium, selenium and zinc in striped marsh frog tadpoles exposed during early post-embryonic development
    (Elsevier, 2017-10) Lanctôt, CM; Cresswell, T; Melvin, SD
    Metals and metalloids released through anthropogenic activities can accumulate in aquatic organisms, resulting in adverse effects in sensitive species. We investigated the influence of feeding regime and exposure complexity (i.e., mixture) on bioaccumulation kinetics and body distribution of common metal(loid) pollutants in Limnodynastes peronii during early post-embryonic development. Tadpoles were exposed to radiolabelled 109Cd, 75Se and 65Zn alone and in a mixture for 4 days, followed by 3 days depuration in clean water. One group was fed directly in exposure aquaria, whereas a second group was transferred to clean water for feeding, to investigate the potential influence of sorption to food on uptake. Bioconcentration factor and retention was observed to be greatest for Se. Results demonstrate that tadpoles accumulated and retained half the amount of Cd when exposed in mixture, suggesting that Se and/or Zn may have antagonistic effects against Cd uptake. Additionally, tadpoles fed directly in exposure water accumulated 2–3–times more Cd and Zn compared to tadpoles fed in clean water, indicating that the presence of food particles is an important factor that may influence uptake. Interestingly, this had a negligible impact on Se uptake. The study reveals how exposure conditions can influence the bioaccumulation of metal(loid)s, highlighting experimental factors as important considerations for both controlled toxicity experiments and for understanding exposure risks for amphibian populations. © 2017 Elsevier Inc.