Improved Algal Toxicity Test System for Robust <i>Omics</i>-Driven Mode-of-Action Discovery in <i>Chlamydomonas reinhardtii</i>

Algae are key components of aquatic food chains. Consequently, they are internationally recognised test species for the environmental safety assessment of chemicals. However, existing algal toxicity test guidelines are not yet optimized to discover molecular modes of action, which require highly-rep...

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Main Authors: Stefan Schade, Emma Butler, Steve Gutsell, Geoff Hodges, John K. Colbourne, Mark R. Viant
Format: Article
Language:English
Published: MDPI AG 2019-05-01
Series:Metabolites
Subjects:
Online Access:https://www.mdpi.com/2218-1989/9/5/94
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spelling doaj-94a469f2df4e422c9a632e377f5c4d2e2020-11-25T01:23:18ZengMDPI AGMetabolites2218-19892019-05-01959410.3390/metabo9050094metabo9050094Improved Algal Toxicity Test System for Robust <i>Omics</i>-Driven Mode-of-Action Discovery in <i>Chlamydomonas reinhardtii</i>Stefan Schade0Emma Butler1Steve Gutsell2Geoff Hodges3John K. Colbourne4Mark R. Viant5School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UKSafety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook MK44 1LQ, UKSafety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook MK44 1LQ, UKSafety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook MK44 1LQ, UKSchool of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UKSchool of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UKAlgae are key components of aquatic food chains. Consequently, they are internationally recognised test species for the environmental safety assessment of chemicals. However, existing algal toxicity test guidelines are not yet optimized to discover molecular modes of action, which require highly-replicated and carefully controlled experiments. Here, we set out to develop a robust, miniaturised and scalable <i>Chlamydomonas reinhardtii</i> toxicity testing approach tailored to meet these demands. We primarily investigated the benefits of synchronised cultures for molecular studies, and of exposure designs that restrict chemical volatilisation yet yield sufficient algal biomass for omics analyses. Flow cytometry and direct-infusion mass spectrometry metabolomics revealed significant and time-resolved changes in sample composition of synchronised cultures. Synchronised cultures in sealed glass vials achieved adequate growth rates at previously unachievably-high inoculation cell densities, with minimal pH drift and negligible chemical loss over 24-h exposures. Algal exposures to a volatile test compound (chlorobenzene) yielded relatively high reproducibility of metabolic phenotypes over experimental repeats. This experimental test system extends existing toxicity testing formats to allow highly-replicated, <i>omics</i>-driven, mode-of-action discovery.https://www.mdpi.com/2218-1989/9/5/94synchronisationalgaebioassaybiomarkerkey eventadverse outcome pathway
collection DOAJ
language English
format Article
sources DOAJ
author Stefan Schade
Emma Butler
Steve Gutsell
Geoff Hodges
John K. Colbourne
Mark R. Viant
spellingShingle Stefan Schade
Emma Butler
Steve Gutsell
Geoff Hodges
John K. Colbourne
Mark R. Viant
Improved Algal Toxicity Test System for Robust <i>Omics</i>-Driven Mode-of-Action Discovery in <i>Chlamydomonas reinhardtii</i>
Metabolites
synchronisation
algae
bioassay
biomarker
key event
adverse outcome pathway
author_facet Stefan Schade
Emma Butler
Steve Gutsell
Geoff Hodges
John K. Colbourne
Mark R. Viant
author_sort Stefan Schade
title Improved Algal Toxicity Test System for Robust <i>Omics</i>-Driven Mode-of-Action Discovery in <i>Chlamydomonas reinhardtii</i>
title_short Improved Algal Toxicity Test System for Robust <i>Omics</i>-Driven Mode-of-Action Discovery in <i>Chlamydomonas reinhardtii</i>
title_full Improved Algal Toxicity Test System for Robust <i>Omics</i>-Driven Mode-of-Action Discovery in <i>Chlamydomonas reinhardtii</i>
title_fullStr Improved Algal Toxicity Test System for Robust <i>Omics</i>-Driven Mode-of-Action Discovery in <i>Chlamydomonas reinhardtii</i>
title_full_unstemmed Improved Algal Toxicity Test System for Robust <i>Omics</i>-Driven Mode-of-Action Discovery in <i>Chlamydomonas reinhardtii</i>
title_sort improved algal toxicity test system for robust <i>omics</i>-driven mode-of-action discovery in <i>chlamydomonas reinhardtii</i>
publisher MDPI AG
series Metabolites
issn 2218-1989
publishDate 2019-05-01
description Algae are key components of aquatic food chains. Consequently, they are internationally recognised test species for the environmental safety assessment of chemicals. However, existing algal toxicity test guidelines are not yet optimized to discover molecular modes of action, which require highly-replicated and carefully controlled experiments. Here, we set out to develop a robust, miniaturised and scalable <i>Chlamydomonas reinhardtii</i> toxicity testing approach tailored to meet these demands. We primarily investigated the benefits of synchronised cultures for molecular studies, and of exposure designs that restrict chemical volatilisation yet yield sufficient algal biomass for omics analyses. Flow cytometry and direct-infusion mass spectrometry metabolomics revealed significant and time-resolved changes in sample composition of synchronised cultures. Synchronised cultures in sealed glass vials achieved adequate growth rates at previously unachievably-high inoculation cell densities, with minimal pH drift and negligible chemical loss over 24-h exposures. Algal exposures to a volatile test compound (chlorobenzene) yielded relatively high reproducibility of metabolic phenotypes over experimental repeats. This experimental test system extends existing toxicity testing formats to allow highly-replicated, <i>omics</i>-driven, mode-of-action discovery.
topic synchronisation
algae
bioassay
biomarker
key event
adverse outcome pathway
url https://www.mdpi.com/2218-1989/9/5/94
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