Saturday, December 10, 2016

Small traces, large impact

Already some time ago we participated in writing an article on Anthropogenic Trace Compounds (ATCs). ATCs are an issue for water quality, since they increased in numbers and concentrations over the last years. This very heterogenous group of chemicals is a major challenge for research and policy making, in regards of identification, detection, monitoring, fate, toxicity and mitigation. They represent a complex network of interrelations of physical-chemical properties and behaviour, and biological activity. Literally, the substances only have in common that they are introduced into the water cycle by humanity, are found at still rather low concentrations, but anyway represent a potential danger for human and environmental health.

Together with our colleagues we reviewed current trends monitoring and management, and identified innovative and effective strategies as well as knowledge gaps and urgent needs. We highlight the lack of generally accepted indicator substances as one major issue that has to be solved for future monitoring. Also, we advocate for the implementation of effect-based tools in water monitoring, and for an appropriate risk assessment of ATCs.

There's a whole lot more to find in this comprehensive review article. Read the entire story about "Anthropogenic Trace Compounds (ATCs) in aquatic habitats — Research needs on sources, fate, detection and toxicity to ensure timely elimination strategies and risk management". And you really can read it, it's Open Access!

Tuesday, November 29, 2016

Communicating research findings and uncertainties - a Nantes experience

Our session "Communicating research findings and uncertainties: Strategies, tools, and new platforms for environmental sciences" at the SETAC Europe annual meeting 2016 in Nantes, France, received only minor contributions. However, we were assigned a poster corner, which is in my opinion the best format for presentation and discussion at conferences.

In a poster corner, the posters are presented in short five-minutes talks and then discussed with the attending audience. The seven posters provided a stage for our presenters that they extensively used to introduce their works. The more informal atmosphere with much less distance to the audience than at platform presentations fueled very interesting and lively discussions. Also, the weaker time restrictions allowed us to just let the disucussions going on, without the need to eventually cut them of.

Leonie Nüßer, Erica Brockmeier, Mattia Meli and I as the chairs of the session very much enjoyed this event, and we wrote a session brief for the SETAC Globe to let everyone participate in our excitement.

Friday, October 21, 2016

Should we drink an drive tea?

Research on biofuels recently suggested compounds that are already known as solvents or flavors to be alternatives for fossil fuels. We investigated the three candidate substances ethyl levulinate, methyltetrahydrofuran, and 2-methylfuran regarding their embryotoxic effectiveness using zebrafish.

Especially ethyl levulinate gave considerable toxicity. Very specifically it tended to reduce head length of zebrafish larvae. As a consequence, we recommended to not further continue developing this substance into a potential biofuel. Moreover, use of ethyl levulinate in, e.g., flavored tea should be critically revised. Read the full story on "Acute embryo toxicity and teratogenicity of three potential biofuels also used as flavor or solvent" (fulltext only with a subscription to the journal, sorry...).

Friday, October 14, 2016

Fish behaviour trajectories converted to usefulness

Zebrafish behaviour is a novel and upcoming endpoint in toxicity assessment of - at large - neuromodulating substances. This includes direct neurotoxicity as well as repellency and any other type of avoidance. Since zebrafish react to contaminants in the water at low nanograms per liter, behaviour measurement has the potential to be used for biological early warning systems.

However, usefulness of such data can be hampered by the independence of the distance moved (as one of the most common endpoints) from the trajectory's shape. A parameter is hence required to identify directed movement as an indication of avoidance behaviour.

In the W3-Hydro project we tested permethrin and cadmium as model substances using a Noldus DanioVision system. Obtained trajectories were converted to polar coordiantes and parametrized. Results showed that by this procedure pure distance-moved-data can be used to identify impact of contamination on zebrafish larvae behaviour. Read more on early detecting water contaminants Ecotoxicology and Environmental Safety (fulltext temporarily free, then limited to subscribers, sorry...).

Monday, October 10, 2016

Why we do not just talk about our science

It is not easy to communicate science, and it is especially difficult from environmental research. Most findings we make are rather directly connected to every day lifes and thus human wellbeing. As a consequence, people tend to assess such research based on their personal feelings, desires, and - in particular - concerns. This can lead to misunderstandings that produce even stronger opinions and are hence even more difficult to solve.

We environmental researchers seem to react with avoidance: before we do something wrong, we do not do anything at all in terms of communicating our science. Thomas Backhaus and I wrote an Editorial in Integrated Environmental Assessment and Management on "Communicating environmental science to the general public", where we shortly analyse this situation and the associated problems and try to encourage our colleagues to anyway take on the challenge. 

Saturday, June 18, 2016

Who's afraid of a little picene?

Picenes and alkalyted chrysenes are highly abundant compound classes in lignites. Hence, we found them in high concentrations in a German lignite extract from a former study. Since this extract gave only low PAH content but showed high mutagenicity and dioxin-like activity we decided to separately test these compounds for their toxic potential. Furthermore, we investigated bioavailability of picenes and chrysenes by means of a Lumbriculus variegatus bioaccumulation test.

All experiments yielded data that let us conclude that alkylated chrysenes and picenes, though highly abundant in lignite, pose only a low environmental risk (fulltext access limited to subscribers of the journal, sorry...).

Friday, April 29, 2016

Water quality monitoring of tomorrow - A tools vision

Current water quality monitoring relies mainly on chemical analytics to monitor occurence of a few fistful of priority compounds. This bears a great risk of missing new and emerging pollutants. To account for these the EU-FP7 SOLUTIONS project aims at developing, establishing and recommending (novel) analytical tools, that would be able to identify and also assess yet unknown substances in the aquatic environment.

Our three-pronged approach is to heavily improve target and non-target chemcial analytics, build a strong array of highly sophisticated bioanalytical test systems - i.e. effect-based tools - and further establish effect-directed analysis as a method to reliably identify drivers of toxicity. This whole vision was published in Science of the Total Environment as "Future water quality monitoring — Adapting tools to deal with mixtures of pollutants in water resource management" (fulltext access only through subscription, sorry...).

Friday, March 25, 2016

Marine research in Aachen - with a fresh water model organism


Oil spills in cold Baltic and Arctic Sea waters are a special challenge to investigate, and hence they are the research focus of our new EU H2020-funded collaborative project "Integrated oil spill response actions and environmental effects - GRACE". The project is coordinated by Kirsten Jörgensen of SYKE in Helsinki, Finland, and made it successfully through a two-stage process. This means that not only the initial project draft has been considered sufficiently good by a couple of reviewers, but also the then submitted full proposal received positive reviews.

In the project we strive together with our partners from Finland, Denmark, Estonia, Spain, Norway, Greenland, Sweden and Canada to comprehensively investigate the environmental impact of oil spills and provide measures for mitigation. Our part will be to establish the zebrafish as a model organism for oil spill detection and assessment. This brings a number of challenges:

  1. The zebrafish is a fresh water organism. Any effects of oil constituents have to be related to marine environments, including the impact of temperature and salinity. We will make comparisons to parallel experiments with marine stickleback to calibrate our model to the Baltic and Arctic Sea.
  2. We will develop a biosensor based on fish larvae behaviour that can travel on a ferry and make online measurements. The device will trigger an alert upon changes in behaviour and lead to more detailed effect-based investigations using reportergen assays.
  3. By means of a broad battery of assays and together with other partners of the project we intend to derive toxicity fingerprints of oil contaminations.
I am leader of the work package on the bioanalytical investigations. Two PhD students will work on the biosensor and the zebrafish model, respectively.

The whole project aims at developing novel tools and strategies for oil spill response, and increase the knowledge on the distribution, mobility, severity, impact and possibilities for mitigation of oil contaminations.

More information can be found later on the official project website, the project webpage of our institute and several press releases.
Currently, further information is available in a press release by SYKE.

Once more I happened to design the logo.

The EDA guide to surviving environmental analysis

Colleague Werner Brack at the UFZ in Leipzig, Germany is an outstanding expert on effect-directed analysis (EDA). EDA stands for an analytical approach that uses chemical and biological analysis to identify single contaminants as the culprits for toxicity in environmental samples.

It combines the best of both worlds. The ability to detect effects and the power to identify as well as elucidate molecule structures are interconnected by a sophisticated fractionation. The EDA principle is easily explained: (1) samples are tested for their effects in one or more bioassays, (2) effective samples are fractionated and fractions tested again, (3) effective fractions are further fractionated and tested, and finally (4) the substances in the few remaining effective fractions are chemically identified.

While sounding quite easy, EDA can be highly complex effort, due to the multitude of options for experimental design. Which bioassays should be used for screening, which biological effect should be targetted? How to properly fractionate the samples, for a most succesful separation of the compounds of interest? What techniques and methods are suitable for structure identification and elucidation?

These and many other crucial questions form a seemingly uncontrolled network of possibilities, that makes EDA a major challenge in environmental toxicology and chemistry. Werner however set out to tame this beast. He invited a large number of colleagues to write a comprehensive overview article about all aspects involving and impacting experimental design in EDA. We were among the lucky ones he asked to contribute to "Effect-directed analysis supporting monitoring of aquatic environments — An in-depth overview".

Tuesday, March 08, 2016

A nature protocol on dioxin-like activity

Dioxin-like activity is an important biomarker for the contamination with several of the most prominent pollutants, such as polycyclic aromatic hydrocarbons (PAH), Polychlorinated Biphenyls (PCB), and Polychlorinated Dibenzodioxins and -furans (PCDD/F).
We have longstanding experience with measuring this activity using a variety of different assays. 

Maybe this is why we were asked by nature protocols to write an article about the bioanalysis of dioxin-like activity. Since nature protocols publishes detailed procedures for laboratory techniques, we decided to communicate why and how to use the micro-EROD assay with the H4IIE permanent rat liver cell line.

The main reason for choosing this particular assay was its peak performance in a direct comparison of alternative bioassays we conducted earlier.



Thursday, February 18, 2016

Quantitative assessment of oxidative stress in zebrafish

We initially developed and established an assay to quantitatively determine oxidative stress in exposed zebrafish larvae.

Oxidative stress is an important mechanism for cell damage and generally occures when organisms are exposed to environmental stressors, such as food scarcity, unusual environmental conditions, parasite infections, or of course intoxication. What happens then is the formation of reactive oxygen species (ROS), like for instance hydroxy radicals. These molecules chemically react with any component of the cells, be it proteins, nucleic acids, lipopolysaccharides of membranes, etc. The reaction is not targeted but highly random, leading to damage and eventually cell death. ROS induction is not necessarily by accident. The mechanism of programmed cell death, so called apoptosis, includes the effectiveness of ROS.

The good thing about ROS is that they appear very early in stressed cells, and clearly before cytotoxicity is measurable. Hence, ROS induction is a sensitive early alert marker also for chemical exposure. No surprise that assays were already described to determine ROS induction in a variety of different test organisms. The method is rather simple: a fluorescent dye that gets activated by reaction with ROS is added to the experiment, and subsequently the fluorescence is being measured. For cells and cellular organisms like algae this can be done quantitatively by means of a multiwell photometer.

However, for zebrafish larvae only a semi-quatitative procedure was developed so far, by colleagues from Spain. This involves inspection of the zebrafish using a fluorescence microscope and a subsequent categorisation of the fluorescence intensity - and thus the level of ROS induction.
We now took their protocol and combined it with a method for fluorescence measurement in a multiwell photometer that determines endocrine activity in a transgenic fish strain. We adapted the whole test procedure to the requirements of automatic fluorescence readout, and came up with a test system that initially allows detection of ROS induction in zebrafish larvae by a control substance.
ROS induction in zebrafish, semi-quantitative assessment by means of microscopy

In the next steps we will testdrive the method with a several single substances and created mixtures. We will further finetune the assay where necessary, and finally will verify suitability for detecting the biological activity of complex environmental samples, such as water samples and extracts.

Our hope is that the assay will help to better understand and assess other effects determined using the zebrafish model. It will be included in our upcoming integrated zebrafish test battery that measures a multitude of biomarkers and endpoints in just one experiment.

Zebrafish-directed identification of culprits

The zebrafish has become a standard test species in ecotoxicology, and a versatile tool for effect measurement and assessment. Being a complex vertebrate organism it allows for a multitude of biomarker investigations on various sublethal endpoints. Since such effects are determined after exposure of a whole animal, environmental relevance is higher than for microscale cellbased assays.

Environmental relevance is also the focus of the integrated approach of effect-directed analysis (EDA). This recursive process of sample testing and fractionation helps to seperate the key toxicity drivers for final chemical identification. Thus, the real culprits for toxicity in environmental samples can be revealed and distinct measures taken for mitigation or remediation.

It sounds hence logical to combine zebrafish testing and EDA for environmental risk assessment. For our EDA Emerge project we reviewed the utility of zebrafish in EDA studies to date, described advantages and shortconings as well as further requirenents for method development.

Saturday, February 13, 2016

Is one of the best materials known to mankind toxic?

Graphene is a two-dimensional carbon layer and in many aspects the best material known to mankind. It is highly robust, has very good conductive properties, and due to its stucture an immense surface to mass ratio.

Graphene exists as nanoplatelets. Like all nanoparticles it is subject to environmental and toxicological investigations. Nanoparticles are suspected to enter cells and cause damage, harm cell membranes, and act as transport vehicles for contaminats due to their sorptive capacity for unpolar molecules.

http://polpix.sueddeutsche.com/bild/1.1008406.1355787097/640x360/physiknobelpreis.jpg
It is this possible sorption of putative pollutants that makes graphene also very interesting in terms of soil and sediment remediation. The vast surface of only a little amount of graphene platelets promises a high efficiency in capturing toxic organic molecules and thus making them unavailable for uptake by organisms.

However, prior to application in remediation measures two crucial questions need to be answered:
1. How strong is the sorption? Will the particles be a reliable sink?
2. Are graphene platelets toxic, and if yes, at which concentration? Could they be still successfully applied in concentrations where they do no harm?

We investigated these questions within two bachelor's theses in collaboration with colleagues from the Polytechnical University of Bucharest (UPB), Romania, and the RWTH Aachen University Institute of Plant Physiology. Objects of study were not only pure graphene platelets but also differently oxidised types. Since we knew from previous studies that nanoparticles cause mainly oxidative stress, we investigated induction of reactive oxygen species (ROS) in different test systems.

Graphene platelet suspensions were subjected to transgenic yeasts that can reveal different modes of action for ROS induction. They were further used to expose algae and also zebrafish embryos. The assays made use of dyes that react with ROS after metabolic activation to fluorescent molecules. Fluorescence is hence proportional to the strength of ROS induction and can be determined by means of microscopy or photometric measurement. For zebrafish investigations we used a new protocol from colleagues in Spain on semi-quantitative evaluation of ROS induction.

Our study showed that graphene nanoplatelets do not induce ROS induction in yeasts and zebrafish up to a nominal concentration of 2 mg/L. However, higher concentrations were not yet tested, since this concentration would be likely the one for environmental application according to the sorption studies conducted by the UPB. Algae gave weak ROS induction, but with high variability and hence not significant.

While our results give a first good indication that graphene platelets are suitable for soil and sediment remediation, these were only initial investigations. Further studies will test higher concentrations, as graphene platelets are likely to accumulate. Thus, the relevant environmental concentrations could clearly exceed the applied. Also, more sensitive assays using yeasts and zebrafish will be carried out. But most importantly, we will measure the exposure concentration, since chances exist that the real concentrations of platelets were lower than the one of the initial suspension.

Saturday, February 06, 2016

An evidence on failure in sediment risk assessment

Recently, we put out a paper on an ecotoxicological investigation of sediments from an oxbow lake of the River Rhine. What looks just like another research paper about a study of contaminated sediments holds an important finding about standard sediment assessment: it might fail.

We tested the samples using a comprehensive bioassay battery that goes far beyond the regulatory requirements. Besides the commonly employed test on immobilisation of Daphnia magna, we used assays to reveal estrogenicity, teratogenicity, embryotoxicity and cytotoxicity. Surprisingly, all tests gave clear effects of the sediments, except for the standard test with daphnids.

So, are sediments a risk? Read our discussion and conclusions of this important topic in our paper published in the Journal of Soils and Sediments.