Making things smaller to make them bigger

One of our main research directions is the development and optimisation of bioanalytical tools. In terms of optimisation, among others we seek to make the bioassays more versatile, meaning to include several different effect meaurements and integrate results; to allow for a higher throughput of samples, thus reducing required work force and other resources; and to miniaturise the bioassays where possible, especially with regard to saving sample.

The latter one was the focus of a study we conducted on an assay that detects androgen receptor binding, thus indicating potential for hormon-like activity and disturbance of the endocrine system. Samples containing such substances are often available in only very small amounts, for instance as extracts from water samples. And especially in terms of drinking water the presence of androgen-like chemicals is a great concern.

We succeeded in reducing the medium volume to dilute the sample to one third of what is recommended by the standard protocol, thus also significantly reducing the required amount of sample. Results obtained for standard substances were compared to data obtained using the conventional procedures and found to be similar. This proved that the optimised method can be applied as an alternative to the standard protocol, if limitations by small sample amounts would otherwise prohibit scientifically meaningful investigations, and thus compromise proper risk assessment.

Take a closer look at the "Downscaling procedures reduce chemical use in androgen receptor reporter gene assay". (fulltext only with a subscription to the journal, sorry...)

This is a boring headline about zebrafish embryos exposed to heavy metals

Today I report on a study that was published already a while ago, but tells a nice story about the challenge and necessity to design meaningful experiments. Also, this one deals with heavy metals, which is not common in our research; we mainly focus on organic contaminants.

In this particular study we investgated whether heavy metals spiked into sediments are bioavailable to unhatched zebrafish embryos, and whether it makes a difference if the sediment was a natural one - just taken from, e.g., a riverbed out there - or a formulated, meaning components that typically make up a sediment mixed together. Besides the single heavy metals we also spiked mixtures.

We investigated mortality, several heavy metal-specific proteins and the regulation of a couple of genes that are known to react to heavy metal exposure. What we found was actually not very surprising: the heavy metals in the formulated sediment were better bioavailable than those in the natural one. An artificial mixture of sediment components can never resemble a real "grown" sediment. The matrix in the natural sediment is just much more complex and provides a multitude of possibilities for heavy metals to be trapped, bound, blocked, and thus not able to enter the test organism. Nevertheless, this had to be proven first. Science does not rely on hypotheses. We  have to challenge them to be sure.

However, formulated sediments are widely used in research. And our study shows that using such matrices could largely overestimate bioavailability and thus risk of heavy metal contaminations in sediments. Furthermore, the study revealed that the accumulation of the individual heavy metals from a mixture is relatively lower compared to that in the single metal exposure experiments. Since not all metals show the same toxicity for the embryos this has to be taken into account when doing risk assessment of heavy metal burden.

Last not least we identified some promising biomarkers for low-dose detection of heavy metal exposure. Read the full story on "Bioaccumulation and molecular effects of sediment-bound metals in zebrafish embryos". (fulltext only with a subscription to the journal, sorry...)

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!

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.

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...).

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...).

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.