news | 2021-01-22
A double picure. To the left: a woman woking at her laptop. To the right: a water flea.

Photo Amira Perez: Private. Photo water flea: Dieter Ebert (Creative Commons)

The water flea – one of the tools in Mistra SafeChem

Can the little water flea be of help in developing a screening tool for ecotoxicological testing of chemicals? That is investigated by Amira Perez and her colleagues in a Mistra SafeChem PhD project.

It is estimated that 86 million tonnes of environmentally hazardous chemicals are produced in Europe every year. This volume of potentially harmful chemicals makes traditional assessments using live organisms too costly and time-consuming.

To address these challenges, toxicogenomic, high-throughput and high content screening (HCS) methods have started to evolve. Image-based HCS is relatively new and consists, in its basic form, of a biological sample (cells, tissue, or whole organism), which is processed to extract a visible readout (commonly by fluorescent dyes, molecular probes, antibodies or induced expression of fluorescent proteins) by automated microscopy and then analysed and quantified by image analysis.

Possible to study many features simultaneously

Amira Perez, a biologist at Stockholm University with a master’s degree in integrated water management, is part of a PhD project in Mistra SafeChem. The aim is to develop image-based HCS as a tool to estimate the hazard properties of chemicals.

– The ability to study many features simultaneously is what makes HCS a powerful tool with several applications, she explains.

The PhD project uses water flea (Daphnia Magna) as a model organism, as it is considered “keystone” species in most freshwater habitats. It is small (1-5 mm), has a short life cycle and a particular way of reproduction and is one of most well-studied aquatic invertebrates. It is commonly used in ecotoxicological research and as a standard test specie in the OECD guidelines for testing chemicals.

The objective is to establish as staining toolbox

– The water flea is very sensitive to changes in the environment which reflects in the way they reproduce. Therefore, growth and reproduction are common toxicity endpoints studied in them. Thus, we can identify possible biomarkers which can be used as sensitive measures that show the capability of a chemical causing negative effects in these organisms, says Amira Perez.

The PhD project has the objective to establish a staining toolbox for imaged based HCS. It is expected that the methods can help to apply HCS in Daphnia Magna to visualize and detect the toxicity effect of chemicals of industrial interest.

May be of use in other applications

Amira Perez is working closely with another PhD student in SafeChem, Cedric Abele, who is interested in expanding the toolbox to other organisms.

They are also exploring the possibility to cooperate with a project in partnership with Stockholm Vatten och Avfall, which will try to apply HCS with the water flea as a bioanalytical monitoring tool.