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Examination of estrogenic substances with zebrafish lines used as biomarkers 

Among the hazardous priority compounds entering our environment due to urbanization processes, there are a large number of EDC (endocrine disrupting compounds), primarily estrogenic compounds, which pollute water to the greatest extent among natural media. 

The chemical diversity of the substances in this group makes their examination and the modeling of their environmental fate difficult, since different analytical methods are required for their detection. This problem is overcome by effect-based methods, such as the use of biomonitor/bioindicator organisms. The use of these organisms, e.g. for the analysis of environmental samples, is supported by several international organizations (EPA; OECD). 

Taking advantage of the demand for biosensor transgenic organisms, we created a zebrafish line (vtg1:mCherry) in our Institute, whose liver produces a red fluorescent protein in the presence of estrogenic substances. The basis of the functioning of the line is that the expression of the red fluorescent protein is under the control of the regulatory region of the vitellogenin gene, which can be induced by estrogenic substances. Vitellogenin genes are usually only active in adult females, not expressed in larvae and males, or expressed at very low levels, but are activated in the presence of estrogen, making them particularly suitable for studies on the effect side. The presence of the fluorescent protein in the transgenic line can be easily detected in vivo under a fluorescent microscope and analyzed based on photographs. The usability of the line was validated with several EDC compounds and environmental samples, and its characterization from a developmental biological perspective was carried out, in detail. During further development work on the line, we will primarily focus on the in vivo detection of the long-term effects of estrogenic compounds. 

Work with our vtg1:mCherry biomarker zebrafish line also plays a role in two international collaborative projects started this year (BioTreatED (Water4All 2023-334); PFAQuatic (2024-1.2.3-HU-RIZONT-2024-00100)). 

Dr. Zsolt Csenki-Bakos 

Research Excellence Programme 2024 

Red fluorescent signal in the liver of vtg1:mCherry transgenic adult zebrafish and embryos, following 17-ß-estradiol (E2) induction.