There is an increasing concern about the environmental impacts of chemicals that have the ability to disrupt the endocrine system, which can result in adverse effects on developmental, reproduction, neurological and/or immune function in both humans and wildlife. Concern about thyroid hormone disrupting chemicals (TDCs) in particular has increased because of the critical role that thyroid hormones play during development. Biobide has developed a bioassay to screen the Thyroid Disrupting (TD) potential of chemical compounds using tg(tg:mcherry) transgenic embryos, which express red fluorescence in the thyroid gland under the thyroglobulin promoter.
Increases in thyroglobulin levels will lead to an increase in fluorescence. The signal intensity is assessed in vivo to screen and characterize potential TD, either directly or after metabolization by the zebrafish embryo. Additionally, a gene expression analysis is carried out to obtain a more extensive characterization of the thyroid disrupting effect.
The assay has been validated with different reference toxicants and environmental pollutants targeting various Molecular Initiating Events (MIE) for disruption of the thyroid hormone axis.