Summary of the in vivo stickleback tests aimed to be part of the official OECD guidelines for endocrine disruptor testing

The potential of developing a biomarker for androgens in the three-spined stickleback (via the kidney glue protein that breeding males use to construct a nest) was recognised 10 years ago. As a consequence, under the UK EDMAR programme an ELISA for the only known so far androgen-regulated protein in fish, the stickleback glue spiggin, was developed and validated. More recently the stickleback assay was modified in two different ways to detect anti-androgens, a group of EDCs that poses an increasing risk to the aquatic environment as the in vitro data obtained from two nationwide surveys of final sewage effluents suggest. Importantly, the stickleback is present in Europe (and across all of the North hemisphere) and can bring together lab and field studies providing a sound basis for environmental risk assessment. To this end, the UK (Defra CN) has financed three research programmes that underpinned the background and validation data requirements that could lead to the inclusion of the stickleback as a recommended species for EDCs screening. Here we present the outcomes of this research and provide an update of the current state of fish test guidelines for EDCs. In addition we will be referring to a new project, funded by the National Centre of 3Rs, UK and is aiming to validate the fish sexual development test (another OECD guideline line under development) using the stickleback. The presence of a genetic sex marker in the stickleback (as in the medaka) has the potential of reducing the number of fish needed for this test because genetic sex (as opposed to phenotypic) can be assigned.