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Fish Sex Testing Attracts Research Grant

UK - Dr Ioanna Katsiadaki, a researcher from the Centre for Environment, Fisheries & Aquaculture Science (Cefas) and based in Weymouth, received confirmation today of grant funding for her work to replace, reduce or refine the use of animals (the "3Rs") in research and testing.

Dr Ioanna Katsiadaki, a researcher from the Centre for Environment, Fisheries & Aquaculture Science
Photo: CEFAS

The National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), an independent funding organisation set up by the Government in 2004, awarded Dr Katsiadaki a grant of £398,640.

European legislation requires chemicals to be tested to ensure that they are safe for humans and the environment. Many of the tests require the use of fish. Dr Katsiadaki's proposal for validating a Fish Sexual Development Test (FSDT) evaluates the effects of chemicals on sexual development and uses newly hatched fish to determine if such exposure poses risk to the fish or, potentially, to humans.

Endocrine disruptors (EDs) are a group of man-made chemicals that can mimic the function of hormones such as oestrogen, affecting the normal functioning of hormones. Exposure to EDs in the environment is raising concerns that sexual development in humans could be affected. For example, a number of studies have attempted to link exposure to EDs with a decline in sperm count and the increased incidence of some cancers.

The fish endocrine system is strikingly similar to that of humans. For that reason, fish have been used as a surrogate to assess the effect of EDs on the human endocrine system, in addition to assessing the effects of EDs in the environment. Dr Katsiadaki's grant-funded project will use the three-spined stickleback, a particularly useful species of fish, for addressing the 3Rs in fish toxicity testing, with the aim of reducing the total number of fish used from nearly 500 to 160 per chemical.

Dr Katsiadaki said: "In the three-spined stickleback, a genetic test can be used to determine the sex of an individual fish, rather than inferring sex from appearance alone. This makes the stickleback more suitable for the FSDT test compared with other fish.

"While a fish is growing and maturing, EDs can alter the apparent sex so differences between the actual (genetic) sex and the developed (phenotypic) sex could indicate the presence of EDs. The lack of a molecular marker for sex in other fish means that sex ratios can only be estimated, so more fish are used to gain a more accurate estimate of the effect. The ability to assign genetic sex increases the power of the test and will therefore reduce the number of fish used."

Dr Vicky Robinson, chief executive of the NC3Rs, said: "I am delighted that we have been able to increase our investment in research. Our funding scheme has developed into a highly competitive funding stream attracting very high quality proposals, from leading UK scientists and institutions. We are starting to see the results of this in terms of reducing the number of animals used, improving animal welfare and supporting research to understand and develop treatments for human diseases." Dr Katsiadaki's grant is part of a wider funding package of £2.6 million for a total of ten new projects.