Use of animals in the present study complied with relevant UK legislation. Mice were killed by a listed competent person using a Home Office approved method as detailed in schedule 1 of the Animal (Scientific Procedures) Act 1986 (ASPA). In consultation with the Home Office ASPA inspectorate, the work was not considered to involve any scientific procedures on living animals (merely housing for a short period before killing [18] ) and was therefore not subject to regulation by ASPA.