PROJECT SUMMARY The Ambystoma Genetic Stock Center (AGSC) is a P40 Research Resource that distributes laboratory axolotls (Ambystoma mexicanum) to researchers and educators nationally and internationally. The AGSC houses approximately 880 adults in aquatic recirculating systems and static bowls to sustain a captive, wildtype breeding population and a small number of mutant and transgenic lines. Several dozen axolotl transgenic and knock-out axolotl lines have been created by the axolotl community in the past couple of years and more lines are anticipated in the future. The AGSC does not have enough tanks or infrastructure to house all adult breeders or newly created lines as living stocks. An effort is underway to develop a sperm cryopreservation protocol so that axolotl lines can be managed as both living stocks and cryopreserved stocks. Until the sperm cryopreservation protocol is developed and shown to reproducibly allow for the re-derivation of axolotl lines from frozen sperm, there is critical need to increase the number of tanks in the AGSC. This Administrative Supplement will be used to purchase two recirculating systems that will add 240 tanks to the AGSC. The addition of these new tanks to the AGSC will provide infrastructure that is critically needed to sustain lines for the axolotl community.