PROJECT SUMMARY This is a proposal to modernize mouse Animal Biosafety Level 2 (ABSL2) facilities at the Salk Institute for Biological Studies by replacing antiquated static cages with racks of individually ventilated cages (IVCs). Together with proposed renovations to the ABSL2 animal holding room, this will double cage capacity and enable operational efficiencies that reduce animal stress and improve the rigor and reproducibility of experimental outcomes. Within Salk’s Conventional Research Animal Facility (CRAF) is an ABSL2 suite, which includes a 220-ft2 animal holding room. This holding room is currently comprised of three small cubicles adjoined to a common space. Each cubicle holds one double-sided shelving unit capable of accommodating up to 112 static mouse cages, for a maximum of 336 cages in the holding room. Given the large number of labs who utilize this space (33 of 54 Salk faculty), this facility is often at >80% capacity and labs have had to delay studies until space becomes available. The proposed project removes the cubicles and installs high-density Allentown NexGen MAX racks. The increased useable floorspace will accommodate 3 double-sided racks (192 cages each) and 1 single-sided rack (96 cages), doubling the capacity to 672 cages. The proposed modernization will also improve living conditions and reduce stress experienced by the mice, thereby helping to promote rigor and reproducibility of Salk research. Non-ventilated cages are associated with poor air quality and require frequent cage changing, resulting in greater handling of the mice and higher levels of stress for the animals. Because humidity levels are so high at Salk, cages often must be changed twice a week. Switching to ventilated caging will extend the time between cage changes to 10–14 days. Further, the proposed floor plan minimizes the need to roll racks to access mice, thereby reducing mouse exposure to noise and vibration. Thus, a critical feature of the modernized CRAF ABSL2 suite is a reduction in non-experimental husbandry variables that could potentially affect research results. Finally, improvements to this facility are an Institute priority, as mouse ABSL2 work is at the center of the Institute’s future research endeavors, which include cancer biology, neuroscience, and aging. Researchers within each of these programs use, and often develop, cutting-edge technologies that require ABSL2 facilities to target and manipulate specific cell types within mouse models. Salk’s long-term commitment to these research efforts and associated mouse ABSL2 work is reflected in fundraising initiatives dedicated to conquering cancer, neuroscience, and healthy aging. In support of these research priorities, this proposal seeks to: 1) replace static cages within the CRAF ABSL2 suite with state-of-the-art IVC racks, 2) increase cage capacity within the ABSL2 suite to meet research demands for the foreseeable future, and 3) enhance the rigor and reproducibility of mouse ABSL...