PROJECT SUMMARY GENETIC ENGINEERING CORE (GEC) The overall goal of the Genetic Engineering Core (GEC) is to support the needs of MARMO-AD by providing services to (1) genetically engineer marmosets using CRISPR/Cas9 gene editing, (2) develop and optimize enabling technologies for germline gene editing in marmoset, and (3) create fibroblast cell lines and differentiate them into induce neuronal stem cells and neurons. The common marmoset (Callithrix jacchus) is a New World non-human primate with numerous practical advantages in biomedical research and is quickly becoming a much sought-after model organism by the neuroscience community. The rapidly growing appreciation of marmoset neurobiology is synergizing with contemporaneous advances in gene editing techniques to make marmosets the genetically engineered non-human primate of choice for understanding brain function and to study brain disorders such as Alzheimer’s Disease. The GEC will provide all services required to use CRISPR/Cas9 gene editing to produce novel genetically engineered marmosets that harbor human high-risk alleles for early and late onset Alzheimer’s disease. While creating these gene-edited animals, the GEC will simultaneously develop and optimize enabling technologies for efficient germline gene editing. These technologies include novel methods of ovarian stimulation to enhance production of mature marmoset oocytes, and novel approaches to reduce mosaicism in gene edited marmosets. Improved technologies will reduce the cost and increase the speed at which genetically engineered marmosets can be produced while also reducing animal numbers. Lastly, the GEC will produce marmoset fibroblast cell lines and differentiate them into induced neuronal stem cells and neurons. Cell lines will be used to create DNA sequencing libraries and for in vitro phenotypic characterization of gene edited animals in support of the Project goals.