Kichoon Lee Awarded Two USDA Grants

June 29, 2020

Dr. Kichoon Lee, Professor in the Department of Animal Sciences, has been awarded two grants from the United States Department of Agriculture (USDA). The two USDA grant awards have been approved with a total budget of $500,000 for 2 years. The titles of the two projects are “Characterization of CRISPR/Cas9-mediated myostatin knockout quail" and “Improvement of CRISPR/Cas9-mediated genome editing in poultry”. Both projects started on June 01, 2020.

The Non-Technical Summaries of the two projects are below.

A greater understanding of mechanisms regulating muscle growth and development is essential to improve meat production in domestic animals. Muscle growth results from increases in numbers and/or size of muscle fibers. Myostatin (MSTN) inhibits muscle growth and natural or induced mutations of the MSTN gene increases muscle growth in mammals and fish. However, mechanisms (fiber number/size) of enhancing muscle growth by inactivation of the MSTN gene are different and degrees of the differences vary among different species. So far, any avian model with an inactive MSTN gene has not been developed. We recently developed a quail line with an inactive MSTN gene. The proposed research is focused on characterization of pro-myogenic activity of MSTN inactivation in the quail model. In mammals, increased total myofiber numbers (hyperplasia) are determined during fetal development with a continuous maternal supply of nutrients and energy. However, avian embryogenesis occurs independent of the hens in an egg consisting of a fixed size and containing a limited supply of nutrients. Therefore, we will also investigate the interaction of these egg environmental factors and genetics on the resulting phenotype of MSTN inactivation in the avian model. This exploratory grant will generate valuable information that will be a foundation for a future study focusing on 1) determining the critical time window of MSTN function so as to develop approaches to inactivate MSTN at specific permissive stages of muscle development or ages, 2) studying comparative aspects in molecular and cellular mechanisms, and 3) extending this proof-of concept in other major poultry species.

CRISPR/Cas9-mediated genome edition (GE) in food-animals can benefit both the scientific community and the future agricultural industry. The current method for GE in chickens requires highly skilled expertise for: 1) isolation, culture, and GE of primordial germ cells (PGCs) in vitro, 2) transfer of genome-edited PGCs into recipient embryos, and 3) generation of germline chimeras and its offspring with GE. In addition, the current PGC-mediated method has not been successful for other avian species. Therefore, it is necessary to develop an easy and efficient method without mediating PGCs in culture. To improve efficiency and overcome these technical barriers, we developed an optimized CRISPR/Cas9 vector and generated genome-edited poultry using adenovirus as a delivery system of the optimized CRISPR/cas9 into blastoderms without mediating PGC in culture. The efficiency of targeted genome modification in poultry depends on the rate of genome modification in the germ cell population. Therefore, this proposal is focusing on the development of a strategy to directly target more germ cells by injecting the CRISPR/Cas9 adenovirus into the embryo. With four objectives, we will inject the CRISPR/Cas9 adenovirus into four different locations where PGCs are dispersed, circulating or congregated during early embryo developmental processes to provide the most efficient next-generation method for GE in poultry. Successful development of the proposed next generation method of GE in poultry is expected to advance avian research and develop more productive genomic lines of poultry for infectious disease resistance, higher growth and feed efficiency, and increased muscle with reduced fat.