Abstract #205

Section: Transgenesis
Session: Transgenesis
Format: Poster
Location: Rio Exhibit Hall B
# 205
S.-E. Hahn*1, S.-Y. Yum1, S.-J. Lee2, C.-I. Lee1, H.-S. Kim2, H.-J. Kim2, W.-J. Choi1, J.-H. Lee1, G. Jang1, 1Laboratory of Theriogenology, Department of Veterinary Clinical Science, College of Veterinary Medicine and the Research Institute of Veterinary Science, Seoul National University, Seoul, Republic of Korea;, 2Embryo Research Center in Seoul Milk Coop, Gyeongi-Do, Republic of Korea.

A genome-editing technology, CRISPR/Cas9 system is proved to be a powerful tool for knockout and knock-in in various species. When 2 components [Cas9 and single guide (sg) RNA] are delivered into cells or embryos, the events of gene editing occur. Because Cas9 is essential for every gene editing based on the CRISPR/Cas9 system, some studies reported that efficiency of gene editing would be increased as Cas9 was integrated into cells or animals. Accordingly, if the Cas9-expressing cattle is born, it would be broadly used for gene editing in cattle. For this study, the Cas9 and RFP genes were cloned into the PiggyBac transposon system. PiggyBac-Cas9-RFP and transposase were microinjected into 1436 IVF embryos and 241 blastocysts were formed. Blastocysts with RFP expression accounted for 14.1% of total formed blastocysts. Five blastocysts were selected and transferred into 5 recipient cow (1 embryo per recipient). After gestation periods, 4 transgenic cattle were delivered without any veterinary assistance. From transgenic cattle, ear skin tissue was collected for primary culture. On those primary cells, sgRNA in DNA form for various genes such as PRNP, RB1, and BLG were transfected with 2 μg of sgRNA per 5 × 105 cells using electroporation. As expected, every group of each sgRNA delivered was confirmed to be mutated by T7E1 assay. The data demonstrated that, for the first time, transgenic cattle with Cas9 expression were born, grown up to date (age = 5 months) and will be a valuable resource for genome editing in cattle.