Five NANOS2 Knockout (KO) Bucks (IMAGE) Proceedings of the National Academy of Sciences Caption Image of five NANOS2 knockout (KO) bucks generated by somatic cell nuclear transfer of CRISPR-Cas9 gene edited fetal goat fibroblasts.� Credit Image credit: Jon Oatley. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.