sentence: GGTA1 / iGb3S and GGTA1 / CMAH double knockout and GGTA1 / iGb3S / CMAH triple knockout pigs , which have potential for xenotransplantation , were created by a single-step transfection of multiplexed sgRNA and Cas9 nuclease together with a single nuclear transfer ( Li et al ., 2015 ) .