Smirnov A, Fishman V, Yunusova A, Korablev A, Serova I, Skryabin BV, Rozhdestvensky TS, Battulin N.

Nucleic Acids Res. 2020 Jan 24;48(2):719-735. doi:10.1093/nar/gkz1085

DNA barcoding reveals that injected transgenes are predominantly processed by homologous recombination in mouse zygote.

A library of constructs bearing a different barcode at each end was injected in mouse pronuclei and the resulting transgenes were sequenced from 10 embryos. New combinations of barcodes were observed in the majority of the copies inside concatemers. The data does not support the hypothesis of a rolling circle replication of individual constructs. The model is: first, some linear constructs are concatemerised by NHEJ (non-homologous end joining), then HR (homologous recombination) incorporates extra copies, causing exchange of barcodes as side effect.