Cp36 serine recombinase as a new tool for zebrafish transgenesis

One feature key to the versatility of zebrafish as an animal model for biomedical research is the breadth of genetic tools available, including for transgenesis. While the Tol2 transposase system remains the gold standard, its efficiency can be highly variable. Here, we explored the potential of a complementary transgenesis system, Cp36, a large serine recombinase identified from Clostridium perfringens previously found to efficiently integrate target cargo into the human genome without a preinstalled attB site. We generated Cp36-based plasmid constructs for zebrafish transgenesis and compared their performance to matched Tol2 plasmids across multiple experimental contexts, including transient expression, germline transmission, and multi-transgene expression. Cp36 integrates small ~3.5kb cargo into the zebrafish genome and transmits to the next generation as efficiently as Tol2, but Cp36 performance declines substantially for larger ~7.5kb constructs. Both Cp36 and Tol2 have comparable efficiency in transiently expressing a second construct regardless of the transposase/recombinase used to integrate the first construct, indicating compatibility with sequential transgenesis strategies. In summary, we demonstrate that Cp36 functions as a new alternative transgenesis method in zebrafish.