Co-expression of multiple transgenes in mouse CNS: a comparison of strategies

The introduction of two transgenes into one animal is increasingly common a s transgenic experiments become more sophisticated. In this study we examin e two strategies for creating double transgenic founders from a single micr oinjection. In the first approach, two constructs, each with its own promot er element, were coinjected into the pronucleus. In the second approach, bo th transgenes were cloned into one vector, separated by an internal ribosom al entry site (IRES), and placed under control of a single promoter. Both s trategies save time and increase the percentage of double transgenic offspr ing over the standard method of mating single transgenic lines. However, de spite high transgene copy numbers, the bicistronic lines did not show robus t expression of either protein. Copy number and protein expression correlat ed much better in the coinjected lines, with expression levels in one line approaching that observed in some of our best single transgenic controls. T hus we recommend coinjection of individual plasmids for the generation of m ultiply transgenic founders. (C) 2001 Elsevier Science B.V. All rights rese rved.