Minimally invasive brain injections for viral-mediated transgenesis: New tools for behavioral genetics in sticklebacks

Behavioral genetics in non-model organisms is currently gated by technological limitations. However, with the growing availability of genome editing and functional genomic tools, complex behavioral traits such as social behavior can now be explored in diverse organisms. Here we present a minimally invasive neurosurgical procedure for a classic behavioral, ecological and evolutionary system: threespine stickleback ( Gasterosteus aculeatus ). This method of direct brain injection enables viral-mediated transgenesis and pharmaceutical delivery which bypasses the blood-brain barrier. This method is flexible, fast, and amenable to statistically powerful within-subject experimental designs, making it well-suited for use in genetically diverse animals such as those collected from natural populations. Viral-mediated transgenesis in the brain allows for a direct examination of the genetic mechanisms underlying behavior in wild-caught animals from natural populations. Using this method, we were able to detect changes in aggression from the knockdown of either of two different genes, arginine vasopressin ( AVP ) and monoamine oxidase ( MAOA ), in outbred animals in less than one month. In addition, we demonstrate that widely available mammalian plasmids work with this method, lowering the barrier of entry to the technique.