RAIDAR

The current standard for neurocircuitry experiments in vivo is typically limited to utilizing a tracing virus alongside a genetic driver, a system which confers one-sided specificity to either the projecting or the receiving population of neurons. RAIDAR (tRacer Attached Intein Dre Assisted Recombination) is a new tool for in vivo construct expression which aims to expand specificity to both projecting and receiving neurons, something that is not currently possible with modern in vivo techniques. RAIDAR is designed to express a Dre recombinase only in cells of a target neuron population which project to another specific connected neuron population, allowing targeted manipulation of a circuit-defined neuron. To do this, RAIDAR utilizes a split intein Dre recombinase, separated into a static and a traveling portion which utilizes a wheat germ agglutinin (WGA) as a ferry. When expressed in two connected neuron populations, the traveling portion will make its way to the neuron which contains the static portion through transsynaptic transport. When the two pieces of RAIDAR meet, the split intein Dre recombines into a functional Dre recombinase. The production of the traveling and static portion of RAIDAR is gated behind the activity of Flp or Cre recombinase, which allows the use of RAIDAR to study any connected set of molecularly defined neuron populations utilizing recombinase-based genetic models. RAIDAR is able to travel between two molecularly defined neurons, form a functional Dre recombinase, and activate a Dre-dependent vector in vivo, making it a useful tool for furthering our understanding of neuronal circuits in living animals.