A combination of both in vivo and in vitro techniques is invaluable for studying semaphorin signaling in the avian central nervous system. Here we describe how both types of approaches can be used to compliment each other in order to unravel the role that semaphorins play during embryonic development and elucidate the functional consequences of semaphorin knockdown using RNA interference vectors. We describe and discuss specifically the use of in ovo electroporation and primary oculomotor neuron culture to identify the role of semaphorins in oculomotor neuron migration and assess functional consequences of semaphorin disruption in this system.

Elucidating the local function of proteins is essential for understanding not only the individual proteins but also the organization of the cell or even tissue as a whole. However, until now, few attempts have been made to understand local proteins function in cells because of a lack of acute inactivation technique of local proteins with high versatility. Here we describe the application of the chromophore-assisted light inactivation (CALI) method to elucidate the role of the semaphorin signaling component CRMP located within the growth cone area in axon growth and growth cone turning.