The nervous system of Loligo pealei provides multiple models for analysis of organelle motility

Abstract

This chapter discusses the use of the squid giant axon and giant synapse in the study of organelle motility. Special attention is paid to the construction of the model systems, and each preparation is illustrated with an example of the model's utility in research on translocating organelles. The popularity of the squid giant axon for electrophysiological studies was derived mainly from unique features of the squid nervous system. The absence of myelin in cephalopods led to the development of unusually large axons in the highly mobile squid. In turn, these giant axons required synaptic contact of similar magnitude to assure proper coupling of pre- and postsynaptic action potentials at a synapse. The giant axon and the giant synapse have taught the principles regarding the enzymology, pharmacology and biochemistry of organelle transport. The squid nervous system has continued to provide insights into neuronal cell biology, in part through development of novel preparations for dissection of cellular mechanisms. Two of these preparations have proven to be invaluable for the study of motility in the axon and presynaptic terminal. Isolated axoplasm from the squid giant axon may be experimentally manipulated by perfusion with suitable buffers, and materials can be microinjected into the presynaptic terminal of the giant synapse during intracellular recording of electrical properties. Both experimental models are discussed in this chapter with reference to their utility in studying the mechanism of organelle transport.