Meeting Abstract
Cephalopods have independently evolved complex centralized brains that demonstrate extreme innovations in the organization of virtually every organ and tissue. Their nervous systems utilize a distinct molecular toolkit that diverges from many other bilaterians, while still maintaining similar functions. The Cephalopod Vertical Lobe (VL) is one of the memory centers whose function and structure are analogous to the mammalian hippocampus. The objective of this study is to identify and map the expression of candidate signaling molecules responsible for neurotransmission in the VL-circuit of Cephalopods. Some candidates are novel and unique to Cephalopods or Molluscs, while others are conserved through the animal kingdom. First, we performed computational and manual annotation of RNA-seq data obtained from the Vertical and Superior Frontal Lobes of Octopus vulgaris. Next, candidate signal molecules were validated by cloning and localized using in-situ hybridization. Specifically, four neuropeptides were mapped to the Octopus brain – each revealing a unique expression pattern. While the function of these neuropeptides is yet unknown, our localization studies suggest that WhP may play a role at the first synapse of the simplified VL-circuitry and relay messages to the VL for processing. Two other neuropeptides, TkP and IRP, likely function at the second synapse of the VL-circuitry and process sensory inputs. In summary, the unique organization of the VL provides an illustrative example of convergent evolution and is an important model to understand the structural and molecular constraints on the development of mechanisms responsible for complex behaviors in cephalopods.
