Meeting Abstract
Cone snails are a family of venomous predatory gastropods that use a harpoon-like radular tooth and peptide neurotoxin containing venom to paralyze their prey. We used amplicon sequencing to identify a non-glycosylated venom peptide (c4g) from the species Conus catus. From this, we have synthesized and folded active venom peptide. This study focuses on investigating the activity of the folded, active peptide via a novel zebrafish spinal motility assay developed in the lab. Through decapitation of larval fish, this novel assay removes any descending inputs from the hindbrain, allowing for a focus directly on spinal motor circuits. It also results in the removal of the heart, thereby ceasing blood flow, allowing for the peripheral application of the venom exclusively. Utilizing this assay, we can correlate the subsequent movement of the zebrafish spines with specific neuronal circuit activation. For example, application of c4g confers neuroexcitatory behavior with body bends in the spines, mimicking the escape response and “C-starting” behavior of live fish. These episodes of activity differ from the coordinated swimming movement elicited by control NMDA application, suggesting a target distinct from the central pattern generators (CPG) for swimming. Interestingly, the assay responses do not fully account for the sustained paralytic effect of the cone snail toxins in live, stung fish prey, inferring the possible requirement for hindbrain descending glutamatergic drive for full tetanic paralysis. Consequently, we are employing other neuroexcitatory peptides and antagonists in the larvae assay, as well as additional neurophysiologic techniques such as patch clamping and calcium imaging to elucidate a specific molecular target for the synthetic venom peptides and the neuronal circuits they regulate.
