Meeting Abstract
The freshwater annelid Lumbriculus variegatus regenerates from as little as three body segments (Martinez-Acosta and Zoran, 2015). Recent electrophysiological studies demonstrate recovery of function as early as 24hr post amputation (Lybrand and Zoran, 2012). Using immuhistochemical analysis, we describe the emergence of serotonergic neurons 24hr post amputation which begin formation of the cephalic ganglion in regenerating head blastema. These data suggest that Lumbriculus has one of the fastest regenerating nervous systems in the metazoan phyla. To further investigate this rapid recovery of function, we describe changes in expression of synaptic proteins during regeneration. In other species such as lamprey, researchers have found the upregulation of synapsin in the brain after spinal cord injury which plays a big role in neurite outgrowth and synapse formation (Lau et al 2011). Antibodies were tested for cross-reactivity against synaptic proteins like synapsin, synaptic vesicle protein (SV2), syntaxin, and synapse associated protein 47 (DSAP47). Of these DSAP 47 (Developmental Hybridoma Bank) immunoreactivity is found along the ventral nerve cord (VNC), more closely associated with the lateral giant fibers. DSAP47 epitopes were also found in co-lateral extensions that arise from the VNC and are thought to be points of sensory integration from the periphery. In cross-section, SV2 and syntaxin are found at active synapses within the neuropil of the VNC in regenerating fragments. As we move forward, changes in expression of these synaptic proteins will be quantified at different time points of regeneration: 24 hrs, 72 hrs, and 1 wk post-amputation to provide insight for how they may be functioning in this remarkable regenerating system.
