Transcriptional expression changes during compensatory plasticity in the prothoracic ganglion of the adult cricket Gryllus bimaculatus

Most adult organisms are limited in their capacity to recover from neurological damage. The auditory system of the Mediterranean field cricket, Gryllus bimaculatus, presents a compelling model for investigating neuroplasticity due to its unusual capabilities for structural reorganization into adulthood. Specifically, the dendrites of the central auditory neurons of the prothoracic ganglion sprout in response to the loss of auditory afferents. Deafferented auditory dendrites grow across the midline, a boundary they normally respect, and form functional synapses with the contralateral auditory afferents, restoring tuning-curve specificity. The molecular pathways underlying these changes are entirely unknown. Here, we used a multiple k-mer approach to re-assemble a previously reported prothoracic ganglion transcriptome that included ganglia collected one, three, and seven days after unilateral deafferentation in adult, male animals. We used EdgeR and DESeq2 to perform differential expression analysis and we examined Gene Ontologies to further understand the potential molecular basis of this compensatory anatomical plasticity. Enriched GO terms included those related to protein translation and degradation, enzymatic activity, and Toll signaling. Extracellular space GO terms were also enriched and included the upregulation of several protein yellow family members one day after deafferentation. Investigation of these regulated GO terms help to provide a broader understanding of the types of pathways that might be involved in this compensatory growth and can be used to design hypotheses around identified molecular mechanisms that may be involved in this unique example of adult structural plasticity.

Transcriptional Expression Changes During Compensatory Plasticity in the Central Nervous System of the Adult Cricket Gryllus Bimaculatus: I. Auditory System Plasticity in the Prothoracic Ganglia

Most adult organisms are limited in their capacity to recover from neurological damage. The auditory system of the Mediterranean field cricket, Gryllus bimaculatus, presents a compelling model for investigating neuroplasticity due to its unusual capabilities for structural reorganization into adulthood. Specifically, the dendrites of the central auditory neurons of the prothoracic ganglion sprout in response to the loss of auditory afferents. Deafferented auditory dendrites grow across the midline, a boundary they normally respect, and form functional synapses with the contralateral auditory afferents, restoring tuning-curve specificity. The molecular pathways underlying these changes are entirely unknown. Here, we used a multiple k-mer approach to re-assemble a previously reported prothoracic ganglion transcriptome that included ganglia collected one, three, and seven days after unilateral deafferentation in adult, male animals. We used EdgeR and DESeq2 to perform differential expression analysis and we examined Gene Ontologies to further understand the potential molecular basis of this compensatory anatomical plasticity. Enriched GO terms included those related to protein translation and degradation, enzymatic activity, and Toll signaling. Extracellular space GO terms were also enriched and included the upregulation of several protein yellow family members one day after deafferentation. Investigation of these regulated GO terms help to provide a broader understanding of the types of pathways that might be involved in this compensatory growth and can be used to design hypotheses around identified molecular mechanisms that may be involved in this unique example of adult structural plasticity.

Contralateral Deafferentation Does Not Affect Regeneration Processes in the Auditory System of Schistocerca gregaria (Orthoptera)

The auditory system of locusts has high regeneration capacity following injury of the peripheral afferents. Regenerating auditory afferents can re-innervate their target areas even after changed neuronal pathways. Here, possible influences of contralateral deafferentation on regenerating afferents were investigated. Contralateral deafferentation was performed at different stages of the regeneration. Regeneration was triggered by crushing the tympanal nerve. The regenerated fibers showed aberrant fiber outgrowth, reduced density of terminations in the target area, the auditory neuropile and collateral sprouts crossing the midline. However, these results were not significantly influenced by the contralateral deafferentation. Therefore the bilateral symmetrical systems seem to be largely independent from each other.