Swimming in Transcriptomics: Using Next-Gen sequencing to study the evolution of neural circuitry and swimming behavior of sea slugs

Sea slugs (Mollusca, Gastropoda, Nudipleura) provide unique opportunities for studying the evolution of behavior at the levels of single neurons, neural circuits, and their synaptic connections. Of particular interest to us are the mechanisms by which analogous forms of swimming behavior, such as dorsal-ventral (DV) or left-right (LR) body flexions, evolved independently in certain sea slug clades. Transcriptome sequencing has been useful for this research in two ways: first, it provides a means for characterizing the phylogenetic relationships amongst sea slug species, where robust phylogenetic trees can be constructed using hundreds of orthologous gene sequences. Indeed, a strong understanding of species phylogeny is a necessary pre-requisite for formulating hypotheses about how DV and LR swimming might have evolved in different lineages. Secondly, transcriptome sequencing provides unprecedented access to gene sequences from the sea slug brain, which can be used to probe the molecular mechanisms by which single neurons are recruited into rhythmic circuits to drive analogous forms of swimming. To illustrate, the lab previously found that in two species that independently evolved DV swimming, homologous single neurons called C2 independently acquired sensitivity to serotonin (5HT) to potentiate their synapses and activate their corresponding DV swimming neural circuits. We are now testing the hypothesis that convergent alterations in 5HT receptor function/expression in C2 neurons is responsible for this synaptic potentiation, having identified from the transcriptomes full length sequences for all known molluscan 5HT receptors.

• Learn how transcriptome sequencing has been useful for the research of sea slugs and the mechanisms by which analogous forms of swimming behavior, such as dorsal-ventral (DV) or left-right (LR) body flexions, evolved independently in certain sea slug clades
• Learn how transcriptome sequencing provides a means for characterizing the phylogenetic relationships amongst sea slug species, where robust phylogenetic trees can be constructed using hundreds of orthologous gene sequences.
• Learn how transcriptome sequencing provides unprecedented access to gene sequences from the sea slug brain, which can be used to probe the molecular mechanisms by which single neurons are recruited into rhythmic circuits to drive analogous forms of swimming