Transcriptomic signatures associated with developmental transitions in the gill of lake sturgeon (Acipenser fulvescens)

The developmental transition from the larval to juvenile stage, represents one of the highest periods of mortality for many species of fish. Thus, understanding the factors that may influence susceptibility to environmental stressors at this vulnerable stage is likely to be important for predicting responses to environmental change. Here, we compared gill mRNA transcript abundance during this critical developmental transition in fish from two geographically distinct populations of lake sturgeon (Acipenser fulvescens) that experience highly divergent thermal environments. Throughout the developmental transition from the larval to juvenile stage (30 to 60 days post-fertilization), the 'colder' northern population exhibited differential expression of approximately twice as many transcripts as compared to their 'warmer' southern counterparts. Transcriptional modifications that were conserved across both populations during the transition from the larva to juvenile stage were involved in histone methylation, protein binding, and apoptotic signaling associated with cell death and turnover. The northern population, specifically, had increased changes associated with GTPase signaling activation, cell surface proteins, mitochondrial and epithelial development which may have contributed to the larger magnitude of transcriptional change in this population, compared to their southern counterparts. Together these findings demonstrate the impacts of transcriptional shifts in the gill during development in lake sturgeon, as well as the potential for population-specific developmental processes.