The gene regulatory mechanisms underlying the rapid replenishment of snake venom following expenditure are currently unknown. Using a comparative transcriptomic approach we find that venomous and non-venomous species produce similar numbers of secreted products in their venom or salivary glands and that only one transcription factor (Tbx3) is expressed in venom glands but not salivary glands. We also find evidence for temporal variation in venom production. We have generated a draft genome sequence for the painted saw-scaled viper, Echis coloratus, and identified conserved transcription factor binding sites in the upstream regions of venom genes. We find binding sites to be conserved across members of the same gene family, but not between gene families, indicating that multiple gene regulatory networks are involved in venom production. Finally, we suggest that negative regulation may be important for rapid activation of the venom replenishment cycle.

Genomic and transcriptomic insights into the regulation of snake venom production