Figure 2

The venom-gland transcriptome of Micrurus fulvius was dominated by phospholipases A ₂ and three-finger toxins. Toxin gene expression was dominated by phospholipases A₂ (PLA₂s) and three-finger toxins (3FTxs). Full-length transcripts accounted for 57.1% of the total reads; toxin sequences accounted for 45.8% of the total reads. PLA₂s and 3FTxs represent both the most abundant and most diverse toxin classes identified; 31 PLA₂ clusters accounted for 64.9% of the toxin reads, and 15 3FTx clusters accounted for 21.1% of the toxin reads. Toxin sequences accounted for 10.4% more of the total reads in M. fulvius than in C. adamanteus, while nontoxins in C. adamanteus accounted for more than twice the total read percentage than in M. fulvius. The venom of M. fulvius was dominated by small neurotoxic components while the venom of C. adamanteus was dominated by larger hemorrhage-inducing proteins, suggesting that the transcriptional effort expended on toxins versus nontoxins may differ between venoms dominated by high-molecular weight components and venoms dominated by smaller proteins, with small-component venoms expressing toxins at much higher levels relative to nontoxin production.