Comparative venom-gland transcriptomics and venom proteomics of four Sidewinder Rattlesnake (Crotalus cerastes) lineages reveal little differential expression despite individual variation

Abstract

Changes in gene expression can rapidly influence adaptive traits in the early stages of lineage diversification. Venom is an adaptive trait comprised of numerous toxins used for prey capture and defense. Snake venoms can vary widely between conspecific populations, but the influence of lineage diversification on such compositional differences are unknown. To explore venom differentiation in the early stages of lineage diversification, we used RNA-seq and mass spectrometry to characterize Sidewinder Rattlesnake (Crotalus cerastes) venom. We generated the first venom-gland transcriptomes and complementary venom proteomes for eight individuals collected across the United States and tested for expression differences across life history traits and between subspecific, mitochondrial, and phylotranscriptomic hypotheses. Sidewinder venom was comprised primarily of hemorrhagic toxins, with few cases of differential expression attributable to life history or lineage hypotheses. However, phylotranscriptomic lineage comparisons more than doubled instances of significant expression differences compared to all other factors. Nevertheless, only 6.4% of toxins were differentially expressed overall, suggesting that shallow divergence has not led to major changes in Sidewinder venom composition. Our results demonstrate the need for consensus venom-gland transcriptomes based on multiple individuals and highlight the potential for discrepancies in differential expression between different phylogenetic hypotheses.

Trait differentiation and modular toxin expression in palm-pitvipers

“…1, Table 1). The number of recovered toxins and recovered families were generally consistent with those of other viperid transcriptomes [25,[34][35][36][37] and with estimates of toxin family size in early high-throughput transcriptomes of B. schlegelii and B. lateralis [38] (Table 2, Table 3).…”

The origin and diversification of a novel protein family in venomous snakes

“…We note, however, that while mdc-1 is present in the genomes of at least five Crotalids, it is not expressed in the C. atrox venom gland (Fig. 1D) nor has it been reported in any Crotalid venom gland transcriptomes or proteomes (35)(36)(37)(38)(39). Therefore, gene duplication and partial deletion alone are not sufficient to account for the genesis of a P-III class venom MP.…”

Variation in the Venom of Parasitic Wasps, Drift, or Selection? Insights From a Multivariate QST Analysis

“…studies of the geographical variation in venom composition was conducted on several venomous taxa (Wuster et al, 1992;Francischetti et al, 2000;Binford, 2001;Alape-Giron et al, 2008;Remigio and Duda, 2008;Abdel-Rahman et al, 2009, 2011Calvete et al, 2011;Rodríguez-ravelo et al, 2013;Holding et al, 2016;Perez-Riverol et al, 2017;Hofmann et al, 2018), it was not the case for parasitoids. This is surprising since, in parasitoid wasps, venom should constrain the capacity to succeed on locally available hosts.…”

“…Although data for parasitoids are still scarce, geographic variations in venom composition have been investigated in most venomous taxa, e.g., wasps (Perez-Riverol et al, 2017), spiders (Binford, 2001), scorpions (Abdel-Rahman et al, 2009;Rodríguez-ravelo et al, 2013), cone snails (Remigio and Duda, 2008;Abdel-Rahman et al, 2011), and snakes (Wuster et al, 1992;Francischetti et al, 2000;Alape-Giron et al, 2008;Calvete et al, 2011;Holding et al, 2016;Hofmann et al, 2018).…”