Figure 1

The venom composition of X. aruana. (a) Adult female X. aruana (the specimen that was used in this study). (b) Total ion chromatogram from LC–MS/MS analysis of X. aruana venom with peaks corresponding to identified venom peptides labelled. Additional proteins were detected in the reduced, alkylated and trypsin-digested venom sample. The signal corresponding to XYTX₁-Xa1a is saturated. Asterisks mark derivatives of XYTX₁-Xa1a. (c) Complete CID-MS/MS spectrum of the [M + 4H]⁺⁴ precursor ion of XYTX₁-Xa1a. Inset: [M + 4H]⁺⁴ MS spectrum (theoretical [M + 4H]⁺⁴ = 483.075). (d) Complete CID-MS/MS spectrum of the [M + 6H]⁺⁶ precursor ion of XYTX₂-Xa2a (in the reduced and alkylated venom sample). Inset: [M + 6H]⁺⁶ MS spectrum (theoretical [M + 6H]⁺⁶ = 449.734). b-, y- and internal ions (#) are labelled (for clarity, other ions are not labelled). Inset: MS spectrum. (e) Venom component-encoding transcripts (i.e., those encoding peptides detected in the venom by MS) comprised 74.1% of total transcript expression. Of these, transcripts encoding XYTX₁-Xa1a, XYTX₂-Xa2a, PLA₂, and other venom proteins comprised 93.4, 3.0, 3.4, and 0.2%, respectively, of venom component expression. (f) Venom component-encoding transcripts (highlighted in yellow) are found exclusively in the highly expressed portion of the venom apparatus transcriptome. TPM transcripts per million.