Scorpion venoms are composed of a vast variety of bioactive peptides including neurotoxins that target receptors and ion channels, enzymes, and peptides with cytolytic activity. The order Scorpiones constitute one of the most ancient groups of animals on earth (>400 million years), with ~1,700 known species that can be divided into four groups. The venoms of scorpions from the most studied group, the Buthida, are a rich source for these bioactive peptides. Most of the venom peptides are small (23-78 amino acids-long), are well-packed by several disulfide bridges, and affect ion channel function in excitable and non-excitable tissues.
Here we report the identification of venom gland-specific transcripts from the Israeli scorpion Buthacus leptochelys. By using next generation RNA-seq, we have generated transcriptomes for two different abdomen segments: one with (telson) and one without the venom glands. Out of ~70,000 contigs in the telson transcriptome, 270 coded for venom-selective secreted proteins, out of which 110 were homologous to known toxins. An additional 360 contigs coded for paralogs of the venom-selective proteins but were not selectively expressed in the venom glands. Based on the two data sets, we were able to distinguish between venom gland-expressed and venom gland-selective proteins. Furthermore, most of the venom gland-selective proteins were found to have paralogs, which are not specifically expressed within the venom gland, as well as orthologs. This information will help us to learn about the process of protein recruitment into the venom gland and subsequently the evolution of several toxin families.