Scorpion Venom Gland Transcriptomics

Abstract

For decades, the study of venomous animals has focused on the isolation and biochemical characterization of specific venom components that have medical or biotechnological importance. Indeed, scorpions have been extensively studied under this optics, which has led to the identification of hundreds of different transcripts encoding toxic peptides. However, scorpions are interesting organisms not only because of their toxin diversity but also because they represent the most ancient terrestrial animals that fossil records have identified. About 2,000 species have been described around the world, which also implies that scorpions are extremely well-adapted arthropods that have managed to survive in different environmental conditions. Even though the divergence timing of scorpions places them as interesting model organisms for evolutionary inferences, little is known about the genomic organization, speciation events, and population dynamics of these arthropods.Different "omic" approaches have become a very powerful strategy for understanding the complexity of venomous animals. Transcriptomics, in particular, has been widely used to explore the transcriptional diversity of venom glands of several scorpion species. Recently, high-throughput sequencing platforms have substantially improved our capacity to describe biological features of scorpions but, most importantly, have outlined new directions toward a more complete understanding of the evolution of these arthropods.In this chapter, those transcriptomic strategies followed in the last two decades that went from cDNA cloning to next-generation sequencing methods will be described. Some biological and evolutionary questions about scorpion speciation and venom diversification will also be addressed. Finally, an attempt to raise some future directions in the field will be made.

An efficient transcriptome analysis pipeline to accelerate venom peptide discovery and characterisation

“…In addition to novel toxin discoveries Viala et al, 2015), venomics has helped uncover the mechanisms governing toxin diversification Jin et al, 2013), distinct defensive and predatory venom gland specialisation in Conidae , and the morphological constraints driving the evolution of centipede venoms (Undheim et al, 2015). In the absence of reference genomes for many venomous animals, transcriptome sequencing of venom glands has come to underpin the venomics approach and has enabled novel toxin discovery at an unprecedented level from snakes (Durban et al, 2011), spiders (Pineda et al, 2014), scorpions (Rendón-Anaya et al, 2015), cone snails (Prashanth et al, 2014), and even relatively poorly characterised animals such as ants (Bouzid et al, 2013).…”

In Silico Identification of Protein Disulfide Isomerase Gene Families in the De Novo Assembled Transcriptomes of Four Different Species of the Genus Conus

“…Therefore an RNA sequencing (RNA-seq) approach is particularly abundant in information about the mRNAs (and by inference the proteins) produced in a precise tissue. This is particularly important for venomous organisms [ 17 ], such as Conus snails, where production and storage of venom are restricted to a specific organ–the venom gland; which because of its shape, in the case of the Conus genus, is known as the venom duct. Furthermore, one hurdle in transcriptomic researches is when the species studied lacks a sequenced reference genome, typically needed for transcriptome assembly and gene model annotation (especially at the isoform level).…”