The project thus far has focused mainly on Aims 1 and 3.
For Aim 1, we have completed sample collection for transcriptional evolvability and sequenced tissues for regulatory network analyses. To facilitate accurate measurements of gene expression we have, in collaboration with the Earth Biogenome Project Norway (EBP-Nor), generated and annotated a chromosome-level reference genome for the heterogametic sex (male) from our focal population of C. carnea.
For Aim 3, we have collected samples from species that represent a broad sampling across Neuroptera as well as the distribution of C. carnea. For venom system comparisons between neuropteran families, we have generated 3D reconstructions of venom delivery structures, musculature, and venom glands using µCT, including a redescription of the venom system. We have in collaboration with EBP-Nor completed three reference-quality genomes from Neuroptera (Chrysopa perla, Myrmeleon formicarius, in addition to the afore-mentioned Chrysoperla carnea), while Osmylus fulvicephalus is being sequenced in collaboration with the Biodiversity Genomics Europe (BGE) consortium.
To provide a solid foundation for the remaining experiments, our first scientific deliverable (manuscript in final stages of preparation) provides the first comprehensive insight into the venom of Neuroptera via C. carnea. Using high-quality genomes from a male and female, long-read-based reference transcriptomes from their offspring across each life stage, and venom proteomics, we provide a complete paralog, allele, and splice-variant resolved venom proteome. These data revealed surprisingly few examples of large toxin gene family expansions, that alternative splicing provides a mechanism that facilitates exon-specific neofunctionalization of co-opted genes, and that the only previously characterised toxin described from Neuroptera (a bacterially derived chaperonin) is not a significant venom component. We also found that the most abundant toxin is an ABC-toxin-like protein secreted via a non-canonical secretory pathway, that was obtained by horizontal gene transfer (HGT) from a commensal bacterium. Our results contrast the canonical mechanisms of venom evolution and highlight the importance of studying neglected taxa for understanding mechanisms involved in the evolution of molecular novelties.
As part of our genome annotation efforts, we have made a bioinformatic pipeline that uses a combination of proteomic and functional annotation to identify toxin sequences from transcriptome data, and where applicable map these onto a reference genome to identify paralogs, allelic variants, and splice-forms. The pipeline will be made available via GitHub upon publication of the manuscript on the detailed description of C. carnea venom.
