Venom gland transcriptomes of two elapid snakes (Bungarus multicinctus and Naja atra) and evolution of toxin genes

<p>Abstract</p> <p>Background</p> <p>Kraits (genus <it>Bungarus</it>) and cobras (genus <it>Naja</it>) are two representative toxic genera of elapids in the old world. Although they are closely related genera and both of their venoms are very toxic, the compositions of their venoms are very different. To unveil their detailed venoms and their evolutionary patterns, we constructed venom gland cDNA libraries and genomic bacterial artificial chromosome (BAC) libraries for <it>Bungarus multicinctus </it>and <it>Naja atra</it>, respectively. We sequenced about 1500 cDNA clones for each of the venom cDNA libraries and screened BAC libraries of the two snakes by blot analysis using four kinds of toxin probes; <it>i.e</it>., three-finger toxin (3FTx), phospholipase A2 (PLA2), kunitz-type protease inhibitor (Kunitz), and natriuretic peptide (NP).</p> <p>Results</p> <p>In total, 1092 valid expressed sequences tags (ESTs) for <it>B. multicinctus </it>and 1166 ESTs for <it>N. atra </it>were generated. About 70% of these ESTs can be annotated as snake toxin transcripts. 3FTx (64.5%) and <it>β </it>bungarotoxin (25.1%) comprise the main toxin classes in <it>B. multicinctus</it>, while 3FTx (95.8%) is the dominant toxin in <it>N. atra</it>. We also observed several less abundant venom families in <it>B. multicinctus </it>and <it>N. atra</it>, such as PLA2, C-type lectins, and Kunitz. Peculiarly a cluster of NP precursors with tandem NPs was detected in <it>B. multicinctus</it>. A total of 71 positive toxin BAC clones in <it>B. multicinctus </it>and <it>N. atra </it>were identified using four kinds of toxin probes (3FTx, PLA2, Kunitz, and NP), among which 39 3FTx-postive BACs were sequenced to reveal gene structures of 3FTx toxin genes.</p> <p>Conclusions</p> <p>Based on the toxin ESTs and 3FTx gene sequences, the major components of <it>B. multicinctus </it>venom transcriptome are neurotoxins, including long chain alpha neurotoxins (<it>α</it>-ntx) and the recently originated <it>β </it>bungarotoxin, whereas the <it>N. atra </it>venom transcriptome mainly contains 3FTxs with cytotoxicity and neurotoxicity (short chain <it>α</it>-ntx). The data also revealed that tandem duplications contributed the most to the expansion of toxin multigene families. Analysis of nonsynonymous to synonymous nucleotide substitution rate ratios (<it>dN</it>/<it>dS</it>) indicates that not only multigene toxin families but also other less abundant toxins might have been under rapid diversifying evolution.</p

Summer school

Summer School utilizes an open-ended exhibition format that activates the gallery space with performances, discussions, lectures and workshops, exploring creative pedagogical approaches to art making and the provocation that ‘small acts of resistance can create change’. Summer School includes projects by Australian artists who explore and exploit the creative potential of pedagogical forms, explore the social, dialogic or participatory contexts of learning and idea exchange and engage with ideas and practices of experimental pedagogies. Summer School considers how artist run activity may act as a site of resistance and the potential of these spaces and dialogues to open up new ways of thinking and doing