Data from: Targeted sequencing of venom genes from cone snail genomes improves understanding of conotoxin molecular evolution

To expand our capacity to discover venom sequences from the genomes of venomous organisms, we applied targeted sequencing techniques to selectively recover venom gene superfamilies and non-toxin loci from the genomes of 32 cone snail species (family, Conidae), a diverse group of marine gastropods that capture their prey using a cocktail of neurotoxic peptides (conotoxins). We were able to successfully recover conotoxin gene superfamilies across all species with high confidence (> 100X coverage) and used these data to provide new insights into conotoxin evolution. First, we found that conotoxin gene superfamilies are composed of 1-6 exons and are typically short in length (mean = ~85bp). Second, we expanded our understanding of the following genetic features of conotoxin evolution: (a) positive selection, where exons coding the mature toxin region were often three times more divergent than their adjacent noncoding regions, (b) expression regulation, with comparisons to transcriptome data showing that cone snails only express a fraction of the genes available in their genome (24%-63%), and (c) extensive gene turnover, where Conidae species varied from 120-859 conotoxin gene copies. Finally, using comparative phylogenetic methods, we found that while diet specificity did not predict patterns of conotoxin evolution, dietary breadth was positively correlated with total conotoxin gene diversity. Overall, the targeted sequencing technique demonstrated here has the potential to radically increase the pace at which venom gene families are sequenced and studied, reshaping our ability to understand the impact of genetic changes on ecologically relevant phenotypes and subsequent diversification.

为拓展从有毒生物基因组中发掘毒液序列的研究能力，我们采用靶向测序（targeted sequencing）技术，从32种芋螺科（Conidae）物种的基因组中选择性回收毒液基因超家族与非毒素基因座。芋螺科是一类多样化的海洋腹足类动物，可通过分泌神经毒性肽混合物——芋螺毒素（conotoxins）捕获猎物。我们成功在所有物种中以高置信度（覆盖度＞100倍）获取芋螺毒素基因超家族，并利用该数据集为芋螺毒素的演化研究提供了全新视角。其一，我们发现芋螺毒素基因超家族由1至6个外显子构成，且序列长度普遍偏短（平均长度约85bp）。其二，我们深化了对芋螺毒素演化相关遗传特征的认知：（a）正选择现象：编码成熟毒素区域的外显子，其序列分化程度通常为相邻非编码区域的三倍；（b）表达调控机制：结合转录组（transcriptome）数据对比分析可知，芋螺仅表达基因组中24%至63%的可用基因；（c）广泛的基因周转现象：不同芋螺物种的芋螺毒素基因拷贝数差异显著，跨度为120至859个。最后，通过比较系统发育（phylogenetic）分析方法，我们发现尽管食性特异性无法预测芋螺毒素的演化模式，但食性广度与总芋螺毒素基因多样性呈显著正相关。总体而言，本研究采用的靶向测序技术有望大幅提速毒液基因家族的测序与研究进程，重塑我们解析遗传变化对生态相关表型及后续物种多样化的影响的能力。