Data from: The role of defensive ecological interactions in the evolution of conotoxins

Venoms comprise of complex mixtures of peptides evolved for predation and defensive purposes. Remarkably, some carnivorous cone snails can inject two distinct venoms in response to predatory or defensive stimuli, providing a unique opportunity to study separately how different ecological pressures contribute to toxin diversification. Here, we report the extraordinary defensive strategy of the Rhizoconus subgenus of cone snails. The defensive venom from this worm-hunting subgenus is unusually simple, almost exclusively composed of αD-conotoxins instead of the ubiquitous αA-conotoxins found in the more complex defensive venom of mollusc- and fish-hunting cone snails. A similarly compartmentalised venom gland as those observed in the other dietary groups facilitates the deployment of this defensive venom. Transcriptomic analysis of a C. vexillum venom gland revealed the αD-conotoxins as the major transcripts, with lower amounts of 15 known and 4 new conotoxin superfamilies also detected with likely roles in prey-capture. Our phylogenetic and molecular evolution analysis of the αD-conotoxins from five subgenera of cone snails suggests they evolved episodically as part of a defensive strategy in the Rhizoconus subgenus. Thus, our results demonstrate an important role for defence in the evolution of conotoxins.

毒液是一类为实现捕食与防御功能而演化形成的复杂肽类混合物。尤为引人注目的是，部分肉食性芋螺可根据捕食或防御刺激分泌两种截然不同的毒液，这为独立探究不同生态压力如何推动毒素多样性演化提供了绝佳的研究契机。
本研究报道了芋螺Rhizoconus亚属（Rhizoconus subgenus）非同寻常的防御策略。该以蠕虫为食的亚属，其防御毒液异乎寻常地简洁，几乎完全由αD-芋螺毒素（αD-conotoxins）构成，而非软体动物捕食型与鱼类捕食型芋螺复杂防御毒液中普遍存在的αA-芋螺毒素（αA-conotoxins）。
其毒液腺结构与其他食性类群的芋螺类似，呈分隔式布局，这保障了该防御毒液的顺利分泌与释放。
对织锦芋螺（C. vexillum）毒液腺的转录组学分析显示，αD-芋螺毒素为其主要转录产物，同时还检测到15个已知及4个全新的芋螺毒素超家族，这类毒素可能在猎物捕获过程中发挥功能。
针对来自5个芋螺亚属的αD-芋螺毒素开展的系统发育与分子进化分析表明，这类毒素作为Rhizoconus亚属防御策略的组成部分，经历了阶段性适应性演化。
综上，本研究结果证实了防御压力在芋螺毒素演化进程中发挥的关键作用。