英国利物浦热带医学院N. R. Casewell研究小组揭示了吐痰眼镜蛇中诱导疼痛防御性毒液成分的趋同进化。这一研究成果于2021年1月22日发表在国际学术期刊《科学》上。

利用基因、蛋白质和功能分析，研究人员发现三个吐痰眼镜蛇谱系都有以磷脂酶A2（PLA2）毒素上调为特征的毒液，这些毒素增强了已有毒液细胞的毒素作用，其可以激活哺乳动物的感觉神经元并引起疼痛加剧。这些重复的独立变化提供了一个令人着迷的范例，即在防御选择的驱动下可形成跨多个表型的趋同进化。

据介绍，趋同进化为理解进化变化潜在选择因素提供了见解。蛇毒具有直接的遗传基础和明确的功能表型，是探索适应性重复进化的理想模型。尽管蛇主要利用毒液捕食，并且毒液成分通常反映了饮食特殊性，但眼镜蛇的三个谱系形成了不同的向敌方吐毒液的能力。

附：英文原文

Title: Convergent evolution of pain-inducing defensive venom components in spitting cobras

Author: T. D. Kazandjian, D. Petras, S. D. Robinson, J. van Thiel, H. W. Greene, K. Arbuckle, A. Barlow, D. A. Carter, R. M. Wouters, G. Whiteley, S. C. Wagstaff, A. S. Arias, L.-O. Albulescu, A. Plettenberg Laing, C. Hall, A. Heap, S. Penrhyn-Lowe, C. V. McCabe, S. Ainsworth, R. R. da Silva, P. C. Dorrestein, M. K. Richardson, J. M. Gutiérrez, J. J. Calvete, R. A. Harrison, I. Vetter, E. A. B. Undheim, W. Wüster, N. R. Casewell

Issue&Volume: 2021/01/22

Abstract: Convergent evolution provides insights into the selective drivers underlying evolutionary change. Snake venoms, with a direct genetic basis and clearly defined functional phenotype, provide a model system for exploring the repeated evolution of adaptations. While snakes use venom primarily for predation, and venom composition often reflects diet specificity, three lineages of cobras have independently evolved the ability to spit venom at adversaries. Using gene, protein, and functional analyses, we show that the three spitting lineages possess venoms characterized by an up-regulation of phospholipase A2 (PLA2) toxins, which potentiate the action of preexisting venom cytotoxins to activate mammalian sensory neurons and cause enhanced pain. These repeated independent changes provide a fascinating example of convergent evolution across multiple phenotypic levels driven by selection for defense.

DOI: 10.1126/science.abb9303

Source: https://science.sciencemag.org/content/371/6527/386