Venom evolution in glycerid polychaetes (Annelida, Glyceridae) with special emphasis on alpha-glycerotoxin

毒液系统在广泛的动物系统发育中进化，用于防御或捕食。有毒的动物在大多数主要的后生动物类群中都有发现，突出的和研究充分的例子是蛇、锥螺和蜘蛛。尽管毒液在这些分类群中独立进化，但很明显，在整个进化过程中，许多蛋白质家族都是趋同的。在环节动物中，有毒的物种可以在春虫形和甘油酯多毛纲中找到。虽然有超过1000种潜在的有毒环节动物，但它们的毒液特性在很大程度上是未知的，并且没有一项DNA水平的研究。所有食蚜蝇科成员的咽部都装备有与突出的毒腺相连的大的几丁质牙齿。我们将进行一个详细的形态学研究的甘油酯毒液腺系统。在这些腺体中发现了一种非常有趣的毒素（甘油毒素），它在特异性刺激电压门控钙通道（N型）方面是独一无二的，这使这种蛋白质具有潜在的医学重要性。我们的目标是建立五个甘油酯物种的毒腺转录组，给出甘油酯毒液组成的第一个表征。使用系统发育的方法，我们将分析在这一组的毒液蛋白的收敛招聘。此外，使用实验方法，我们的目标是确定域的甘油毒素特异性结合的钙通道。将使用基于ML的测试在甘油酯中推断这些结构域上的选择迹象。最后，我们使用一个已建立的Glyceridae的分子生物学来追踪这组内的毒液进化。这项分析将使我们能够比较毒液蛋白基因树与甘油酯物种树，并将提供第一个详细的调查环节动物的毒液进化。

Venom systems evolved in a broad phylogenetic range of animals and are used for defence or predation. Venomous animals are found across most major metazoan taxa and prominent and wellstudied examples are snakes, cone snails, and spiders. Even though venoms evolved independently in these taxa, it is obvious that throughout evolution, many protein families have been recruited convergently. Within annelids, venomous species can be found within aphroditiform and glycerid polychaetes. Although there are more than 1000 potential venomous annelid species their venom characteristics are largely unknown and not a single study at DNA level is available. The pharynx of all members of the Glyceridae is equipped with large chitinous teeth which are connected to prominent venom glands. We will conduct a detailed morphological investigation of the glycerid venom gland system. A highly interesting toxin (glycerotoxin) has been found in these glands which is unique in specifically stimulating voltage gated calcium channels (N-type), giving this protein a potential medical importance. We aim to characterise the venom gland transcriptome of five glycerid species to give a first characterisation of glycerid venom composition. Using phylogenetic methods, we will analyse convergent recruitment of venom proteins in this group. Moreover, using an experimental approach we aim to identify domains of the glycerotoxin which specifically bind to the calcium channels. Signs of selection on these domains will be inferred across glycerids using ML based tests. Finally, we use a established molecular phylogeny of Glyceridae to trace venom evolution within this group. This analysis will allow us to compare venom protein gene trees with glycerid species trees and will provide the first detailed investigation into venom evolution in annelids.