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进化中进化，用于防御或捕食。在大多数主要的后生动物分类群中都发现了有毒动物，其中最突出和研究最充分的例子是蛇、锥体蜗牛和蜘蛛。尽管毒液在这些分类群中是独立进化的，但很明显，在整个进化过程中，许多蛋白质家族都是聚集在一起的。在环节动物中，可在拟阳体和甘油多毛体中发现有毒物种。虽然有超过1000种潜在的有毒环节动物，但它们的毒液特征在很大程度上是未知的，而且没有一项DNA水平的研究是可用的。所有甘油科成员的咽部都装备有巨大的几丁质牙齿，这些牙齿与突出的毒腺相连。我们将对甘油蛇毒腺系统进行详细的形态学研究。在这些腺体中发现了一种非常有趣的毒素（甘油毒素），这种毒素在特异性刺激电压门控钙通道（n型）方面是独一无二的，这使得这种蛋白质具有潜在的医学重要性。我们的目标是表征五种甘油物种的毒液腺转录组，以给予甘油毒液组成的第一个特征。利用系统发育方法，我们将分析该群体毒液蛋白的趋同募集。此外，使用实验方法，我们的目标是确定甘油毒素特异性结合钙通道的域。在这些领域的选择的迹象将推断甘油使用ML为基础的测试。最后，我们使用一个已建立的甘油科分子系统发育来追踪这一群体内的毒液进化。这一分析将使我们能够将毒液蛋白基因树与甘油物种树进行比较，并将首次详细研究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.