DISSERTATION RESEARCH: Phylogenomic insights into the origins and evolution of anticoagulants and bloodfeeding in leeches

抗凝剂是一种有助于防止血液凝结的蛋白质。据广泛报道，抗凝剂来自食血水蚤，并被广泛用于医药和虫害防治。这项研究将记录水蚤近亲体内抗凝剂的存在和进化。在水蛭的直系亲属中发现抗凝剂将有助于揭示蛋白质的来源，并可能导致新的抗凝化合物的发现。两名代表不足的市中心高中生将接受实验室方法的指导和培训。此外，研究人员将根据抗凝剂的进化，为市中心的高中生制作一个专注于自然选择的课外教学模块。这项研究将重建棘形纲、小鞭纲和水蚤之间的系统发育关系，这将有助于解决长期以来关于节段性蠕虫进化的问题。由此产生的进化框架将被用来调查：1)抗凝剂在棘水蚤、Branchiobdellida、蚯蚓和水蚤中的分布，2)是否有证据表明在从水蚤近缘到水蚤的分支上存在正选择，这与专性吸血的进化一致，3)Acanthobdellida是否是水蚤的姐妹群，以及4)Rhynchobdellida(喙水蚤)是否与摄食器官的形态和群内的家庭关系模式一致。原始材料将在美国和瑞典的实地考察中收集。对每个样本物种的唾液腺进行无菌解剖，然后提取RNA，检查质量，并进行测序。然后将使用系统发生学和比较系统发生学分析来重建关系，并测试直系基因之间的正向选择的证据。

Anticoagulants are a class of proteins that help prevent the coagulation of blood. Anticoagulants are widely reported from blood-feeding leeches and are used extensively in medicine and for pest control. This research will document the presence and evolution of anticoagulants in the closest relatives of leeches. Finding anticoagulants in immediate leech relatives will shed light on the origin of the proteins and may lead to the discovery of novel anticoagulant compounds. Two underrepresented inner-city high school students will be mentored and trained in laboratory methods. Additionally, the researchers will produce an extracurricular teaching module for inner-city high school students focused on natural selection, based on the evolution of anticoagulants. This research will reconstruct phylogenetic relationships among Acanthobdellida, Branchiobdellida, and leeches that will help resolve long-standing questions about the evolution of segmented worms. The resulting evolutionary framework will then be used to investigate: 1) the distribution of anticoagulants within Acanthobdellida, Branchiobdellida, Lumbriculida, and leeches, 2) whether there is evidence of positive selection along the branches from leech relatives to leeches, coincident with the evolution of obligate blood-feeding, 3) whether Acanthobdellida are the sister group to leeches, and 4) whether the Rhynchobdellida (proboscis leeches) are monophyletic in line with feeding apparatus morphologies, and the pattern of family relationships within the group. Source material will be collected on field expeditions within the U.S.A. and Sweden. Salivary glands will be aseptically dissected for each sampled species and then RNA will be extracted, checked for quality, and sequenced. Phylogenomic and comparative phylogenetic analyses will then be used to reconstruct relationships and test for evidence of positive selection among orthologous genes.