Chromosomal Phylogeny of the Anopheles gambiae Complex

描述（由申请人提供）：冈比亚按蚊复合体的形态难以区分的成员具有显著不同的生态适应，地理分布和行为。这一复合体包括主要的疟疾病媒（阿拉伯疟蚊、冈比亚疟蚊），以及次要的病媒（布瓦姆疟蚊、黑疟蚊、黑疟蚊）和非病媒（四环疟蚊A、四环疟蚊B）。发展疟疾管理的新方法意味着找到通过用非病媒取代病媒种群来中断传播的方法。我们目前对载体和非载体之间基因组成差异的了解不足以实现成功的种群替换。推断冈比亚拟南猿复合体的祖先基因组特征对于确定与人类血液选择的起源和丧失、生态和行为适应以及与人类栖息地的关联相关的进化变化至关重要。应该有针对性地控制这些基因组变化，从而减少并最终消除疟疾传播。尽管冈比亚芽胞杆菌的分子标记和基因组序列已经确定，但是冈比亚芽胞杆菌成员之间的系统发育关系尚未完全确定。由于该复合体的起源较晚，高水平的序列相似性、遗传渗入和共享的分子祖先多态性混淆了明确确定进化方向的能力。这个探索性R21项目的主要目标是确定冈比亚亚种复合体的祖先和衍生染色体排列。我们的方法的优势在于，它是基于观察到的祖先排列在群内和群外物种之间是共享的，断点结构可以指示染色体进化的方向。我们计划(1)确定冈比亚拟南猿复合体和外群种斯氏拟南猿之间共有的染色体排列；(2)确定反转断点的衍生结构特征，如转座/重复元件和基因重复的存在。对群内和群外断点的比较分析将首次评估反转的唯一性，并明确确定复杂结构中祖先X和2R的排列。虽然鉴定和测序断点在技术上是具有挑战性的任务，但2La断点的成功表征和我们的初步研究表明，我们的研究目标是可以实现的。我们的建议有两个具体目的：1。将固定倒位Xag， Xbcd， 2Rop的断点物理映射到A. gambiae复合体和A. stephensi的染色体上，并计算群内和群外物种之间的倒位距离。2. 对阿拉伯沙蚕的Xc、四环沙蚕的Xa+、Xc+、美洲沙蚕的2Ro以及斯氏沙蚕的同源序列进行测序和表征。公共卫生相关性：该建议将推断冈比亚按蚊复合体的祖先染色体排列。它们对于确定与人类血液选择的起源和丧失、生态和行为适应以及与人类栖息地的关联相关的进化基因组变化至关重要。应该有针对性地控制这些基因组变化，从而减少并最终消除疟疾传播。

DESCRIPTION (provided by applicant): Morphologically indistinguishable members of the Anopheles gambiae complex have remarkably distinct ecological adaptations, geographical distributions, and behaviors. This complex includes the major malaria vectors (A. arabiensis, A. gambiae), as well as minor vectors (A. bwambae, A. melas, A. merus) and nonvectors (A. quadriannulatus A, A. quadriannulatus B). Development of novel approaches to malaria management implies finding the ways to interrupt transmission by replacing populations of vectors with nonvectors. Our current knowledge about differences in genetic make-up among vectors and nonvectors is insufficient for implementing the successful population replacement. Inferring ancestral genomic features in the A. gambiae complex is crucial in identifying the evolutionary changes associated with the origin and loss of human blood choice, ecological and behavioral adaptations, and association with human habitats. These genomic changes should be targeted and manipulated so that malaria transmission can be reduced and eventually eliminated. Despite the availability of molecular markers and the genome sequence for A. gambiae, the phylogenetic relationships among the members are not fully resolved. Because of the recent origin of the complex, the high level of sequence similarity, genetic introgression, and shared molecular ancestral polymorphisms confound the ability to determine the direction of evolution unambiguously. The major goal of this exploratory R21 project is to determine the ancestral and derived chromosomal arrangements in the A. gambiae complex. The advantage of our approach is that it is based on observations that the ancestral arrangements are shared between ingroup and outgroup species and that the breakpoint structure can indicate the direction of chromosomal evolution. We plan to (1) identify chromosomal arrangements shared between the A. gambiae complex and the outgroup species A. stephensi and (2) determine derived structural features of inversion breakpoints such as the presence of transposable/repetitive elements and gene duplications. The comparative analysis of the ingroup and outgroup breakpoints will for the first time assess the uniqueness of the inversions and unambiguously determine the ancestral X and 2R arrangements in the complex. Although identifying and sequencing breakpoints are technically challenging tasks, the successful characterization of the 2La breakpoints and our preliminary studies suggest that our research aims are achievable. Our proposal has two specific aims: 1. To physically map the breakpoints of fixed inversions Xag, Xbcd, 2Rop to the chromosomes of the A. gambiae complex and A. stephensi and to calculate the inversion distances between ingroup and outgroup species. 2. To sequence and characterize the inversion breakpoints of Xc in A. arabiensis, Xa+, Xc+ in A. quadriannulatus, and 2Ro in A. merus, and the homologous sequences in A. stephensi. PUBLIC HEALTH RELEVANCE: This proposal will infer ancestral chromosome arrangements in the Anopheles gambiae complex. They are crucial in identifying the evolutionary genomic changes associated with the origin and loss of human blood choice, ecological and behavioral adaptations, and association with human habitats. These genomic changes should be targeted and manipulated so that malaria transmission can be reduced and eventually eliminated.