A lifetime of attrition: post-genomic analyses of ecological and evolutionary processes in nematode - vertebrate systems.

事实上，每一种陆生、淡水和海洋脊椎动物都被线虫（蛔虫）寄生。线虫感染在宿主的整个生命周期中表现出持续感染和再感染，感染强度具有强烈的性别、年龄和季节效应。因此，这些寄生虫构成了脊椎动物环境的重要组成部分，并影响个体的适应性和种群的动态。现在有一个及时的机会，从基因组学的新方法来探索在自然环境中的脊椎动物和线虫相互作用的生态和进化后果。这些工作有很大的希望，但将基因组学从实验室扩展到自然人群也面临着重大挑战。特别是，个体之间的差异使得自然群体的研究如此重要，也使得一些基因组学方法难以应用，例如高通量基因表达（微阵列）分析。我们对这些挑战的反应是建立一个联盟的基础上，围绕三个良好的特点脊椎动物-线虫系统，Soay羊和Teladorsagia circumcincta，红鸡和Trichostrongylus tenuis和棕色大鼠和Strongyloides ratti。我们将使用一系列的方法，从模拟野生环境的实验室实验中的微阵列研究，到对生活在野生种群中的个体进行实验操作的微阵列研究。因此，我们希望相互学习，并向研究界展示这些新方法可以在多大程度上应用于自然种群。在这个过程中，我们希望培养一批训练有素的工人，他们的技能可以在英国更广泛地发展该领域。该联盟内的工作将探索一系列相关问题，这些问题相结合，使我们能够解决两个广泛的目标，这对促进我们对宿主-寄生虫生态学和进化的理解至关重要：（1）解剖和量化宿主-寄生虫相互作用的遗传基础与宿主和寄生虫的种群生物学之间的联系。感染是一个作用于个体但影响种群动态的过程;通过感染对个体的生长、生存和繁殖的影响。同样，种群的密度也会影响个体之间争夺食物或配偶的程度，从而影响个体的状况及其对感染的易感性。现在的关键挑战是了解感染的个体过程如何影响宿主和寄生虫的群体生物学，以及如何受到宿主和寄生虫的群体生物学的影响。(2)研究宿主和寄生虫种群遗传多样性的起源和维持。在一个种群中，个体宿主在对感染的易感性方面表现出遗传差异。同样，寄生线虫的种群在遗传上是可变的，这对感染的持续性和传播有影响。现在要解决的关键挑战是确定区域的脊椎动物和线虫基因组中的遗传多样性是通过两个拮抗剂之间的持续相互作用，这种遗传多样性的后果和选择性的过程，这种多样性是保持。

Virtually every species of terrestrial, freshwater and marine vertebrate is parasitized by nematodes (roundworms). Nematode infections exhibit persistent infection and re-infection throughout the life of a host, with strong sex, age and season effects on intensities of infection. These parasites therefore constitute an important component of the environment of vertebrates and affect the fitness of individuals and the dynamics of populations. There is now a timely opportunity to apply new methods from genomics to explore the ecological and evolutionary consequences of vertebrate-nematode interactions in the natural environment. Such work holds great promise but extending genomics from the bench-top to natural populations also presents significant challenges. In particular, the variation between individuals that makes research in natural populations so important also makes it difficult to apply some genomics methods, such as high throughput gene expression (microarray) analyses. Our response to these challenges is to build a consortium based around three well-characterised vertebrate - nematode systems, the Soay sheep and Teladorsagia circumcincta, the red grouse and Trichostrongylus tenuis and the brown rat and Strongyloides ratti. We will use a series of approaches ranging from microarray studies within laboratory experiments that mimic the wild situation, through to microarray studies on individuals living in wild populations subject to experimental manipulations. As a result, we hope to learn from each other, and demonstrate to the research community, just how far these new methodologies can be applied to natural populations in situ. In the process, we expect to generate a trained group of workers with the skills to develop the field more widely in the UK. Work within the consortium will explore a set of related questions that, in combination, allow us to address two broad objectives that are crucial to advancing our understanding of host-parasite ecology and evolution: (1) To dissect and quantify the link between the genetic basis of host-parasite interactions and the population biology of hosts and parasites. Infection is a process that acts on individuals but impacts on the dynamics of populations; through the effects of infection on the growth, survival and reproduction of individuals. Equally, the density of a population will impact on the level of competition between individuals for food or mates and consequently on the condition of individuals and their susceptibility to infection. The key challenge now is to understand how individual processes of infection influence, and are influenced by, the population biology of hosts and parasites. (2) To examine the origins and maintenance of genetic diversity in host and parasite populations. Within a population, individual hosts exhibit genetic differences in their susceptibility to infection. Equally, populations of parasitic nematodes are genetically variable with consequences for the persistence and transmission of infection. The key challenges to be addressed now are to identify regions of vertebrate and nematode genomes where genetic diversity is maintained through the continued interaction between both antagonists, the consequences of this genetic diversity and the selective processes by which this diversity is maintained.