Ecological functional genomics: phenotyping Hox mutants

描述(申请人提供)：过去十年中最大的基因惊喜之一是，许多基因在被破坏时没有表现出表型变化。这通常被解释为基因之间的功能冗余。或者，许多表型在很大程度上是看不见的，直到个体受到压力或以其他方式受到实验室环境中缺失的因素的挑战。例如，近亲繁殖对小鼠的有害影响在实验室检测中几乎检测不到(10%的影响)，但当在竞争性生态条件下进行分析时，雄性显示出500%的影响。这种生态学方法也被用来揭示Hoxa3D3易位的一个很强的适应性缺陷，以前人们认为Hoxa3D3易位在功能上与野生型相当。HOX基因是指导哺乳动物身体计划发展的转录因子，包括成年特征，如乳腺、行为、神经和免疫系统。靶向突变已经应用于小鼠HOX基因家族的所有39个成员，虽然大多数中断突变都显示出发育缺陷，但令人惊讶的是，发现其中一些没有可检测到的表型变化。我们将使用半自然小鼠种群中存在的生态竞争来确定八个隐匿表型Hox突变体的表现(适合性)后果。对于每个HOX突变体，将进行5个种群分析。每个种群将由15个突变型和15个野生型创始人组成。据估计，每测试一只霍克斯，就会有1000只后代出生。行为观察和遗传亲子关系分析可以为每个创始人分配健康。检测到的任何适合性差异都允许对遗传缺陷的生理和分子基础进行表征。这项研究计划的长期目标是继续开发这些敏感的生态学方法来表征小鼠的健康和表现缺陷(表型)。这些方法不仅对于表征基因功能和复杂的表型很重要，而且对于评估潜在的健康风险，如环境毒素、疫苗和治疗剂的安全性也很重要。

DESCRIPTION (provided by applicant): One of the great genetic surprises of the last decade is that many genes when disrupted reveal no phenotypic change. This is usually interpreted as functional redundancy among genes. Alternatively, many phenotypes are largely invisible until the individual is stressed or otherwise challenged by factors absent from the lab environment. For example, the deleterious effects of inbreeding in mice are barely detectable using lab assays (10% effect), but when analyzed under competitive ecological conditions, males show a 500% effect. This ecological approach has also been used to reveal a strong fitness defect for the Hoxa3D3 translocation, previously thought to be 'functionally equivalent' to wild type. Hox genes are transcription factors that direct development of the mammalian body plan, including adult traits such as mammary glands, behavior, nervous and immune systems. Targeted mutagenesis has been applied to all 39 members of the mouse Hox gene family and while most disruption mutants show developmental defects, it was surprising to discover that some have no detectable phenotypic change. We will use ecological competition present in seminatural mouse populations to determine the performance (fitness) consequences of eight cryptic-phenotype Hox mutants. For each Hox mutant, 5 populations assays will be conducted. Each population will consist of 15 mutant and 15 wild type founders. An estimated 1000 progeny will be born for each Hox tested. Behavioral observations and genetic parentage analyses allow fitness assignments to each founder. Any fitness differences detected allows characterization of the physiological and molecular basis of the genetic defect to proceed. The long-term goal of this research program is to continue developing these sensitive ecological methods for characterizing health and performance defects (phenotypes) in mice. These methods are important not only for characterizing gene function and complex phenotypes, but also for evaluating the safety of potential health risks such as environmental toxins, vaccines and therapeutic agents.