DISSERTATION RESEARCH: Mutant models reveal latent developmental potential with roles in evolutionary change

论文研究：突变模型揭示了潜在的发展潜力及其在进化变化中的作用

• 批准号: 1600920
• 负责人: James Hanken
• 金额: $ 1.89万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1600920&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Mutant; models; reveal

This project will investigate the genetic factors that cause elaborated bone pattern in fish fins. Bone pattern elaboration results from increases in bone numbers and connections, and such research is important for understanding processes of both evolution and development. In evolution, increase in the number of bones arranged end-to-end helped transform fins into limbs and aided the colonization of land by extinct vertebrates. In development, normal function and movement depends upon formation of the proper bone numbers and connections, and defective development can lead to severe impairment. Currently, the mechanisms that led to elaboration of the fin skeleton to form limbs are unknown. To identify the genetic factors involved, the researchers will study strains of the model species, zebrafish, that have genetic changes that result in the formation of new fin bones. They will also investigate naturally occurring variation in two species, gar and bowfin, that have different numbers of bones extending from the shoulder. These complementary approaches will reveal the mechanisms regulating growth and formation of the skeleton of fins and limbs, and show how simple genetic changes can lead to the formation of limbs from fins. Understanding the mechanisms of bone pattern elaboration and development has implications for human health and developmental abnormalities, and may provide clues for the evolution of life on land. Additionally, the project will provide research opportunities for Native American undergraduates. While tetrapod vertebrates have increased the number of bones along the proximo-distal (P-D) axis of the limb, teleost fishes such as the zebrafish have reduced the pectoral fin skeleton; only a single long bone is found along the P-D axis. The researchers performed a forward mutagenesis screen in zebrafish and isolated a novel mutant that forms supernumerary bones along the P-D axis of the fin through a process similar to that seen in the development of tetrapod limbs. The proposed research will extend results from mutant analysis to natural populations to determine if the mutation is producing supernumerary bones by activating ancestral genetic mechanisms. Transcriptome profiling by RNA sequencing will be used to compare gene-expression levels in the developing pectoral fins of wild-type and mutant zebrafish, as well as two species that exhibit natural variation in P-D axis elaboration. This analysis will reveal patterns of differential gene expression that correlate with P-D axis elaboration. Differentially expressed genes will be tested in the zebrafish to determine if their modified expression has an effect on fin morphology. This study will elucidate how additive phenotypic changes arise in development and identify candidate pathways by which additional fin/limb bones are formed in both evolution and disease.

该项目将研究引起鱼鳍中阐述骨骼模式的遗传因素。骨骼模式阐述是由于骨数和连接的增加而导致的，并且这种研究对于理解进化和发育的过程很重要。在进化中，端到端排列的骨骼数量的增加有助于将鳍转化为四肢，并通过灭绝的脊椎动物帮助土地殖民。在发育中，正常功能和运动取决于形成适当的骨数和连接，并且有缺陷的发育会导致严重的损害。当前，导致鳍骨架形成四肢的机制尚不清楚。为了确定所涉及的遗传因素，研究人员将研究模型物种斑马鱼的菌株，斑马鱼具有遗传变化，从而形成了新的鳍骨。他们还将研究两个物种GAR和BOWFIN的自然变化，它们的骨骼数量不同。这些互补方法将揭示调节鳍和四肢骨骼的生长和形成的机制，并显示简单的遗传变化如何导致鳍片的四肢形成。了解骨骼模式阐述和发育的机制对人类健康和发育异常具有影响，并可能为土地上生命的进化提供线索。此外，该项目将为美国原住民的本科生提供研究机会。虽然四足动物脊椎动物增加了肢体沿近距离（P-d）轴的骨骼数量，但斑马鱼等硬骨鱼类却减少了胸鳍骨架。沿P-D轴只发现一个长骨。研究人员在斑马鱼中进行了正向诱变筛选，并隔离了一种新型突变体，该突变体沿着鳍片的p-d轴形成超骨的骨骼，通过与四肢发展的发展相似的过程。拟议的研究将将结果从突变分析扩展到自然群体，以确定突变是否通过激活祖先遗传机制产生超非努力的骨骼。 RNA测序的转录组分析将用于比较野生型和突变斑马鱼的发育中的胸鳍中的基因表达水平，以及两个在p轴阐明中表现出自然变化的物种。该分析将揭示与P轴阐述相关的差异基因表达的模式。差异表达的基因将在斑马鱼中进行测试，以确定其修饰的表达是否对鳍形态有影响。这项研究将阐明在发育中如何出现添加剂表型变化，并确定在进化和疾病中形成其他鳍/肢体骨骼的候选途径。