RUI: Smelling in water and air: Evolution of olfaction in plethodontid salamanders

RUI：在水和空气中嗅觉：无齿蝾螈嗅觉的进化

• 批准号: 2050018
• 负责人: John Reiss
• 金额: $ 39.76万
• 依托单位: Humboldt State University Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2050018&HistoricalAwards=false
• 关键词: RUI; Smelling; water; air; Evolution

This project focuses on how the olfactory system of amphibians is modified to function in water and in air. The emergence of vertebrate animals from water onto land was one of the major transitions of vertebrate evolution. For many living amphibians, this historical transition is mirrored by a current developmental transition, as they metamorphose from an aquatic larva to a terrestrial juvenile. Like other sensory systems, the olfactory system must be able to adjust and function in both environments across this developmental transition. This project breaks new ground by examining olfactory morphology and gene expression patterns across eight related salamander species with a wide range of life histories, ranging from typical larvae with metamorphosis, to direct development with no free-living larval stage, to secondarily re-evolved larvae. The study will answer the following questions: (1) Are patterns of olfactory organization consistent across species with the same developmental mode, regardless of evolutionary history? (2) Are water-sensing olfactory components lost in terrestrial, direct-developing species? (3) Do species that have re-evolved a larval period regain water-sensing olfactory components? This work will take place at Humboldt State University, an Hispanic Serving Institution located on the rural northern coast of California. It will directly support 15-20 undergraduate and two graduate students in hands-on research, enhancing their skills and thereby furthering their careers and job prospects. The research will be integrated into classes, benefitting approximately 300 students per year. A public outreach component will involve lectures to local community members, increasing scientific literacy on evolution and development and promoting appreciation for this understudied group of vertebrates.This project will examine how the evolution of alternative developmental modes impacts olfactory system structure and function in the most speciose family of salamanders, the plethodontid or lungless salamanders. Olfactory morphology and gene expression patterns of eight plethodontid species and one outgroup species that span a wide range of developmental modes will be examined. Techniques used will include traditional histology to compare the basic structure of the olfactory organs, transmission and scanning electron microscopy to establish morphological classes of olfactory receptor neurons and supporting cells, microCT scanning and 3-D reconstruction to provide a visual image of overall olfactory organ anatomy, neuronal tracing to establish pathways of olfactory receptor neuron connection to the brain, and protein and mRNA localization of olfactory marker genes. This work will for the first time elucidate patterns of olfactory evolution with respect to olfaction in water and air, in larvae and adults, within an explicit phylogenetic framework. By doing so, it will allow a better understanding of how the olfactory system evolves in living amphibians, and of changes associated with the evolutionary emergence of tetrapods onto land. A total of 15-20 undergraduates and two graduate students will participate directly in the project, and the research will be incorporated into five courses that enroll approximately 300 students. The research will also be presented to the public at the institution’s natural history museum and at a science lecture series at a local coffeehouse.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这个项目的重点是两栖动物的嗅觉系统如何被修改，以在水中和空气中发挥作用。脊椎动物从水中出现到陆地上是脊椎动物进化的主要转变之一。对于许多现存的两栖动物来说，这一历史转变反映在当前的发育转变中，因为它们从水生幼虫蜕变为陆生幼虫。像其他感觉系统一样，嗅觉系统必须能够在这两种环境中进行调整和发挥作用。该项目通过检查八个相关蝾螈物种的嗅觉形态和基因表达模式来开辟新天地，这些物种具有广泛的生活史，从典型的变态幼虫到没有自由生活的幼虫阶段的直接发育，再到二次重新进化的幼虫。该研究将回答以下问题：（1）无论进化历史如何，具有相同发育模式的物种的嗅觉组织模式是否一致？(2)在陆地直接发育的物种中，水感嗅觉成分丢失了吗？(3)重新进化了幼虫期的物种是否重新获得了感知水的嗅觉成分？这项工作将在洪堡州立大学进行，这是一所位于加州北方沿海农村的西班牙裔服务机构。它将直接支持15-20名本科生和两名研究生进行实践研究，提高他们的技能，从而促进他们的职业生涯和就业前景。这项研究将被纳入课堂，每年约有300名学生受益。公共宣传部分将包括对当地社区成员的讲座，提高对进化和发展的科学素养，并促进对这一未得到充分研究的脊椎动物群体的欣赏。该项目将研究替代发展模式的进化如何影响蝾螈中最具物种的家族，即无肺蝾螈的嗅觉系统结构和功能。嗅觉形态和基因表达模式的八plethodontid物种和一个外类群物种，跨越了广泛的发展模式将进行检查。所使用的技术将包括传统的组织学比较嗅觉器官的基本结构，透射和扫描电子显微镜建立嗅觉受体神经元和支持细胞的形态分类，microCT扫描和3-D重建提供整体嗅觉器官解剖的视觉图像，神经元追踪建立嗅觉受体神经元连接到大脑的通路，嗅觉标记基因的蛋白质和mRNA定位。这项工作将首次在明确的系统发育框架内阐明幼虫和成虫在水和空气中嗅觉的嗅觉进化模式。通过这样做，它将允许更好地了解嗅觉系统如何在活着的两栖动物中进化，以及与四足动物进化出现在陆地上相关的变化。共有15-20名本科生和两名研究生将直接参与该项目，研究将纳入五门课程，招收约300名学生。该研究还将在该机构的自然历史博物馆和当地咖啡馆的科学讲座系列中向公众展示。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。