| 项目编号: | 1406802
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| 项目名称: | DISSERTATION RESEARCH: Mechanisms of Mammalian Middle Ear Ossicle Transition from the Reptilian Jaw Joint |
| 作者: | Karen Sears
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| 承担单位: | University of Illinois at Urbana-Champaign
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| 批准年: | 2013
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| 开始日期: | 2014-06-01
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| 结束日期: | 2016-01-31
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| 资助金额: | USD19869
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Biological Sciences - Environmental Biology
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| 英文关键词: | transition
; project
; mammalian middle ear
; reptilian jaw
; hearing sensitivity
; opossum
; early mammal lineage
; middle ear element
; reptile middle ear
; mammalian jaw
; mammal middle ear
; middle ear
; ear development
; middle ear region
; middle ear change
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| 英文摘要: | The transition from reptile to mammal was one of the most important events in leading to the eventual evolution of humans. This transition is characterized by many changes, one of the most important is the evolution of the mammalian middle ear. The goal of this project is to investigate the developmental basis of the evolution of the mammalian middle ear, using an opossum species as a model organism. Because opossum are primitive mammals, they can provide significant insights into mammalian evolution, and the improved understanding of ear development that this project will generate has the potential to positively impact human health. This project will also serve as a foundation for the STEM training of several undergraduates and for community outreach events geared toward K-12 students. Results of this project are also being incorporated into a three-part PBS documentary based upon Neil Shubin's best-selling book, Your Inner Fish.
The reptilian jaw consists of multiple bones, while there is only a single bone in the reptile middle ear. Conversely, the mammalian jaw consists of a single bone, while there are multiple bones in the mammal middle ear. It has been shown, via paleontology and embryology, that the extra bones in the mammalian middle ear originated from the extra bones in the reptilian jaw. Separation from the jaw would allow more flexibility in the evolution of the middle ear elements, resulting in increased hearing sensitivity and amplified frequency range. The middle ear changes observed in the transition from reptiles to mammals in the fossil record also occur during development in opossum. Opossum are born with a middle ear similar to reptiles, but in adults the middle ear is mammalian, providing a unique opportunity to study the evolutionary development of mammalian middle ear bones in an currently living organism rather than with fossils. The project is based on a detailed characterization of the transition using micro-computed tomography scans to create three-dimensional images at five day intervals, beginning at birth, and studying the cellular processes underlying the transition by cryosectioning at the noted stages, followed by immunohistochemistry for cell proliferation and apoptosis. The project will uncover the genes responsible for the transition using in situ hybridization and RNA sequencing. Alterations in the timing of expression and concentration of particular genes (e.g., TGTbr2 and Eya1) are expected to be correlated with the separation of Meckel's cartilage and functional changes in the ossicles. The research will determine if the active genes in opossum are also expressed in the middle ear region of placental mammals. The project will compare the transition that occurs during opossum development to that observed in fossil record leading to early mammal lineages. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/96734
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| Appears in Collections: | 影响、适应和脆弱性
气候减缓与适应
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| Recommended Citation: | |
Karen Sears. DISSERTATION RESEARCH: Mechanisms of Mammalian Middle Ear Ossicle Transition from the Reptilian Jaw Joint. 2013-01-01.
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