Evolution of Eye Regression in Cavefish

洞穴鱼眼睛回归的进化

• 批准号: 9726561
• 负责人: William Jeffery
• 金额: $ 33.5万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-03-15 至 2001-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9726561&HistoricalAwards=false
• 关键词: Evolution; Eye; Regression; Cavefish

9726561 Jeffery The purpose of this project is to study the genetic basis of eye degeneration in a vertebrate animal. As a model system, we will use the fish Astyanax mexicanus. The Astyanax system is well suited for studying eye degeneration for the following reasons. First, during the last ice age, surface dwelling Astyanax, which have large eyes, were isolated in caves. The descendants of these cave-dwelling Astyanax subsequently lost their eyes. Both surface and cave dwelling Astyanax populations have been collected and are currently available for research in my laboratory. Using these animals we will compare eye development and degeneration in animals with and without eyes. Second, eyeless Astyanax are found in at least 29 different caves, and some of these cave dwelling populations appear to have lost their eyes independently. Therefore, we can study the genetic basis of eye degeneration under potentially different environmental and evolutionary conditions. Third, surface and cave dwelling Astyanax are easily cultured in the laboratory, breed readily, are inter-fertile, and the eye structure of the surface fish is similar to that found in humans. Thus, Astyanax can be used as a convenient experimental system to help understand human eye degeneration. This proposal has three objectives. First, we want to determine the evolutionary history of eye degeneration in different populations of cave dwelling Astyanax. This will be done by comparing DNA sequences of surface and various cave dwelling populations. The results will answer the question of whether eye degeneration appeared only once or many times during the evolutionary history of these animals. Second, we want to determine the mechanisms of eye degeneration at the tissue level, that is which eye tissues (lens, retina, cornea, etc.) actually degenerate. This will be done by examining cell proliferation and cell death in degenerating eye tissues. These results will allow us to focus on specific genes that function in vario us eye tissues. Third, we want to identify the genes involved in eye degeneration. The existence and function of previously identified eye genes will be studied in surface and various cave dwelling Astyanax populations. This objective is intended to establish the genetic basis of eye degeneration. The significance of this project spans the areas of evolutionary biology, developmental biology, and function of the visual system. In evolutionary biology, this project is significant because it will define the genetic basis of an evolutionary change which may have occurred multiple times during the last ice age. The open question of whether parallel changes in evolution are controlled by the same or different mechanisms and genes will be answered. In developmental biology, this project is significant because it will investigate the mechanisms underlying developmental changes during evolution. There is little current understanding of how development of organ systems is modified during evolution, and we expect to fill this void. Finally, this project is significant in regard to visual system function because it addresses the genetic basis of eye degeneration. Some of the mechanisms and genes underlying eye degeneration in Astyanax may be the same as those involved in visual system deficiencies in humans.

小行星9726561 该项目的目的是研究脊椎动物眼睛退化的遗传基础。 作为一个模型系统，我们将使用鱼Astyanax墨西哥。 Astyanax系统非常适合研究眼退化，原因如下。 首先，在最后一个冰河时代，有着大眼睛的地表生物Astyanax被隔离在洞穴中。 这些洞穴居住的Astyanax的后代后来失去了他们的眼睛。 地表和洞穴生活的Astyanax种群都已被收集，目前可在我的实验室进行研究。 利用这些动物，我们将比较有和没有眼睛的动物的眼睛发育和退化。第二，在至少29个不同的洞穴中发现了无眼的Astyanax，其中一些洞穴居民似乎已经失去了他们的眼睛。因此，我们可以在潜在的不同环境和进化条件下研究眼睛退化的遗传基础。 第三，水面和洞穴生活的Astyanax很容易在实验室中培养，容易繁殖，相互繁殖，水面鱼的眼睛结构与人类相似。 因此，Astyanax可以作为一个方便的实验系统，以帮助了解人类的眼睛退化。 这项建议有三个目标。首先，我们想确定不同洞穴居住的Astyanax种群中眼睛退化的进化历史。 这将通过比较地表和各种洞穴居住人口的DNA序列来完成。 研究结果将回答眼睛退化在这些动物的进化史上只出现一次还是多次的问题。 其次，我们希望在组织水平上确定眼睛退化的机制，即哪些眼睛组织（透镜、视网膜、角膜等）实际上是退化的。 这将通过检查退化眼组织中的细胞增殖和细胞死亡来完成。这些结果将使我们能够专注于在各种眼睛组织中发挥作用的特定基因。 第三，我们想确定与眼睛退化有关的基因。 先前确定的眼睛基因的存在和功能将在地表和各种洞穴居住的Astyanax种群进行研究。 本研究旨在建立眼退化的遗传基础。 这个项目的意义跨越了进化生物学、发育生物学和视觉系统功能的领域。 在进化生物学中，这个项目是重要的，因为它将定义在最后一个冰河时期可能发生多次的进化变化的遗传基础。 进化中的平行变化是由相同还是不同的机制和基因控制的开放性问题将得到回答。 在发育生物学中，该项目意义重大，因为它将研究进化过程中发育变化的机制。 目前对器官系统的发育在进化过程中是如何改变的了解很少，我们希望填补这一空白。 最后，该项目在视觉系统功能方面具有重要意义，因为它解决了眼睛退化的遗传基础。 Astyanax眼睛退化的一些机制和基因可能与人类视觉系统缺陷的机制和基因相同。