Heat shock genes and the response to environmental stress during zebrafish development.

热休克蛋白在细胞暴露于环境应激（如高温或有毒金属）后表达，并帮助细胞在这些应激期存活。几种热休克蛋白还作为分子伴侣发挥重要作用，通常帮助其他蛋白质折叠并到达细胞中的正确目的地。对于细胞来说，能够调节热休克蛋白表达的位置、时间和数量是很重要的，而这主要是通过调节编码hsp的基因的表达来实现的。汞和镉等有毒金属是一个重大问题，对发育中的胚胎有负面影响。汞会导致一系列问题，包括人类和鱼类的视觉缺陷。镉会损害人类和鱼类的嗅觉器官，导致嗅觉丧失。关于有毒金属的一个主要问题是，它们是否在某些细胞和组织中积累得比其他细胞和组织更多，以及金属的化学形式是否影响这一过程。我们的工作使用斑马鱼胚胎作为模型来研究环境压力对发育的影响。斑马鱼是一个受欢迎的模型系统，因为它们的大部分发育过程与人类的发育过程相似，而且是研究鱼类发育本身的一个很好的模型。我们已经用同步加速器x射线检测了有毒金属汞在斑马鱼胚胎中的聚集部位。我们发现，其中一个主要目标是感觉系统的细胞，特别是眼睛，嗅觉器官和鱼类中被称为侧线的专门感觉器官的部分。我们还研究了一种称为hsp70的特殊热休克蛋白。有趣的是，热休克蛋白70在眼睛发育过程中正常表达，并且是正常眼睛形成所必需的。这种基因也在暴露于另一种有毒金属镉后的嗅觉器官和侧线中表达。这项提案中的实验将研究将斑马鱼胚胎暴露于不同类型的汞的影响，以及吸收大量汞的细胞是否也是最敏感的。这将包括观察感觉器官中的细胞是否更容易死亡，以及器官的正常功能是否被破坏。我们还将研究hsp70基因是如何在汞和镉处理的胚胎中打开和关闭的，以及在眼睛透镜的正常发育过程中。一些工作将使用我们开发的转基因鱼模型，该模型在表达hsp70的细胞中发出明亮的绿色荧光，允许非常快速地检测应激细胞。总之，这项工作将使我们能够开发一个综合模型，说明在正常发育过程中和胚胎暴露于环境压力后，hsp70基因的调控是如何微调的，以及这与靶细胞中发生的其他事件如何相关，从有毒金属的摄取和积累到靶器官的功能缺陷。这项工作对于我们理解胚胎细胞如何在分子和细胞水平上对环境应激做出反应并在暴露于环境应激中生存下来将是重要的。我们将能够将对感觉细胞及其功能的影响与i）这些细胞中有毒金属的实际量，ii）hsp70基因如何响应这种压力而被激活，iii）这种激活如何帮助胚胎细胞在压力事件中存活。这也将使我们能够更好地了解hsp70基因在眼睛正常发育过程中是如何表达的，并进一步阐明这一事件的重要性。这项工作将进一步确定我们的转基因鱼品系是否可以用作某些感觉器官中负面结果的快速荧光预测器。

Heat shock proteins are expressed in cells following exposure to environmental stress such as elevated temperature or toxic metals, and help cells survive these periods of stress. Several hsps also play important roles as molecular chaperones that normally help other proteins fold and reach their correct destination in the cell. It is important for a cell to be able to regulate where, when, and how much a heat shock protein is expressed, and it does this largely be regulating the expression of the gene that codes for the hsp. Toxic metals such as mercury and cadmium are a significant concern, and have negative effects on developing embryos. Mercury causes a range of problems, including visual defects in both humans and fish. Cadmium can damage the olfactory organ of both humans and fish, causing a loss of the sense of smell. A major question regarding toxic metals is whether they accumulate more in some cells and tissues than others, and whether the chemical form of the metal affects this process. Our work uses the zebrafish embryo as a model to examine the effects of environmental stress on development. Zebrafish are a popular model system since much of their development occurs in a similar way to human development, in addition to being an excellent model to look at fish development itself. We have used synchrotron x-rays to examine where in zebrafish embryos the toxic metal mercury accumulates. We found that one of the major targets is cells of sensory systems, in particular parts of the eye, olfactory organ, and a specialized sensory organ in fish known as the lateral line. We have also examined a specific heat shock protein known as hsp70. Interestingly, hsp70 is expressed normally during eye development, and is required for normal eye formation. This gene is also expressed in both the olfactory organ and lateral line following exposure to another toxic metal, cadmium. Experiments in this proposal will examine the impact of exposing zebrafish embryos to different types of mercury, and whether the cells that take up large amounts of mercury are also the most sensitive. This will include looking at whether cells in the sensory organs are more prone to death, and whether the proper function of the organs is disrupted. We will also examine how the hsp70 gene is turned on and off in mercury and cadmium treated embryos, and during normal development of the eye lens. Some of the work will use a transgenic fish model we have developed that fluoresces bright green in cells that express hsp70, allowing for very rapid detection of stressed cells. In summary, the work will allow us to develop an integrated model of how regulation of the hsp70 is gene is fine-tuned during normal development and following exposure of embryos to environmental stress, and how this relates to other events occurring in target cells ranging from toxic metal uptake and accumulation to functional defects in target organs. This work will be important to our understanding of how cells in an embryo respond to and survive exposure to environmental stress at the molecular and cellular level. We will be able to correlate impacts on sensory cells and their function with i) the actual amount of a toxic metal in these cells, ii) how the hsp70 gene is activated in response to this stress, and iii) how this activation may assist embryonic cells in surviving the stress event. It will also allow us to develop a better understanding of how the hsp70 gene is expressed during normal development of the eye, and further elucidate the importance of this event. This work will further determine if our transgenic fish strain can be used as a rapid fluorescent predictor of negative outcomes in some sensory organs.