A Physical Characterisation of Assembly Mechanisms and Light Transmission in Cornea.

角膜是眼睛前部透明的部分。它对正常的视力至关重要，因为它让光线进入并将其聚焦在眼睛后部的视网膜上。因此，形成了清晰的图像，我们可以正确地看到。角膜是一种特殊的组织，因为它是透明的，在这方面，它不像身体中的其他相关组织-例如连接我们骨骼和肌肉的肌腱或巩膜（眼睛的白色）-由类似的成分组成。科学家们认为，角膜是透明的，因为形成角膜的大部分蛋白质称为胶原蛋白，主要是长而细的绳状结构，称为原纤维。此外，这些胶原纤维形成了一个非常明确的安排，让光通过。如果这种排列被破坏，角膜就会失去透明度并变得浑浊。因此，视力严重受损。我们提出了一个研究计划，使用新的物理学为基础的技术来调查角膜的内部精细结构及其如何发展。我们将使用鸡角膜作为模型系统，因为它已经被研究了很多次。我们将把我们的结构数据与我们在美国的同事将与我们一起获得的角膜透明度的测量结果进行比较。我们还将利用我们的技术研究日本科学家在实验室中制造的新型人工角膜。通过发现生物工程角膜中的胶原纤维与自然发育的角膜相比是如何组装的，我们可以帮助指导制造透明的功能性角膜的努力。首先，我们将设计新的方法来制备角膜组织，以便在电子显微镜中进行非常高的放大率检查。这些制备方法将使用高压冷冻技术，以便当放置在电子显微镜下时，角膜的薄切片将比其他常规化学方法制备组织后更好地保留天然结构。然后可以在高达50，000倍的放大倍数下检查胶原纤维的超微结构。如果我们要建立角膜透明的数学模型，这些信息是必不可少的。我们还指出，这种新的电子显微镜技术的发展也将是非常有用的科学家在其他领域谁研究其他生物组织，系统和组件。我们还将使用一种技术称为X射线衍射研究角膜超微结构使用更集中的X射线束比以往任何时候都用来研究角膜的发展。我们将使用的X射线将是非常强烈的，由同步加速器源产生。这些都是高度专业化的大型粒子加速器，我们将与日本、法国和英国的同事一起进行实验。这些数据将以比以前更好的分辨率提供结构信息。同样，我们将把结构数据与透明度联系起来，以了解是什么使角膜透明。有趣的是，科学家们怀疑角膜中含有硫酸盐成分的分子会影响胶原纤维，迫使它们采取特殊的排列方式，从而使角膜透明。以前没有直接测量角膜中的硫酸盐水平，因为这是非常困难的。我们将带来通常用于太空研究的天体物理光谱学专业知识，以量化角膜中硫酸盐的变化。这将告诉我们硫酸化分子如何控制胶原蛋白的排列。总的来说，这项研究将告诉我们角膜在发育过程中如何自我组装，以及在实验室中如何进行工程改造，以及为什么角膜是透明的。我们还将开发生物物理学研究的新技术，使其他科学家受益。

The cornea is the front clear part of the eye. It is essential for proper vision because it lets in light and focuses it on the retina at the back of the eye. Thus, a sharp image is formed and we can see properly. The cornea is a special tissue because it is transparent, and in this respect it is unlike other related tissues in the body -- the tendons that link our bones and muscles or the sclera (the white of the eye), for example -- that are made of similar components. Scientists believe that the cornea is transparent because the protein called collagen that forms much of the cornea is mostly in the form of long, thin rope-like structures called fibrils. Moreover, these collagen fibrils are formed into a very well defined arrangement that lets light through. If this arrangement breaks down the cornea looses its transparency and becomes cloudy. As a result vision is severely compromised.We propose a programme of research that uses new physics-based techniques to investigate the internal fine structure of the cornea and how it develops. We will use the chick cornea as a model system because it has been studied many times before. We will compare our structural data with measurements of corneal transparency that our colleagues in the United States will obtain in conjunction with us. We will also use our techniques to study new artificial corneas that are being made in the laboratory by scientists in Japan; by discovering how the collagen fibrils assemble in the bioengineered cornea compared to in the naturally developing cornea we can help guide efforts to make transparent, functional corneas.First, we will devise new ways of preparing cornea tissue for examination at very high magnification in an electron microscope. These preparation methods will use high-pressure freezing technology so that when placed in the electron microscope thin sections of the cornea will retain native structure much better than after other conventional chemical ways of preparing the tissue. The ultrastructure of collagen fibrils can then be examined at a magnification of up to 50,000 times. This information essential if we are to create mathematical models of why the cornea is transparent. We also point out that the development of this new electron microscopy technique will also be of great use to scientists in other fields who investigate other biological tissues, systems and components.We will also use a technique called x-ray diffraction to study corneal ultrastructure using more focused x-ray beams than have ever been used before to study corneal development. The x-rays we will use will be very intense and produced by synchrotron sources. These are highly specialised, large particle accelerators and we will conduct experiments with colleagues in Japan, in France as well as here in the UK. The data will provide structural information at a much better resolution than has previously been possible. Again, we will link structural data with transparency to understand what makes the cornea transparent.Interestingly, scientists suspect that molecules with sulphate components in the cornea influence the collagen fibrils and force them to take up the special arrangement that allows corneal transparency. Sulphate levels have not been measured directly in cornea previously because this is very difficult to do. We will bring astrophysical spectroscopy expertise ordinarily used in space research to quantify sulphate changes in the cornea as it develops. This will teach us how sulphated molecules control collagen arrangement.Overall, the research will teach us how the cornea assembles itself during development and when it is engineered in the laboratory, and why the cornea is transparent. We will also develop new technologies in biophysics research that other scientists can benefit from.