Understanding biomineralisation in the fish dermal skeleton and its role in health and development

到2020年，全球鱼类产量已经超过1.79亿吨，据信为英国经济贡献了6亿英镑。除此之外，斑马鱼是生物医学研究中第二大最常用的物种，仅次于小鼠。因此，了解与鱼类健康和福祉相关的机制至关重要。鱼类的发展在许多方面与人类和哺乳动物的发展相呼应。例如，需要矿化骨骼来提供器官保护，流动性和钙磷稳态。然而，与哺乳动物不同，鱼类通常拥有第二个矿化骨骼，通过它们的鳞片。除了上面列出的作用外，这种真皮骨架还提供保护，使其免受恶劣的外部环境的伤害和感染。已证明，Skeleton矿化对快速生长的农业重要动物（如猪和鸡）以及几种人类疾病具有重要影响。在生产更可持续、更便宜的蛋白质的竞赛中，对这些养殖方法如何影响这些鱼的钙维持（通过鳞片矿化）以及如何影响它们的健康和福祉的研究非常缺乏。我们知道这些鳞片以类似于骨骼的方式矿化，但对于骨骼和鳞片，我们并不完全了解潜在的过程如何导致矿化。矿化开始于细胞外富含胶原蛋白的基质，其赋予组织韧性并充当其上嵌入矿物质组分羟基磷灰石（钙-磷酸盐复合物）的支架，赋予复合材料刚度。羟基磷灰石最初是如何形成的已经被广泛争论了很多年，但现在认为它集中在基质囊泡内的钙和磷酸盐浓度上，这些囊泡本身由骨和鳞片细胞释放。基质囊泡是小的（100- 300 nm）囊泡，其中含有许多负责钙和磷酸盐积累的蛋白质。目前还不可能确定基质囊泡是如何从细胞中释放出来的。我假设基质囊泡从细胞表面释放，细胞骨架重排后，在一些细胞膜为基础的过程中确定。我建议制定一项工作计划，使我能够了解矿化在鱼类健康和福祉中的重要性，并对分子水平上的矿化理解产生更广泛的影响。在这个奖学金，我将开发强大的成像技术来成像基质囊泡。使用活细胞成像，我将操纵感兴趣的蛋白质，以阐明它们在囊泡生物发生和蛋白质运输中的作用。我将进一步发展这些成像技术来研究鱼鳞中的基质囊泡生物发生。此外，我将使用具有一系列矿化表型的鱼线来研究鳞片矿化在鱼类伤口愈合中的重要性，并对肉类养殖水产养殖物种的矿化变化程度进行初步研究。这些研究将提供机会，高影响力的出版物在这个奖学金，以及形成未来的高级奖学金，赠款申请和助学金的基础。

By 2020 global fish production had already exceeded 179 million tonnes, and is thought to contribute £600 million to the British economy. In addition to this, zebrafish are the second most highly used species in biomedical research, after mouse. Therefore, understanding mechanisms relating to health and wellbeing of fish is vital.Much of fish development echoes that of humans and mammals in many ways. For example, the requirement for a mineralised skeleton to provide organ protection, mobility, and calcium-phosphorous homeostasis. However, unlike mammals, fish often possess a second mineralised skeleton, by way of their scales. In addition to the roles listed above, this dermal skeleton provides protection from the hostile external environment from injury and infection. Skeletal mineralisation has been shown to be detrimentally impacted in rapidly grown animals of agricultural importance, such as pigs and chickens, as well as several human disorders. In the race to produce more sustainable, cheaper protein, research into how these farming methods might affect calcium maintenance in these fish (via scale mineralisation), and how that may impact on their health and wellbeing is sorely lacking. We know that these scales mineralise in a similar way to bones, but for both bones and scales, we don't fully understand how the underlying processes lead to mineralisation. Mineralisation begins with an extracellular collagen rich matrix, which confers toughness to the tissue and acts as a scaffold on which the mineral component, hydroxyapatite (calcium - phosphate complex) is embedded, conferring stiffness to the composite material. How hydroxyapatite is initially formed has been widely debated for many years, but it is now considered to centre upon the concentration of calcium and phosphate within matrix vesicles which are themselves released by bone and scale cells. Matrix vesicles are small (100-300nm) vesicles, which contain a number of proteins responsible for the accumulation of calcium and phosphate. It has not been possible to ascertain how matrix vesicles are released from the cell. I hypothesise that matrix vesicles are released from the surface of the cell, following cytoskeletal rearrangement as identified in a number of cell membrane-based processes. I propose developing a scheme of work that will allow me to understand the importance of mineralisation in fish health and wellbeing, as well as having broader implications for the understanding of mineralisation at the molecular level, across species. In this fellowship, I will develop robust imaging techniques to image matrix vesicles. Using live cell imaging, I will manipulate proteins of interest, to elucidate their role in vesicle biogenesis and trafficking of proteins. I will further develop these imaging techniques to study matrix vesicle biogenesis in fish scales. Furthermore, I will use fish lines with a range of mineralisation phenotypes to study the importance of scale mineralisation in wound healing for fish and develop preliminary research into the extent of mineralisation changes in aquaculture species bred for meat. These studies will offer opportunities for high impact publications within this fellowship, as well as forming the basis for future senior fellowships, grant applications and studentships.