RUI: Collaborative Research: Exploring Barnacle Exoskeleton Development and Materials Properties as a Function of Growth Environment

非技术概述几千年来，藤壶一直吸引着探险家、科学家和水手的注意。它们是甲壳类动物，类似于虾、龙虾和螃蟹，但与它们自由移动的亲戚不同的是，它们被包裹在坚硬的外壳中，牢牢地粘在表面上。藤壶外壳是一种生物矿物，是一种由蛋白质、甲壳素(糖分子的纤维链)和矿物组成的混合物，在藤壶中主要是碳酸钙。尽管藤壶扮演着巨大的生态和经济角色--因为它们附着在船只、船体和其他表面上，导致船只减速并消耗更多燃料--但人们对藤壶外骨骼是如何形成的，或者未来几年预测的气候变化是否会改变这一形成过程知之甚少。拟议的工作完全由本科生在两个项目PI的监督下完成，重点是通过检查外骨骼发育的非常早期阶段来确定外骨骼是如何形成的。此外，该项目还将探索当藤壶生长在更温暖、更酸性的水域时，形成过程是如何变化的。这项工作不仅将提供关于一种有趣的和潜在有用的材料的形成的信息，而且还将提供一种具有经济和生态重要性的生物将如何对预测的未来海洋条件做出反应的信息。除了这些基本知识外，该项目还将为高露洁和TCNJ的本科生以及来自纽约代表性不足社区的高中生提供宝贵的STEM培训机会。技术概述藤壶外骨骼是一种健壮的生物矿化组织，但在原子到微米的水平上结构紊乱。这与大多数研究良好的生物矿化组织(如脊椎动物骨骼、软体动物贝壳)形成鲜明对比，后者具有有序的等级结构。该项目的目标是描述这种无序外骨骼形成的发育过程，以及环境条件对外骨骼材料的影响程度。第一个目标是确定藤壶外骨骼在变态后的一段时间内的组成、结构和材料特性，直到在周围海洋条件下完全矿化。通过结合多种技术(共聚焦显微镜、扫描电子显微镜、拉曼光谱、X射线光电子显微镜(X-PEEM)、微压痕和纳米压痕)，可以跟踪幼年藤壶从幼虫变态后的情况，从而确定某些材料特性，如断裂韧性，是否与无序结构有关。第二个目标是研究发育中的外骨骼的成分、结构和材料特性在pH降低和温度上升(用当前的气候变化预测模拟2100年的预测海洋条件)下的表现。这些实验的结果将为无序生物材料的功能提供洞察，同时也为一个具有生态和经济重要性的生物体是否会受到即将到来的环境变化的影响提供信息。除了从这些实验中获得的重要基础知识外，拟议的工作将对本科生和高中生产生更广泛的影响。本科生研究人员将在两个私人投资促进机构的监督下进行整个拟议工作，不仅参与研究，还参与会议和手稿准备。纽约代表不足的社区的高中生研讨会将与五人营一起，以拟议工作的结果为基础，揭露并让高中生参与科学研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical SummaryBarnacles have attracted the attention of explorers, scientists, and sailors for millennia. They are crustaceans, similar to shrimp, lobsters, and crabs, but unlike their freely moving relatives are encased in a hard outer shell and securely stuck to a surface. The barnacle outer shell is a biomineral, a composite material consisting of a mixture of proteins, chitin (fibrous strings of sugar molecules), and minerals, which in barnacles are largely calcium carbonate. Despite the fact that barnacles play a large ecological and economical role -as they stick to ships, hulls, amongst other surfaces, causing the ships to slow down and use more fuel- little is known about how the barnacle exoskeleton forms or if climate changes predicted in coming years will alter this formation process. The proposed work, done entirely by undergraduate students under the supervision of the two project PIs, focuses on determining how the exoskeleton forms by examining the very early stages of exoskeleton development. In addition, the project will explore how the formation process changes when barnacles are grown in warmer and more acidic waters. This work will not only provide information on the formation of an interesting and potentially useful material, but also how an economically and ecologically important organism will respond to predicted future ocean conditions. Beyond this basic knowledge, the project will provide invaluable training opportunities in STEM to undergraduates at both Colgate and TCNJ, as well as to high school students from underrepresented communities in New York. Technical SummaryThe barnacle exoskeleton is a robust biomineralized tissue, yet it is structurally disordered on the atomic to micrometer level. This is in contrast to most well-studied biomineralized tissues (e.g. vertebrate bone, mollusk shells) which have ordered, hierarchical structures. The goal of this project is to characterize the developmental process by which this disordered exoskeleton forms and the extent to which environmental conditions impact the exoskeletal material. The first objective is to identify the composition, structure, and materials properties of the barnacle exoskeleton during the time period immediately following metamorphosis through to full mineralization under ambient marine conditions. Juvenile barnacles will be tracked following metamorphosis from larval cyprids through a combination of techniques (confocal microscopy, scanning electron microscopy, Raman spectroscopy, x-ray photoemission electron microscopy (X-PEEM), micro-indentation, and nano-indentation), allowing determination on whether certain materials properties, such as fracture toughness, are linked to a disordered structure. The second objective is to examine how the composition, structure, and materials properties of the developing exoskeleton behave under decreased pH and increased temperature (mimicking predicted ocean conditions in the year 2100 with current climate change predictions). The results from these experiments will provide insight into the functionality of disordered biological materials, while also providing information into whether an ecologically and economically important organism will be impacted by impending environmental changes. In addition to the important fundamental knowledge derived from these experiments is the broader impact the proposed work will have on undergraduate and high school students. Undergraduate researchers, under the supervision of the two PIs, will conduct the entirety of the proposed work, participating in not only the research, but also conferences and manuscript preparation. A workshop for high school students from underrepresented communities in New York, in conjunction with Camp Fiver, will be based on the results of the proposed work, exposing and involving the high school students in scientific research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.