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Deep time evolution of bone cells and the implications for bone metabolism in vertebrate history

骨细胞的深度时间演化及其对脊椎动物历史中骨代谢的影响

基本信息

批准号：
388827550
负责人：
Dr. Florian Witzmann
金额：
--
依托单位：
Museum für Naturkunde - Leibniz-Institut für Evolutions- und Biodiversitätsforschung (MfN)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/388827550?language=en
关键词：
Deep time evolution bone cells

项目摘要

Most vertebrates have cellular bone in which bone cells (osteocytes) are enclosed in cave-like lacunae within the bone matrix and are connected to each other via dendritic cell processes that extend in a highly complex network of tubules (canaliculi). Recent studies have shown that this so called lacunocanalicular network plays a pivotal role in bone metabolism, like orchestrating modeling and reshaping of bone surfaces according to strain changes, detecting micro-cracks in bone and inducing their repair, and playing a significant role in mineral homoeostasis. Furthermore, it has been shown that the number of osteocytes per unit of bone volume is proportional to bone growth rate, and their density and shape varies depending on the local strain environment that acts on a certain bone during its formation. Given the multitude of functions in bone metabolism of extant vertebrates, it is inferred that patterns of osteocyte distribution and morphology allow new insights into the biology of fossil vertebrates. However, despite the fact that the lacunocanalicular network is usually well preserved in fossil bone, the evolutionary history of osteocytes is poorly known. In the proposed project, the lacunocanalicular network will be investigated quantitatively and qualitatively throughout vertebrate history to gain a deep time perspective on the evolution of osteocytes, spanning the range from the first vertebrates with cellular bone, the jawless osteostracans, to basal jawed vertebrates (placoderms and acanthodians), osteichthyan fishes, stem-tetrapods, amphibians, and amniotes. Fossil bone will be investigated by light microscopy, scanning electron microscopy (SEM), and synchrotron X-ray phase contrast tomography. The focus will lie on lacunar density and arrangement, lacunar shape and size, morphology of canaliculi, as well as the type of bone matrix in which the lacunocanalicular system is embedded. The results obtained from fossil taxa will be compared with osteological thin sections derived from extant vertebrates for which the metabolic rate is known, and with data from modern bone cell biology. This will allow to draw inferences about metabolic rate, bone modeling and remodeling, and local strain regimes that acted on the skeleton in long-extinct animals and will be regarded in the context of body size, ontogenetic age, and habitat (e.g., aquatic versus terrestrial). A test of phylogenetic signal of lacunocanalicular characters in different lineages of vertebrates will be conducted using different metrics. The results of this project will be important for our understanding of the development of bone metabolism throughout vertebrate history and especially against the background of major evolutionary transitions.

大多数脊椎动物都有细胞骨，其中骨细胞(骨细胞)被包裹在骨基质内的洞状陷窝中，并通过树突状细胞相互连接，树突状细胞在高度复杂的小管(小管)网络中延伸。最近的研究表明，这种所谓的骨陷窝网络在骨代谢中起着关键作用，如根据应变变化协调骨表面的建模和重塑，检测骨中的微裂纹并诱导其修复，并在矿物质平衡中发挥重要作用。此外，研究还表明，单位骨体积中的骨细胞数量与骨生长速度成正比，其密度和形状取决于在骨形成过程中作用于骨的局部应变环境。鉴于现存脊椎动物在骨代谢中的多种功能，可以推断骨细胞的分布和形态模式可以为研究脊椎动物化石的生物学提供新的见解。然而，尽管骨化石中通常保存完好的骨陷窝网络，骨细胞的进化史却鲜为人知。在拟议的项目中，将对整个脊椎动物历史进行定量和定性的研究，以深入了解骨细胞的进化，范围从第一代具有细胞骨的脊椎动物--无颌骨肉动物，到基颌脊椎动物(贝壳类和棘类)、鱼纲鱼类、茎-四足动物、两栖动物和羊膜动物。化石骨骼将通过光学显微镜、扫描电子显微镜(SEM)和同步辐射X射线相衬断层扫描技术进行研究。重点将放在骨陷窝的密度和排列、骨陷窝的形状和大小、骨小管的形态以及嵌入骨陷窝系统的骨基质类型上。化石分类的结果将与已知代谢率的现存脊椎动物的骨学切片进行比较，并与现代骨细胞生物学的数据进行比较。这将允许得出关于代谢率、骨骼建模和重塑以及作用于长期灭绝动物骨骼的局部应变制度的推断，并将根据身体大小、个体发育年龄和栖息地(例如，水生动物与陆地动物)进行考虑。将使用不同的度量标准对不同脊椎动物谱系中的腔颈特征进行系统发育信号的测试。这个项目的结果将对我们理解脊椎动物历史上的骨代谢发展，特别是在重大进化转变的背景下，具有重要意义。