Collaborative Proposal: RUI: Obliquely striated muscle: A soft-bodied invertebrate solution for tuning length-force properties to meet functional demands?

合作提案：RUI：斜横纹肌：一种软体无脊椎动物解决方案，用于调整长度力特性以满足功能需求？

• 批准号: 1755314
• 负责人: Joseph Thompson
• 金额: $ 28.91万
• 依托单位: Franklin and Marshall College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1755314&HistoricalAwards=false
• 关键词: Collaborative; Proposal; RUI; Obliquely; striated

Three types of muscle cells (smooth and the cross-striated cardiac and skeletal muscles) are well known from any introductory text, yet few biologists are familiar with obliquely striated muscles. Obliquely striated muscle cells are common in soft-bodied animals, occurring in members of at least 17 phyla, yet the implications of oblique striation for the function and performance of this important muscle type are unknown. It has been assumed for decades that oblique striation permits relatively high force output over an extraordinary range of muscle lengths. Recent work, however, suggests that the contractile properties and operating length ranges of obliquely striated muscles are very diverse, even among muscles within the same individual animal. The project will investigate the contractile properties and operating length ranges of obliquely striated muscles from diverse animals. This research is likely to reveal fundamental new principles of the structure and function of muscle that would otherwise remain obscure, and provide new insight into the diversity of function and the evolution of this fiber type. The project will provide opportunities for undergraduates, especially first-generation college students and those from underrepresented backgrounds, to gain experience in physiology, biomechanics, and science communication. In partnership with the Maine State Aquarium Discovery Center, the project will develop programs for K-12 students and the general public. The project will also impact secondary education through collaboration with the UNC Baccalaureate Education in Science and Teaching (UNC-BEST) program, which offers undergraduate Biology majors opportunities to obtain licensure as a secondary school teacher in North Carolina.Although obliquely striated muscle occurs in at least 17 animal phyla, the functional implications of this striation pattern remain unclear. Early studies suggested that oblique striation allows high force output over a much wider range of muscle lengths than possible in cross-striated muscle. Recent work, however, shows that many obliquely striated muscles are incapable of such wide operating ranges and instead, there is considerable variation in this parameter. The current understanding thus fails as a general explanation for the functional significance of oblique striation. The goal of the investigation is to test a new model, based on mathematical analysis of the geometry of the myofilament array, which suggests that oblique striation evolved to allow adjustment of the length-force relationship in animals with hydrostatic skeletons. The model predicts that the length-force relationship can be adjusted by altering the stagger angle (i.e., the degree of stagger of the myofilaments), with greater stagger resulting in a wider operating range. Measurements of length-force properties, in vivo muscle activation and length changes, and muscle fiber ultrastructure will be used to test the model predictions and assess the functional significance of oblique striation. The initial investigation will focus on the myofilament stagger and the length-force relationship of muscles in the squid Doryteuthis pealeii that vary widely in function and operating length range. In addition, muscles with similar roles and length-force relationships among select taxa that span the range of Bilaterian diversity will be studied, thus identifying structural and functional convergence in obliquely striated muscles.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.

从任何入门文本中众所周知，三种类型的肌肉细胞（光滑和跨对心脏和骨骼肌肉）是众所周知的，但是很少有生物学家熟悉倾斜的肌肉。 倾斜的肌肉细胞在柔软的动物中很常见，发生在至少17个门的成员中，但是倾斜条纹对这种重要肌肉类型的功能和性能的影响尚不清楚。 几十年来，倾斜条纹允许在肌肉长度的非凡范围内输出相对较高的力量。 然而，最近的工作表明，即使在同一个单个动物的肌肉中，倾斜的肌肉的收缩特性和操作长度也非常多样化。 该项目将调查来自不同动物的倾斜肌肉的收缩性质和工作长度。 这项研究很可能揭示了肌肉结构和功能的基本新原理，这些原则和功能原本会保持晦涩难懂，并提供了对功能多样性和这种纤维类型的发展的新见解。 该项目将为大学生，尤其是第一代大学生以及代表性不足的背景的学生提供机会，以获得生理学，生物力学和科学传播方面的经验。 该项目与缅因州国家水族馆发现中心合作，将为K-12学生和公众开发计划。 该项目还将通过与UNC科学和教学学士学位教育（UND-Besst）计划的合作来影响中学教育，该计划提供了本科生物学专业的专业机会，有机会获得北卡罗来纳州的中学老师的许可。尽管如此，倾斜的肌肉仍然存在于至少17个动物门中，这是这种矫正模式的功能，是这种纹理模式的影响。 早期研究表明，倾斜条纹可以使肌肉长度范围更大的肌肉长度高于交叉分解的肌肉。 然而，最近的工作表明，许多倾斜的肌肉无法具有如此宽的操作范围，而是，此参数有很大的变化。 因此，当前的理解是对倾斜条纹功能意义的一般解释。 研究的目的是基于对肌丝阵列的几何形状的数学分析来测试一个新模型，这表明倾斜条纹演变为允许在具有静水骨架的动物中调整长度力关系。 该模型预测，可以通过更改交错角（即肌丝的交错程度）来调整长度的关系，并更大的交错导致更广泛的工作范围。 长度力特性的测量，体内肌肉激活和长度变化，以及肌肉纤维超微结构将用于测试模型预测并评估倾斜条纹的功能意义。 最初的研究将集中于肌丝的交错以及鱿鱼Doryteuthis pealeii中肌肉的长度力关系，其功能和工作长度范围差异很大。 此外，将研究跨越横向肌肉的结构和功能融合的精选分类单元之间具有相似角色和长度力量关系的肌肉。该奖项反映了NSF的法定任务，并通过基金会的知识优点和广泛的影响来评估NSF的法定任务。

项目成果

One size does not fit all: diversity of length–force properties of obliquely striated muscles

一种尺寸并不适合所有情况：斜纹肌长度和力特性的多样性

• DOI: 10.1242/jeb.244949
• 发表时间: 2023
• 期刊: Journal of Experimental Biology
• 影响因子: 2.8
• 作者: Thompson, Joseph T.;Taylor-Burt, Kari R.;Kier, William M.
• 通讯作者: Kier, William M.