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.

三种类型的肌肉细胞（平滑肌和横纹肌和骨骼肌）在任何介绍性文本中都是众所周知的，但很少有生物学家熟悉斜纹肌。 斜纹肌细胞在软体动物中很常见，至少存在于 17 个门的成员中，但斜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，人们一直认为斜条纹可以在非常大的肌肉长度范围内输出相对较高的力。 然而，最近的研究表明，斜纹肌的收缩特性和工作长度范围非常不同，即使在同一个体动物的肌肉之间也是如此。 该项目将研究不同动物斜纹肌的收缩特性和工作长度范围。 这项研究可能会揭示肌肉结构和功能的基本新原理，否则这些原理将仍然晦涩难懂，并为功能多样性和这种纤维类型的进化提供新的见解。 该项目将为本科生，特别是第一代大学生和来自弱势背景的学生提供获得生理学、生物力学和科学传播经验的机会。 该项目将与缅因州水族馆探索中心合作，为 K-12 学生和公众开发项目。 该项目还将通过与北卡罗来纳大学科学与教学学士学位教育 (UNC-BEST) 项目合作影响中学教育，该项目为生物学专业的本科生提供获得北卡罗来纳州中学教师执照的机会。 尽管斜纹肌存在于至少 17 种动物门中，但这种条纹模式的功能含义仍不清楚。 早期研究表明，斜纹允许在比横纹肌更广泛的肌肉长度范围内输出高力。 然而，最近的研究表明，许多斜纹肌无法进行如此广泛的操作范围，相反，该参数存在相当大的变化。 因此，目前的理解不能作为对斜条纹功能意义的一般解释。 该研究的目的是测试一个基于肌丝阵列几何形状的数学分析的新模型，该模型表明斜条纹的进化允许调整具有静水骨骼的动物的长度-力关系。 该模型预测，可以通过改变交错角（即肌丝的交错程度）来调整长度-力关系，交错度越大，操作范围越宽。 长度力特性、体内肌肉激活和长度变化以及肌纤维超微结构的测量将用于测试模型预测并评估斜纹的功能意义。 初步研究将重点关注 Doryteuthis pealeii 鱿鱼的肌丝交错和肌肉的长度-力关系，这些肌肉的功能和工作长度范围差异很大。 此外，还将研究跨越两侧对称多样性范围的选定类群之间具有相似作用和长度-力关系的肌肉，从而确定斜纹肌的结构和功能趋同。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。

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.