RUI: Body Size, Limb Posture and Muscle Strain During Terrestrial Locomotion

身体大小、肢体姿势和陆地运动时的肌肉劳力。四足哺乳动物体型差异很大，通常在运动时采取不同的肢体姿势。小动物采用蜷缩的姿势，四肢更弯曲，而大型动物采用直立的姿势，四肢相对挺直。尽管我们了解肢体结构的这种比例，但我们对这种姿势差异如何影响不同大小动物的同源肢体肌肉的行为知之甚少。事实上，我们对四足哺乳动物肢体肌肉在体内的行为知之甚少；因为没有一种动物的髋关节、膝关节和踝关节伸肌的动作能很好地解释任何步态。拟议的工作包括研究长度变化和主要后肢肌肉的激活模式，选择在大小上差异很大的哺乳动物物种。两种实验方法将被用来探讨身体大小和肢体姿势如何影响肢体肌肉功能在运动。首先，使用声速测量法和肌电图，将测量和比较三个数量级以上的多种啮齿类动物（小鼠到水豚）肢体肌肉的张力和激活模式。数据将被用来检验一个普遍的假设，即在大小和肢体姿势不同的近亲动物中，同源肌肉的功能不同。在第二种方法中，肢体姿势、肌肉结构和肌肉劳损和激活模式将在几个哺乳动物物种的个体发生中被表征。这种方法将解决在生长过程中发生的大小变化是否以类似于各种哺乳动物物种之间进化出的大小差异的方式影响肢体肌肉。总之，这些不同的方法将(1)提供关于整个哺乳动物后肢肌肉在运动过程中如何在体内运作的关键见解；(2)将有助于阐明动物大小在个体发育和跨系统发育中塑造单个肢体肌肉动作的重要性。拟议的工作还将产生更广泛的影响，为对生物科学感兴趣的有才华的年轻女性提供研究机会。PI在一所单一性别的机构工作，每年有两名学生将在项目上合作，学习有价值的研究技能，在国家会议上展示他们的工作成果，并共同撰写论文。

RUI: Body Size, Limb Posture and Muscle Strain During Terrestrial LocomotionGary B. GillisMount Holyoke CollegeQuadrupedal mammals that differ greatly in size generally adopt distinct limb postures during locomotion. Small animals use a crouched posture with their limbs held more flexed while large animals use a more upright posture with their limbs held relatively straight. Despite our understanding of this scaling of limb configuration, we know little about how such postural differences influence the actions of homologous limb muscles in animals of varying size. Indeed, we have little appreciation for the in vivo behavior of quadrupedal mammalian limb muscles more generally; for no animal are actions of a hip, knee and ankle extensor well understood for any gait. The proposed work involves studying patterns of length change and activation in major hindlimb muscles of select mammalian species that differ widely in size. Two experimental approaches will be used to explore how body size and limb posture affect limb muscle function during locomotion. First, using sonomicrometry and electromyography, strain and activation patterns will be measured and compared among limb muscles of multiple rodent species ranging in size over three orders of magnitude (mice to capybara). Data will be used to test the general hypothesis that homologous muscles function differently in closely related animals that differ in size and limb posture. In the second approach, limb posture, muscle architecture and patterns of muscle strain and activation will be characterized in several mammal species over ontogeny. This approach will address whether changes in size that occur during growth influence limb muscles in a manner similar to size differences that have evolved among various mammalian species. Together, these distinct approaches will (1) provide critical insight into how muscles throughout the mammalian hindlimb operate in vivo during locomotion and (2) will help clarify the importance of animal size in shaping the actions of individual limb muscles both through ontogeny and across phylogeny. The proposed work will also have the broader impact of fostering research opportunities for talented young women interested in the biological sciences. The PI works at a single-gender institution and two students each year will collaborate on the projects, learning valuable research skills, presenting results from their work at national meetings, and co-authoring papers.