More Like this

1. Relative hindlimb length and hindlimb segmental proportions as indicators of locomotor category in primates, rodents, and tree shrews

   Yapuncich GS, Hegarty E (March 2022, American journal of biological anthropology)

   Leaping is an important locomotor behavior for arboreal taxa such as primates, providing means to cross discontinuous substrates, escape predation, and/or capture prey. Primates that leap frequently have relatively longer hindlimbs than those taxa that leap less often. However, it is unknown if this pattern holds across a broader phylogenetic sample that includes non-primate arboreal taxa and non-primate specialized leapers. Here, we examine if relative hindlimb length and segmental proportions correlate with locomotor category across a sample of small-bodied (800g) mammals. Lengths of six hindlimb elements (summing to total hindlimb length) were measured on micro-computed tomography scans. Total hindlimb length was regressed against body mass to calculate relative hindlimb length. Segmental proportions were calculated as the ratio of femoral, tibial, and pedal (the sum of calcaneal, cuboidal, metatarsal, and phalangeal lengths) lengths to total hindlimb length. We found that while three arboreal/scansorial taxa (common marmosets, greater dwarf lemurs, and palm squirrels) exhibit short hindlimbs relative to their body mass, all other arboreal and scansorial taxa have relatively long hindlimbs. Most arboreal, scansorial, terrestrial, and fossorial taxa distribute length evenly across segments (femur, tibia, and pes each comprise 33% of total hindlimb length). Saltatorialists (e.g., jerboas and kangaroo rats) were the only locomotor group with exceptional proportions, with pedal segments contributing 38% of total hindlimb length. These results suggest to us that segmental proportions may distinguish specialized ricochetal hoppers from taxa that leap sporadically, while relative hindlimb length may predict general leaping ability across mammals. 

   more » « less
2. Development of a Robotic Rat Hindlimb Model

   Aronhalt, E. (July 2023, Cham: Springer Nature Switzerland.)

   Aronhalt, E., Abramson, E., Goldsmith, C., Andrada, E., Nourse, W., Sutton, G., Szczecinski, N. S., & Quinn, R. D. (2023, July). Development of a Robotic Rat Hindlimb Model. In Conference on Biomimetic and Biohybrid Systems (pp. 115-130). Cham: Springer Nature Switzerland. 

   more » « less
3. VCA supercooling in a swine partial hindlimb model

   https://doi.org/10.1038/s41598-024-63041-8  

   Berkane, Yanis; Filz_von_Reiterdank, Irina; Tawa, Pierre; Charlès, Laura; Goutard, Marion; Dinicu, Antonia_T; Toner, Mehmet; Bertheuil, Nicolas; Mink_van_der_Molen, Aebele_B; Coert, J_Henk; et al (June 2024, Scientific Reports)

   Abstract Vascularized composite allotransplantations are complex procedures with substantial functional impact on patients. Extended preservation of VCAs is of major importance in advancing this field. It would result in improved donor-recipient matching as well as the potential for ex vivo manipulation with gene and cell therapies. Moreover, it would make logistically feasible immune tolerance induction protocols through mixed chimerism. Supercooling techniques have shown promising results in multi-day liver preservation. It consists of reaching sub-zero temperatures while preventing ice formation within the graft by using various cryoprotective agents. By drastically decreasing the cell metabolism and need for oxygen and nutrients, supercooling allows extended preservation and recovery with lower ischemia–reperfusion injuries. This study is the first to demonstrate the supercooling of a large animal model of VCA. Porcine hindlimbs underwent 48 h of preservation at − 5 °C followed by recovery and normothermic machine perfusion assessment, with no issues in ice formation and favorable levels of injury markers. Our findings provide valuable preliminary results, suggesting a promising future for extended VCA preservation. 

   more » « less
4. Canonical Motor Microcircuit for Control of a Rat Hindlimb

   https://doi.org/10.1007/978-3-031-20470-8_31  

   Jackson, C.; Nourse, W.; Heckman, C.; Tresch, M.; Quinn, R. (December 2022, Biomimetic and Biohybrid Systems)

   This work focuses on creating a controller for the hip joint of a rat using a canonical motor microcircuit. It is thought that this circuit acts to modulate motor neuron activity at the output stage. We first created a simplified biomechanical model of a rat hindlimb along with a neural model of the circuit in a software tool called Animatlab. The canonical motor microcircuit controller was then tuned such that the trajectory of the hip joint was similar to that of a rat during locomotion. This work describes a successful method for hand-tuning the various synaptic parameters and the influence of Ia feedback on motor neuron activity. The neuromechanical model will allow for further analysis of the circuit, specifically, the function and significance of Ia feedback and Renshaw cells. 

   more » « less
5. RECONSTRUCTIONS OF HINDLIMB MUSCULATURE IN EXTINCT PRE-THERIAN SYNAPSIDS

   https://doi.org/10.3099/MCZ82  

   Bishop, P J; Pierce, S E (October 2024, Bulletin of the Museum of Comparative Zoology)

   Previously, the authors published a framework for phylogenetically informed reconstruction of appendicular musculature in extinct synapsids. In the present study, this framework is employed to rigorously infer the arrangement of muscles in the hindlimb of eight exemplar taxa that capture the evolutionary transformation from basal synapsids to crown therians. Muscle maps detailing origins and insertions are presented for each taxon. These will aid the interpretation of fossil material in the future, especially fragmentary remains of related species, and provide a foundation for functional analysis of the appendicular skeleton and its evolution. 

   more » « less