Limb bone morphology, bone strength, and cursoriality in lagomorphs.
*Arm Bones/anatomy & histology/physiology; *Lagomorpha/anatomy & histology/physiology; *Leg Bones/anatomy & histology/physiology; *Tensile Strength; Animals; Bone Density/physiology; Mechanical; mechanical advantage; mineralization; Pliability; polar section modulus; robusticity; Running/*physiology; safety factor; Stress; Tomography; X-Ray Computed
The primary aim of this study is to broadly evaluate the relationship between cursoriality (i.e. anatomical and physiological specialization for running) and limb bone morphology in lagomorphs. Relative to most previous studies of cursoriality, our focus on a size-restricted, taxonomically narrow group of mammals permits us to evaluate the degree to which 'cursorial specialization' affects locomotor anatomy independently of broader allometric and phylogenetic trends that might obscure such a relationship. We collected linear morphometrics and muCT data on 737 limb bones covering three lagomorph species that differ in degree of cursoriality: pikas (Ochotona princeps, non-cursorial), jackrabbits (Lepus californicus, highly cursorial), and rabbits (Sylvilagus bachmani, level of cursoriality intermediate between pikas and jackrabbits). We evaluated two hypotheses: cursoriality should be associated with (i) lower limb joint mechanical advantage (i.e. high 'displacement advantage', permitting more cursorial species to cycle their limbs more quickly) and (ii) longer, more gracile limb bones, particularly at the distal segments (as a means of decreasing rotational inertia). As predicted, highly cursorial jackrabbits are typically marked by the lowest mechanical advantage and the longest distal segments, non-cursorial pikas display the highest mechanical advantage and the shortest distal segments, and rabbits generally display intermediate values for these variables. Variation in long bone robusticity followed a proximodistal gradient. Whereas proximal limb bone robusticity declined with cursoriality, distal limb bone robusticity generally remained constant across the three species. The association between long, structurally gracile limb bones and decreased maximal bending strength suggests that the more cursorial lagomorphs compromise proximal limb bone integrity to improve locomotor economy. In contrast, the integrity of distal limb bones is maintained with increasing cursoriality, suggesting that the safety factor takes priority over locomotor economy in those regions of the postcranial skeleton that experience higher loading during locomotion. Overall, these findings support the hypothesis that cursoriality is associated with a common suite of morphological adaptations across a range of body sizes and radiations.
Young Jesse W; Danczak Robert; Russo Gabrielle A; Fellmann Connie D
Journal of anatomy
2014
2014-10
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1111/joa.12220" target="_blank" rel="noreferrer noopener">10.1111/joa.12220</a>
Transgenic Expression of Osteoactivin/gpnmb Enhances Bone Formation In Vivo and Osteoprogenitor Differentiation Ex Vivo.
Animals; Bone and Bones/*metabolism; Bone Density/physiology; Bone Remodeling/genetics/*physiology; Bone Resorption/metabolism; Cell Differentiation/genetics/*physiology; Eye Proteins/genetics/*metabolism; Membrane Glycoproteins/genetics/*metabolism; Mice; Osteoblasts/*cytology; Osteoclasts/*cytology; Osteogenesis/genetics; Protein-Serine-Threonine Kinases/metabolism; Receptor; Receptors; Transforming Growth Factor beta/metabolism; Transforming Growth Factor-beta Type I; Transgenic
Initial identification of osteoactivin (OA)/glycoprotein non-melanoma clone B (gpnmb) was demonstrated in an osteopetrotic rat model, where OA expression was increased threefold in mutant bones, compared to normal. OA mRNA and protein expression increase during active bone regeneration post-fracture, and primary rat osteoblasts show increased OA expression during differentiation in vitro. To further examine OA/gpnmb as an osteoinductive agent, we characterized the skeletal phenotype of transgenic mouse overexpressing OA/gpnmb under the
Frara Nagat; Abdelmagid Samir M; Sondag Gregory R; Moussa Fouad M; Yingling Vanessa R; Owen Thomas A; Popoff Steven N; Barbe Mary F; Safadi Fayez F
Journal of cellular physiology
2016
2016-01
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1002/jcp.25020" target="_blank" rel="noreferrer noopener">10.1002/jcp.25020</a>