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Integrative Organismal Biology (Oxford,... 2020Salamanders and newts (urodeles) are often used as a model system to elucidate the evolution of tetrapod locomotion. Studies range from detailed descriptions of...
Salamanders and newts (urodeles) are often used as a model system to elucidate the evolution of tetrapod locomotion. Studies range from detailed descriptions of musculoskeletal anatomy and segment kinematics, to bone loading mechanics and inferring central pattern generators. A further area of interest has been muscle activity patterns, measured through electromyography (EMG). However, most prior EMG work has primarily focused on muscles of the forelimb or hindlimb in specific species or the axial system in others. Here we present data on forelimb, hindlimb, and epaxial muscle activity patterns in one species, , during steady state walking. The data are calibrated to limb stride cycle events (stance phase, swing phase), allowing direct comparisons to homologous muscle activation patterns recorded for other walking tetrapods (e.g., lizards, alligators, turtles, mammals). Results demonstrate that has similar walking kinematics and muscle activity patterns to other urodele species, but that interspecies variation does exist. In the forelimb, both the and are active for 80% of the forelimb swing phase, while the is active at the swing-stance phase transition and continues through 86% of the stance phase. In the hindlimb, both the and are active for 30% of the hindlimb swing phase, while the is active 65% through the swing phase and remains active for most of the stance phase. With respect to the axial system, both the anterior and posterior display two activation bursts, a pattern consistent with stabilization and rotation of the pectoral and pelvic girdles. In support of previous assertions, comparison of muscle activity timings to other walking tetrapods revealed broad-scale similarities, potentially indicating conservation of some aspects of neuromuscular function across tetrapods. Our data provide the foundation for building and testing dynamic simulations of fire salamander locomotor biomechanics to better understand musculoskeletal function. They could also be applied to future musculoskeletal simulations of extinct species to explore the evolution of tetrapod locomotion across deep-time.
PubMed: 33791558
DOI: 10.1093/iob/obaa015 -
Journal of Anatomy Oct 2016In fish, the pectoral appendage is adjacent to the head, but during vertebrate evolution a long neck region emerged via caudal relocation of the pectoral appendage. The...
In fish, the pectoral appendage is adjacent to the head, but during vertebrate evolution a long neck region emerged via caudal relocation of the pectoral appendage. The pectoral appendage is comprised of endochondral portions, such as the humerus and the scapula, and a dermal portion, such as the clavicle, that contributes to the shoulder girdle. In the search for clues to the mechanism of the caudal relocation of the pectoral appendage, the cell lineage of the rostral lateral plate mesoderm was analyzed in chickens. It was found that, despite the long neck region in chickens, the origin of the clavicle attached to the head mesoderm ranged between 1 and 14 somite levels. Because the pectoral limb bud and the endochondral pectoral appendage developed on 15-20 and 15-24 somite levels, respectively, the clavicle-forming region corresponds to the embryonic neck, which suggests that the relocation would have been executed by the expansion of the source of the clavicle. The rostral portion of the clavicle-forming region overlaps the source of the cucullaris muscle, embraces the pharyngeal arches caudally, and can be experimentally replaced with the head mesoderm to form the cucullaris muscle, which implies that the mesodermal portion could have been the head mesoderm and that the clavicle would have developed at the head/trunk boundary. The link between the head mesoderm and the presumptive clavicle appears to have been the developmental constraint needed to create the evolutionarily conserved musculoskeletal connectivities characterizing the gnathostome neck. In this sense, the dermal girdle of the ganathostomes would represent the wall of the branchial chamber into which the endochondral pectoral appendage appears to have attached since its appearance in evolution.
Topics: Animals; Biological Evolution; Chick Embryo; Chickens; Clavicle; Mesoderm; Neck; Vertebrates
PubMed: 27279028
DOI: 10.1111/joa.12502 -
Molecular Ecology Jan 2021Phenotypic integration is an important metric that describes the degree of covariation among traits in a population, and is hypothesized to arise due to selection for...
Phenotypic integration is an important metric that describes the degree of covariation among traits in a population, and is hypothesized to arise due to selection for shared functional processes. Our ability to identify the genetic and/or developmental underpinnings of integration is marred by temporally overlapping cell-, tissue- and structure-level processes that serve to continually 'overwrite' the structure of covariation among traits through ontogeny. Here, we examine whether traits that are integrated at the phenotypic level also exhibit a shared genetic basis (e.g. pleiotropy). We micro-CT scanned two hard tissue traits, and two soft tissue traits (mandible, pectoral girdle, atrium and ventricle, respectively) from an F hybrid population of Lake Malawi cichlids, and used geometric morphometrics to extract 3D shape information from each trait. Given the large degree of asymmetric variation that may reflect developmental instability, we separated symmetric from asymmetric components of shape variation. We then performed quantitative trait loci (QTL) analysis to determine the degree of genetic overlap between shapes. While we found ubiquitous associations among traits at the phenotypic level, except for a handful of notable exceptions, our QTL analysis revealed few overlapping genetic regions. Taken together, this indicates developmental interactions can play a large role in determining the degree of phenotypic integration among traits, and likely obfuscate the genotype to phenotype map, limiting our ability to gain a comprehensive picture of the genetic contributors responsible for phenotypic divergence.
Topics: Animals; Cichlids; Genotype; Phenotype; Quantitative Trait Loci
PubMed: 33231336
DOI: 10.1111/mec.15748 -
Integrative Organismal Biology (Oxford,... 2019Mature skates (Batoidea: Rajoidei) display a unique form of sexual dimorphism in which males develop a concave anterior pectoral fin, giving them a bell-shaped...
Mature skates (Batoidea: Rajoidei) display a unique form of sexual dimorphism in which males develop a concave anterior pectoral fin, giving them a bell-shaped appearance. Recent work has linked the male-specific transformation to differential skeletal development that is coincident with the rapid elongation of claspers, cartilage-supported intromittent organs. Still, little is known about the prevalence of pectoral dimorphism across skates or of interspecific variation in its expression. Here, we use various morphological approaches to broadly explore pectoral dimorphism in skates, with the goal of understanding its significance in their evolutionary history. We find that pectoral fin sexual dimorphism exists across skate diversity, positively identifying its presence in at least 131 species spanning 33 genera, approximately 40% of valid species. Further, we show that the nature of male-female shape change is largely consistent across species, but that it differs in its magnitude at a biologically meaningful scale. Finally, we use the pygmy skate as a case study to illustrate ontogenetic patterns in the development of pectoral fin dimorphism, additionally identifying sex-based differences in the pelvic girdle and jaw. Our work suggests that the diversity of pectoral dimorphism in skates is linked to comparative growth and maturation, and potentially to processes underlying reproductive and life history diversification within the group.
PubMed: 33791527
DOI: 10.1093/iob/obz012 -
PeerJ 2020The evolution of upright limb posture in mammals may have enabled modifications of the forelimb for diverse locomotor ecologies. A rich fossil record of non-mammalian...
The evolution of upright limb posture in mammals may have enabled modifications of the forelimb for diverse locomotor ecologies. A rich fossil record of non-mammalian synapsids holds the key to unraveling the transition from "sprawling" to "erect" limb function in the precursors to mammals, but a detailed understanding of muscle functional anatomy is a necessary prerequisite to reconstructing postural evolution in fossils. Here we characterize the gross morphology and internal architecture of muscles crossing the shoulder joint in two morphologically-conservative extant amniotes that form a phylogenetic and morpho-functional bracket for non-mammalian synapsids: the Argentine black and white tegu and the Virginia opossum . By combining traditional physical dissection of cadavers with nondestructive three-dimensional digital dissection, we find striking similarities in muscle organization and architectural parameters. Despite the wide phylogenetic gap between our study species, distal muscle attachments are notably similar, while differences in proximal muscle attachments are driven by modifications to the skeletal anatomy of the pectoral girdle that are well-documented in transitional synapsid fossils. Further, correlates for force production, physiological cross-sectional area (PCSA), muscle gearing (pennation), and working range (fascicle length) are statistically indistinguishable for an unexpected number of muscles. Functional tradeoffs between force production and working range reveal muscle specializations that may facilitate increased girdle mobility, weight support, and active stabilization of the shoulder in the opossum-a possible signal of postural transformation. Together, these results create a foundation for reconstructing the musculoskeletal anatomy of the non-mammalian synapsid pectoral girdle with greater confidence, as we demonstrate by inferring shoulder muscle PCSAs in the fossil non-mammalian cynodont .
PubMed: 32117627
DOI: 10.7717/peerj.8556 -
Integrative Organismal Biology (Oxford,... 2021Lateral undulation and trunk flexibility offer performance benefits to maneuverability, stability, and stride length (via speed and distance traveled). These benefits...
Lateral undulation and trunk flexibility offer performance benefits to maneuverability, stability, and stride length (via speed and distance traveled). These benefits make them key characteristics of the locomotion of tetrapods with sprawling posture, with the exception of turtles. Despite their bony carapace preventing lateral undulations, turtles are able to improve their locomotor performance by increasing stride length via greater limb protraction. The goal of this study was to quantify the effect of reduced lateral flexibility in a generalized sprawling tetrapod, the tiger salamander (). We had two potential predictions: (1) either salamanders completely compensate by changing their limb kinematics, or (2) their performance (i.e., speed) will suffer due to the reduced lateral flexibility. This reduction was performed by artificially limiting trunk flexibility by attaching a 2-piece shell around the body between the pectoral and pelvic girdles. Adult tiger salamanders ( = 3; SVL = 9-14.5 cm) walked on a 1-m trackway under three different conditions: unrestricted, flexible shell (Tygon tubing), and rigid shell (PVC tubing). Trials were filmed in a single, dorsal view, and kinematics of entire midline and specific body regions (head, trunk, tail), as well as the fore and hind limbs, were calculated. Tygon individuals had significantly higher curvature than both PVC and unrestricted individuals for the body, but this trend was primarily driven by changes in tail movements. PVC individuals had significantly lower curvature in the trunk region compared with unrestricted individuals or Tygon; however, there was no difference between unrestricted and Tygon individuals suggesting the shells performed as expected. PVC and Tygon individuals had significantly higher curvature in the tails compared with unrestricted individuals. There were no significant differences for any limb kinematic variables among treatments including average, minimum, and maximum angles. Thus, salamanders respond to decreased lateral movement in their trunk by increasing movements in their tail, without changes in limb kinematics. These results suggest that tail undulations may be a more critical component to sprawling-postured tetrapod locomotion than previously recognized.
PubMed: 34708185
DOI: 10.1093/iob/obab029 -
Molecular Genetics and Metabolism Dec 2014Mottled-dappled (Mo-dp) is a mouse model of Menkes disease caused by a large, previously uncharacterized deletion in the 5' region of Atp7a, the mouse ortholog of ATP7A....
Mottled-dappled (Mo-dp) is a mouse model of Menkes disease caused by a large, previously uncharacterized deletion in the 5' region of Atp7a, the mouse ortholog of ATP7A. Affected mutants die in utero at embryonic day 17, and show bending and thickening of the ribs and distortion of the pectoral and pelvic girdles and limbs. To characterize this allele, we designed a custom 4x180K microarray on the mouse X chromosome and performed comparative genomic hybridization using extracted DNA from normal and carrier Mo-dp females, and identified an approximately 9 kb deletion. We used PCR to fine-map the breakpoints and amplify a junction fragment of 630 bp. Sequencing of the junction fragment disclosed the exact breakpoint locations and that the Mo-dp deletion is precisely 8990 bp, including approximately 2 kb in the promoter region of Atp7a. Western blot analysis of Mo-dp heterozygous brains showed diminished amounts of Atp7a protein, consistent with reduced expression due to the promoter region deletion on one allele. In heterozygous females, brain copper levels tended to be lower compared to wild type whereas neurochemical analyses revealed higher dihydroxyphenylacetic acid:dihydroxyphenylglycol (DOPAC:DHPG) and dopamine:norepinephrine (DA:NE) ratios compared to normal (P=0.002 and 0.029, respectively), consistent with partial deficiency of dopamine-beta-hydroxylase, a copper-dependent enzyme. Heterozygous females showed no significant differences in body weight compared to wild type females. Our results delineate the molecular details of the Mo-dp mutation for the first time and define novel biochemical findings in heterozygous female carriers of this allele.
Topics: Adenosine Triphosphatases; Alleles; Animals; Blotting, Western; Body Weight; Brain; Cation Transport Proteins; Comparative Genomic Hybridization; Copper; Copper-Transporting ATPases; Disease Models, Animal; Dopamine beta-Hydroxylase; Female; Heterozygote; Humans; Menkes Kinky Hair Syndrome; Mice; Oligonucleotide Array Sequence Analysis; Phenotype; Polymerase Chain Reaction; Sequence Analysis, DNA; Sequence Deletion; X Chromosome
PubMed: 25456742
DOI: 10.1016/j.ymgme.2014.10.001 -
Journal of Clinical Orthopaedics and... May 2021Sprengel deformity is a rare congenital anomaly of the pectoral girdle of unknown incidence. Surgical intervention is indicated in moderate to severe cases having...
Sprengel deformity is a rare congenital anomaly of the pectoral girdle of unknown incidence. Surgical intervention is indicated in moderate to severe cases having functional and cosmetic impairment. Various surgical corrective procedures have evolved over the past decades, however the extensive magnitude of some of the surgical techniques have sometimes resulted in an unwarranted worse outcome due to associated complications like brachial plexus palsy, scapular winging, sternoclavicular joint prominence, improper scar healing and keloid formation which restrict such procedures to experienced hands at few centres. We report a case of Cavendish grade 3 Sprengel deformity in a five-year-old boy managed with a minimally aggressive modified technique of preserving the trapezius and restricting the surgery to excision of omovertebral bar and supraspinatous part of scapula by a transverse incision overlying the spine of scapula. In Sprengel deformity, the trapezius attached to the elevated scapula is underdeveloped and the technique of retraction instead of detachment of this muscle during surgery, can prevent scar adhesions and improve wound healing. In our patient, satisfactory cosmetic correction and good functional shoulder movements were achieved with minimal intervention.
PubMed: 33717937
DOI: 10.1016/j.jcot.2020.12.009 -
Archives of Rheumatology Dec 2020Polymyositis (PM) is an autoimmune disease progressing in the form of a break down of the muscles that is induced by chronic inflammation in skeletal muscles. Muscle...
Polymyositis (PM) is an autoimmune disease progressing in the form of a break down of the muscles that is induced by chronic inflammation in skeletal muscles. Muscle weakness is painless and concentrates on proximal muscles, involving the pectoral and pelvic girdle. If the disease is not treated properly, it may progress and lead to a considerable decrease in the quality of life. Its conventional treatment involves drugs that suppress inflammation such as steroids, methotrexate, azathioprine, and intravenous immunoglobulin. However, conventional treatment may prove insufficient to halt the progression of the disease and offer only a limited improvement because of the adverse effects it causes in some patients. In this article, we present a 48-year-old female patient diagnosed with PM nearly 13 years ago that did not sufficiently respond to the pharmaceutical agents that were indicated for the conventional treatment of the disease and developed femoral head avascular necrosis because of the treatment and was, in the end, successfully treated with abatacept monotherapy at our clinic.
PubMed: 33758820
DOI: 10.46497/ArchRheumatol.2020.7406 -
PeerJ 2017Australian Oligo-Miocene mekosuchines (Crocodylia; Crocodyloidea) display wide diversity in cranial shape and inferred hunting strategies. Terrestrial habitus has been...
Australian Oligo-Miocene mekosuchines (Crocodylia; Crocodyloidea) display wide diversity in cranial shape and inferred hunting strategies. Terrestrial habitus has been inferred for these distinctive predators. A direct morphological signal for locomotion can be expected in the postcrania, particularly the pelvic and pectoral girdles. Here we describe fossil materials of the girdles, which chart their morphological variation in the subfamily from Eocene through to Middle Miocene. Over this period, both girdles undergo significant morphological changes. Notably, an enclosed, ventrally orientated acetabulum in the ilium is developed in one lineage. This recapitulates the erect parasagittal configuration of the pelvic limb seen in many Mesozoic crocodylomorph lineages, suggesting consistent use of erect high-walking in these mekosuchines. Other pelves from the same Oligo-Miocene deposits display morphology closer to modern crocodilians, suggesting a partitioning of locomotory strategy among sympatric mekosuchines. Plesiomorphic and derived pelvic girdles are distinguishable by parsimony analysis, and the earliest examples of the mekosuchine pelvis more closely resemble gavialids and alligatorids while latter forms converge on crown group crocodylids in the morphology of the iliac crest. This suggests that a revaluation of the base relationship of Mekosuchinae within Eusuchia is necessary.
PubMed: 28674657
DOI: 10.7717/peerj.3501