225 research outputs found

    New tools suggest a middle Jurassic origin for mammalian endothermy Advances in state-of-the-art techniques uncover new insights on the evolutionary patterns of mammalian endothermy through time

    Get PDF
    We suggest that mammalian endothermy was established amongst Middle Jurassic crown mammals, through reviewing state-of-the-art fossil and living mammal studies. This is considerably later than the prevailing paradigm, and has important ramifications for the causes, pattern, and pace of physiological evolution amongst synapsids. Most hypotheses argue that selection for either enhanced aerobic activity, or thermoregulation was the primary driver for synapsid physiological evolution, based on a range of fossil characters that have been linked to endothermy. We argue that, rather than either alternative being the primary selective force for the entirety of endothermic evolution, these characters evolved quite independently through time, and across the mammal family tree, principally as a response to shifting environmental pressures and ecological opportunities. Our interpretations can be tested using closely linked proxies for both factors, derived from study of fossils of a range of Jurassic and Cretaceous mammaliaforms and early mammals.Peer reviewe

    Encouraging Physical Activity during and after Pregnancy in the COVID-19 Era, and beyond

    Get PDF
    Physical activity is known to decline during pregnancy and the postnatal period, yet physical activity is recommended during this time due to the significant health benefits for mothers and their offspring. As a result of the COVID-19 pandemic and the restrictions imposed to reduce infection rates, pregnant and postnatal women have experienced disruption not just to their daily lives but also to their pregnancy healthcare experience and their motherhood journey with their new infant. This has included substantial changes in how, when and why they have engaged with physical activity. While some of these changes undoubtedly increased the challenge of being sufficiently active as a pregnant or postnatal woman, they have also revealed new opportunities to reach and support women and their families. This commentary details these challenges and opportunities, and highlights how researchers and practitioners can, and arguably must, harness these short-term changes for long-term benefit. This includes a call for a fresh focus on how we can engage and support those individuals and groups who are both hardest hit by COVID-19 and have previously been under-represented and under-served by antenatal and postnatal physical activity research and interventions

    Regenerating zebrafish scales express a subset of evolutionary conserved genes involved in human skeletal disease

    Get PDF
    BACKGROUND: Scales are mineralised exoskeletal structures that are part of the dermal skeleton. Scales have been mostly lost during evolution of terrestrial vertebrates whilst bony fish have retained a mineralised dermal skeleton in the form of fin rays and scales. Each scale is a mineralised collagen plate that is decorated with both matrix-building and resorbing cells. When removed, an ontogenetic scale is quickly replaced following differentiation of the scale pocket-lining cells that regenerate a scale. Processes promoting de novo matrix formation and mineralisation initiated during scale regeneration are poorly understood. Therefore, we performed transcriptomic analysis to determine gene networks and their pathways involved in dermal scale regeneration. RESULTS: We defined the transcriptomic profiles of ontogenetic and regenerating scales of zebrafish and identified 604 differentially expressed genes (DEGs). These were enriched for extracellular matrix, ossification, and cell adhesion pathways, but not in enamel or dentin formation processes indicating that scales are reminiscent to bone. Hypergeometric tests involving monogenetic skeletal disorders showed that DEGs were strongly enriched for human orthologues that are mutated in low bone mass and abnormal bone mineralisation diseases (P< 2× 10(−3)). The DEGs were also enriched for human orthologues associated with polygenetic skeletal traits, including height (P< 6× 10(−4)), and estimated bone mineral density (eBMD, P< 2× 10(−5)). Zebrafish mutants of two human orthologues that were robustly associated with height (COL11A2, P=6× 10(−24)) or eBMD (SPP1, P=6× 10(−20)) showed both exo- and endo- skeletal abnormalities as predicted by our genetic association analyses; col11a2(Y228X/Y228X) mutants showed exoskeletal and endoskeletal features consistent with abnormal growth, whereas spp1(P160X/P160X) mutants predominantly showed mineralisation defects. CONCLUSION: We show that scales have a strong osteogenic expression profile comparable to other elements of the dermal skeleton, enriched in genes that favour collagen matrix growth. Despite the many differences between scale and endoskeletal developmental processes, we also show that zebrafish scales express an evolutionarily conserved sub-population of genes that are relevant to human skeletal disease. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12915-021-01209-8

    Muscle fiber conduction velocity is more affected after eccentric than concentric exercise

    No full text
    It has been shown that mean muscle fiber conduction velocity (CV) can be acutely impaired after eccentric exercise. However, it is not known whether this applies to other exercise modes. Therefore, the purpose of this experiment was to compare the effects of eccentric and concentric exercises on CV, and amplitude and frequency content of surface electromyography (sEMG) signals up to 24 h post-exercise. Multichannel sEMG signals were recorded from biceps brachii muscle of the exercised arm during isometric maximal voluntary contraction (MVC) and electrically evoked contractions induced by motor-point stimulation before, immediately after and 2 h after maximal eccentric (ECC group, N = 12) and concentric (CON group, N = 12) elbow flexor exercises. Isometric MVC decreased in CON by 21.7 ± 12.0% (± SD, p < 0.01) and by 30.0 ± 17.7% (p < 0.001) in ECC immediately post-exercise when compared to baseline. At 2 h post-exercise, ECC showed a reduction in isometric MVC by 24.7 ± 13.7% (p < 0.01) when compared to baseline, while no significant reduction (by 8.0 ± 17.0%, ns) was observed in CON. Similarly, reduction in CV was observed only in ECC both during the isometric MVC (from baseline of 4.16 ± 0.3 to 3.43 ± 0.4 m/s, p < 0.001) and the electrically evoked contractions (from baseline of 4.33 ± 0.4 to 3.82 ± 0.3 m/s, p < 0.001). In conclusion, eccentric exercise can induce a greater and more prolonged reduction in muscle force production capability and CV than concentric exercis

    Design and Evaluation of Meningococcal Vaccines through Structure-Based Modification of Host and Pathogen Molecules

    Get PDF
    Neisseria meningitis remains a leading cause of sepsis and meningitis, and vaccines are required to prevent infections by this important human pathogen. Factor H binding protein (fHbp) is a key antigen that elicits protective immunity against the meningococcus and recruits the host complement regulator, fH. As the high affinity interaction between fHbp and fH could impair immune responses, we sought to identify non-functional fHbps that could act as effective immunogens. This was achieved by alanine substitution of fHbps from all three variant groups (V1, V2 and V3 fHbp) of the protein; while some residues affected fH binding in each variant group, the distribution of key amino underlying the interaction with fH differed between the V1, V2 and V3 proteins. The atomic structure of V3 fHbp in complex with fH and of the C-terminal barrel of V2 fHbp provide explanations to the differences in the precise nature of their interactions with fH, and the instability of the V2 protein. To develop transgenic models to assess the efficacy of non-functional fHbps, we determined the structural basis of the low level of interaction between fHbp and murine fH; in addition to changes in amino acids in the fHbp binding site, murine fH has a distinct conformation compared with the human protein that would sterically inhibit binding to fHbp. Non-functional V1 fHbps were further characterised by binding and structural studies, and shown in non-transgenic and transgenic mice (expressing chimeric fH that binds fHbp and precisely regulates complement system) to retain their immunogenicity. Our findings provide a catalogue of non-functional fHbps from all variant groups that can be included in new generation meningococcal vaccines, and establish proof-in-principle for clinical studies to compare their efficacy with wild-type fHbps
    corecore