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      Comparative microstructural study on the teeth of Mesozoic birds and non-avian dinosaurs


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          Although it is commonly considered that, in birds, there is a trend towards reduced dentition, teeth persisted in birds for 90 Ma and numerous macroscopic morphologies are observed. However, the extent to which the microstructure of bird teeth differs from other lineages is poorly understood. To explore the microstructural differences of the teeth of birds in comparison with closely related non-avialan dinosaurs, the enamel and dentine-related features were evaluated in four Mesozoic paravian species from the Yanliao and Jehol biotas. Different patterns of dentinal tubular tissues with mineralized extensions of the odontoblast processes were revealed through the examination of histological sectioning under electron microscopy. Secondary modification of the tubular structures, forming reactive sclerotic dentin of Longipteryx, and the mineralization of peritubular dentin of Sapeornis were observed in the mantle dentin region. The new observed features combined with other dentinal-associated ultrastructure suggest that the developmental mechanisms controlling dentin formation are quite plastic, permitting the evolution of unique morphologies associated with specialized feeding behaviours in the toothed birds. Proportionally greater functional stress placed on the stem bird teeth may have induced reactive dentin mineralization, which was observed more often within tubules of these taxa. This suggests modifications to the dentin to counteract potential failure.

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          Plasma Hsp90 levels in patients with systemic sclerosis and relation to lung and skin involvement: a cross-sectional and longitudinal study

          Our previous study demonstrated increased expression of Heat shock protein (Hsp) 90 in the skin of patients with systemic sclerosis (SSc). We aimed to evaluate plasma Hsp90 in SSc and characterize its association with SSc-related features. Ninety-two SSc patients and 92 age-/sex-matched healthy controls were recruited for the cross-sectional analysis. The longitudinal analysis comprised 30 patients with SSc associated interstitial lung disease (ILD) routinely treated with cyclophosphamide. Hsp90 was increased in SSc compared to healthy controls. Hsp90 correlated positively with C-reactive protein and negatively with pulmonary function tests: forced vital capacity and diffusing capacity for carbon monoxide (DLCO). In patients with diffuse cutaneous (dc) SSc, Hsp90 positively correlated with the modified Rodnan skin score. In SSc-ILD patients treated with cyclophosphamide, no differences in Hsp90 were found between baseline and after 1, 6, or 12 months of therapy. However, baseline Hsp90 predicts the 12-month change in DLCO. This study shows that Hsp90 plasma levels are increased in SSc patients compared to age-/sex-matched healthy controls. Elevated Hsp90 in SSc is associated with increased inflammatory activity, worse lung functions, and in dcSSc, with the extent of skin involvement. Baseline plasma Hsp90 predicts the 12-month change in DLCO in SSc-ILD patients treated with cyclophosphamide.
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            An Archaeopteryx-like theropod from China and the origin of Avialae.

            Archaeopteryx is widely accepted as being the most basal bird, and accordingly it is regarded as central to understanding avialan origins; however, recent discoveries of derived maniraptorans have weakened the avialan status of Archaeopteryx. Here we report a new Archaeopteryx-like theropod from China. This find further demonstrates that many features formerly regarded as being diagnostic of Avialae, including long and robust forelimbs, actually characterize the more inclusive group Paraves (composed of the avialans and the deinonychosaurs). Notably, adding the new taxon into a comprehensive phylogenetic analysis shifts Archaeopteryx to the Deinonychosauria. Despite only tentative statistical support, this result challenges the centrality of Archaeopteryx in the transition to birds. If this new phylogenetic hypothesis can be confirmed by further investigation, current assumptions regarding the avialan ancestral condition will need to be re-evaluated.
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              Epoxy embedding methods of Glauert and Kushida have been modified so as to yield rapid, reproducible, and convenient embedding methods for electron microscopy. The sections are robust and tissue damage is less than with methacrylate embedding.

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                R Soc Open Sci
                R Soc Open Sci
                Royal Society Open Science
                The Royal Society
                May 17, 2023
                May 2023
                May 17, 2023
                : 10
                : 5
                : 230147
                [ 1 ] Institute of Geology and Paleontology, Linyi University, , Linyi, Shandong 276000
                [ 2 ] Tianyu Natural History Museum of Shandong, , Pingyi, Shandong 273300
                [ 3 ] Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, , 142 Xi-zhi-men-wai Street, Beijing 100044
                [ 4 ] National Synchrotron Radiation Research Center, , Hsinchu 30076
                [ 5 ] Department of Geosciences, National Taiwan University, , Taipei City 10617
                [ 6 ] Negaunee Integrative Research Center, Field Museum of Natural History, , Chicago, IL 60605
                [ 7 ] Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences (IGGCAS), , Beijing 100029
                [ 8 ] Xinghai Paleontological Museum of Dalian, , Dalian, Liaoning 116023
                Author notes

                Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c.6631006.

                Author information
                © 2023 The Authors.

                Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.

                : Feburary 13, 2023
                : April 24, 2023
                Funded by: Chinese Academy of Sciences, http://dx.doi.org/10.13039/501100002367;
                Award ID: XDB26000000
                Funded by: MOST;
                Award ID: 107–2112-M-213-007
                Award ID: 110-2116-M-213-001
                Award ID: MOST 108–2116-M-213-001
                Funded by: Shandong Provincial Natural Science Foundation;
                Award ID: ZR2020MD026
                Funded by: Linyi Key Research and Development Project;
                Award ID: 2020ZX028
                Funded by: National Natural Science Foundation of China, http://dx.doi.org/10.13039/501100001809;
                Award ID: NSFC 42288201
                Funded by: NSFC;
                Award ID: 41402017
                Organismal and Evolutionary Biology
                Research Articles

                bird,non-avian dinosaur,diet,tooth,dentin,enamel
                bird, non-avian dinosaur, diet, tooth, dentin, enamel


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