The timescale of early land plant evolution Morris, Jennifer L.; Puttick, Mark N.; Clark, James W. ...
Proceedings of the National Academy of Sciences - PNAS,
03/2018, Letnik:
115, Številka:
10
Journal Article
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Establishing the timescale of early land plant evolution is essential for testing hypotheses on the coevolution of land plants and Earth’s System. The sparseness of early land plant megafossils and ...stratigraphic controls on their distribution make the fossil record an unreliable guide, leaving only the molecular clock. However, the application of molecular clock methodology is challenged by the current impasse in attempts to resolve the evolutionary relationships among the living bryophytes and tracheophytes. Here, we establish a timescale for early land plant evolution that integrates over topological uncertainty by exploring the impact of competing hypotheses on bryophyte−tracheophyte relationships, among other variables, on divergence time estimation. We codify 37 fossil calibrations for Viridiplantae following best practice. We apply these calibrations in a Bayesian relaxed molecular clock analysis of a phylogenomic dataset encompassing the diversity of Embryophyta and their relatives within Viridiplantae. Topology and dataset sizes have little impact on age estimates, with greater differences among alternative clock models and calibration strategies. For all analyses, a Cambrian origin of Embryophyta is recovered with highest probability. The estimated ages for crown tracheophytes range from Late Ordovician to late Silurian. This timescale implies an early establishment of terrestrial ecosystems by land plants that is in close accord with recent estimates for the origin of terrestrial animal lineages. Biogeochemical models that are constrained by the fossil record of early land plants, or attempt to explain their impact, must consider the implications of a much earlier, middle Cambrian–Early Ordovician, origin.
The morphology of plant fossils from the Rhynie chert has generated longstanding questions about vascular plant shoot and leaf evolution, for instance, which morphologies were ancestral within land ...plants, when did vascular plants first arise and did leaves have multiple evolutionary origins? Recent advances combining insights from molecular phylogeny, palaeobotany and evo–devo research address these questions and suggest the sequence of morphological innovation during vascular plant shoot and leaf evolution. The evidence pinpoints testable developmental and genetic hypotheses relating to the origin of branching and indeterminate shoot architectures prior to the evolution of leaves, and demonstrates underestimation of polyphyly in the evolution of leaves from branching forms in ‘telome theory’ hypotheses of leaf evolution. This review discusses fossil, developmental and genetic evidence relating to the evolution of vascular plant shoots and leaves in a phylogenetic framework.
This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.
The evolutionary emergence of land plant body plans transformed the planet. However, our understanding of this formative episode is mired in the uncertainty associated with the phylogenetic ...relationships among bryophytes (hornworts, liverworts, and mosses) and tracheophytes (vascular plants). Here we attempt to clarify this problem by analyzing a large transcriptomic dataset with models that allow for compositional heterogeneity between sites. Zygnematophyceae is resolved as sister to land plants, but we obtain several distinct relationships between bryophytes and tracheophytes. Concatenated sequence analyses that can explicitly accommodate site-specific compositional heterogeneity give more support for a mosses-liverworts clade, “Setaphyta,” as the sister to all other land plants, and weak support for hornworts as the sister to all other land plants. Bryophyte monophyly is supported by gene concatenation analyses using models explicitly accommodating lineage-specific compositional heterogeneity and analyses of gene trees. Both maximum-likelihood analyses that compare the fit of each gene tree to proposed species trees and Bayesian supertree estimation based on gene trees support bryophyte monophyly. Of the 15 distinct rooted relationships for embryophytes, we reject all but three hypotheses, which differ only in the position of hornworts. Our results imply that the ancestral embryophyte was more complex than has been envisaged based on topologies recognizing liverworts as the sister lineage to all other embryophytes. This requires many phenotypic character losses and transformations in the liverwort lineage, diminishes inconsistency between phylogeny and the fossil record, and prompts re-evaluation of the phylogenetic affinity of early land plant fossils, the majority of which are considered stem tracheophytes.
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•Early land plant relationships are extremely uncertain•We resolve the “Setaphyta” clade of liverworts plus mosses•The simple body plan of liverworts results from loss of ancestral characters•The ancestral land plant was more complex
Puttick et al. resolve a “Setaphyta” clade uniting liverworts and mosses and support for bryophyte monophyly. Their results indicate that the ancestral land plant was more complex than has been envisaged based on phylogenies recognizing liverworts as the sister lineage to all other embryophytes.
Abstract Background/Aim Three-dimensional kinematic measures of gait are routinely used in clinical gait analysis and provide a key outcome measure for gait research and clinical practice. This ...systematic review identifies and evaluates current evidence for the inter-session and inter-assessor reliability of three-dimensional kinematic gait analysis (3DGA) data. Method A targeted search strategy identified reports that fulfilled the search criteria. The quality of full-text reports were tabulated and evaluated for quality using a customised critical appraisal tool. Results Fifteen full manuscripts and eight abstracts were included. Studies addressed both within-assessor and between-assessor reliability, with most examining healthy adults. Four full-text reports evaluated reliability in people with gait pathologies. The highest reliability indices occurred in the hip and knee in the sagittal plane, with lowest errors in pelvic rotation and obliquity and hip abduction. Lowest reliability and highest error frequently occurred in the hip and knee transverse plane. Methodological quality varied, with key limitations in sample descriptions and strategies for statistical analysis. Reported reliability indices and error magnitudes varied across gait variables and studies. Most studies providing estimates of data error reported values (S.D. or S.E.) of less than 5°, with the exception of hip and knee rotation. Conclusion This review provides evidence that clinically acceptable errors are possible in gait analysis. Variability between studies, however, suggests that they are not always achieved.
50 I. 50 II. 52 III. 53 IV. 66 V. 71 VI. 72 VII. 74 75 References 75 SUMMARY: Cryptospores, recovered from Ordovician through Devonian rocks, differ from trilete spores in possessing distinctive ...configurations (i.e. hilate monads, dyads, and permanent tetrads). Their affinities are contentious, but knowledge of their relationships is essential to understanding the nature of the earliest land flora. This review brings together evidence about the source plants, mostly obtained from spores extracted from minute, fragmented, yet exceptionally anatomically preserved fossils. We coin the term ‘cryptophytes’ for plants that produced the cryptospores and show them to have been simple terrestrial organisms of short stature (i.e. millimetres high). Two lineages are currently recognized. Partitatheca shows a combination of characters (e.g. spo‐rophyte bifurcation, stomata, and dyads) unknown in plants today. Lenticulatheca encompasses discoidal sporangia containing monads formed from dyads with ultrastructure closer to that of higher plants, as exemplified by Cooksonia. Other emerging groupings are less well characterized, and their precise affinities to living clades remain unclear. Some may be stem group embryophytes or tracheophytes. Others are more closely related to the bryophytes, but they are not bryophytes as defined by extant representatives. Cryptophytes encompass a pool of diversity from which modern bryophytes and vascular plants emerged, but were competitively replaced by early tracheophytes. Sporogenesis always produced either dyads or tetrads, indicating strict genetic control. The long‐held consensus that tetrads were the archetypal condition in land plants is challenged.
Summary
The earliest evidence for land plants comes from dispersed cryptospores from the Ordovician, which dominated assemblages for 60 million years. Direct evidence of their parent plants comes ...from minute fossils in Welsh Borderland Upper Silurian to Lower Devonian rocks. We recognize a group that had forking, striated axes with rare stomata terminating in valvate sporangia containing permanent cryptospores, but their anatomy was unknown especially regarding conducting tissues.
Charcoalified fossils extracted from the rock using HF were selected from macerates and observed using scanning electron microscopy. Promising examples were split for further examination and compared with electron micrographs of the anatomy of extant bryophytes.
Fertile fossil axes possess central elongate cells with thick walls bearing globules, occasional strands and plasmodesmata‐sized pores. The anatomy of these cells best matches desiccation‐tolerant food‐conducting cells (leptoids) of bryophytes. Together with thick‐walled epidermal cells and extremely small size, these features suggest that these plants were poikilohydric.
Our new data on conducting cells confirms a combination of characters that distinguish the permanent cryptospore‐producers from bryophytes and tracheophytes. We therefore propose the erection of a new group, here named the Eophytidae (eophytes).
See also the Commentary on this article by Tomescu, 233: 1018–1021.
The Janus kinase (JAK) family of tyrosine kinases includes JAK1, JAK2, JAK3 and TYK2, and is required for signaling through Type I and Type II cytokine receptors. CP-690,550 is a potent and selective ...JAK inhibitor currently in clinical trials for rheumatoid arthritis (RA) and other autoimmune disease indications. In RA trials, dose-dependent decreases in neutrophil counts (PBNC) were observed with CP-690,550 treatment. These studies were undertaken to better understand the relationship between JAK selectivity and PBNC decreases observed with CP-690,550 treatment.
Potency and selectivity of CP-690,550 for mouse, rat and human JAKs was evaluated in a panel of in vitro assays. The effect of CP-690,550 on granulopoiesis from progenitor cells was also assessed in vitro using colony forming assays. In vivo the potency of orally administered CP-690,550 on arthritis (paw edema), plasma cytokines, PBNC and bone marrow differentials were evaluated in the rat adjuvant-induced arthritis (AIA) model.
CP-690,550 potently inhibited signaling through JAK1 and JAK3 with 5-100 fold selectivity over JAK2 in cellular assays, despite inhibiting all four JAK isoforms with nM potency in in vitro enzyme assays. Dose-dependent inhibition of paw edema was observed in vivo with CP-690,550 treatment. Plasma cytokines (IL-6 and IL-17), PBNC, and bone marrow myeloid progenitor cells were elevated in the context of AIA disease. At efficacious exposures, CP-690,550 returned all of these parameters to pre-disease levels. The plasma concentration of CP-690,550 at efficacious doses was above the in vitro whole blood IC50 of JAK1 and JAK3 inhibition, but not that of JAK2.
Results from this investigation suggest that CP-690,550 is a potent inhibitor of JAK1 and JAK3 with potentially reduced cellular potency for JAK2. In rat AIA, as in the case of human RA, PBNC were decreased at efficacious exposures of CP-690,550. Inflammatory end points were similarly reduced, as judged by attenuation of paw edema and cytokines IL-6 and IL-17. Plasma concentration at these exposures was consistent with inhibition of JAK1 and JAK3 but not JAK2. Decreases in PBNC following CP-690,550 treatment may thus be related to attenuation of inflammation and are likely not due to suppression of granulopoiesis through JAK2 inhibition.
An adaptive immune response triggered by obesity is characterized by the activation of adipose tissue CD4+ T cells by unclear mechanisms. We have examined whether interactions between adipose tissue ...macrophages (ATMs) and CD4+ T cells contribute to adipose tissue metainflammation. Intravital microscopy identifies dynamic antigen-dependent interactions between ATMs and T cells in visceral fat. Mice deficient in major histocompatibility complex class II (MHC II) showed protection from diet-induced obesity. Deletion of MHC II expression in macrophages led to an adipose tissue-specific decrease in the effector/memory CD4+ T cells, attenuation of CD11c+ ATM accumulation, and improvement in glucose intolerance by increasing adipose tissue insulin sensitivity. Ablation experiments demonstrated that the maintenance of proliferating conventional T cells is dependent on signals from CD11c+ ATMs in obese mice. These studies demonstrate the importance of MHCII-restricted signals from ATMs that regulate adipose tissue T cell maturation and metainflammation.
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•Adipose tissue T cells dynamically interact with ATMs•MHCII in ATMs is required to generate effector/memory T cells with obesity•MHC II in resident ATMs is required for obesity-induced insulin resistance•Ablation of CD11c+ ATMs in obesity attenuates conventional T cell proliferation
Obesity triggers an innate and adaptive immune response in adipose tissue, but little is known about how these signals are coordinated. Cho et al. demonstrate the importance of MHC II class-restricted signals from adipose tissue macrophages in controlling obesity-induced T cell activation and the development of insulin resistance. Loss of MHC II from resident tissue macrophages is sufficient to prevent the generation of active effector/memory T cells identifying a target for intervention in metainflammation.
Abstract This systematic review critically evaluates the literature to identify the demographic and clinical factors that predict the health-related quality of life (HRQOL) of people with Parkinson’s ...disease (PD). Understanding how these factors relate to HRQOL in people with PD may assist clinicians minimise the functional and social impact of the disease by optimising their assessment and clinical decision making processes. A tailored search strategy in six databases identified 29 full-text reports that fulfilled the pre-defined inclusion and exclusion criteria. The quality of included studies was assessed by two independent reviewers using a customised assessment form. A best-evidence synthesis was used to summarise the demographic and clinical factors that were examined in relation to HRQOL. Depression was the most frequently identified determinant of HRQOL in people with idiopathic PD. Disease severity and disease disability were also found to be predictive of poor HRQOL outcomes in many studies. The motor symptoms that contributed most often to overall life quality were gait impairments and complications arising from medication therapy. To minimise the impact of PD on HRQOL, it may be necessary to consider the extent to which demographic factors and motor and non-motor symptoms contribute to life quality.
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