Lycaugea edieae gen. et sp. nov., a Late Devonian Lycopsid from New South Wales, Australia

International audiencePremise of research. Resolving the time and patterns of origination of the Isoetales that thrived in the wet habitats of the late Paleozoic and have extant representatives in the genus Isoetes requires a better understanding of their early members and precursors. Recent studies conducted for a large part in South China acknowledged the diversification of Middle to Late Devonian taxa that possessed isoetalean traits and either were closely related to the Isoetales or occupied a basal position within this plant order. Recent investigations of Late Devonian floras from Australia show that this area, on the northeastern edge of Gondwana, also yields taxa with combinations of characters unknown elsewhere.Methodology. The anatomy and external morphology of an anatomically preserved fragment of a lycopsid axis from the Famennian locality of Barraba, in New South Wales, are described. The new specimen is compared to lycopsid taxa on the basis of anatomically preserved specimens ranging from the Middle Devonian to the Late Carboniferous.Pivotal results. The Barraba specimen shows a new combination of characters consisting of a medullated protostele, three-zoned cortex with a wide middle cortex, homogeneous primary outer cortex, presumably deciduous leaves, and slightly protuberant widely spaced leaf bases. Leaf bases show a single large parichnos and are covered adaxially by a thick translucent layer. The specimen is interpreted as the distal branch of a new arborescent taxon, Lycaugea edieae. Taxa with the closest morphoanatomical characters, such as Wexfordia hookense, belong to the Isoetales and are found in deposits of Europe and the eastern United States.Conclusions. Lycaugea edieae is the third lycopsid taxon described from Barraba, which, to date, has yielded a majority of spore-producing plants. It increases the diversity of the early Isoetales around the Devonian-Carboniferous boundary. The Barraba flora is more similar to the contemporaneous flora in southern Laurussia than to that in China

A Late Devonian plant assemblage from New South Wales, Australia: Diversity and specificity

International audienceGondwanan floras of Late Devonian age are poorly known. In Australia, the rare studies that have been published on Late Devonian plants are old and need reinvestigation. This paper is an account of the plant macro- and micro-remains found in the Mandowa Mudstone at Barraba, New South Wales. According to the miospores, plants are late to latest Famennian in age. The record of anatomically preserved specimens is diversified, with nine taxa assigned to the Lycopsida, Cladoxylopsida, Iridopteridales and Archaeopteridales. One specimen is referrable to the spermatophytes. Several taxa are specific to Barraba, i.e., the lycopsid genera Cymastrobus and Lycaugea, the iridopteridalean genus Keraphyton, the cladoxylopsid species Polyxylon australe, and possibly a plant represented by a large Hierogramma branch showing exarch protoxylem strands. The adpression record is dominated by axes of the cosmopolitan lycopsid genus Leptophloeum. It also includes specimens interpreted as seed plants such as a possible ovule resembling Pseudosporogonites, and two types of foliage differing by their petiole width. One of this foliage consists of delicate fronds broadly comparable to those of Cosmosperma. The closest flora from Barraba is the late Famennian–earliest Tournaisian flora of the New Albany Shale in eastern USA, suggesting floral connexion and comparable environmental conditions between Northern Gondwana and Southern Laurussia

The Famennian flora of Barraba, New South Wales, Australia

International audienceStructurally preserved fossils reveal details of the internal organization that can be used to reconstruct the physiology of extinct plants and the evolution of significant functional traits. When looking at well-preserved fossil wood, one important feature that is relatively easy to spot is the presence of tyloses. Tyloses are protoplasmic swellings formed by a parenchyma cell into the lumen of an adjacent conducting cell. They have been reported in a diversity of vascular plants dating back to the Carboniferous. Plants may form tyloses in response to embolism to seal off air-filled conducting cells, but they may also help the plant to attenuate or prevent the spreading of pathogens through the vascular tissues. As a result, tyloses play important roles in the physiology and autecology of vascular plants, and investigating when and how these structures evolved based on the fossil record is critical to understand (1) the evolution of plant defense mechanisms, and (2) the establishment of hydraulic traits, especially strategies to render embolized conducting cells harmless.Here, we report on tyloses in Dameria hueberi, a progymnosperm or gymnosperm from the Tournaisian (lower Mississippian) of Australia. The secondary xylem of the specimens is composed of tracheids and low, uniseriate parenchymatous rays. Pitting consists of one, rarely two, rows of circular pits with a circular aperture. Two of the nine D. hueberi specimens provide evidence of tyloses, which typically occur in tracheids and fill the entire lumen of the cells. Small structures with a circular to irregular shape that also protrude into tracheids here and there are interpreted as early stages in tylosis formation. The trigger for the development of tyloses in D. hueberi remains unknown. There are no clear growth ring boundaries in the wood, suggesting relatively constant growth conditions. There is also no indication of increased fungal activity. Finally, the distribution of the tylose-filled tracheids does not seem to reflect heartwood formation. The discovery of D. hueberi is nevertheless important because this taxon predates the heretofore oldest fossil evidence of tylosis formation in vascular plants by several million years

Principes de Paléontologie

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The Middle Devonian plant assemblage from Dechra Aït Abdallah (Central Morocco) revisited

ACL-12-37International audienceThe composition of the allochthonous flora from Dechra Aït Abdallah (Central Morocco), initially described by Termier and Termier (1950), is reassessed from newly collected fossil material. Our work provides an updated taxonomic treatment of the plant remains. The flora comprises two lycophytes (including Leclercqia complexa), the probable iridopterid Anapaulia moodyi, and two aneurophytalean progymnosperms: Rellimia sp. and "Aneurophyton" maroccanum. Our revision confirms the Termiers' main conclusions that this Devonian flora is to date the most diverse and best known from Africa. Based on the complete paleontological evidence available from this locality, a Givetian age is as likely as an Eifelian age for the flora. The abundance of plant remains associated with the extreme scarcity of fertile organs may be accounted for by a taphonomic sorting, climatic conditions and/or specific ecological strategies. The flora of Dechra Aït Abdallah shows similarities with the Middle Devonian floras from the European part of Laurussia. This suggests that the paleogeographical position of Central Morocco permitted exchanges with Laurussia, and infers proximity of the latter with the north-western border of Gondwana during Middle Devonian time

Arterial abnormalities identified in kidneys transplanted into children during the COVID‐19 pandemic

International audienceGraft artery stenosis can have a significant short- and long-term negative impact on renal graft function. From the beginning of the COVID-19 pandemic, we noticed an unusual number of graft arterial anomalies following kidney transplant (KTx) in children. Nine children received a KTx at our center between February and July 2020, eight boys and one girl, of median age of 10 years. Seven presented Doppler features suggesting arterial stenosis, with an unusual extensive pattern. For comparison, over the previous 5-year period, persistent spectral Doppler arterial anomalies (focal anastomotic stenoses) following KTx were seen in 5% of children at our center. We retrospectively evidenced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in five of seven children with arterial stenosis. The remaining two patients had received a graft from a deceased adolescent donor with a positive serology at D0. These data led us to suspect immune postviral graft vasculitis, triggered by SARS-CoV-2. Because the diagnosis of COVID-19 is challenging in children, we recommend pretransplant monitoring of graft recipients and their parents by monthly RT-PCR and serology. We suggest balancing the risk of postviral graft vasculitis against the risk of prolonged dialysis when considering transplantation in a child during the pandemic

Saliva for molecular detection of SARS‐CoV ‐2 in pre‐school and school‐age children

International audienceSARS-CoV-2 diagnosis is a cornerstone for the management of coronavirus disease 2019 (COVID-19). Numerous studies have assessed saliva performance over nasopharyngeal sampling (NPS), but data in young children are still rare. We explored saliva performance for SARS-CoV-2 detection by RT-PCR according to the time interval from initial symptoms or patient serological status. We collected 509 NPS and saliva paired samples at initial diagnosis from 166 children under 12 years of age (including 57 children under 6), 106 between 12 and 17, and 237 adults. In children under 12, overall detection rate for SARS-CoV-2 was comparable in saliva and NPS, with an overall agreement of 89.8%. Saliva sensitivity was significantly lower than that of NPS (77.1% compared to 95.8%) in pre-school and school-age children but regained 96% when considering seronegative children only. This pattern was also observed to a lesser degree in adolescents but not in adults. Sensitivity of saliva was independent of symptoms, in contrary to NPS, whose sensitivity decreased significantly in asymptomatic subjects. Performance of saliva is excellent in children under 12 at early stages of infection. This reinforces saliva as a collection method for early and unbiased SARS-CoV-2 detection and a less invasive alternative for young children

Complement activation is a crucial driver of acute kidney injury in rhabdomyolysis

International audienceRhabdomyolysis is a life-threatening condition caused by skeletal muscle damage with acute kidney injury being the main complication dramatically worsening the prognosis. Specific treatment for rhabdomyolysis-induced acute kidney injury is lacking and the mechanisms of the injury are unclear. To clarify this, we studied intra-kidney complement activation (C3d and C5b-9 deposits) in tubules and vessels of patients and mice with rhabdomyolysis-induced acute kidney injury. The lectin complement pathway was found to be activated in the kidney; likely via an abnormal pattern of Fut2-dependent cell fucosylation, recognized by the pattern recognition molecule collectin-11 and this proceeded in a C4-independent, bypass manner. Concomitantly, myoglobin-derived heme activated the alternative pathway. Complement deposition and acute kidney injury were attenuated by pre-treatment with the heme scavenger hemopexin. This indicates that complement was activated in a unique double-trigger mechanism, via the alternative and lectin pathways. The direct pathological role of complement was demonstrated by the preservation of kidney function in C3 knockout mice after the induction of rhabdomyolysis. The transcriptomic signature for rhabdomyolysis-induced acute kidney injury included a strong inflammatory and apoptotic component, which were C3/complement-dependent, as they were normalized in C3 knockout mice. The intra-kidney macrophage population expressed a complement-sensitive phenotype, overexpressing CD11b and C5aR1. Thus, our results demonstrate a direct pathological role of heme and complement in rhabdomyolysis-induced acute kidney injury. Hence, heme scavenging and complement inhibition represent promising therapeutic strategies