The colonization of the land by plants, sometime before 470 million years ago, was accompanied by the evolution tissue systems 1–3. Specialized structures with diverse functions—from nutrient ...acquisition to reproduction—derived from single cells in the outermost layer (epidermis) were important sources of morphological innovation at this time 2, 4, 5. In extant plants, these structures may be unicellular extensions, such as root hairs or rhizoids 6–9, or multicellular structures, such as asexual propagules or secretory hairs (papillae) 10–12. Here, we show that a ROOTHAIR DEFECTIVE SIX-LIKE (RSL) class I basic helix-loop-helix transcription factor positively regulates the development of the unicellular and multicellular structures that develop from individual cells that expand out of the epidermal plane of the liverwort Marchantia polymorpha; mutants that lack MpRSL1 function do not develop rhizoids, slime papillae, mucilage papillae, or gemmae. Furthermore, we discovered that RSL class I genes are also required for the development of multicellular axillary hairs on the gametophyte of the moss Physcomitrella patens. Because class I RSL proteins also control the development of rhizoids in mosses and root hairs in angiosperms 13, 14, these data demonstrate that the function of RSL class I genes was to control the development of structures derived from single epidermal cells in the common ancestor of the land plants. Class I RSL genes therefore controlled the generation of adaptive morphological diversity as plants colonized the land from the water.
•Class I RSL genes control the development of structures derived from single cells•Class I RSL function is conserved among land plants•Class I RSL controlled epidermal development in the land plant common ancestor•These genes controlled the development of the first plant rooting systems
The colonization of the land by plants was accompanied by the evolution of specialized cells and structures that develop from single cells. Proust et al. show that RSL class I basic helix-loop-helix transcription factors controlled the development of specialized structures from single epidermal cells in the last common ancestor of the land plants.
Alzheimer's disease (AD) genetics implies a causal role for innate immune genes, TREM2 and CD33, products that oppose each other in the downstream Syk tyrosine kinase pathway, activating microglial ...phagocytosis of amyloid (Aβ). We report effects of low (Curc-lo) and high (Curc-hi) doses of curcumin on neuroinflammation in APPsw transgenic mice. Results showed that Curc-lo decreased CD33 and increased TREM2 expression (predicted to decrease AD risk) and also increased TyroBP, which controls a neuroinflammatory gene network implicated in AD as well as phagocytosis markers CD68 and Arg1. Curc-lo coordinately restored tightly correlated relationships between these genes' expression levels, and decreased expression of genes characteristic of toxic pro-inflammatory M1 microglia (CD11b, iNOS, COX-2, IL1β). In contrast, very high dose curcumin did not show these effects, failed to clear amyloid plaques, and dysregulated gene expression relationships. Curc-lo stimulated microglial migration to and phagocytosis of amyloid plaques both in vivo and in ex vivo assays of sections of human AD brain and of mouse brain. Curcumin also reduced levels of miR-155, a micro-RNA reported to drive a neurodegenerative microglial phenotype. In conditions without amyloid (human microglial cells in vitro, aged wild-type mice), Curc-lo similarly decreased CD33 and increased TREM2. Like curcumin, anti-Aβ antibody (also reported to engage the Syk pathway, increase CD68, and decrease amyloid burden in human and mouse brain) increased TREM2 in APPsw mice and decreased amyloid in human AD sections ex vivo. We conclude that curcumin is an immunomodulatory treatment capable of emulating anti-Aβ vaccine in stimulating phagocytic clearance of amyloid by reducing CD33 and increasing TREM2 and TyroBP, while restoring neuroinflammatory networks implicated in neurodegenerative diseases.
•Curcumin (Curc) restores innate immune gene expression in AD models.•Curc increased TREM2 and TYROBP, while decreasing CD33 expression.•Curc stimulates phagocytosis and increases CD68 and Arg1 expression.•Curc reduces pro-inflammatory microglia markers CD11b, iNOS, COX-2, IL1β.•These results support a novel mechanism for Curc, which emulates the Aβ vaccine.
Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch. ...However, the same thermokarst lakes can also sequester carbon, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000 years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47 ± 10 grams of carbon per square metre per year; mean ± standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160 petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears, potentially negating the climate stabilization provided by thermokarst lakes during the late Holocene.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Singly ionized ytterbium, with ultranarrow optical clock transitions at 467 and 436 nm, is a convenient system for the realization of optical atomic clocks and tests of present-day variation of ...fundamental constants. We present the first direct measurement of the frequency ratio of these two clock transitions, without reference to a cesium primary standard, and using the same single ion of Yb+171. The absolute frequencies of both transitions are also presented, each with a relative standard uncertainty of 6x10-16. Combining our results with those from other experiments, we report a threefold improvement in the constraint on the time variation of the proton-to-electron mass ratio, mu super(.)/ mu =0.2(1.1)x10-16 yr-1, along with an improved constraint on time variation of the fine structure constant, alpha super(.)/ alpha =-0.7(2.1)x10-17 yr-1
The blood system is maintained by a small pool of haematopoietic stem cells (HSCs), which are required and sufficient for replenishing all human blood cell lineages at millions of cells per second ...throughout life. Megakaryocytes in the bone marrow are responsible for the continuous production of platelets in the blood, crucial for preventing bleeding--a common and life-threatening side effect of many cancer therapies--and major efforts are focused at identifying the most suitable cellular and molecular targets to enhance platelet production after bone marrow transplantation or chemotherapy. Although it has become clear that distinct HSC subsets exist that are stably biased towards the generation of lymphoid or myeloid blood cells, we are yet to learn whether other types of lineage-biased HSC exist or understand their inter-relationships and how differently lineage-biased HSCs are generated and maintained. The functional relevance of notable phenotypic and molecular similarities between megakaryocytes and bone marrow cells with an HSC cell-surface phenotype remains unclear. Here we identify and prospectively isolate a molecularly and functionally distinct mouse HSC subset primed for platelet-specific gene expression, with enhanced propensity for short- and long-term reconstitution of platelets. Maintenance of platelet-biased HSCs crucially depends on thrombopoietin, the primary extrinsic regulator of platelet development. Platelet-primed HSCs also frequently have a long-term myeloid lineage bias, can self-renew and give rise to lymphoid-biased HSCs. These findings show that HSC subtypes can be organized into a cellular hierarchy, with platelet-primed HSCs at the apex. They also demonstrate that molecular and functional priming for platelet development initiates already in a distinct HSC population. The identification of a platelet-primed HSC population should enable the rational design of therapies enhancing platelet output.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Commercial-scale mining for polymetallic nodules could have a major impact on the deep-sea environment, but the effects of these mining activities on deep-sea ecosystems are very poorly known. The ...first commercial test mining for polymetallic nodules was carried out in 1970. Since then a number of small-scale commercial test mining or scientific disturbance studies have been carried out. Here we evaluate changes in faunal densities and diversity of benthic communities measured in response to these 11 simulated or test nodule mining disturbances using meta-analysis techniques. We find that impacts are often severe immediately after mining, with major negative changes in density and diversity of most groups occurring. However, in some cases, the mobile fauna and small-sized fauna experienced less negative impacts over the longer term. At seven sites in the Pacific, multiple surveys assessed recovery in fauna over periods of up to 26 years. Almost all studies show some recovery in faunal density and diversity for meiofauna and mobile megafauna, often within one year. However, very few faunal groups return to baseline or control conditions after two decades. The effects of polymetallic nodule mining are likely to be long term. Our analyses show considerable negative biological effects of seafloor nodule mining, even at the small scale of test mining experiments, although there is variation in sensitivity amongst organisms of different sizes and functional groups, which have important implications for ecosystem responses. Unfortunately, many past studies have limitations that reduce their effectiveness in determining responses. We provide recommendations to improve future mining impact test studies. Further research to assess the effects of test-mining activities will inform ways to improve mining practices and guide effective environmental management of mining activities.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•A survey of deep learning research in classifying weeds in crop images.•A taxonomy of the techniques and classify the papers based on the taxonomy.•An analysis on weed detection and classification ...methods.•An overview of data acquisition and data preparation, and evaluation metrics.
The rapid advances in Deep Learning (DL) techniques have enabled rapid detection, localisation, and recognition of objects from images or videos. DL techniques are now being used in many applications related to agriculture and farming. Automatic detection and classification of weeds can play an important role in weed management and so contribute to higher yields. Weed detection in crops from imagery is inherently a challenging problem because both weeds and crops have similar colours (‘green-on-green’), and their shapes and texture can be very similar at the growth phase. Also, a crop in one setting can be considered a weed in another. In addition to their detection, the recognition of specific weed species is essential so that targeted controlling mechanisms (e.g. appropriate herbicides and correct doses) can be applied. In this paper, we review existing deep learning-based weed detection and classification techniques. We cover the detailed literature on four main procedures, i.e., data acquisition, dataset preparation, DL techniques employed for detection, location and classification of weeds in crops, and evaluation metrics approaches. We found that most studies applied supervised learning techniques, they achieved high classification accuracy by fine-tuning pre-trained models on any plant dataset, and past experiments have already achieved high accuracy when a large amount of labelled data is available.
IL‐27: a double agent in the IL‐6 family Jones, G. W.; Hill, D. G.; Cardus, A. ...
Clinical and experimental immunology,
July 2018, Letnik:
193, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Summary
The cytokine interleukin (IL)‐6 is a major therapeutic target for the treatment of various inflammatory and autoimmune diseases. While IL‐6 receives considerable attention in studies of ...innate and adaptive immunity, the IL‐6‐related family member IL‐27 is recognized increasingly for its effects on cellular proliferation, differentiation and leucocyte effector functions. Both cytokines activate responses in myeloid and stromal tissue cells, where they direct the transition from innate to adaptive immunity. However, they are identified frequently as lymphokines that control responses in T cells and B cells. In this regard, IL‐27 often opposes the action of IL‐6. Here, we will review the role of IL‐6 and IL‐27 in inflammation, with a particular focus on inflammatory arthritis, and discuss their importance in the diagnosis, stratification and treatment of autoimmune disease.
Review of IL‐6 and IL‐27 biology in the context of inflammatory arthritis and inflammation.
About 62,000 dead or dying common murres (Uria aalge), the trophically dominant fish-eating seabird of the North Pacific, washed ashore between summer 2015 and spring 2016 on beaches from California ...to Alaska. Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Three-quarters of murres were found in the Gulf of Alaska and the remainder along the West Coast. Studies show that only a fraction of birds that die at sea typically wash ashore, and we estimate that total mortality approached 1 million birds. About two-thirds of murres killed were adults, a substantial blow to breeding populations. Additionally, 22 complete reproductive failures were observed at multiple colonies region-wide during (2015) and after (2016-2017) the mass mortality event. Die-offs and breeding failures occur sporadically in murres, but the magnitude, duration and spatial extent of this die-off, associated with multi-colony and multi-year reproductive failures, is unprecedented and astonishing. These events co-occurred with the most powerful marine heatwave on record that persisted through 2014-2016 and created an enormous volume of ocean water (the "Blob") from California to Alaska with temperatures that exceeded average by 2-3 standard deviations. Other studies indicate that this prolonged heatwave reduced phytoplankton biomass and restructured zooplankton communities in favor of lower-calorie species, while it simultaneously increased metabolically driven food demands of ectothermic forage fish. In response, forage fish quality and quantity diminished. Similarly, large ectothermic groundfish were thought to have increased their demand for forage fish, resulting in greater top-predator demands for diminished forage fish resources. We hypothesize that these bottom-up and top-down forces created an "ectothermic vise" on forage species leading to their system-wide scarcity and resulting in mass mortality of murres and many other fish, bird and mammal species in the region during 2014-2017.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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