The Arctic is warming far faster than the global average, threatening the release of large amounts of carbon presently stored in frozen permafrost soils. Increasing Earth's albedo by the injection of ...sulfate aerosols into the stratosphere has been proposed as a way of offsetting some of the adverse effects of climate change. We examine this hypothesis in respect of permafrost carbon-climate feedbacks using the PInc-PanTher process model driven by seven earth system models running the Geoengineering Model Intercomparison Project (GeoMIP) G4 stratospheric aerosol injection scheme to reduce radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Permafrost carbon released as CO
is halved and as CH
by 40% under G4 compared with RCP4.5. Economic losses avoided solely by the roughly 14 Pg carbon kept in permafrost soils amount to about US$ 8.4 trillion by 2070 compared with RCP4.5, and indigenous habits and lifestyles would be better conserved.
For backfill projects in seasonally frozen regions, freeze-thaw and compaction are two critical factors that affect engineering safety by changing the soil structure. This study investigated the ...effects of freeze-thaw cycles on the microstructure characteristics of saline soil with different compaction degrees using mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and laser particle size analysis (LPSA). The compacted soil samples show a bimodal pore size distribution (PSD). With an increase in the freeze-thaw cycles, the volume of intra-aggregate pores (<4 μm) gradually decreases, while that of inter-aggregate pores (>4 μm) varies with the density of soil samples. Furthermore, compaction has a decisive effect on the volume of inter-aggregate pores. Under the effect of freeze-thaw cycles, the void ratio of the low-density soil sample decreases, and the soil structure gradually becomes denser, showing thaw settlement deformation. However, in the high-density soil sample, the void ratio increases and the soil structure becomes loose, showing frost heaving deformation. Moreover, the freeze-thaw cycle also leads to the breakage of coarse particles and the aggregation of fine particles. Correspondingly, the soil structure type changes from a flocculent structure to a granular stacked structure and then to a cemented-aggregated structure. After 60 freeze-thaw cycles, the cracks are penetrated and the water migration channels are formed, the soil structures all reach a new equilibrium state. Meanwhile, the void ratios of different compacted soil samples are close to the same residual value. Test results suggest that there may be an optimal compaction degree between 90% and 95%, where the soil microstructure is least affected by freeze-thaw cycles. This study may provide theoretical guidance for the construction of backfill engineering projects in seasonally frozen regions from a micro-perspective.
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•The pore size distribution (PSD) of compacted soil samples is bimodal.•The freeze-thaw cycle is also a process of adjusting soil compactness.•After 60 cycles, the different compacted soil samples reach almost the same residual void ratio.•The coefficient of freeze–thaw (γe) is proposed to describe the changes in soil microstructure.•During the freeze-thaw cycles, the breakage of coarse particles and the aggregation of fine particles occur simultaneously.
Abstract
Widespread lake drainage can lead to large-scale drying in Arctic lake-rich areas, affecting hydrology, ecosystems and permafrost carbon dynamics. To date, the spatio-temporal distribution, ...driving factors, and post-drainage dynamics of lake drainage events across the Arctic remain unclear. Using satellite remote sensing and surface water products, we identify over 35,000 (~0.6% of all lakes) lake drainage events in the northern permafrost zone between 1984 and 2020, with approximately half being relatively understudied non-thermokarst lakes. Smaller, thermokarst, and discontinuous permafrost area lakes are more susceptible to drainage compared to their larger, non-thermokarst, and continuous permafrost area counterparts. Over time, discontinuous permafrost areas contribute more drained lakes annually than continuous permafrost areas. Following drainage, vegetation rapidly colonizes drained lake basins, with thermokarst drained lake basins showing significantly higher vegetation growth rates and greenness levels than their non-thermokarst counterparts. Under warming, drained lake basins are likely to become more prevalent and serve as greening hotspots, playing an important role in shaping Arctic ecosystems.
ADP-ribosylation is a ubiquitous post-translational addition of either monomers or polymers of ADP-ribose to target proteins by ADP-ribosyltransferases, usually by interferon-inducible diphtheria ...toxin-like enzymes known as PARPs. While several PARPs have known antiviral activities, these activities are mostly independent of ADP-ribosylation. Consequently, less is known about the antiviral effects of ADP-ribosylation. Several viral families, including Coronaviridae, Togaviridae, and Hepeviridae, encode for macrodomain proteins that bind to and hydrolyze ADP-ribose from proteins and are critical for optimal replication and virulence. These results suggest that macrodomains counter cellular ADP-ribosylation, but whether PARPs or, alternatively, other ADP-ribosyltransferases cause this modification is not clear. Here we show that pan-PARP inhibition enhanced replication and inhibited interferon production in primary macrophages infected with macrodomain-mutant but not wild-type coronavirus. Specifically, knockdown of two abundantly expressed PARPs, PARP12 and PARP14, led to increased replication of mutant but did not significantly affect wild-type virus. PARP14 was also important for the induction of interferon in mouse and human cells, indicating a critical role for this PARP in the regulation of innate immunity. In summary, these data demonstrate that the macrodomain is required to prevent PARP-mediated inhibition of coronavirus replication and enhancement of interferon production.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Climate change is the challenge of the century, and achieving the goals of the Paris Agreement will require worldwide cooperation and mutual effort. Over 120 countries have made their ...net-zero commitments, and quantifying the social cost of carbon (SCC), i.e. the climate damage caused by an additional ton of CO
2
emissions, under a carbon-neutral pathway would provide a carbon price benchmark for policymakers. Here, we set in detail the emission trajectories of different jurisdictions under a carbon-neutral pathway based on the submitted nationally determined contributions. We then assess global and regional warming, climate change damages, and the SCC with the Policy Analysis of Greenhouse Effect integrated assessment model. We find a peak warming of about 2.1 °C relatives to pre-industrial levels in this century under our carbon-neutral emission pathway. And even if all countries meet their carbon-neutral commitments, this would not be sufficient to limit global warming to 1.5 °C relative to pre-industrial levels. We compare the SCC using fixed discount rates, dynamic discounting, and an equity weighting approach. Notably, the introduction of equity weights would increase the estimated SCC from 79 (11–186) to 291 (83–592) US$ per tCO
2
. Climate change damages will be borne primarily by warmer and poorer countries, and this profound inequality would likely undermine efforts to eradicate extreme poverty. Statistics on current carbon taxes and carbon trading prices show that they are notably lower than global or even regional SCCs, suggesting that the current system does not adequately reflect the global externalities of CO
2
emissions. More studies are needed to assess the equity aspects of climate change impacts, to help refine mechanisms to align domestic interests with global interests, and to facilitate the implementation of national carbon-neutral commitments in place.
•Properties of hydraulic conductivity of dispersive soil had been rarely reported.•Permeability of dispersive soil is proposed to be characterized by kmax and krs.•Increasing soil salinity leads to ...an exponential increase in kmax but not in krs.•Effect of freeze-thaw cycles on kmax and krs is not monotonous.•Correlations of osmotic and matric suctions to kmax are respectively positive and negative.
The hydraulic conductivity of soil is a fundamental parameter that should be obtained both in hydrological and geotechnical studies since it relates to a series of hazards in earthen engineering projects, whereas investigations on dispersive soils, especially those distributed in cold regions, have rarely been reported. This study aims to explore the characteristics of permeability by using a dispersive soil from northeastern China, as well as the effects of soil salinity and freeze-thaw on the variation in hydraulic conductivity. Indoor constant-head permeation tests were conducted on artificially prepared specimens, and initial soil suctions were measured by the filter paper method to assist the analyses. The results demonstrated that the hydraulic conductivity decayed with permeation time until reaching relative stability, and both maximum and relatively-stable values (kmax and krs, respectively) should be adopted for comprehensively characterizing the permeability of dispersive soils. Increasing salt content increased the kmax exponentially, and the inflection salt content was approximately 1.5%, from which a sharp increase in kmax appeared; the krs showed a slight increase with initial salt contents as well. Freeze-thaw yielded nonmonotonic changes in the permeability as kmax peaked at 5 freeze-thaw cycles; the variation in krs was similar. The osmotic suction positively correlated with kmax but did not fully contribute to the sharp increase in kmax since it increased linearly with the salt content without mutation points. The number of freeze-thaw cycles influenced the relationship between the osmotic suction and kmax. The matric and osmotic suctions posed opposite impacts on the permeability. More importantly, detailed discussions for the underlying mechanisms of the abovementioned novel observations were illustrated. These results may serve as good references for understanding the features of the permeability of dispersive soils in seasonally frozen regions domestically or worldwide.
Butyrate is one of the most important intermediates during anaerobic digestion of protein wastewater, and its oxidization is considered as a rate-limiting step during methane production. However, ...information on syntrophic butyrate-oxidizing bacteria (SBOB) is limited due to the difficulty in isolation of pure cultures. In this study, two anaerobic chemostats fed with butyrate as the sole carbon source were operated at different dilution rates (0.01/day and 0.05/day). Butyrate- and acetate-oxidizing bacteria in both chemostats were investigated, combining DNA-Stable Isotope Probing (DNA-SIP) and 16S rRNA gene high-throughput sequencing. The results showed that, in addition to known SBOB, Syntrophomonas, other species of unclassified Syntrophomonadaceae were putative butyrate-oxidizing bacteria. Species of Mesotoga, Aminivibrio, Acetivibrio, Desulfovibrio, Petrimonas, Sedimentibacter, unclassified Anaerolineae, unclassified Synergistaceae, unclassified Spirochaetaceae, and unclassified bacteria may contribute to acetate oxidation from butyrate metabolism. Among them, the ability of butyrate oxidation was unclear for species of Sedimentibacter, unclassified Synergistaceae, unclassified Spirochaetaceae, and unclassified bacteria. These results suggested that more unknown species participated in the degradation of butyrate. However, the corresponding function and pathway for butyrate or acetate oxidization of these labeled species need to be further investigated.
Cognitive impairment, a significant problem in older adults, may be associated with diet. This study aims to examine the association between the dietary diversity score (DDS), dietary pattern (DP), ...and cognitive impairment in elderly Chinese. This research further explored the role of psychological balance (PB) as a mediator in the relationship between diet and cognitive impairment.
A total of 14,318 older adults from the Chinese Longitudinal Healthy Longevity Study (CLHLS) in 2018 were included. Latent class analysis (LCA) was used to identify patterns in seven food varieties. Binary logistic regression models were used to determine factors associated with the DDS, DP, and cognitive impairment. The multiple mediation effect model was evaluated using model 6 in the PROCESS version 3.5 program.
Among the participants, 4294 (29.99%) developed cognitive impairment. Compared to people in food variety group two or lower, people with a high dietary diversity score (DDS) had lower odds of cognitive impairment. Compared to DP1, DP2 (OR = 1.24, 95%CI = 1.09 to 1.40) was associated with a higher risk of cognitive impairment, and DP4 (OR = 0.79, 95%CI = 0.69 to 0.89) was associated with a lower risk of cognitive impairment. PB mediated the relationship between DDS, DP, and cognitive impairment, with a mediating effect of 27.24% and 41.00%.
A DP that is rich in fruits, vegetables, red meat, fish, eggs, beans, nuts, and milk was related to a lower risk of cognitive impairment. PB has an indirect impact on cognitive impairment. Our findings underscore the importance of promoting a diverse diet, which may contribute to a lower risk of cognitive impairment in older adults. The PB of the elderly should also be taken into consideration.
Thermokarst lakes in permafrost regions are highly dynamic due to drainage events triggered by climate warming. This study focused on mapping lake drainage events across the Northeast Siberian ...coastal tundra from 2000 to 2020 and identifying influential factors. An object-based lake analysis method was developed to detect 238 drained lakes using a well-established surface water dynamics product. The LandTrendr change detection algorithm, combined with continuous Landsat satellite imagery, precisely dated lake drainage years with 83.2% accuracy validated against manual interpretation. Spatial analysis revealed the clustering of drained lakes along rivers and in subsidence-prone Yedoma regions. The statistical analysis showed significant warming aligned with broader trends but no evident temporal pattern in lake drainage events. Our machine learning model identified lake area, soil temperature, summer evaporation, and summer precipitation as the top predictors of lake drainage. As these climatic parameters increase or surpass specific thresholds, the likelihood of lake drainage notably increases. Overall, this study enhanced the understanding of thermokarst lake drainage patterns and environmental controls in vulnerable permafrost regions. Spatial and temporal dynamics of lake drainage events were governed by complex climatic, topographic, and permafrost interactions. Integrating remote sensing with field studies and modeling will help project lake stability and greenhouse gas emissions under climate change.
Fairy shrimp are the most divergent taxon of large branchiopod crustaceans and have a worldwide distribution. Yet the diversity and distribution of fairy shrimps in the “Roof of the World” remain ...poorly known. Here, based on morphology, we identified three species of fairy shrimp (
Branchinecta orientalis
,
Chirocephalus graziellae
and
Branchipodopsis affinis
), among 14 fairy-shrimp populations from the Tibetan Plateau, China. Their phylogenetic relationships were verified based on mitochondrial DNA sequences (cytochrome
c
oxidase subunit I gene) and two nuclear markers (18S ribosomal RNA gene and internal transcribed spacer 2). Syntopy of different species of fairy shrimp was observed. Some haplotypes were shared among populations, and sequences from
B. affinis
exhibited a star-like pattern in haplotype networks, suggesting a recent rapid expansion. Finally, a high genetic diversity of fairy shrimp was detected on the Tibetan Plateau. Obtained results contribute to a better knowledge of the diversity of high-altitude fairy shrimps.
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