Previous studies have revealed inconsistent correlations between fungal diversity and plant diversity from local to global scales, and there is a lack of information about the diversity–diversity and ...productivity–diversity relationships for fungi in alpine regions.
Here we investigated the internal relationships between soil fungal diversity, plant diversity and productivity across 60 grassland sites on the Tibetan Plateau, using Illumina sequencing of the internal transcribed spacer 2 (ITS2) region for fungal identification.
Fungal alpha and beta diversities were best explained by plant alpha and beta diversities, respectively, when accounting for environmental drivers and geographic distance. The best ordinary least squares (OLS) multiple regression models, partial least squares regression (PLSR) and variation partitioning analysis (VPA) indicated that plant richness was positively correlated with fungal richness. However, no correlation between plant richness and fungal richness was evident for fungal functional guilds when analyzed individually.
Plant productivity showed a weaker relationship to fungal diversity which was inter-correlated with other factors such as plant diversity, and was thus excluded as a main driver. Our study points to a predominant effect of plant diversity, along with other factors such as carbon: nitrogen (C: N) ratio, soil phosphorus and dissolved organic carbon, on soil fungal richness.
Microbial biofilms are communities of aggregated microbial cells embedded in a self-produced matrix of extracellular polymeric substances (EPS). Biofilms are recalcitrant to extreme environments, and ...can protect microorganisms from ultraviolet (UV) radiation, extreme temperature, extreme pH, high salinity, high pressure, poor nutrients, antibiotics, etc., by acting as "protective clothing". In recent years, research works on biofilms have been mainly focused on biofilm-associated infections and strategies for combating microbial biofilms. In this review, we focus instead on the contemporary perspectives of biofilm formation in extreme environments, and describe the fundamental roles of biofilm in protecting microbial exposure to extreme environmental stresses and the regulatory factors involved in biofilm formation. Understanding the mechanisms of biofilm formation in extreme environments is essential for the employment of beneficial microorganisms and prevention of harmful microorganisms.
Subsoils contain >50% of soil organic carbon (SOC) globally yet remain under‐investigated in terms of their response to climate changes. Recent evidence suggests that warmer, drier conditions in ...alpine grasslands induce divergent responses in SOC decomposition and carbon accrual in top‐ versus subsoils. However, longer term effects on microbial activity (i.e., catabolic respiration vs. anabolic growth) and belowground carbon cycling are not well understood. Here we utilized a field manipulation experiment on the Qinghai‐Tibetan Plateau and conducted a 110‐day soil incubation with and without 13C‐labeled grass litter to assess microbes' role as both SOC “decomposers” and “contributors” in the top‐ (0–10 cm) versus subsoils (30−40 cm) after 5 years of warming and drought treatments. Microbial mineralization of both SOC and added litter was examined in tandem with potential extracellular enzyme activities, while microbial biomass synthesis and necromass accumulation were analyzed using phospholipid fatty acids and amino sugars coupled with 13C analysis, respectively. We found that warming and, to a lesser extent, drought decreased the ratio of inorganic nitrogen (N) to water‐extractable organic carbon in the subsoil, intensifying N limitation at depth. Both SOC and litter mineralization were reduced in the subsoil, which may also be related to N limitation, as evidenced by lower hydrolase activity (especially leucine aminopeptidase) and reduced microbial efficiency (lower biomass synthesis and necromass accumulation relative to respiration). However, none of these effects were observed in the topsoil, suggesting that soil microbes became inactive and inefficient in subsoil but not topsoil environments. Given increasing belowground productivity in this alpine grassland under warming, both elevated root deposits and diminished microbial activity may contribute to new carbon accrual in the subsoil. However, the sustainability of plant growth and persistence of subsoil SOC pools deserve further investigation in the long term, given the aggravated N limitation at depth.
Warming and drought is found to reduce microbial mineralization potentials of soil organic carbon and grass litter in the subsoil of an alpine grassland on the Qinghai‐Tibetan Plateau. This phenomenon appears be related to an intensified N (and moisture) limitation, evidenced by lower hydrolase (especially leucine aminopeptidase) activity and reduced microbial efficiency for both biomass synthesis and necromass accumulation (relative to respiration). However, none of these effects are observed in the topsoil, suggesting that soil microbes become inactive and inefficient under warming and drought in the alpine grassland subsoil but not topsoil.
Background The first successful local resection of a periampullary tumor was performed by Halsted in 1898. Kausch performed the first regional resection in 1909, and the operation was popularized by ...Whipple in 1935. The operation was infrequently performed until the 1980s and 1990s. Study Design Two thousand consecutive pancreaticoduodenectomies performed by 1 surgeon (JLC) from the 1960s to the 2000s were retrospectively reviewed from a prospectively maintained database. The first 1,000 were performed over a period of 34 years, the second 1,000 over a period of 9 years. Results The most common indication throughout was adenocarcinoma of the head of the pancreas (PDAC, 46%). Benign intraductal papillary mutinous neoplasm (IPMN) increased from 1% (1990s) to 8% (2000s) (p = 0.002). Age range was 13 years to 103 years. Mean age increased from 59 years (1980s) to 66 (2000s) (p = 0.001), as did those older than 80 (3% to 12%, p = 0.002). Thirty-day mortality was 1.4%; hospital mortality was 1.7%. Delayed gastric emptying (23%), pancreatic fistulas (16%), and wound infections (11%), were the most frequent morbidity, and have not decreased. The median number of blood transfusions decreased from 2 (1980s) to 0 (1990s and 2000s) (p = 0.004). Length of stay decreased from 21 days (1980s) to 13 (1990s) days to 10 days (2000s) (p = 0.002). Five-year survival for PDAC increased from 19% (1990s) to 24% (2000s) (p = 0.02), and 5-year survival for node-negative, margin-negative PDAC patients was 39%. Conclusions The volume of pancreatic pathology has attracted 22 basic and clinical scientists to Hopkins, which has $28.5 million of direct support and more than $30 million in endowments, to support research in pancreatic cancer. The volume of clinical material has also supported the training of many young surgeons, 15 of whom have become department chairmen, and more than 20 have become division chiefs.
Propagation of α-synuclein aggregates has been suggested as a contributing factor in Parkinson's disease (PD) progression. However, the molecular mechanisms underlying α-synuclein aggregation are not ...fully understood. Here, we demonstrate in cell culture, nematode, and rodent models of PD that leucine-rich repeat kinase 2 (LRRK2), a PD-linked kinase, modulates α-synuclein propagation in a kinase activity-dependent manner. The PD-linked G2019S mutation in LRRK2, which increases kinase activity, enhances propagation efficiency. Furthermore, we show that the role of LRRK2 in α-synuclein propagation is mediated by RAB35 phosphorylation. Constitutive activation of RAB35 overrides the reduced α-synuclein propagation phenotype in lrk-1 mutant C. elegans. Finally, in a mouse model of synucleinopathy, administration of an LRRK2 kinase inhibitor reduced α-synuclein aggregation via enhanced interaction of α-synuclein with the lysosomal degradation pathway. These results suggest that LRRK2-mediated RAB35 phosphorylation is a potential therapeutic target for modifying disease progression.
The prevalence and prognosis of digestive system involvement, including gastrointestinal symptoms and liver injury, in patients with COVID-19 remains largely unknown. We aimed to quantify the effects ...of COVID-19 on the digestive system.
In this systematic review and meta-analysis, we systematically searched PubMed, Embase, and Web of Science for studies published between Jan 1, 2020, and April 4, 2020. The websites of WHO, CDC, and major journals were also searched. We included studies that reported the epidemiological and clinical features of COVID-19 and the prevalence of gastrointestinal findings in infected patients, and excluded preprints, duplicate publications, reviews, editorials, single case reports, studies pertaining to other coronavirus-related illnesses, and small case series (<10 cases). Extracted data included author; date; study design; country; patient demographics; number of participants in severe and non-severe disease groups; prevalence of clinical gastrointestinal symptoms such as vomiting, nausea, diarrhoea, loss of appetite, abdominal pain, and belching; and digestive system comorbidities including liver disease and gastrointestinal diseases. Raw data from studies were pooled to determine effect estimates.
We analysed findings from 35 studies, including 6686 patients with COVID-19, that met inclusion criteria. 29 studies (n=6064) reported gastrointestinal symptoms in patients with COVID-19 at diagnosis, and the pooled prevalence of digestive system comorbidities was 4% (95% CI 2-5; range 0-15; I
=74%). The pooled prevalence of digestive symptoms was 15% (10-21; range: 2-57; I
=96%) with nausea or vomiting, diarrhoea, and loss of appetite being the three most common symptoms. The pooled prevalence of abnormal liver functions (12 studies, n=1267) was 19% (9-32; range 1-53; I
=96%). Subgroup analysis showed patients with severe COVID-19 had higher rates of abdominal pain (odds ratio OR 7·10 95% CI 1·93-26·07; p=0·003; I
=0%) and abnormal liver function including increased ALT (1·89 1·30-2·76; p=0·0009; I
=10%) and increased AST (3·08 2·14-4·42; p<0·00001; I
=0%) compared with those with non-severe disease. Patients in Hubei province, where the initial COVID-19 outbreak occurred, were more likely to present with abnormal liver functions (p<0·0001) compared with those outside of Hubei. Paediatric patients with COVID-19 had a similar prevalence of gastrointestinal symptoms to those of adult patients. 10% (95% CI 4-19; range 3-23; I
=97%) of patients presented with gastrointestinal symptoms alone without respiratory features. Patients who presented with gastrointestinal system involvement had delayed diagnosis (standardised mean difference 2·85 95% CI 0·22-5·48; p=0·030; I
=73%). Patients with gastrointestinal involvement tended to have a poorer disease course (eg, acute respiratory distress syndrome OR 2·96 95% CI 1·17-7·48; p=0·02; I
=0%).
Our study showed that digestive symptoms and liver injury are not uncommon in patients with COVID-19. Increased attention should be paid to the care of this unique group of patients.
None.
Anthropogenic climate change has emerged as a critical environmental problem, prompting frequent investigations into its consequences for various ecological systems. Few studies, however, have ...explored the effect of climate change on ecological stability and the underlying mechanisms. We conduct a field experiment to assess the influence of warming and altered precipitation on the temporal stability of plant community biomass in an alpine grassland located on the Tibetan Plateau. We find that whereas precipitation alteration does not influence biomass temporal stability, warming lowers stability through reducing the degree of species asynchrony. Importantly, biomass temporal stability is not influenced by plant species diversity, but is largely determined by the temporal stability of dominant species and asynchronous population dynamics among the coexisting species. Our findings suggest that ongoing and future climate change may alter stability properties of ecological communities, potentially hindering their ability to provide ecosystem services for humanity.
Satellite data indicate significant advancement in alpine spring phenology over decades of climate warming, but corresponding field evidence is scarce. It is also unknown whether this advancement ...results from an earlier shift of phenological events, or enhancement of plant growth under unchanged phenological pattern. By analyzing a 35‐year dataset of seasonal biomass dynamics of a Tibetan alpine grassland, we show that climate change promoted both earlier phenology and faster growth, without changing annual biomass production. Biomass production increased in spring due to a warming‐induced earlier onset of plant growth, but decreased in autumn due mainly to increased water stress. Plants grew faster but the fast‐growing period shortened during the mid‐growing season. These findings provide the first in situ evidence of long‐term changes in growth patterns in alpine grassland plant communities, and suggest that earlier phenology and faster growth will jointly contribute to plant growth in a warming climate.
Climate change reshapes plant growth patterns by shifting phenology earlier, enhancing growth rate, and shortening growth period in a Tibetan alpine grassland over 35 years. The changes in growth patterns alters seasonal, but not annual, biomass production.
Aim
Most existing studies that examined the biotic mechanisms of ecosystem stability have focused on aboveground biodiversity. Whether and how belowground biodiversity affects the stability of ...natural ecosystems is largely unknown. In the present study, we investigated the relationships between above‐ and belowground biodiversity and the temporal stability of grassland biomass production across a large gradient of soil and climatic conditions.
Location
Tibetan Plateau.
Time period
2001–2016.
Major taxa studied
Alpine grass and soil bacteria, arbuscular mycorrhiza (AM) fungi and fauna.
Methods
We coupled a field biodiversity survey conducted in 54 alpine grassland ecosystems across the Tibetan Plateau with a satellite‐sensed proxy (enhanced vegetation index, EVI) of ecosystem productivity during 2001–2016. The temporal stability of primary productivity was calculated as the ratio of the mean annual peak EVI to the standard deviation of the annual peak EVI over this period. Plant diversity was determined using a classic vegetation survey approach, soil bacterial and AM fungal diversity were measured using a high‐throughput sequencing approach, and soil fauna was counted and identified at the order level after being extracted using a modified Berlese–Tullgren method.
Results
Our results demonstrated that both above‐ and belowground biodiversity were positively associated with ecosystem stability. Belowground biodiversity not only affected ecosystem stability directly, but also influenced it indirectly through plant diversity and soil fertility. Furthermore, soil pH, climate and its variability strongly influenced soil biodiversity, which in turn influenced ecosystem stability.
Main conclusions
Our study demonstrates the indispensable role of belowground biodiversity in regulating ecosystem stability, emphasizing the necessity of conserving this ‘hidden’ biodiversity in fragile alpine ecosystems facing ongoing environmental change.
The tremendous reservoir of soil organic carbon (SOC) in wetlands is being threatened by water-table decline (WTD) globally. However, the SOC response to WTD remains highly uncertain. Here we examine ...the under-investigated role of iron (Fe) in mediating soil enzyme activity and lignin stabilization in a mesocosm WTD experiment in an alpine wetland. In contrast to the classic 'enzyme latch' theory, phenol oxidative activity is mainly controlled by ferrous iron Fe(II) and declines with WTD, leading to an accumulation of dissolvable aromatics and a reduced activity of hydrolytic enzyme. Furthermore, using dithionite to remove Fe oxides, we observe a significant increase of Fe-protected lignin phenols in the air-exposed soils. Fe oxidation hence acts as an 'iron gate' against the 'enzyme latch' in regulating wetland SOC dynamics under oxygen exposure. This newly recognized mechanism may be key to predicting wetland soil carbon storage with intensified WTD in a changing climate.
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