Previously, from the human intestinal flora we isolated the bacterial strain Bacteroides uniformis ZL1, which could convert secoisolariciresinol diglucoside (SDG) to its aglycone secoisolariciresinol ...(SECO) in vivo. In this study, 24 putative β-glucosidase genes were screened from the genome of B. uniformis ATCC 8492, which were used as templates to design PCR primers for the target genes in B. uniformis ZL1. Fifteen genes (bgl1–bgl15) were amplified from strain ZL1, and among them we identified bgl8 as the gene encoding the SDG-hydrolyzing β-glucosidase. We sequenced the bgl8 gene, cloned it into the expression vector and then transformed Escherichia coli to construct the recombinant bacteria that could synthesize the target β-glucosidase (BuBGL8). We purified and characterized BuBGL8, which showed maximal activity and stability under the culture conditions of pH 6.0 and 30 °C. SDG (2.0 mg/ml) was converted to SECO by both the purified BuBGL8 (0.035 mg/ml) and crude enzyme extract (0.23 mg crude protein/ml) with the efficiency of more than 90 % after 90 min at the reaction conditions. This is, to our knowledge, the first report of using recombinant bacteria to synthesize the SDG-hydrolyzing β-glucosidase, which could be used to produce SECO from SDG conveniently and highly efficiently.
The singly Cabibbo-suppressed decay D+s → K + π + π − π 0 is observed by using a data set corresponding to an integrated luminosity of 6.32 fb − 1 recorded by the BESIII detector at the ...centre-of-mass energies between 4.178 and 4.226 GeV. The first amplitude analysis of D+s → K + π + π − π 0 reveals the sub-structures in this decay and determines the fractions and relative phases of different intermediate processes. The dominant intermediate process is D+s → K *0 ρ + , with a fit fraction of (40 . 5 ± 2 . 8 stat . ± 1 . 5 syst . )%. With the detection efficiency based on our amplitude analysis, the absolute branching fraction for D+s → K + π + π − π 0 is measured to be (9 . 75 ± 0 . 54 stat . ± 0 . 17 syst . ) × 10 − 3 .
Aims
Oxidative stress limited the growth of cells and 2‐keto‐l‐gulonic acid (2‐KGA) production in vitamin C (Vc) fermentation system. The study aims to investigate the antioxidant effect of ...glutathione on promoting 2‐KGA in Vc fermentation system using Ketogulonicigenium vulgare 25B‐1 and Bacillus endophyticus ST‐1 as the co‐culturing microbes.
Methods and Results
The activities of antioxidant‐related enzymes and qPCR were used to study the antioxidant effect of glutathione addition in Vc fermentation system. The addition of GSH and GSH/GSSG increased 2‐KGA production and decreased fermentation time, and the highest 2‐KGA production increased by 40·63% and the lowest fermentation time shortened to 60 h when the addition of optimal concentration ratio of GSH/GSSG was 50 : 1. Moreover, the increased production of 2‐KGA was accompanied by up‐regulated the activities of total antioxidant capacity (T‐AOC), total superoxide dismutase (T‐SOD), catalase (CAT) and over‐expressed oxidative stress‐related genes sod, gst, gr, zwf, gp, which resulted in scavenging reactive oxygen species to reduce oxidative stress in Vc fermentation system.
Conclusions
Glutathione showed a significant effect on increasing 2‐KGA production and decreasing fermentation time in Vc fermentation system. GSH/GSSG could maintain a dynamic balance with two forms of glutathione and the optimal concentration ratio of GSH/GSSG was 50 : 1.
Significance and Impact of the Study
Glutathione is proved to be effective to relieve oxidative stress. The promotion effects of GSSG and GSH on 2‐KGA production could help to further explore the optimization of co‐culture fermentation process for Vc industrial production.
Abstract
We present the analysis of the brightest flare that was recorded in the Insight-HMXT data set in a broad energy range (2–200 keV) from the microquasar GRS 1915+105 during an unusual ...low-luminosity state. This flare was detected by Insight-HXMT among a series of flares during 2019 June 2 UTC 16:37:06–20:11:36 with a 2–200 keV luminosity of 3.4–7.27 × 10
38
erg s
−1
. Basing on the broadband spectral analysis, we find that the flare spectrum shows different behaviors during bright and faint epochs. The spectrum of the flare can be fitted with a model dominated by a power-law component. Additional components show up in the bright epoch with a hard tail and in the faint epoch with an absorption line of ∼6.78 keV. The reflection component of the latter is consistent with an inner disk radius ∼five times larger than that of the former. These results on the giant flare during the “unusual” low-luminosity state of GRS 1915+105 may suggest that the source experiences a possible fast transition from a jet-dominated state to a wind-dominated state. We speculate that the evolving accretion disk and the large-scale magnetic field may play important roles in this peculiar huge flare.
Grazing can directly or indirectly influence carbon (C) inputs, turnover, and retention in grassland soil. However, relative to the plant response to grazing, belowground biota and process responses ...are more complex and often do not correlate with the aboveground responses. Ungulate grazing involves three mechanisms; defoliation (removal of plant shoot tissue), dung and urine return, and trampling. An evaluation of the relative roles of these mechanisms and their combinations in grazing can explain the causes of changes in grasslands, thereby explaining soil C sequestration in a steppe ecosystem. In this study, we examined changes in plant attributes, soil abiotic characteristics, and the soil microbial community in response to mowing (M), dung and urine addition (DU), simulated trampling (T), and their combinations by conducting a 3-yr experiment in a steppe ecosystem in Inner Mongolia, China. Most of the variation in the grazing effects on grasslands was explained by defoliation through decreased plant production and soil respiration and altered vegetation composition. Dung and urine return was second to defoliation in explaining grazing effects on grassland, and led to increasing plant C inputs to the soil, while simultaneously, potential loss of soil C due to the increase of the abundance of bacteria and soil respiration eventually accelerated soil C cycling. An interaction between defoliation and trampling on microbial growth was observed in our study: trampling increased the abundance of total bacteria, fungi, and arbuscular mycorrhizal fungi (AMF) only in the no-mowing plots. Trampling led to plant allocation to belowground tissues and increased the abundance of fungi and AMF, which are critical for soil C sequestration, and trampling with defoliation further decreased the abundance of soil microbes, which may decelerate soil C cycling and increase its retention time. These results indicate that defoliation and dung and urine return play major roles in explaining grazing effects on grassland systems, including plant, soil, and microbial parameters, but the trampling effects and the interaction between defoliation and trampling are two key factors that contribute to explaining the overall effects of grazing on soil C sequestration in a typical steppe ecosystem in Inner Mongolia.
Abstract
Gamma rays from HESS J1849−000, a middle-aged TeV pulsar wind nebula (PWN), are observed by the Tibet air shower array and the muon detector array. The detection significance of gamma rays ...reaches 4.0
σ
and 4.4
σ
levels above 25 TeV and 100 TeV, respectively, in units of the Gaussian standard deviation
σ
. The energy spectrum measured between 40 TeV <
E
< 320 TeV for the first time is described with a simple power-law function of
dN
/
dE
=
(
2.86
±
1.44
)
×
10
−
16
(
E
/
40
TeV
)
−
2.24
±
0.41
TeV
−
1
cm
−
2
s
−
1
. The gamma-ray energy spectrum from the sub-TeV (
E
< 1 TeV) to sub-PeV (100 TeV <
E
< 1 PeV) ranges, including the results of previous studies, can be modeled with the leptonic scenario, i.e., inverse Compton scattering by high-energy electrons accelerated by the PWN of PSR J1849−0001. On the other hand, the gamma-ray energy spectrum can also be modeled with the hadronic scenario in which gamma rays are generated from the decay of neutral pions produced by collisions between accelerated cosmic-ray protons and the ambient molecular cloud found in the gamma-ray-emitting region. The cutoff energy of cosmic-ray protons
E
p,cut
is estimated as
log
10
(
E
p
,
cut
/
TeV
)
=
3.73
−
0.66
+
2.98
, suggesting that protons are accelerated up to the PeV energy range. Our study thus proposes that HESS J1849−000 should be further investigated as a new candidate as a Galactic PeV cosmic-ray accelerator, or “PeVatron.”
Summary Objective To determine whether mandibular condylar cartilage degradation induced by experimentally abnormal occlusion could be ameliorated via systemic administration of strontium or NBD ...peptide. Methods Six-week-old female C57BL/6J mice were used. From the seventh day after mock operation or unilateral anterior crossbite (UAC) treatment, the control and UAC mice were further respectively pharmacologically treated for 2 weeks or 4 weeks of saline (CON + Saline and UAC + Saline groups), SrCl2 (CON + SrCl2 and UAC + SrCl2 groups) or NBD peptide (CON + NBD peptide and UAC + NBD peptide groups). Changes in condylar cartilage and subchondral bone were assessed 21 and 35 days after mock operation or UAC procedure by histology and micro-CT. Real-time PCR and/or immunohistochemistry (IHC) were performed to evaluate changes in expression levels of col2a1, aggrecan, ADAMTS-5, tnf-α, il-1β, nfkbia, nuclear factor-kappaB phospho-p65 in condylar cartilage, and rankl/rank/opg in both condylar cartilage and subchondral bone. Results Cartilage degradation with decreased col2a1 and aggrecan expression, and increased ADAMTS-5, tnf-α/il1-β, nfkbia and NF-κB phospho-p65 was observed in UAC + Saline groups. Subchondral bone loss with increased osteoclast numbers and decreased opg/rankl ratio was found in UAC + Saline groups compared to age-match CON + Saline groups. Cartilage degradation and subchondral bone loss were reversed by treatment of SrCl2 or NBD peptide while the same dosage in control mice induced few changes in condylar cartilage and subchondral bone. Conclusions The results demonstrate reverse effect of systemic administration of strontium or NBD peptide on UAC-induced condylar cartilage degradation and subchondral bone loss.
Aims/hypothesis
Sirtuin-1 (SIRT1) is a potential therapeutic target to combat insulin resistance and type 2 diabetes. This study aims to identify a microRNA (miRNA) targeting SIRT1 to regulate ...hepatic insulin sensitivity.
Methods
Luciferase assay combined with mutation and immunoblotting was used to screen and verify the bioinformatically predicted miRNAs. miRNA and mRNA levels were measured by real-time PCR. Insulin signalling was detected by immunoblotting and glycogen synthesis. Involvement of SIRT1 was studied with adenovirus, inhibitor and SIRT1-deficient hepatocytes. The role of
miR-181a
in vivo was explored with adenovirus and locked nucleic acid antisense oligonucleotides.
Results
miR-181a
targets the 3′ untranslated region (3′UTR) of
Sirt1
mRNA through a
miR-181a
binding site, and downregulates SIRT1 protein abundance at the translational level.
miR-181a
is increased in insulin-resistant cultured hepatocytes and liver, and in the serum of diabetic patients. Overexpression of
miR-181a
decreases SIRT1 protein levels and activity, and causes insulin resistance in hepatic cells. Inhibition of
miR-181a
by antisense oligonucleotides increases SIRT1 protein levels and activity, and improves insulin sensitivity in hepatocytes. Ectopic expression of
SIRT1
abrogates the effect of
miR-181a
on insulin sensitivity, and inhibition of SIRT1 activity or SIRT1 deficiency markedly attenuated the improvement in insulin sensitivity induced by antisense
miR-181a
. In addition, overexpression of
miR-181a
by adenovirus impairs hepatic insulin signalling, and intraperitoneal injection of locked nucleic acid antisense oligonucleotides for
miR-181a
improves glucose homeostasis in diet-induced obesity mice.
Conclusions/interpretation
miR-181a
regulates SIRT1 and improves hepatic insulin sensitivity. Inhibition of
miR-181a
might be a potential new strategy for treating insulin resistance and type 2 diabetes.
Non-small-cell lung cancer (NSCLC) demonstrates remarkable molecular diversity. With the completion of The Cancer Genome Atlas (TCGA), there is opportunity for systematic analyses of the entire TCGA ...NSCLC cohort, including comparisons and contrasts between different disease subsets. On the basis of multidimensional and comprehensive molecular characterization (including DNA methylation and copy, and RNA and protein expression), 1023 NSCLC cases-519 from TCGA adenocarcinoma (AD) project and 504 from TCGA squamous cell carcinoma (SQCC) project-were classified using a 'cluster-of-clusters' analytic approach. Patterns from TCGA NSCLC subsets were examined in independent external databases, including the PROSPECT (Profiling of Resistance patterns and Oncogenic Signaling Pathways in Evaluation of Cancers of the Thorax) NSCLC data set. Nine genomic subtypes of NSCLC were identified, three within SQCC and six within AD. SQCC subtypes were associated with transcriptional targets of SOX2 or p63. One predominately AD subtype (with a large proportion of SQCC) shared molecular features with neuroendocrine tumors. Two AD subtypes manifested a CpG island methylator phenotype. Three AD subtypes showed high p38 and mTOR pathway activation. AD subtypes associated with low differentiation showed relatively worse prognosis. SQCC subtypes and two of the AD subtypes expressed cancer testis antigen genes, whereas three AD subtypes expressed several immune checkpoint genes including PDL1 and PDL2, corresponding with patterns of greater immune cell infiltration. Subtype associations for several immune-related markers-including PD1, PDL1, CD3 and CD8-were confirmed in the PROSPECT cohort using immunohistochemistry. NSCLC molecular subtypes have therapeutic implications and lend support to a personalized approach to NSCLC management based on molecular characterization.
PDF
