Coupling between 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) debromination and methanogenesis in anaerobic soil microcosms.

Polybrominated diphenyl ethers (PBDEs) are persistent pollutants that may undergo microbial-mediated debromination in anoxic environments, where diverse anaerobic microbes such as methanogenic archaea co-exist. However, current understanding of the relations between PBDE pollution and methanogenic process is far from complete. To address this knowledge gap, a series of anaerobic soil microcosms were established. BDE-47 (2, 2', 4, 4'-tetrabromodiphenyl ether) was selected as a model pollutant, and electron donors were supplied to stimulate the activity of anaerobes. Debromination and methane production were monitored during the 12 weeks incubation, while obligate organohalide-respiring bacteria (OHRBs), methanogenic, and the total bacterial communities were examined at week 7 and 12. The results demonstrated slow debromination of BDE-47 in all microcosms, with considerable growth of Dehalococcoides and Dehalogenimonas over the incubation observed in most BDE-47 spiked treatments. In addition, the accumulation of intermediate metabolites positively correlated with the abundance of Dehalogenimonas at week 7, suggesting potential role of these OHRBs in debromination. Methanosarcinaceae were identified as the primary methanogenic archaea, and their abundance were correlated with the production of debrominated metabolites at week 7. Furthermore, it was observed for the first time that BDE-47 considerably enhanced methane production and increased the abundance of mcrA genes, highlighting the potential effects of PBDE pollution on climate change. This might be related to the inhibition of reductive N- and S-transforming microbes, as revealed by the quantitative microbial element cycling (QMEC) analysis. Overall, our findings shed light on the intricate interactions between PBDE and methanogenic processes, and contribute to a better understanding of the environmental fate and ecological implication of PBDE under anaerobic settings.

Contrasting responses of bacterial community to 4,4'-dibromodiphenyl ether (BDE-15) contamination in soil microcosms at different temperatures.

Polybrominated diphenyl ethers (PBDEs) are biodegradable organic pollutants and pose potential risks to microorganisms exposed to the contamination, which are also affected by a variety of factors, such as temperature, in real environmental settings. A better understanding of the microbial community responses to PBDEs at different temperatures has practical significance for assessing ecological risks or possible degraders of these widely used flame retardants. In this study, soil microcosms spiked with or without 100 mg kg-1 4,4'-dibromodiphenyl ether (BDE-15) were established and incubated at four different temperatures (4 °C, 20 °C, 37 °C, and varying ambient temperature) for up to 180 days. Concentration and carbon isotope analyses were used to verify the transformation of BDE-15. Bacterial communities were monitored during the incubation to evaluate the community succession under the PBDE stress. The results showed the majority of added BDE-15 remained after the incubation period, with limited degradation occurred at all four temperatures. Temperature significantly shaped the richness, diversity, composition and co-occurrence network of soil bacterial community, while the impacts of PBDE on soil bacteria were temperature dependent. When incubated at 4 °C, BDE-15 substantially reduced the network complexity and changed the ratio of negative to positive interactions between taxa (nodes), highlighting the PBDE-associated risks at low temperature. At higher temperatures, BDE-15 had negligible influence on the community characteristics and network. Random forest model identified distinct taxa that might be related to PBDE degradation at different incubation temperatures. These findings demonstrate contrasting bacterial community effects of PBDE at different temperatures, thus attention should be paid to the ecological impacts of soil pollution under real environmental conditions.

Simultaneous measurement of refractive index and temperature or temperature and axial strain based on an inline Mach-Zehnder interferometer with TCF-TF-TCF structure.

A refractive index (RI) and temperature or a temperature and axial strain sensor based on an inline Mach-Zehnder interferometer with thin core fiber (TCF)-thin fiber (TF)-TCF structure is proposed and experimentally demonstrated, requiring only the cleaving and fusion splicing methods. The operation principle depends on the effect that the TF cladding modes interfere with the core mode as an optical coupler. The RI, temperature, or axial strain variations can lead to resonance dip variations in the interferometer spectra, and the RI, temperature, or axial strain sensitivity can be measured by monitoring the wavelength shifts of resonance dips. Then we can measure both RI and temperature, or temperature and axial strain through the demodulation matrix. Four sensors with different TF lengths are fabricated based on numerical simulation. A 15 mm long TF sensor displays an RI sensitivity as high as -174.357nm/RIU, temperature sensitivities in the glycerin solution and the air of 12.47 and 26.19 pm/°C, and axial strain sensitivity of -3.43×10-4nm/µÎµ. Moreover, due to its simple manufacture, high cost-effectiveness and compactness, the proposed sensor has a broad application prospect in physical, chemical, and biological sensing.

Clinical characteristics of rehospitalized patients with COVID-19 in China.

This study aims to observe the clinical characteristics of recovered patients from Coronavirus Disease 2019 (COVID-19) with positive in reverse transcription-polymerase chain reaction (RT-PCR) or serum antibody. The profile, clinical symptoms, laboratory outcomes, and radiologic assessments were extracted on 11 patients, who tested positive for COVID-19 with RT-PCR or serum antibody after discharged and was admitted to Hubei No. 3 People's Hospital of Jianghan University for a second treatment in March 2020. The average interval time between the first discharge and the second admission measured 16.00 ± 7.14 days, ranging from 6 to 27 days. In the second hospitalization, one patient was positive for RT-PCR and serum antibody immunoglobulin M (IgM)-immunoglobulin G (IgG), five patients were positive for both IgM and IgG but negative for RT-PCR. Three patients were positive for both RT-PCR and IgG but negative for IgM. The main symptoms were cough (54.55%), fever (27.27%), and feeble (27.27%) in the second hospitalization. Compared with the first hospitalization, there were significant decreases in gastrointestinal symptoms (5 vs 0, P = .035), elevated levels of both white blood cell count (P = .036) and lymphocyte count (P = .002), remarkedly decreases in C-reactive protein and serum amyloid A (P < .05) in the second hospitalization. Additionally, six patients' chest computed tomography (CT) exhibited notable improvements in acute exudative lesions. There could be positive results for RT-PCR analysis or serum IgM-IgG in discharged patients, even with mild clinical symptoms, however, their laboratory outcomes and chest CT images would not indicate the on-going development in those patients.

Miniaturized Fabry-Perot probe utilizing PMPCF for high temperature measurement.

We propose a miniaturized optical fiber Fabry-Perot probe for high temperature measurement (up to 1000°C). It is simply fabricated by fusion splicing a short section of polarization-maintaining photonic crystal fiber (PMPCF) with a single-mode fiber (SMF). The interface between the core of the SMF and air holes of the PMPCF, and the end face of the PMPCF work as the mirrors. The pure silica core of the PMPCF is employed as the sensing element. Experimental results show that the probe has a high thermal stability and the temperature sensitivity reaches up to 15.34 pm/°C, which is not affected by the length of the PMPCF. The linearity of temperature response is as high as 99.83%. The proposed sensor has promising prospects in practical applications due to simple fabrication process, low cost, compact size, and excellent repeatability.

The in situ synthesis of silver nanoclusters inside a bacterial cellulose hydrogel for antibacterial applications.

An antibacterial Ag nanocluster-based hydrogel (Ag NC@BC) is prepared by the in situ formation of Ag NCs on the nanofibers of a natural bacterial-cellulose (BC) hydrogel. The Ag NC@BC exhibits superior, broad-spectrum antimicrobial performance against both Gram-positive and Gram-negative bacteria, and has a long-acting bactericidal efficacy compared to pristine Ag NCs due to its controlled-release feature for Ag species. Moreover, this fabricated hydrogel also possesses excellent biocompatibility. All of these advantages of Ag NC@BC endow it with great potentials in battling bacterial infections.

High temperature Vernier probe utilizing photonic crystal fiber-based Fabry-Perot interferometers.

This study proposes a highly sensitive and stable optical fiber probe based on Vernier effect for high temperature measurement (up to 1000 °C), utilizing photonic crystal fiber (PCF)-based Fabry-Perot interferometers (FPIs). The cascaded FPIs are fabricated by fusion splicing a section of polarization maintaining PCF to a lead-in single-mode fiber, and then a section of temperature-insensitive hollow core PCF is spliced between the PMPCF and a multi-mode fiber. The shift of the spectral envelope is monitored to measure the temperature variation. Experimental results show that the sensitivities of three fabricated probes are as high as 173.43 pm/ °C, 230.53 pm/ °C and 535.16 pm/ °C when operating from room temperature to 1000 °C, which are consistent with theoretical results. The sensitivities are magnified about 13, 19 and 45 times compared with the single FPI. The linearity of the temperature response is as high as 99.73%. The proposed probe has great application prospects due to compactness, high sensitivity and low cost.

A network meta-analysis for safety of endothelin receptor antagonists in pulmonary arterial hypertension.

BACKGROUND: Currently, direct comparative safety between endothelin receptor antagonists (ERAs) in pulmonary arterial hypertension (PAH) is limited. Thus, a systematic review with network analysis was conducted. METHODS: An electronic search was performed for randomized controlled trials (RCTs) that reported the interested safety data (abnormal liver function, peripheral edema, and anemia) of ERAs in PAH. Risk ratios (RRs) with their confidence intervals (CIs) and the surface under the cumulative ranking curve (SUCRA) were calculated using a network analysis. RESULTS: Ten RCTs involving 2,288 patients were included. Compared with placebo, bosentan (RR, 2.93; 95% CI, 1.78-4.84) significantly increased the risk of abnormal liver function, ambrisentan (RR, 1.62; 95% CI, 1.23-2.13) significantly increased the risk of peripheral edema, and macitentan (RR, 3.42; 95% CI, 1.65-7.07) significantly increased the risk of anemia. SUCRA analysis suggested that bosentan 125 mg twice daily had the highest risk of abnormal liver function; ambrisentan 10 mg once daily had the highest risk of peripheral edema; macitentan 10 mg once daily had the highest risk of anemia. CONCLUSIONS: Abnormal liver function (bosentan), peripheral edema (ambrisentan), and anemia (macitentan) were the safety indicators of ERAs in patients with PAH. Different monitoring parameters should be considered for individual ERA.

Optimal nonvitamin K antagonist oral anticoagulant therapy in a warfarin-sensitive patient after left atrial appendage closure: A case report.

RATIONALE: Developing an optimal medication strategy poses a challenging task in fragile patients after left atrial appendage closure (LAAC). We report an optimal nonvitamin K antagonist oral anticoagulant (NOAC) therapy in a warfarin-sensitive patient after LAAC. PATIENT CONCERNS: A 77-year-old nonvalvular atrial fibrillation (NVAF) male carrying 2 warfarin-sensitive alleles experienced 2 gum-bleeding with the international normalized ratio (INR) around 3. DIAGNOSES: Persistent NVAF with a history of subtotal gastrectomy and moderate renal insufficiency. INTERVENTIONS: Warfarin was discontinued and vitamin K1 was immediately administrated via intravenous infusion. LAAC was regarded as a preferable option, and rivaroxaban 15 mg daily was managed after LACC. OUTCOMES: Complete endothelialization on the surface of device was detected via transoesophageal echocardiography (TEE), and no peridevice spillage and adverse event occurred. LESSONS: A post-LAAC treatment with NOAC may be a viable regimen in patients intolerant to warfarin.

CaM/BAG5/Hsc70 signaling complex dynamically regulates leaf senescence.

Calcium signaling plays an essential role in plant cell physiology, and chaperone-mediated protein folding directly regulates plant programmed cell death. The Arabidopsis thaliana protein AtBAG5 (Bcl-2-associated athanogene 5) is unique in that it contains both a BAG domain capable of binding Hsc70 (Heat shock cognate protein 70) and a characteristic IQ motif that is specific for Ca(2+)-free CaM (Calmodulin) binding and hence acts as a hub linking calcium signaling and the chaperone system. Here, we determined crystal structures of AtBAG5 alone and in complex with Ca(2+)-free CaM. Structural and biochemical studies revealed that Ca(2+)-free CaM and Hsc70 bind AtBAG5 independently, whereas Ca(2+)-saturated CaM and Hsc70 bind AtBAG5 with negative cooperativity. Further in vivo studies confirmed that AtBAG5 localizes to mitochondria and that its overexpression leads to leaf senescence symptoms including decreased chlorophyll retention and massive ROS production in dark-induced plants. Mutants interfering the CaM/AtBAG5/Hsc70 complex formation leads to different phenotype of leaf senescence. Collectively, we propose that the CaM/AtBAG5/Hsc70 signaling complex plays an important role in regulating plant senescence.

Complete mitochondrial DNA sequences of Saccostrea mordax and Saccostrea cucullata: genome organization and phylogeny analysis.

Classified in the phylum mollusks, oysters are bivalves which are found in estuaries and coastal zones. Because of their plastic shell, mitochondrial DNA analysis of this species becomes an interesting field, necessary to investigate their phylogenetic and evolution of relations. In our study, two oyster species: Saccostrea mordax and Saccostrea cucullata from Indian Ocean (Madagascar) were investigated. The complete sequence of Saccostrea mordax (16 512 bp) and Saccostrea cucullata (16 396 bp) were described and determined, with their mitogenomes deposited in the GenBank with accession number KP769562 and KP967577 respectively. Both mitochondrial genome sequences contained 12 protein-coding genes, 23 tRNAs, and two rRNAs, all encoded in the same heavy strand. High levels of similarity in the gene arrangement of the two Saccostrea species were evident. The phylogenetic analysis shows a closer relationship between the two Saccostrea species and confirms the strong relationship within Saccostrea, Crassostrea and Ostrea genus in taxonomy of Ostreidae family.

Crystallographic analysis of the Arabidopsis thaliana BAG5-calmodulin protein complex.

Arabidopsis thaliana BAG5 (AtBAG5) belongs to the plant BAG (Bcl-2-associated athanogene) family that performs diverse functions ranging from growth and development to abiotic stress and senescence. BAG family members can act as nucleotide-exchange factors for heat-shock protein 70 (Hsp70) through binding of their evolutionarily conserved BAG domains to the Hsp70 ATPase domain, and thus may be involved in the regulation of chaperone-mediated protein folding in plants. AtBAG5 is distinguished from other family members by the presence of a unique IQ motif adjacent to the BAG domain; this motif is specific for calmodulin (CaM) binding, indicating a potential role in the plant calcium signalling pathway. To provide a better understanding of the IQ motif-mediated interaction between AtBAG5 and CaM, the two proteins were expressed and purified separately and then co-crystallized together. Diffraction-quality crystals of the complex were grown using the sitting-drop vapour-diffusion technique from a condition consisting of 0.1 M Tris-HCl pH 8.5, 2.5 M ammonium sulfate. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 64.56, b = 74.89, c = 117.09 Å. X-ray diffraction data were recorded to a resolution of 2.5 Šfrom a single crystal using synchrotron radiation. Assuming the presence of two molecules in the asymmetric unit, a Matthews coefficient of 2.44 Å(3) Da(-1) was calculated, corresponding to a solvent content of approximately 50%.

Structural insight into plant programmed cell death mediated by BAG proteins in Arabidopsis thaliana.

The recently identified plant Bcl-2-associated athanogene (BAG) family plays an extensive role in plant programmed cell death (PCD) processes ranging from growth and development to stress responses and even cell death. In the Arabidopsis thaliana BAG (AtBAG) protein family, four members (AtBAG1-4) have a domain organization similar to that of mammalian BAG proteins. Here, crystal structures of the BAG domains (BDs) of AtBAG1-4 have been determined; they have high homology and adopt a structure comprising three short parallel α-helices, similar to some mammalian BAG proteins. The crystal structure of a complex of the AtBAG1 ubiquitin-like domain and BAG domain (UBD) with the Hsc70 nucleotide-binding domain (NBD) was also determined. The binding of the AtBAG1 BD to the Hsc70 NBD induces conformational change of the Hsc70 NBD to the open state and reduces the affinity of the NBD for ADP. In vivo studies showed that bag2-1 mutant plants are larger than wild-type plants when growing under normal conditions, indicating that the AtBAG proteins might regulate plant PCD and confer tolerance to stresses in plants. These structural and functional analyses indicate that the AtBAG proteins function as nucleotide-exchange factors for Hsp70/Hsc70 in A. thaliana and that the mechanism of regulation of chaperone-mediated protein folding is conserved in plants.

Crystal structures of catalytic core domain of BIV integrase: implications for the interaction between integrase and target DNA.

Integrase plays a critical role in the recombination of viral DNA into the host genome. Therefore, over the past decade, it has been a hot target of drug design in the fight against type 1 human immunodeficiency virus (HIV-1). Bovine immunodeficiency virus (BIV) integrase has the same function as HIV-1 integrase. We have determined crystal structures of the BIV integrase catalytic core domain (CCD) in two different crystal forms at a resolution of 2.45 Å and 2.2 Å, respectively. In crystal form I, BIV integrase CCD forms a back-to-back dimer, in which the two active sites are on opposite sides. This has also been seen in many of the CCD structures of HIV-1 integrase that were determined previously. However, in crystal form II, BIV integrase CCD forms a novel face-to-face dimer in which the two active sites are close to each other. Strikingly, the distance separating the two active sites is approximately 20 Å, a distance that perfectly matches a 5-base pair interval. Based on these data, we propose a model for the interaction of integrase with its target DNA, which is also supported by many published biochemical data. Our results provide important clues for designing new inhibitors against HIV-1.