ALBERT

Description: The establishment of genetic transformation method is crucial for the functional genomics research in filamentous fungi. Although the transformation method has been developed in several types of fungi, a highly efficient and convenient transformation system is desperately needed in Lentinula edodes. Present work established the Agrobacterium-mediated transformation (ATMT) of basidiomycete L. edodes in both monokaryon and dikaryon mycelia by using constructed binary plasmid pCAMBIA-1300-GFP. Then, the transformation efficiency of ATMT was evaluated by using different mediums for recipient incubation and different varieties of L. edodes. The results showed that in dikaryon strain W1, the positive hygromycin-resistant transformants was observed in all medium with the positive frequency of selected transformants that ranged from 0 to 30%. While in the monokaryon strain W1-26, only the millet medium group obtained positive transformants with a positive frequency of 75.48%. Moreover, three dikaryotic wild strains (YS55, YS3334, and YS3357) and two dikaryotic cultivated strains (W1 and S606) showed the highest transformation efficiency, with 32.96% of the germination frequency, and 85.12% of positive frequency for hygromycin-resistant transformants. This work demonstrated that Agrobacterium-mediated transformation was successfully performed in L. edodes, and the genotype of recipients as well as the medium for mycelial incubation were suggested to play key roles in determining the transformation efficiency. These findings may provide new avenues for the genetic modification of edible mushroom and may extend the cognition of DNA-mediated transformation in filamentous fungi.

Description: Exploring the effects of drought on trees of different sizes is an important research topic because the size-dependent mortality pattern of the major dominant species significantly affects the structure and function of plant communities. Here we studied the physiological performance and non-structural carbohydrates (NSCs) dynamics of a small xeric tree species, Haloxylon ammodendron (C.A.Mey.) of different tree size with varying rooting depth, during summer drought. We measured predawn (Ψpd) and midday (Ψm) leaf water potential, osmotic potential at saturated turgor (π100), and turgor lost point (Ψtlp), stomatal conductance (gs) at noon, maximum photochemical efficiency of photosystem II (Fv/Fm) in the morning, and NSCs concentration, from June–September. Our results demonstrated that the summer drought reduces the overall performance of physiological traits of the small young trees more than the larger adult trees. Ψpd, gs and Fv/Fm dropped larger in the small-diameter groups than the larger diameter groups. Substantial osmotic adjustments were observed in small size individuals (with lower π100 and Ψtlp) to cope with summer drought. Furthermore, mean concentration of NSCs for the leaf and shoot were higher in September than in July in every basal stem diameter classes suggested the leaf and shoot acted as reserve for NSC. However the root NSCs concentrations within each basal stem diameter class exhibited less increase in September than in the July. At the same time, the small young tress had lower root NSCs concentrations than the larger adult tree in both July and September. The contrasting root NSC concentrations across the basal stem diameter classes indicated that the roots of smaller trees may be more vulnerable to carbon starvation under non-lethal summer drought. The significant positive relationship between rooting depth and physiological traits & root NSCs concentration emphasize the importance of rooting depth in determining the seasonal variation of water status, gas exchange and NSCs.

Description: In recent years, the acquisition of high-resolution multi-spectral images by unmanned aerial vehicles (UAV) for quantitative remote sensing research has attracted more and more attention, and radiometric calibration is the premise and key to the quantification of remote sensing information. The traditional empirical linear method independently calibrates each channel, ignoring the correlation between spectral bands. However, the correlation between spectral bands is very valuable information, which becomes more prominent as the number of spectral channels increases. Based on the empirical linear method, this paper introduces the constraint condition of spectral angle, and makes full use of the information of each band for radiometric calibration. The results show that, compared with the empirical linear method, the proposed method can effectively improve the accuracy of radiometric calibration, with the improvement range of Mean Relative Percent Error (MRPE) being more than 3% in the range of visible band and within 1% in the range of near-infrared band. Besides, the method has great advantages in agricultural remote sensing quantitative inversion.

Description: Settled dust samples were collected from Qingdao urban area to analyze the spatial distribution, chemical speciation and sources of metals, and to evaluate the health risk of metals from atmospheric dust. The average contents of Hg, Cd, Cr, Cu, Ni, Pb and Zn in the atmospheric settled dust of Qingdao were 0.17, 0.75, 153.1, 456.7, 60.9, 176.0 and 708.3 mg/kg, respectively, which were higher than soil background values. The mean exchangeable metal and carbonated-associated fraction proportions of Cd, Zn and Pb were 43.6%, 26.1% and 15%, which implies that they have high mobility and bioavailability. Higher contents of heavy metals appeared in old city areas because of the historical accumulation of metals. Principal component analysis showed that combustion sources partially contributed to Pb, Zn and other trace metals. Hg, Pb and Zn mainly originated from business, human activities and municipal construction. Cd and Cu from settled dust of the old city originated from the erosion and ageing of construction materials. The non-carcinogenic risk rankings for the seven determined heavy metals were ingestion 〉 dermal 〉 inhalation. Cd, Cr and Ni from settled dust showed a low carcinogenic risk. The health risks of Cr, Cu and Pb were higher in old city areas and, therefore, need special attention.

Description: Non-ferrous metal smelting enterprises produce hundreds of thousands of tons of arsenic sulfide sludge (ASS) each year in China. Most of the ASS are stored at the companies without enough preventive measures. During the storage and natural drying process, arsenic sulfide is easily oxidized, thereby causing secondary pollution and increasing environmental risks. In this paper, experiments of simulated storage were used to study the release characteristics of heavy metals. During the simulated storage, the release concentrations of As, Pb, and Cd increased rapidly at first and then slowly. Although the total amount of arsenic released was the largest, the release ratio was in the order of Cd 〉 Pb 〉 As. The effects of different atmospheres and conditions on the release of arsenic and heavy metals were explored. The more the H2SO4 in the sludge, the higher the release concentration, and the addition of an appropriate amount of Ca(OH)2 is beneficial for reducing the release of heavy metals. Finally, SEM, XRD and TG-DTG techniques were carried out to confirm that the release of heavy metals was caused by the oxidation process resulting from the residual H2SO4 in the ASS and the air.

Description: Inter-system bias (ISB) will affect accuracy and processing time in integrated precise point positioning (PPP), and ISB stochastic models will largely determine the quality of ISB estimation. Thus, the impacts of four different stochastic models of ISB processing will be assessed and studied in detail to further reveal the influence of ISB in positioning. They are ISB-PW considering ISB as a piece-wise constant, ISB-RW considering ISB as random walk, ISB-AD considering ISB as an arc-dependent constant, and ISB-WN considering ISB as white noise. Together with the model without introducing ISB called ISB-OFF, i.e., five different schemes, ISB-OFF, ISB-PW, ISB-RW, ISB-AD, and ISB-WN, will be designed and tested in this study. From the results of pseudorange residuals, it can be noticed that when considering ISB, the Root-Mean-Square (RMS) of ionosphere-free combined pseudorange residuals are much smaller than without ISB (ISB-OFF). The results of convergence time and positioning accuracy analysis show that PPP performance with ISB-AD is even worse than ISB-OFF, when using the precise products from the German Research Centre for Geosciences (GFZ) named as GBM products here; while the strategies of ISB-RW, and ISB-WN achieve the best results. For the products from Wuhan University called WUM products, a completely different result is achieved. PPP with the stochastic models of ISB-PW and ISB-AD perform best. The most likely reason is the ISB stochastic models applied by the analysis centers are consistent with those used in the PPP on the user side. So, ISB-RW, or ISB-WN is recommended when GBM products are used, and for the WUM products, ISB-PW, or ISB-AD is chosen. From the statistics of PPP precision during the convergence period, it can be concluded that considering ISB also has a great improvement on combined PPP accuracy during the initialization phase.

Description: Social networks introduce new potential for people to share knowledge with others. However, it is not clear what factors influence user willingness toward knowledge sharing in social networks. Aiming to answer these questions, in this paper we analyze the major factors influencing user willingness toward knowledge sharing in social networks and propose a new research model that is inspired by the technology acceptance model (TAM). In particular, we introduce a new independent variable called perceived value which is described by four aspects: social value, entertainment value, emotion value, and information value. In addition, we introduce a new mediating variable, trust, to reflect the intermediating relationship between perceived value and knowledge-sharing willingness. We conduct an empirical analysis on questionnaire data and present comprehensive results on reliability and validity, factor analysis, correlation analysis, and mediating effects analysis. The results show that perceived value has a significant impact on knowledge-sharing willingness, and trust plays a partial intermediate role between perceived value and knowledge-sharing willingness. Further, we present some research implications for knowledge sharing and learning innovation in social networks, as well as some suggestions for organizations to advance knowledge sharing and learning innovation in the social-network age.

Description: This study was conducted to elucidate the biological effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on cell proliferation, differentiation and gene expression in C2C12 myoblasts. C2C12 were treated with various concentrations of EPA or DHA under proliferation and differentiation conditions. Cell viability was analyzed using cell counting kit-8 assays (CCK-8). The Edu assays were performed to analyze cell proliferation. To analyze cell differentiation, the expressions of myogenic marker genes were determined at the transcriptional and translational levels by qRT-PCR, immunoblotting and immunofluorescence. Global gene expression patterns were characterized using RNA-sequencing. Phosphorylation levels of ERK and Akt were examined by immunoblotting. Cell viability and proliferation was significantly inhibited after incubation with EPA (50 and 100 μM) or DHA (100 μM). Both EPA and DHA suppressed C2C12 myoblasts differentiation. RNA-sequencing analysis revealed that some muscle-related genes were significantly downregulated following EPA or DHA (50 μM) treatment, including insulin-like growth factor 2 (IGF-2), troponin T3 (Tnnt3), myoglobin (Mb), myosin light chain phosphorylatable fast skeletal muscle (Mylpf) and myosin heavy polypeptide 3 (Myh3). IGF-2 was crucial for the growth and differentiation of skeletal muscle and could activate the PI3K/Akt and the MAPK/ERK cascade. We found that EPA and DHA (50 μM) decreased the phosphorylation levels of ERK1/2 and Akt in C2C12 myoblasts. Thus, this study suggested that EPA and DHA exerted an inhibitory effect on myoblast proliferation and differentiation and downregulated muscle-related genes expression.

Description: Skin cutaneous melanoma (SCM) is a common malignant tumor of the skin and its pathogenesis still needs to be studied. In this work, we constructed a co-expression network and screened for hub genes by weighted gene co-expression network analysis (WGCNA) using the GSE98394 dataset. The relationship between the mRNA expression of hub genes and the prognosis of patients with melanoma was validated by Gene Expression Profiling Interactive Analysis (GEPIA) database. Furthermore, immunohistochemistry in the Human Protein Atlas was used to validate hub genes and grayscale analysis was performed using ImageJ software. It was found that the yellow module was most significantly associated with the difference between common nevus and SCM, and 13 genes whose expression correlation 〉0.9 were candidate hub genes. The expression of three genes (STK26, KCNT2, CASP12) was correlated with the prognosis of SCM. STK26 (P = 0.0024) and KCNT2 (P 〈 0.0001) were significantly different between normal skin and SCM. These three hub genes have potential value as predictors for accurate diagnosis and prognosis of SCM in the future.

Description: The stability of hydrate-bearing near-wellbore reservoirs is one of the key issues in gas hydrate exploitation. In most previous investigations, the damage evolution process of the sediment structure and its effect on near-wellbore reservoir stability have been neglected. Therefore, the damage variable is introduced into a multi-field coupled model based on continuous damage theory and multi-field coupling theory. A thermo-hydro-mechanical-chemical (THMC) multi-field coupling mathematical model considering damage of hydrate-bearing sediments is established. The effects of damage of hydrate-bearing sediments on the thermal field, seepage field, and mechanical field are considered. Finally, the distributions of hydrate saturation, pore pressure, damage variable, and effective stress of a near-wellbore reservoir in gas hydrate exploitation by depressurization are calculated, and the stability of a hydrate-bearing near-wellbore reservoir is analyzed using the model. Through calculation and analysis, it is found that structural damage of hydrate-bearing sediments has an adverse effect on the stability of hydrate-bearing near-wellbore reservoirs. The closer to the wellbore, the worse the reservoir stability, and the near-wellbore reservoir stability is the worst in the direction of minimum horizontal ground stress.