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Flammulina filiformis, the most produced edible mushroom species in China, is rich in lysine. Further enhancing its lysine biosynthesis is vital for improving its quality in industrialized cultivation. Citric acid induction significantly increases both the biomass and growth rate of F. filiformis hyphae, as well as the lysine content. The genes encoding enzymes in the lysine biosynthesis pathway were detected under the optimal induction, revealing that the expression levels of hcs, hac, and hah were 2.67, 1.97, and 1.90 times greater, respectively, relative to the control, whereas no significant difference was seen for hdh, aat, sr, and shd, and the expression of aar decreased. Furthermore, the transcriptional levels of Ampk, GCN2, GCN4, and TOR were found significantly upregulated, with the most upregulated, Ampk, reaching a level 42.68 times greater than that of the control, while the phosphorylation of AMPK rose by nearly 54%. In AMPK-silencing strains under the optimal induction, however, the phosphorylation increment dropped to about 16% and the lysine content remained at the same level as in the WT. Thus, AMPK is presented as the critical intermediary in citric acid's regulation of lysine biosynthesis in F. filiformis. [ABSTRACT FROM AUTHOR]

In order to study the transient motion of the space charge around the air tower insulator and the charge distribution of the insulator, a two-dimensional mixed numerical model of the insulator string based on chemical reaction is proposed. The simulation is used to obtain the space charge generation mechanism and its distribution on the insulator surface. The chemical reaction of particles mainly involves ionisation and recombination. Based on the simulation model, it is found that the accumulation of electrons on the surface of the insulation is the main reason for the distortion of the surface of the insulator. With the increase of the discharge time, the electron temperature decreases and the reaction rate decreases. The ionisation reaction gradually reaches the dynamic equilibrium. The umbrella skirt under the surface of the ion to stabilise the moment to be earlier than the umbrella skirt surface ions to achieve the steady state of the moment. A numerical model of air discharge based on Monte Carlo collision is proposed, which can well simulate the distribution of charge around the insulator of atmospheric tower. It is very important to study the phenomenon of the insulator along the surface discharge. [ABSTRACT FROM AUTHOR]

Anti-pollution flashover of insulator is important for power systems. In recent years, haze-fog weather occurs frequently, which makes discharge occurs easily on the insulator surface and accelerates insulation aging of insulator. In order to study the influence of haze-fog on the surface discharge of room temperature vulcanized silicone rubber, an artificial haze-fog lab was established. Based on four consecutive years of insulator contamination accumulation and atmospheric sampling in haze-fog environment, the contamination configuration appropriate for RTV-coated surface discharge test under simulation environment of haze-fog was put forward. ANSYS Maxwell was used to analyze the influence of room temperature vulcanized silicone rubber surface attachments on electric field distribution. The changes of droplet on the polluted room temperature vulcanized silicone rubber surface and the corresponding surface flashover voltage under alternating current (AC), direct current (DC) positive polar (+), and DC negative polar (-) power source were recorded by a high speed camera. The results are as follows: The main ion components from haze-fog atmospheric particles are NO3-, SO42-, NH4+, and Ca2+. In haze-fog environment, both the equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD) of insulators are higher than that under general environment. The amount of large particles on the AC transmission line is greater than that of the DC transmission line. The influence of DC polarity power source on the distribution of contamination particle size is not significant. After the deposition of haze-fog, the local conductivity of the room temperature vulcanized silicone rubber surface increased, which caused the flashover voltage reduce. Discharge is liable to occur at the triple junction point of droplet, air, and room temperature vulcanized silicone rubber surface. After the deformation or movement of droplets, a new triple junction point would be formed, which would seriously reduce the dielectric strength of room temperature vulcanized silicone rubber. [ABSTRACT FROM AUTHOR]

Equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD) measurements are a basic requirement of power systems. In order to predict the site pollution severity (SPS) of insulators, a new method based on random forests (RFs) is proposed. Using mutual information (MI) theory and RFs, the weights of factors related to the SPS of insulators are analyzed. The samples of contaminated insulators are extracted from the transmission lines of high voltage alternating current (HVAC) and high voltage direct current transmission (HVDC). The regression models of RFs and support vector machines (SVM) are constructed and compared, which helps to support the lack of information in predicting NSDD in previous works. The results are as follows: according to themean decrease accuracy (MDA),mean decrease Gini, (MDG), andMI, the types of the insulators (including surface area, surface orientation, and total length) as well as the hydrophobicity are the main factors affecting both ESDD and NSDD. Compared with NSDD, the electrical parameters have a significant effect on ESDD. For the influence factors of ESDD, the weights of the insulator type, hydrophobicity, and meteorological factors are 52.94%, 6.35%, and 21.88%, respectively. For the influence factors of NSDD, the weights of the insulator type, hydrophobicity, and meteorological factors are 55.37%, 11.04%, and 14.26%, respectively. The influence voltage level (vl), voltage type (vt), polarity/phases (pp) exerted on ESDD are 1.5 times, 3 times, and 4.5 times of NSDD, respectively. The influence that distance from the coastline (d), wind velocity (wv), and rainfall (rf ) exert on NSDD are 1.5 times, 2 times, and 2.5 times that of ESDD, respectively. Compared with the natural contamination test and the SVM regression model, the RFs regression model can effectively predict the contamination degree of insulators, and the relative error of the predicted ESDD and NSDD is 8.31% and 9.62%, respectively. [ABSTRACT FROM AUTHOR]

Ganoderma lucidum is a medicinal macrofungus that is widely used in traditional Chinese medicine. Nonetheless, the scarcity of basic biological studies of this organism has hindered the further development of its commercial value. The pH-responsive transcription factor PacC/Rim101 governs the adaptation to environmental pH, the development and the secondary metabolism of many fungi. In this study, a homologue of PacC/Rim101 that encodes GlPacC was identified in the higher basidiomycete G. lucidum. GlPacC is composed of 807 amino acids and contains three typical C2H2 zinc-finger domains, two potential PEST domains, a putative PKA phosphorylation site, and a putative nuclear localization signal (NLS). GlPacC was transcribed at a high level when the fungus was under neutral and alkaline conditions, and silencing of GlPacC impaired the fungal response to ambient pH. The distance between the hyphal branches (of vegetative hyphae and aerial hyphae) was significantly increased in the GlPacC-silenced strains. The GlPacCsilenced strains grew abnormally or became sickly on solid culture medium and were unable to form primordia and fruiting bodies. The ganoderic acid content, levels of the sqs and ls transcripts, and contents of the metabolic intermediates squalene and lanosterol were all up-regulated in the GlPacC-silenced strains. Our results indicate that GlPacC is functional and plays complex roles in mycelial growth, fruiting body development and ganoderic acid biosynthesis in G. lucidum. [ABSTRACT FROM AUTHOR]

Ganoderma lucidum is one of the most important medicinal mushrooms; however, molecular genetics research on this species has been limited due to a lack of reliable reverse genetic tools. In this study, the endogenous orotidine 5'-monophosphate decarboxylase gene (URA3) was cloned as a silencing reporter, and four gene-silencing methods using hairpin, sense, antisense, and dual promoter constructs, were introduced into G. lucidum through a simple electroporation procedure. A comparison and evaluation of silencing efficiency demonstrated that all of the four methods differentially suppressed the expression of URA3. Our data unequivocally indicate that the dual promoter silencing vector yields the highest rate of URA3 silencing compared with other vectors (up to 81.9%). To highlight the advantages of the dual promoter system, we constructed a co-silencing system based on the dual promoter method and succeeded in co-silencing URA3 and laccase in G. lucidum. The reduction of the mRNA levels of the two genes were correlated. Thus, the screening efficiency for RNAi knockdown of multiple genes may be improved by the co-silencing of an endogenous reporter gene. The molecular tools developed in this study should facilitate the isolation of genes and the characterization of the functions of multiple genes in this pharmaceutically important species, and these tools should be highly useful for the study of other basidiomycetes. [ABSTRACT FROM AUTHOR]

Ganoderic acids (GAs) isolated from Ganoderma lucidum, which have shown remarkable pharmacological activities and a variety of therapeutic effects on a number of human diseases, have provided an important resource for the development of new medicines. The yield of GAs in field cultivation is still limited, which is mainly due to a scarcity of information regarding its biosynthesis pathway and its regulation. Here, we review the recent publication that has been made in the biosynthesis and regulation of GAs. From these studies, researchers have identified part of the biosynthesis pathway of GAs named mevalonate pathway. They have cloned and characterized the genes involved in the biosynthesis pathway. Additionally, they found that expression of the genes involved in GA biosynthesis is closely related to the impact of environmental factors through transcriptional profiling analysis. Moreover, this review focuses on suggesting new directions for studying GAs and attempts to gain some insights for better understanding of the biosynthesis and regulation of GAs. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the cDNA encoding lanosterol synthase (LS) clone produced from Ganoderma lucidum (G. lucidum) through a homology-based polymerized chain reaction (PCR) method. It discovers that the LS cDNA contains an open-reading frame (ORF) of 2,181 bp while the genomic DNA sequence of LS contains 2,924 bp. It infers that the results of PCR are probably affected by the triterpene biosynthesis regulated network of G. lucidum.

The article presents a study on the characterization and differential expression of a farnesyl-diphosphate synthase gene (GlFPS) from the Basidiomycetous fungus Ganoderma lucidum. It was found that GlFPS cDNA conains an open reading frame of 1083 bp, and its deduced amino acid sequence exhibited a high homology with other fungal FPS genes. GlFPS was also expressed in the mycelium growth stage whereas its transcripts accumulated to high levels rapidly during the process of mushroom primordia.

In this paper, effects of the space charge behavior of silicone rubber (SiR) nanocomposites with SiO2, Al2O3, and MgO nanoparticles on charge transfer were clarified. To investigate the effects of SiO2, Al2O3, and MgO nanoparticles on space charge profiles, the space charge behavior was measured using a thermal step method system under a dc electric field of 2 to 4 kV/mm. In the case of SiR nanocomposites, a negative packet like charge injection with a peak charge density of more than several hundred C/m3 was measured. The effects of space charge behavior were discussed with the response current associated with the conductivity and permittivity affected by a thermal process. The obtained results showed that the relaxation processes had discrete energy differences with distinct peaks in the response currents of space charge affected by nanoparticles. [ABSTRACT FROM AUTHOR]