Breeding a new Ganoderma lucidum strain with increased contents of individual ganoderic acids by mono-mono crossing of genetically modified monokaryons.

Ganoderic acids (GAs) are major functional components of Ganoderma lucidum. The study aimed to breed a new G. lucidum strain with increased contents of individual GAs. Two mating-compatible monokaryotic strains, G. 260125 and G. 260124, were successfully isolated from the dikaryotic G. lucidum CGMCC 5.0026 via protoplast formation and regeneration. The Vitreoscilla hemoglobin gene (vgb) and squalene synthase gene (sqs) were overexpressed in the monokaryotic G. 260124 and G. 260125 strain, respectively. Mating between the G. 260124 strain overexpressing vgb and the G. 260125 strain overexpressing sqs resulted in the formation of the new hybrid dikaryotic G. lucidum strain sqs-vgb. The maximum contents of ganoderic acid (GA)-T, GA-Me, and GA-P in the fruiting body of the mated sqs-vgb strain were 23.1, 15.3, and 39.8 µg/g dry weight (DW), respectively, 2.23-, 1.75-, and 2.69-fold greater than those in G. lucidum 5.0026. The squalene and lanosterol contents increased 2.35- and 1.75-fold, respectively, in the fruiting body of the mated sqs-vgb strain compared with those in the G. lucidum 5.0026. In addition, the maximum expression levels of the sqs and lanosterol synthase gene (ls) were increased 3.23- and 2.13-fold, respectively, in the mated sqs-vgb strain. In summary, we developed a new G. lucidum strain with higher contents of individual GAs in the fruiting body by integrating genetic engineering and mono-mono crossing.

Tetraborated Intrinsically Axial Chiral Multi-resonance Thermally Activated Delayed Fluorescence Materials.

Chiral multi-resonance thermally activated delayed fluorescence (CP-MR-TADF) materials hold promise for circularly polarized organic light-emitting diodes (CP-OLEDs) and 3D displays. Herein, we present two pairs of tetraborated intrinsically axial CP-MR-TADF materials, R/S-BDBF-BOH and R/S-BDBT-BOH, with conjugation-extended bidibenzo[b,d]furan and bidibenzo[b,d]thiophene as chiral sources, which effectively participate in the distribution of the frontier molecular orbitals. Due to the heavy-atom effect, sulfur atoms are introduced to accelerate the reverse intersystem crossing process and increase the efficiency of molecules. R/S-BDBF-BOH and R/S-BDBT-BOH manifest ultra-pure blue emission with a maximum at 458/459 nm with a full width at half maximum of 27 nm, photoluminescence quantum yields of 90 %/91 %, and dissymmetry factors (|gPL|) of 6.8×10-4/8.5×10-4, respectively. Correspondingly, the CP-OLEDs exhibit good performances with an external quantum efficiency of 30.1 % and |gEL| factors of 1.2×10-3.

Increased production and anti-senescence activity of exopolysaccharides in Ganoderma lingzhi by co-overexpression of ß-1,3-glucan synthase and UDP-glucose pyrophosphorylase.

A ß-1,3-glucan synthase gene (gls) was cloned and overexpressed in Ganoderma lingzhi. The content of intracellular polysaccharides (IPS) in G. lingzhi overexpressing gls was 22.36 mg/100 mg dry weight (DW), 19 % higher than those in the wild-type (WT) strain. Overexpression of gls did not affect the expression of the phosphoglucomutase gene and the UDP-glucose pyrophosphorylase gene (ugp) in the polysaccharide biosynthesis. The gls and ugp were then simultaneously overexpressed in G. lingzhi for the first time. The combined overexpression of these two genes increased the IPS content and exopolysaccharides (EPS) production to a greater extent than the overexpression of gls independently. The maximum IPS content of the overexpressed strain was 24.61 mg/100 mg, and the maximum EPS production was 1.55 g/L, 1.31- and 1.50-fold higher than that in the WT strain, respectively. Moreover, the major EPS fractions from the overexpression strain contained more glucose (86.7 % and 72.5 %) than those from the WT strain (78.2 % and 62.9 %). Furthermore, the major fraction G+U-0.1 from the overexpression strain exhibited stronger antioxidant and anti-senescence activities than the WT-0.1 fraction from the WT strain. These findings will aid in the hyperproduction and application of Ganoderma polysaccharides and facilitate our understanding of mushroom polysaccharide biosynthesis.

A methyltransferase LaeA regulates ganoderic acid biosynthesis in Ganoderma lingzhi.

The methyltransferase LaeA is a global regulator involved in the biosynthesis of secondary metabolites by ascomycete fungi. However, little is known of its regulatory role in basidiomycete fungi. In this study, the laeA gene was identified in the basidiomycete Ganoderma lingzhi and its function in regulating the biosynthesis of anti-tumor ganoderic acids was evaluated. A laeA deletion (ΔlaeA) Ganoderma strain exhibited significantly reduced concentration of ganoderic acids. qRT-PCR analysis further revealed that the transcription levels of genes involved in the biosynthesis of ganoderic acids were drastically lower in the ΔlaeA strain. Moreover, deletion of laeA resulted in decreased accumulation of intermediates and abundances of asexual spores in liquid static culture of G. lingzhi. In contrast, constitutive overexpression of laeA resulted in increased concentration of ganoderic acids. These results demonstrate an essential role of LaeA in the regulation of ganoderic acid biosynthesis in Ganoderma.

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Many traditional economic marine fishery resources have been declining in the coastal waters of China. Amblychaeturichthys hexanema has become one of the dominant species in Haizhou Bay and some other coastal areas of China, playing an important role in marine food webs. We analyzed the feeding strategy of A. hexanema based on the bottom trawl surveys conducted in the Haizhou Bay and adjacent waters in spring and autumn of 2011 and 2013-2016. The feeding habits and main influencing factors of A. hexanema were studied using linear mixed model (LMM). The results showed that A. hexanema fed on 14 prey groups, with Amphipoda, shrimps, Bivalvia and Ophiuroidea as the main prey groups. A total of 37 species were identified in the preys. The dominant prey species were Gammarus sp., Leptochela gracilis, Monoculodes sp., Moerella iridescens and Alpheus distinguendus. Results of the linear mixed model showed that the feeding intensity of A. hexanema in Haizhou Bay was influenced by body length, water depth, survey season, and bottom water salinity. Among them, water depth and bottom salinity had significantly negative effects, whereas the impact of body length was significantly positive. The feeding intensity was significantly higher in spring than that in autumn. Results of cluster analysis showed that A. hexanema had different feeding habits between two length groups as divided by a threshold of 70 mm body length. The change of feeding habit was mainly attributed to the variations in predation ability and food availability. Feeding strategy analysis showed that trophic niche of A. hexanema had large components between phenotypes and low intraspecific competition for prey. This study would contribute to our understanding of life history characteristics and ecological habits of A. hexanema, and provide scientific support for the sustainable utilization and management.

Overexpression of phosphomannomutase increases the production and bioactivities of Ganoderma exopolysaccharides.

In this study, we explored a novel approach to enhancing the production and bioactivities of Ganoderma exopolysaccharides. The homologous phosphomannomutase gene (PMM1) was cloned and overexpressed in Ganoderma for the first time. As a result, the maximum production of exopolysaccharides by the PMM1 transformant was 1.53 g/L, which was 1.41-fold higher than of a wild-type (WT) strain in a 5-L bioreactor. The transcription levels of PMM1 and PMM2 increased 40.5- and 2.4-fold, respectively, whereas the value of the GDP-D-mannose pyrophosphorylase gene did not change significantly in this transgenic strain. Furthermore, the major exopolysaccharide fractions from PMM1 transformants contained higher amounts of mannose (56.5 % and 21.1 %) than those from a WT strain (26.7 % and 9.3 %). Moreover, the major fractions from PMM1 transformants exhibited stronger regulation effects on macrophage. In conclusion, this study is helpful for the efficient production and application of Ganoderma exopolysaccharides and facilitates an understanding of polysaccharide biosynthesis regulation.

Targeted Gene Insertion and Replacement in the Basidiomycete Ganoderma lucidum by Inactivation of Nonhomologous End Joining Using CRISPR/Cas9.

Targeted gene insertion or replacement is a promising genome-editing tool for molecular breeding and gene engineering. Although CRISPR/Cas9 works well for gene disruption and deletion in Ganoderma lucidum, targeted gene insertion and replacement remain a serious challenge due to the low efficiency of homologous recombination (HR) in this species. In this work, we demonstrate that the DNA double-strand breaks induced by Cas9 were mainly repaired via the nonhomologous end joining (NHEJ) pathway, at a frequency of 96.7%. To establish an efficient target gene insertion and replacement tool in Ganoderma, we first inactivated the NHEJ pathway via disruption of the Ku70 gene (ku70) using a dual single guide RNA (sgRNA)-directed gene deletion method. Disruption of the ku70 gene significantly decreased NHEJ activity in G. lucidum. Moreover, ku70 disruption strains exhibited 96.3% and 93.1% frequencies of targeted gene insertion and replacement, respectively, when target DNA with the orotidine 5'-monophosphate decarboxylase (ura3) gene and 1.5-kb homologous 5'- and 3'-flanking sequences was used as a donor template, compared to 3.3% and 0%, respectively, at these targeted sites for a control strain (Cas9 strain). Our results indicated that ku70 disruption strains were efficient recipients for targeted gene insertion and replacement. This tool will advance our understanding of functional genomics in G. lucidum. IMPORTANCE Functional genomic studies in Ganoderma have been hindered by the absence of adequate genome-engineering tools. Although CRISPR/Cas9 works well for gene disruption and deletion in G. lucidum, targeted gene insertion and replacement have remained a serious challenge due to the low efficiency of HR in these species, although such precise genome modifications, including site mutations, site-specific integrations, and allele or promoter replacements, would be incredibly valuable. In this work, we inactivated the NHEJ repair mechanism in G. lucidum by disrupting the ku70 gene using the CRISPR/Cas9 system. Moreover, we established a target gene insertion and replacement method in ku70-disrupted G. lucidum that possessed high-efficiency gene targeting. This technology will advance our understanding of the functional genomics of G. lucidum.

Efficient expression of heterologous genes by the introduction of the endogenous glyceraldehyde-3-phosphate dehydrogenase gene intron 1 in Ganoderma lucidum.

BACKGROUND: Ganoderma lucidum, a well-known medicinal mushroom, has received wide attention as a promising cell factory for producing bioactive compounds. However, efficient expression of heterologous genes remains a major challenge in Ganoderma, hindering metabolic regulation research and molecular breeding of this species. RESULTS: We show that the presence of glyceraldehyde-3-phosphate dehydrogenase gene (gpd) intron 1 at the 5' end of, the 3' end of, or within the heterologous phosphinothricin-resistant gene (bar) is efficient for its expression in G. lucidum. The enhanced expression of bar is exhibited by the higher accumulation of mRNA and increased amounts of protein. Moreover, the insertion of the gpd intron 1 in the ß-glucuronidase gene (gus) elevates its mRNA accumulation and enzyme activity, which facilitates the use of this reporter gene in Ganoderma. CONCLUSIONS: This study has demonstrated the importance of the introduction of gpd intron 1 for the efficient expression of bar and gus in G. lucidum. The presence of the gpd intron 1 in heterologous genes increases levels of mRNA accumulation and protein expression in basidiomycete Ganoderma. The developed method may be utilized in upregulating the expression of other heterologous genes in Ganoderma.

Effects of Efficient Expression of Vitreoscilla Hemoglobin on Production, Monosaccharide Composition, and Antioxidant Activity of Exopolysaccharides in Ganoderma lucidum.

A Vitreoscilla hemoglobin (VHb) gene was efficiently expressed by the optimization of codons and intron addition in G. lucidum. Expression of the VHb gene was confirmed by genome PCR, quantitative real-time PCR and carbon monoxide (CO)-difference spectrum analysis in the transformant. The effects of the efficient expression of VHb gene on production, monosaccharide compostion, and antioxidant activity of G. lucidum exopolysaccharides were studied. The maximum production of exopolysaccharides in the VHb gene-bearing transformant was 1.63 g/L, which was 1.5-fold higher than expression in the wild-type strain. Efficient expression of the VHb gene did not change the monosaccharide composition or distribution of molecular weight, but it increased the mole percentage ratio of galactose and mannose in G. lucidum exopolysaccharide. Exopolysaccharides from the transformant had higher scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl (OH) radical capacity and reducing power than those from the wild-type strain. These results may be helpful for increasing production and application of exopolysaccharides produced by G. lucidum fermentation.

Predicting Spatial Variations in Multiple Measures of Oxidative Burden for Outdoor Fine Particulate Air Pollution across Canada.

Fine particulate air pollution (PM2.5) is a leading contributor to the overall global burden of disease. Traditionally, outdoor PM2.5 has been characterized using mass concentrations which treat all particles as equally harmful. Oxidative potential (OP) (per µg) and oxidative burden (OB) (per m3) are complementary metrics that estimate the ability of PM2.5 to cause oxidative stress, which is an important mechanism in air pollution health effects. Here, we provide the first national estimates of spatial variations in multiple measures (glutathione, ascorbate, and dithiothreitol depletion) of annual median outdoor PM2.5 OB across Canada. To do this, we combined a large database of ground-level OB measurements collected monthly prospectively across Canada for 2 years (2016-2018) with PM2.5 components estimated using a chemical transport model (GEOS-Chem) and satellite aerosol observations. Our predicted ground-level OB values of all three methods were consistent with ground-level observations (cross-validation R2 = 0.63-0.74). We found that forested regions and urban areas had the highest OB, predicted primarily by black carbon and organic carbon from wildfires and transportation sources. Importantly, the dominant components associated with OB were different than those contributing to PM2.5 mass concentrations (secondary inorganic aerosol); thus, OB metrics may better indicate harmful components and sources on health than the bulk PM2.5 mass, reinforcing that OB estimates can complement the existing PM2.5 data in future national-level epidemiological studies.

Estimating PM2.5-related premature mortality and morbidity associated with future wildfire emissions in the western US.

Wildfire activity in the western United States (US) has been increasing, a trend that has been correlated with changing patterns of temperature and precipitation associated with climate change. Health effects associated with exposure to wildfire smoke and fine particulate matter (PM2.5) include short- and long-term premature mortality, hospital admissions, emergency department visits, and other respiratory and cardiovascular incidents. We estimate PM2.5 exposure and health impacts for the entire continental US from current and future western US wildfire activity projected for a range of future climate scenarios through the 21st century. We use a simulation approach to estimate wildfire activity, area burned, fine particulate emissions, air quality concentrations, health effects, and economic valuation of health effects, using established and novel methodologies. We find that climatic factors increase wildfire pollutant emissions by an average of 0.40% per year over the 2006-2100 period under Representative Concentration Pathway (RCP) 4.5 (lower emissions scenarios) and 0.71% per year for RCP8.5. As a consequence, spatially weighted wildfire PM2.5 concentrations more than double for some climate model projections by the end of the 21st century. PM2.5 exposure changes, combined with population projections, result in a wildfire PM2.5-related premature mortality excess burden in the 2090 RCP8.5 scenario that is roughly 3.5 times larger than in the baseline period. The combined effect of increased wildfire activity, population growth, and increase in the valuation of avoided risk of premature mortality over time results in a large increase in total economic impact of wildfire-related PM2.5 mortality and morbidity in the continental US, from roughly $7 billion per year in the baseline period to roughly $36 billion per year in 2090 for RCP4.5, and $43 billion per year in RCP8.5. The climate effect alone accounts for a roughly 60% increase in wildfire PM2.5-related premature mortality in the RCP8.5 scenario, relative to baseline conditions.

High-performance reversible aqueous zinc-ion battery based on iron-doped alpha-manganese dioxide coated by polypyrrole.

The development of zinc-ion storage cathode materials for aqueous zinc-ion batteries (AZIBs) is a necessary step for the construction of large-scale electrochemical energy conversion and storage devices. Iron-doped alpha-manganese dioxide (α-MnO2) nanocomposites were achieved in this study via pre-intercalation of Fe3+ during the formation of α-MnO2 crystals. A polypyrrole (PPy) granular layer was fabricated on the surface of α-MnO2 using acid-catalyzed polymerization of pyrroles. The pre-intercalation of Fe3+ effectively enlarges the lattice spacing of α-MnO2 and consequently decreases the hindrance for Zn2+ insertion/extraction in the iron-doped α-MnO2 coated by PPy (Fe/α-MnO2@PPy) composite. Meanwhile, the PPy buffer layer can ameliorate electron and ion conductivity and prevent dissolution of α-MnO2during the charge/discharge process. This unique structure makes the Fe/α-MnO2@PPy composite an efficient zinc-ion storage cathode for AZIBs. The targeted Fe/α-MnO2@PPy cathode achieves superior performance with reversible specific capacity (270 mA h g-1 at 100 mA g-1) and exhibits highdiffusioncoefficientof 10-10-10-14 cm-2 s-1. Therefore, a feasible approach is implemented on advanced electrode materials using in AZIBs for practical applications.

Enhancement of ganoderic acid production by promoting sporulation in a liquid static culture of Ganoderma species.

Ganoderic acids (GAs) produced by Ganoderma are a type of lanostane-type triterpenoids with anticancer and antimetastatic activities; however, low production of GAs limits its wide application. In this study, a novel strategy by promoting sporulation of Ganoderma was developed to increase GA production. First, a high-spore producing Ganoderma strain G. 260125 was obtained from dikaryotic strain CGMCC 5.0026, and the sporulation-specific gene of this strain exhibits a higher transcription level than CGMCC 5.0026. Then, the effect of promoting sporulation on GA content was investigated. The maximum ganoderic acid (GA)-T, GA-Mk, and GA-Me contents in G. 260125 in shake flasks were 358.97, 78.32, and 12.75 µg/100 mg dry weight, respectively, which were 3.42, 2.91, and 1.73 times higher than those obtained in CGMCC 5.0026. Moreover, total and individual GA contents in spores were significantly higher than those in liquid static culture. Both concentrations of intermediates and transcription levels of GA biosynthetic genes also improved in G. 260125 during fermentation compared with those in CGMCC 5.0026. For scaling-up experiments, GA-T, GA-Me, and GA-Mk production in G. 260125 improved by 2.2-, 2.6-, and 2.1-fold compared with those in CGMCC 5.0026. In addition, the effectiveness of the developed strategy was also confirmed in three different Ganoderma strains. This work illustrated that promoting sporulation efficiently improves GA production in liquid static cultures of Ganoderma.

Synthesis and biological evaluation of novel antipsychotic trans-4-(2-(1,2,4,5-tetrahydro-3H-benzo[d]azepin-3-yl)ethyl)cyclohexan-1-amine derivatives targeting dopamine/serotonin receptor subtypes.

In this study, a series of trans-4-(2-(1,2,4,5-tetrahydro-3H-benzo[d]azepin-3-yl)ethyl)cyclohexan-1-amine derivatives as potential antipsychotics were synthesized and biologically evaluated to discover potential antipsychotics with good drug target selectivity. The preliminary structure-activity relationship was discussed, and optimal compound 12a showed both nanomolar affinity for D2/D3/5-HT1A/5-HT2A receptors and weak α1 and H1 receptor binding affinity. In addition, 12a was metabolically stable in vitro, displayed micromolar affinity for the hERG channel, and exhibited antipsychotic efficacy in the animal model of locomotor-stimulating effects of phencyclidine.

SIRT1 Inhibits High Shear Stress-Induced Apoptosis in Rat Cortical Neurons.

INTRODUCTION: Sirtuin1 (SIRT1), one of NAD+-dependent protein deacetylases, is proved to be neuroprotective in aging diseases, but its effect on neuronal apoptosis has not been clarified. To investigate the role of SIRT1 in inhibiting neuronal apoptosis, SIRT1 was interfered or overexpressed in cortical neurons. METHODS: We exerted overloading laminar shear stress with 10 dyn/cm2 for 4, 8, and 12 h on neurons to cause cortical neuronal apoptosis, and the apoptosis percentage was tested by TUNEL assay. The adenovirus plasmids containing SIRT1 RNA interference or SIRT1 wild type gene were transfected into neurons before shear stress loading. SIRT1 mRNA and protein level were tested by Real-time PCR, immunofluorescence and western blots assay. RESULTS: SIRT1 was primarily expressed in nucleus of cortical neurons, and its mRNA level was significantly increased after 4 h stimulation. SIRT1 RNAi cortical neurons had higher TUNEL positive cells, while SIRT1 overexpression significantly decreased the percentage of died cells induced by shear stress compared to control group. CONCLUSIONS: SIRT1 plays a neuroprotective role in shear stress induced apoptosis and could be as potential pharmacological targets against neuronal degeneration in future.

Strigolactone mediates jasmonic acid-induced lipid production in microalga Monoraphidium sp. QLY-1 under nitrogen deficiency conditions.

The roles of jasmonic acid (JA) in the regulation of cell growth and lipid biosynthesis under the combination of strigolactone (SL) treatment and nitrogen deficiency (ND) were investigated. In this work, the optimised ND condition (46.18%) and ND combined with SL treatment (53.71%) showed 1.11- and 1.29-fold increases in lipid content in Monoraphidium sp. QLY-1 compared with the control condition (41.57%). The levels of JA, glutathione (GSH), and γ-aminobutyric acid (GABA) and lipogenic genes expression were upregulated by the combination of SL and ND, but the ROS level was decreased. Furthermore, exogenous JA supplementation induced the highest lipid content (57.12%) and productivity (312.35 mg L-1 d-1) under ND combined with SL treatment. This study provided a combined strategy for enhancing lipid production and supplied novel insights into the role of JA signalling in regulating lipid synthesis and oxidative stress in microalgae by combining SL treatment with ND.

Dual sgRNA-directed gene deletion in basidiomycete Ganoderma lucidum using the CRISPR/Cas9 system.

Ganoderma lucidum is an important medicinal mushroom in traditional Chinese medicine. However, the lack of adequate genetic tools has hindered molecular genetic research in and the genetic modification of this species. Here, we report that the presence of an intron is necessary for the efficient expression of the heterologous phosphinothricin-resistance and green fluorescent protein genes in G. lucidum. Moreover, we improved the CRISPR/Cas9-mediated gene disruption frequency in G. lucidum by adding an intron upstream of the Cas9 gene. Our results showed that the disruption frequency of the orotidine 5'-monophosphate decarboxylase gene (ura3) in transformants containing the glyceraldehyde-3-phosphate dehydrogenase gene intron in the Cas9 plasmid is 14-18 in 107 protoplasts, which is 10.6 times higher than that in transformants without any intron sequence. Furthermore, genomic fragment deletions in the ura3 and GL17624 genes were achieved via a dual sgRNA-directed CRISPR/Cas9 system in G. lucidum. We achieved a ura3 deletion frequency of 36.7% in G. lucidum. The developed method provides a powerful platform to generate gene deletion mutants and will facilitate functional genomic studies in G. lucidum.

Source Contributions to Ambient Fine Particulate Matter for Canada.

Understanding the sectoral contribution of emissions to fine particulate matter (PM2.5) offers information for air quality management, and for investigation of association with health outcomes. This study evaluates the contribution of different emission sectors to PM2.5 in 2013 for Canada using the GEOS-Chem chemical transport model, downscaled with satellite-based PM2.5. Despite the low population-weighted PM2.5 concentrations of 5.5 µg m-3 across Canada, we find that over 70% of population-weighted PM2.5 originates from Canadian sources followed by 30% from the contiguous United States. The three leading sectoral contributors to population-weighted PM2.5 over Canada are wildfires with 1.0 µg m-3 (17%), transportation with 0.96 µg m-3 (16%), and residential combustion with 0.91 µg m-3 (15%). The relative contribution to population-weighted PM2.5 of different sectors varies regionally with residential combustion as the leading contributor in Central Canada (19%), while wildfires dominate over Northern Canada (59%), Atlantic Canada (34%), and Western Canada (18%). The contribution from U.S. sources is larger over Central Canada (33%) than over Western Canada (17%), Atlantic Canada (17%), and Northern Canada (<2%). Sectoral trend analysis showed that the contribution from anthropogenic sources to population-weighted PM2.5 decreased from 7.1 µg m-3 to 3.4 µg m-3 over the past two decades.

Increased production of ganoderic acids by overexpression of homologous farnesyl diphosphate synthase and kinetic modeling of ganoderic acid production in Ganoderma lucidum.

BACKGROUND: Ganoderic acids (GAs), derived from the medicinal mushroom Ganoderma lucidum, possess anticancer and other important pharmacological activities. To improve production of GAs, a homologous farnesyl diphosphate synthase (FPS) gene was overexpressed in G. lucidum. Moreover, the influence of FPS gene overexpression on GA production was investigated by developing the corresponding mathematical models. RESULTS: The maximum levels of total GAs and individual GAs (GA-T, GA-S, and GA-Me) in the transgenic strain were 2.76 mg/100 mg dry weight (DW), 41 ± 2, 21 ± 5, and 28 ± 1 µg/100 mg DW, respectively, which were increased by 2.28-, 2.27-, 2.62-, and 2.80-folds compared with those in the control. Transcription levels of squalene synthase (SQS) and lanosterol synthase (LS) genes during GA biosynthesis were upregulated by 2.28- and 1.73-folds, respectively, in the transgenic G. lucidum. In addition, the developed unstructured models had a satisfactory fit for the process of GA production in submerged cultures of G. lucidum. Analysis of the kinetic process showed that FPS gene overexpression had a stronger positive impact on GA production compared with its influence on cell growth. Also, FPS gene overexpression led to a higher non-growth-associated-constant ß (1.151) over the growth-associated-constant α (0.026) in the developed models. CONCLUSIONS: FPS gene overexpression is an effective strategy to improve the production of GAs in G. lucidum. The developed mathematical models are useful for developing a better GA production process in future large-scale bioreactors.

Enhancement of lipid accumulation in Monoraphidium sp. QLY-1 by induction of strigolactone.

In this study, the effects of strigolactone (SL) on the biomass, lipid content, biochemical properties, and gene transcription of Monoraphidium sp. QLY-1 were examined. The lipid content and lipid productivity increased by 61% and 55% in QLY-1 under 1 µM SL induction compared to the control group, respectively. SL also upregulated the levels of endogenous NO and Ca2+ and lipid biosynthesis gene transcription. Subsequently, the relationship between Ca2+ and nitric oxide (NO) in the regulation of cell growth and lipid accumulation of QLY-1 under SL induction conditions was analysed. An increase in endogenous Ca2+ regulated cell growth and lipid biosynthesis by modulating the levels of NO and lipid biosynthesis-related gene expression. Collectively, this study provided a valuable approach for biofuel production from microalgae under SL induction and demonstrated that there is crucial crosstalk between the Ca2+ and NO signalling in the manipulation of lipid biosynthesis in microalgae under SL treatment.