Ethanolic extract from fruiting bodies of Cordyceps militaris HL8 exhibits cytotoxic activities against cancer cells, skin pathogenic yeasts, and postharvest pathogen Penicillium digitatum

Cordyceps militaris is a well-known medicinal mushroom in Asian countries. This edible fungus has been widely exploited for traditional medicine and functional food production. C. militaris is a heterothallic fungus that requires both the mating-type loci, MAT1-1 and MAT1-2, for fruiting body formation. However, recent studies also indicated two groups of C. militaris, including monokaryotic strains carrying only MAT1-1 in their genomes and heterokaryotic strains harboring both MAT1-1 and MAT1-2. These strain groups are able to produce fruiting bodies under suitable cultivating conditions. In previous work, we showed that monokaryotic strains are more stable than heterokaryotic strains in fruiting body formation through successive culturing generations. In this study, we report a high cordycepin-producing monokaryotic C. militaris strain (HL8) collected in Vietnam. This strain could form normal fruiting bodies with high biological efficiency and contain a cordycepin content of 14.43 mg/g lyophilized fruiting body biomass. The ethanol extraction of the HL8 fruiting bodies resulted in a crude extract with a cordycepin content of 69.15 mg/g. Assays of cytotoxic activity on six human cancer cell lines showed that the extract inhibited the growth of all these cell lines with the IC50 values of 6.41-11.51 µg/mL. Notably, the extract significantly reduced cell proliferation and promoted apoptosis of breast cancer cells. Furthermore, the extract also exhibited strong antifungal activity against Malassezia skin yeasts and the citrus postharvest pathogen Penicillium digitatum. Our work provides a promising monokaryotic C. militaris strain as a bioresource for medicine, cosmetics, and fruit preservation.

Effects of MAT1-2 Spore Ratios on Fruiting Body Formation and Degeneration in the Heterothallic Fungus Cordyceps militaris

The medicinal mushroom Cordyceps militaris is widely exploited in traditional medicine and nutraceuticals in Asian countries. However, fruiting body production in C. militaris is facing degeneration through cultivation batches, and the molecular mechanism of this phenomenon remains unclear. This study showed that fruiting body formation in three different C. militaris strains, namely G12, B12, and HQ1, severely declined after three successive culturing generations using the spore isolation method. PCR analyses revealed that these strains exist as heterokaryons and possess both the mating-type loci, MAT1-1 and MAT1-2. Further, monokaryotic isolates carrying MAT1-1 or MAT1-2 were successfully separated from the fruiting bodies of all three heterokaryotic strains. A spore combination of the MAT1-1 monokaryotic isolate and the MAT1-2 monokaryotic isolate promoted fruiting body formation, while the single monokaryotic isolates could not do that themselves. Notably, we found that changes in ratios of the MAT1-2 spores strongly influenced fruiting body formation in these strains. When the ratios of the MAT1-2 spores increased to more than 15 times compared to the MAT1-1 spores, the fruiting body formation decreased sharply. In contrast, when MAT1-1 spores were increased proportionally, fruiting body formation was only slightly reduced. Our study also proposes a new solution to mitigate the degeneration in the heterokaryotic C. militaris strains caused by successive culturing generations.

Efficient control of the fungal pathogens Colletotrichum gloeosporioides and Penicillium digitatum infecting citrus fruits by native soilborne Bacillus velezensis strains

Destruction of citrus fruits by fungal pathogens during preharvest and postharvest stages can result in severe losses for the citrus industry. Antagonistic microorganisms used as biological agents to control citrus pathogens are considered alternatives to synthetic fungicides. In this study, we aimed to identify fungal pathogens causing dominant diseases on citrus fruits in a specialized citrus cultivation region of Vietnam and inspect soilborne Bacillus isolates with antifungal activity against these pathogens. Two fungal pathogens were characterized as Colletotrichum gloeosporioides and Penicillium digitatum based on morphological characteristics and ribosomal DNA internal transcribed spacer sequence analyses. Reinfection assays of orange fruits confirmed that C. gloeosporioides causes stem-end rot, and P. digitatum triggers green mold disease. By the heterologous expression of the green fluorescent protein (GFP) in C. gloeosporioides using Agrobacterium tumefaciens-mediated transformation, we could observe the fungal infection process of the citrus fruit stem-end rot caused by C. gloeosporioides for the first time. Furthermore, we isolated and selected two soilborne Bacillus strains with strong antagonistic activity for preventing the decay of citrus fruits by these pathogens. Molecular analyses of 16 S rRNA and gyrB genes showed that both isolates belong to B. velezensis. Antifungal activity assays indicated that bacterial culture suspensions could strongly inhibit C. gloeosporioides and P. digitatum, and shield orange fruits from the invasion of the pathogens. Our work provides a highly effective Bacillus-based preservative solution for combating the fungal pathogens C. gloeosporioides and P. digitatum to protect citrus fruits at the postharvest stages.

Ectopic expression of GmHP08 enhances resistance of transgenic Arabidopsis toward drought stress

Ectopic expression of Glycine max two-component system member GmHP08 in Arabidopsis enhanced drought tolerance of transgenic plants, possibly via ABA-dependent pathways. Phosphorelay by two-component system (TCS) is a signal transduction mechanism which has been evolutionarily conserved in both prokaryotic and eukaryotic organisms. Previous studies have provided lines of evidence on the involvement of TCS genes in plant perception and responses to environmental stimuli. In this research, drought-associated functions of GmHP08, a TCS member from soybean (Glycine max L.), were investigated via its ectopic expression in Arabidopsis system. Results from the drought survival assay showed that GmHP08-transgenic plants exhibited higher survival rates compared with their wild-type (WT) counterparts, indicating better drought resistance of the former group. Analyses revealed that the transgenic plants outperformed the WT in various regards, i.e. capability of water retention, prevention of hydrogen peroxide accumulation and enhancement of antioxidant enzymatic activities under water-deficit conditions. Additionally, the expression of stress-marker genes, especially antioxidant enzyme-encoding genes, in the transgenic plants were found greater than that of the WT plants. In contrary, the expression of SAG13 gene, one of the senescence-associated genes, and of several abscisic acid (ABA)-related genes was repressed. Data from this study also revealed that the ectopic expression lines at germination and early seedling development stages were hypersensitive to exogenous ABA treatment. Taken together, our results demonstrated that GmHP08 could play an important role in mediating plant response to drought, possibly via an ABA-dependent manner.

Multiple cotunneling in large quantum dot arrays

We investigate the effects of inelastic cotunneling on the electronic transport properties of gold nanoparticle multilayers and thick films at low applied bias, inside the Coulomb-blockade regime. We find that the zero-bias conductance, g(0)(T), in all systems exhibits Efros-Shklovskii-type variable range hopping transport. The resulting typical hopping distance, corresponding to the number of tunnel junctions participating in cotunneling events, is shown to be directly related to the power-law exponent in the measured current-voltage characteristics. We discuss the implications of these findings in light of models on cotunneling and hopping transport in mesoscopic, granular conductors.

Angiotensin gene polymorphism as a determinant of posttransplantation renal dysfunction and hypertension

BACKGROUND

Polymorphism of the genes associated with angiotensin, including angiotensin-converting enzyme (ACE), angiotensinogen (AGT), and the type 1 (AT1) and type 2 (AT2) angiotensin II receptors, has been implicated in the pathophysiology of hypertension, ischemic heart disease, and progression of chronic renal disease.

METHODS

We investigated the impact of the ACE, AGT, AT1, and AT2 genotypes on renal allograft function in 148 patients (77 men, 71 women) who underwent transplantation over a 5-year period. Patients were genotyped using polymerase chain reaction sequence-specific primers and polymerase chain reaction followed by restriction fragment length polymorphism analysis.

RESULTS

ACE (D) and AGT (A/A) genotypes were associated with poorer chronic renal transplant function and more rapid chronic progression, defined as an increase of serum creatinine level with time. In addition, mean diastolic blood pressure at 3 years was significantly (P<0.02) correlated with C gene dose of AT1 (A-->C, 1166), with levels of 79+/-10 mmHg, 82+/-8.6 mmHg, and 95+/-8.3 mmHg for the A/A, A/C, and C/C genotypes, respectively. An apparent AT2 homozygote disadvantage could be an epiphenomenon because AT2 maps to the X chromosome, and males are homozygous for just one of the AT2 alleles (A/- or G/-).

CONCLUSIONS

Pretransplantation testing of the ACE, AGT, and AT1 genotypes may assist clinicians in identifying patients at risk for chronic renal transplant dysfunction and hypertension.

Severe and complicated malaria treated with artemisinin, artesunate or artemether in Viet Nam

One hundred and seventy five Vietnamese adults with severe and complicated malaria admitted to a rural district hospital were entered into an open randomized comparative study to compare 4 treatment regimens based on artemisinin and its derivatives. The median time of defervescence was 48 h (95% confident interval [CI] 38-58 h) in those given intramuscular (i.m.) artemether, 42 h (95% CI 36-48 h) in those given artemisinin suppositories, 36 h (95% CI 30-42 h) in those receiving artesunate (i.m.) and 30 h (95% CI 18-42 h) in those receiving intravenous artesunate (P = 0.13). The respective median parasite clearance times were 30 h (95% CI 26-34 h), 30 h (95% CI 24-36 h), 24 h (95% CI 15-33 h), and 24 h (95% CI 15-33 h) (P = 0.30); the median times for recovery of consciousness were 47 h (95% CI 31-63 h), 24 h (95% CI 18-30 h), 30 h (95% CI 18-42 h), and 24 h (95% CI 4-44 h) (P = 0.18); and the mortality rates were 11.1%, 17.6%, 10.2% and 16.6%, respectively (P = 0.64). There was no significant difference in efficacy between the 4 treatments.

Cellular lipid and fatty acid compositions of Burkholderia pseudomallei strains isolated from human and environment in Viet Nam

Viet nam is known as an endemic area of melioidosis but its etiologic agent originated in Viet nam was not extensively studied. For the first time, we analyzed the cellular lipid and fatty acid compositions of 15 Vietnamese isolates of Burkholderia pseudomallei, 10 from humans and 5 from the environment. Cellular lipid compositions were analyzed by two-dimensional thin-layer chromatography on silica gel G plates. Cellular fatty acid methyl esters were analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The major lipids in all the isolates were phosphatidylglycerol (PG), two forms of phosphatidylethanolamine (PE-1 and PE-2), and two forms of ornithine-containing lipid (OL-1 and OL-2). PE-1 contained non-hydroxy fatty acids at both sn-1 and -2 positions, while PE-2 possessed 2-hydroxy fatty acids and non-hydroxy fatty acids in a ratio of 1:1. Since snake venom phospholipase A2 digestion of PE-2 liberated 2-hydroxy fatty acids, it was confirmed that these acids are at the sn-2 position of glycerol moiety. In both OL-1 and OL-2, amide-linked fatty acid was 3-hydroxy palmitic acid (3-OH-C16:0), while ester-linked fatty acids were non-hydroxy acids in OL-1 and 2-hydroxy acids in OL-2. The total cellular fatty acid compositions of the test strains were characterized by the presence of 2-hydroxy palmitic (2-OH-C16:0), 2-hydroxy hexadecenoic (2-OH-C16:1), 2-hydroxy octadecenoic (2-OH-C18:1), 2-hydroxy methylene octadecanoic (2-OH-C19CPA), 3-hydroxy myristic (3-OH-C14:0) and 3-hydroxy palmitic (3-OH-C16:0) acids. There were significant differences in the concentration of hexadecenoic (C16:1), methylene hexadecanoic (C17CPA), octadecenoic (C18:1) and methylene octadecanoic (C19CPA) acids among the Vietnamese isolates of B. pseudomallei. However, no significant difference was observed in cellular lipid and fatty acid components between strains of human and environmental origins.

Apparent rates of glutathione turnover in rat tissues

Apparent first-order rate constants for glutathione (GSH) turnover were determined for 14 tissues in male Fischer 344 rats after intravenous injection of [35S]cysteine ([35S]Cys). Rate constants for glutathione turnover were estimated by nonlinear least-squares iterative minimization from the decrease in GSH specific activity 1-102 hr after administration of [35S]Cys. Tissue nonprotein sulfhydryl concentrations were determined by Ellman's assay and compared with GSH and Cys levels detected by high-performance liquid chromatography equipped with an electrochemical detector. Additionally, total radiolabeled [35S]GSH was determined by high-performance liquid chromatography equipped with a flow-through radioactivity detector. There were substantial differences in the apparent rates of GSH turnover between the various tissues examined. For example, both the liver and the kidney had rapid turnover rates with half-lives of 1-5 hr, while those for heart, skeletal muscle, and blood were much slower with half-lives of 68-118 hr. Gastrointestinal tract tissues were shown to have intermediate turnover rates of the following order: glandular stomach = caecum > duodenum = small intestine = large intestine > colon > forestomach. [35S]GSH had a half-life in lung and skin of approximately 63 and 50 hr, respectively.

Rates of ethyl acrylate binding to glutathione and protein

Ethyl acrylate is a monomer used extensively in polymer manufacturing. Although ethyl acrylate is toxic at high concentrations, it is metabolized and detoxified rapidly at low concentrations. In the current studies, in vitro experiments have demonstrated that [14C]ethyl acrylate reacts with both glutathione (GSH) and protein to give either [14C]3-(glutathion-S-yl)ethylpropionate or covalently bound protein adducts, respectively. The second-order rate constant for [14C]ethyl acrylate conjugation with GSH was determined by quantification of [14C]3-(glutathion-S-yl)ethylpropionate using an HPLC system equipped with a flow-through radioactive detector. The rate constant for conjugation was 32.8 M-1 min-1. Additionally, the apparent second-order rate constants were determined for [14C]ethyl acrylate binding to the protein fraction of 14 whole tissue homogenates. Estimation of total protein binding sites was performed by reacting tissue homogenates with high concentrations of [14C]ethyl acrylate, while rates of binding were determined by reacting tissue homogenates with 200 microM [14C]ethyl acrylate at 37 degrees C for various periods of time. Apparent second-order rate constants for ethyl acrylate binding to protein homogenates were similar to that observed for GSH reacting with ethyl acrylate. The role of GSH-transferase in catalyzing 3-(glutathion-S-yl)ethylpropionate formation also was evaluated with whole tissue homogenates. In most tissues, the GSH-transferases poorly catalyzed the conjugation reaction. However, a significant increase in 3-(glutathion-S-yl)ethylpropionate formation was observed with liver homogenate.