This work is the first report on activity concentrations of 40K in Inonotus obliquus sampled in a virgin forest of Siberia. The results have shown that the chaga conk is characterized by high activity concentrations of 40K, averaging 1,641 Bq/kg dry weight (DW) and peaking at 3,502 Bq/kg DW. Activity concentrations of 40K in chaga conks have been defined to increase from the near-trunk stratum to the crust of the conk with increased exposure to the solar radiation. Our measurements have revealed the samples to be mildly contaminated with 137Cs. Intensive assimilation of 40K by chaga conks has been shown as a normal and innate feature of the wild chaga mushroom.
Bassiatin which is produced by some fungi, is morpholine-based depsipeptide. Recent studies show that bassiatin inhibits MCF-7 breast cancer cell proliferation with its anti-oestrogenic effect. In this study, bassiatin's inhibition versus Tamoxifen was examined by comparing the effects on epidermal growth factor receptor and vascular endothelial growth factor receptor in addition to oestrogen receptor on breast cells. For this purpose, 15 concentrations of bassiatin, tamoxifen and combination of both were treated in terms of cytotoxicity on MCF-7, MDA-MB-231, SK-BR-3 and SVCT cell lines. For cell cycle analyses, MCF-7 and SVCT cell lines were incubated with 37.5 μM bassiatin, tamoxifen and combined substance for 24 h and 48 h. After treatment, cell distribution in each phase of the cell cycle was measured with flow cytometer. Furthermore, each interaction related to receptors were investigated with immunoassay ELISA kits. As a result, bassiatin-induced MCF-7 cell cycle arrest was shown in G0/G1 and G2/M phases at the presence of bassiatin. It was also found that bassiatin is more effective at all examined receptors on breast cancer cells than tamoxifen. These results show that bassiatin can be used effectively in breast cancer treatment as a new anticancer agent because of its multiple inhibition effects.
Stropharia rugosoannulata is a popular edible mushroom in the world. High temperature seriously affects its yield and quality. In this study, transcriptome sequencing was performed on the mycelia of heat-resistant strains and heat-sensitive strains heat-treated at 38 °C for 0 h and 24 h. The changes of catalase (CAT) activity, superoxide dismutase (SOD) activity and trehalose content in the mycelia under high temperature stress were also measured and analyzed. We find that the differential genes are mainly enriched in the pathways of glycerophospholipid metabolism, starch and sucrose metabolism, protein processing in the endoplasmic reticulum, etc. The expression levels of genes encoding trehalose-6-phosphate phosphatase (TPP), CAT, SOD, etc. are quite different. And these genes’ variation range in the thermotolerant strain are higher than that in heat-sensitive strain. The CAT activity and trehalose content of the two strains increase first and then decrease, and the SOD activity increase slowly. The CAT, SOD activity and trehalose content of the thermotolerant strain are higher than those of the heat-sensitive strain. This study will provide a basis for further research on important signal pathways and gene function identification of S. rugosoannulata related to high temperature stress.
Identifying the mating-type in Mycoleptodonoides aitchisonii is important for enhancing breeding and cultivation of this edible mushroom. To clarify the molecular mechanisms of the bipolar mating system in M. aitchisonii, the homeodomain protein gene 2 (Mahd2) was characterized. A genomic DNA fragment of Mahd2 in M. aitchisonii 50005-18 strain was 1,851 bp long and encoded a protein of 614 amino acids. Transcriptional analysis revealed that the expression of Mahd2 was higher in monokaryotic strains that produced clamp cells than in those that did not. The highest relative expression level of Mahd2 was observed in monokaryon TUFC 50005-4, which was capable of forming a true clamp. These results suggested that the formation of clamp cells is regulated by A-mating type homeodomain proteins, and the frequency of clamp cell formation might be promoted by high expression of the Mahd2 gene.
The genus Fraxinus (Oleaceae), known as ash trees, currently comprises 43 recognized species that are distributed in temperate and subtropical regions of the northern hemisphere. Two Erysiphe (sect. Uncinula) species have been known on Fraxinus spp. so far. In this study, Fraxinus powdery mildews from different areas of the world were collected to make molecular and morphological analyses. These specimens are divided into three distinct molecular phylogenetic groups, which are distinguishable by their morphology and/or host preference. The powdery mildew occurring on F. apertisquamifera and F. lanuginosa is described as a new species, E. fraxinea. Epitypes are designated for E. fraxinicola and E. salmonii. Applying previous traditional species delimitations, various hosts were shared by E. fraxinicola as well as E. salmonii, but the current analyses strongly suggest strict host specificity among these three powdery mildew species. Evolutionary timing calculated by molecular clock analysis suggests co-evolution of powdery mildews with their Fraxinus hosts.
Pure cultures of Tuber were isolated from ectomycorrhizal root tips in Abies sachalinensis plantations in Hokkaido, Japan. Their phylogenetic relationships as well as vegetative hyphal characteristics on culture media were reported. Phylogenetic analysis based on the internal transcribed spacer within ribosomal DNA settled well-supported eight lineages within Puberulum, Latisporum, and Maculatum clades in Tuber. Three and one lineages were grouped with undescribed species of Puberulum clade in Japan and that of the Latisporum group in China, respectively. Two lineages were closely associated to but distinct from an undescribed species of Puberulum clade in Japan. One lineage did not group with any sequences in the International Nucleotide Sequence Database (INSD), proposing a new taxon in the Latisporum group. One lineage was grouped with T. foetidum in Maculatum clade. All strains in each lineage displayed yellowish white, thin, filamentous colonies on Melin-Norkrans agar medium. Various differences in morphological characteristics of hyphae on pure cultures of various strains were noted, but they were frequently uncommon among strains of the same taxa. Isolation from ectomycorrhizal root tips can be among the effective ways to acquire pure cultures of Tuber strains.
We hypothesised that cadmium exposure would hinder growth and secretion of carbon-degrading enzymes by mycorrhizal fungi, and that this would vary according to their tolerance to cadmium stress. The enzymes measured were β-Glucosidase, β-Xylosidase, β-D-cellubiosidase, N-acetyl-β-Glucosaminidase in three strains of ectomycorrhizal fungi Hebeloma subsaponaceum, Scleroderma sp., Hebeloma sp. and a feremycorrhizal fungus Austroboletus occidentalis. Fungi were subjected to cadmium stress for 28 d (in modified Melin-Norkrans liquid medium). The results showed unanticipated differential response of enzyme activities among the fungal species, including potential hormesis effects. Austroboletus occidentalis showed an increase in enzyme activity under cadmium stress.
Members of Hygrophorus olivaceoalbus-complex or olive waxcaps have both ecological and economic significance. European and North American species diversity of this fungal group has been presented in recent molecular phylogenetic studies, but no Chinese materials were included. In this study, a phylogenetic overview of the H. olivaceoalbus-complex based on internal transcribed spacer (ITS) sequences was made, and a local popular edible species from southwestern China was described as a new species H. annulatus. This new species is characterized by grayish brown, olive brown to dark brown pileus disc, inflexed to deflexed pileus margin, obvious and dark brown annulus, basidiospores measuring (8.0–)8.5–11.0(–12.0) × 5.0–7.5(–8.0) μm, and the distribution in subalpine forests dominated by Abies and/or Picea in southwestern China.