Guo Shun-xing

Morphological characteristics of sclerotia formed from hyphae of Grifola umbellata under artificial conditions

The morphological characteristics of sclerotia were induced in cultures of the fungus Grifola umbellata by introducing an unidentified companion fungus were studied by light microscope, scanning and transmission electron microscope (SEM and TEM). Light microscope and SEM investigations of developing sclerotia revealed that aerial mycelial hyphae diminished with age, and mature sclerotia had two tissue layers, the rind and medulla. The medulla was comprised of thin and thick-walled hyphae of varying diameter. The thick-walled cells always formed below the hyphal tips. Retraction of the cytoplasm was accompanied by the thickening of cell wall. There were crystalline initials in the newly formed sclerotium. Crystalline initials were always formed in the tip of medullary hyphae and were not of regular shape. A series of changes occurred in the cells in which the crystalline initials would be formed, such as enlargement of size, formation of one or several large vacuoles. Crystalline initials developed via amorphous materials in the cytoplasm deposited in the vacuoles. At last crystalline initials was released by degradation of the cell wall.

Phylogenetic constrains on mycorrhizal specificity in eight Dendrobium (Orchidaceae) species

Plant phylogeny constrains orchid mycorrhizal (OrM) fungal community composition in some orchids. Here, we investigated the structures of the OrM fungal communities of eight Dendrobium species in one niche to determine whether similarities in the OrM fungal communities correlated with the phylogeny of the host plants and whether the Dendrobium-OrM fungal interactions are phylogenetically conserved. A phylogeny based on DNA data was constructed for the eight coexisting Dendrobium species, and the OrM fungal communities were characterized by their roots. There were 31 different fungal lineages associated with the eight Dendrobium species. In total, 82.98% of the identified associations belonging to Tulasnellaceae, and a smaller proportion involved members of the unknown Basidiomycota (9.67%). Community analyses revealed that phylogenetically related Dendrobium tended to interact with a similar set of Tulasnellaceae fungi. The interactions between Dendrobium and Tulasnellaceae fungi were significantly influenced by the phylogenetic relationships among the Dendrobium species. Our results provide evidence that the mycorrhizal specificity in the eight coexisting Dendrobium species was phylogenetically conserved.

A Novel Assay for Screening Inhibitors Targeting HIV Integrase LEDGF/p75 Interaction Based on Ni(2+) Coated Magnetic Agarose Beads.

HIV-1 integrase (IN) plays an essential role in viral replication and thus serves as an important target for chemotherapeutic intervention against HIV-1 infection. However, the current three clinical IN inhibitors, raltegravir, elvitegravir and dolutegravir share the same inhibitory mechanism, resulting in a common clinical resistance profile which have emerged in infected patients receiving treatment. Therefore, it is important to develop small molecule inhibitors that impair IN function with distinct mechanisms of action. In this work, a magnetic-beads based biochemical assay targeting the protein-protein interaction (PPI) between HIV IN and the cellular cofactor LEDGF/p75 was developed for identification of HIV-1 IN inhibitors. Furthermore, a library containing 1000 US. Food and Drug Administration (FDA)-approved drugs currently used for human medication was screened to identify inhibitors targeting the PPI. The assay was proved to be quite robust and with the novel assay we successfully identified dexlansoprazole (IC50 of 4.8 μM), a FDA-approved proton pump inhibitor, as a potential inhibitor for the PPI between IN and LEDGF/p75, which bound to the LEDGF/p75 partner with a kinetic dissociation (Kd) constant of 330 nM ± 2.6 nM.