Zhiqiang An

Plant-symbiotic fungi as chemical engineers: multi-genome analysis of the clavicipitaceae reveals dynamics of alkaloid loci

The fungal family Clavicipitaceae includes plant symbionts and parasites that produce several psychoactive and bioprotective alkaloids. The family includes grass symbionts in the epichloae clade (Epichloë and Neotyphodium species), which are extraordinarily diverse both in their host interactions and in their alkaloid profiles. Epichloae produce alkaloids of four distinct classes, all of which deter insects, and some—including the infamous ergot alkaloids—have potent effects on mammals. The exceptional chemotypic diversity of the epichloae may relate to their broad range of host interactions, whereby some are pathogenic and contagious, others are mutualistic and vertically transmitted (seed-borne), and still others vary in pathogenic or mutualistic behavior. We profiled the alkaloids and sequenced the genomes of 10 epichloae, three ergot fungi (Claviceps species), a morning-glory symbiont (Periglandula ipomoeae), and a bamboo pathogen (Aciculosporium take), and compared the gene clusters for four classes of alkaloids. Results indicated a strong tendency for alkaloid loci to have conserved cores that specify the skeleton structures and peripheral genes that determine chemical variations that are known to affect their pharmacological specificities. Generally, gene locations in cluster peripheries positioned them near to transposon-derived, AT-rich repeat blocks, which were probably involved in gene losses, duplications, and neofunctionalizations. The alkaloid loci in the epichloae had unusual structures riddled with large, complex, and dynamic repeat blocks. This feature was not reflective of overall differences in repeat contents in the genomes, nor was it characteristic of most other specialized metabolism loci. The organization and dynamics of alkaloid loci and abundant repeat blocks in the epichloae suggested that these fungi are under selection for alkaloid diversification. We suggest that such selection is related to the variable life histories of the epichloae, their protective roles as symbionts, and their associations with the highly speciose and ecologically diverse cool-season grasses.

THERAPEUTIC MONOCLONAL ANTIBODIES

Therapeutic monoclonal antibodies : , Therapeutic monoclonal antibodies : , کتابخانه دیجیتال جندی شاپور اهواز

Molecular phylogenetic relationships of nonpathogenic grass mycosymbionts and clavicipitaceous plant pathogens

Acremonium sect.Albo-lanosa (Fungi Imperfecti) includes beneficial, endophytic mycosymbionts of various grasses of the subfamilyPooideae, and also the anamorph of the grass choke pathogen,Epichloë typhina (Clavicipitaceae, Ascomycotina). These fungi are seed-disseminated, thus stably maintained for many host generations. To investigate the possibility of long-term coevolution, isolates ofE. typhina and anamorphs were obtained from eight grass species, sequences of their rRNA gene internal transcribed spacers were aligned with those from otherClavicipitaceae, and cladograms were generated by maximum parsimony. The results indicated that the nonpathogenic endophytes have not necessarily coevolved with their host species and that they arose fromE. typhina on multiple occasions.

Handbook of industrial mycology

MYCOLOGY, INDUSTRIAL MYCOLOGY, AND FUNGAL BIOLOGY Industrial Mycology: Past, Present and Future Phylogeny of the Fungal Kingdom and Fungal-like Eukaryotes Biological Activities of Fungal Metabolites Cell Cycle Regulation in Morphogenesis and Development of Fungi Agrobacterium-Mediated Transformation of Filamentous Fungi FUNGAL SECONDARY METABOLITES DISCOVERY Fungal Germplasm for Drug Discovery and Industrial Applications Expression of Cosmid-Size DNA of Slow-Growing Fungi in Aspergillus nidulans for Secondary Metabolite Screening The Isolation and Structure Elucidation of Fungal Metabolites PCR-Based Data and Secondary Metabolites as Chemotaxonomical Markers in High Throughput Screening for Bioactive Compounds from Fungi Screening for Biological Activities in Fungal Extracts Sordarins, Inhibitors of Fungal Elongation Factor 2 BIOSYNTHESIS OF FUNGAL SECONDARY METABOLITES Secondary Metabolite Gene Clusters The Aflatoxin Biosynthetic Pathway Indole-Diterpene Biosynthesis in Ascomycetous Fungi Loline and Ergot Alkaloids in Grass Endophytes Biosynthesis of N-methylated peptides in fungi The Molecular Genetics of Lovastatin and Compactin Biosynthesis The Aspergillus nidulans Polyketide Synthase WA FERMENTATION, STRAIN IMPROVEMENT, AND BIOCONVERSION Pneumocandin B0 Production by Fermentation of the Fungus Glarea lozoyensis: Physiological and Engineering Factors Affecting Titer and Structural-Analogue Formation Strain Improvement for the Production of Secondary Metabolites Fungal Bioconversions: Applications to the Manufacture of Pharmaceuticals METABOLIC ENGINEERING Metabolomics Metabolic Engineering Fungal Secondary Metabolic Pathways HETEROLOGOUS PROTEIN AND ENZYME EXPRESSION IN FUNGI Heterologous Protein and Enzyme Expression in Fungi MYCOTOXIN Toxigenic Fungi and Mycotoxin FUNGI IN BIOLOGICAL CONTROL Biochemical Basis of Fungi in Biocontrol of Plant Diseases

Suppression of mycorrhizal fungi in fescue by the acremonium coenophialum endophyte

Abstract Propagule population densities of the nine mycorrhizal species detected in field plots planted to tall fescue free of the Acremonium coenophialum endophyte were more than double those in plots planted to fescue heavily infected with Acremonium . Seedlings of Acremonium -free fescue detected more propagules of most of the eleven mycorrhizal species detected in a field soil than seedlings infected with Acremonium . Sporulation by three mycorrhizal isolates over 17 weeks was higher on fescue seedlings free of Acremonium than on seedlings infected with Acremonium . Since mycorrhizal fungi are believed to be confined to roots and Acremonium endophytes to shoots, the inhibitory effect of Acremonium on mycorrhizal fungi may be due to the translocation to roots of alkaloids produced by the Acremonium-Festuca symbiosis.

Evolution of nematode-trapping cells of predatory fungi of the Orbiliaceae based on evidence from rRNA-encoding DNA and multiprotein sequences

Among fungi, the basic life strategies are saprophytism, parasitism, and predation. Fungi in Orbiliaceae (Ascomycota) prey on animals by means of specialized trapping structures. Five types of trapping devices are recognized, but their evolutionary origins and divergence are not well understood. Based on comprehensive phylogenetic analysis of nucleotide sequences of three protein-coding genes (RNA polymerase II subunit gene, rpb2; elongation factor 1-α gene, ef1-α; and ß tubulin gene, bt) and ribosomal DNA in the internal transcribed spacer region, we have demonstrated that the initial trapping structure evolved along two lineages yielding two distinct trapping mechanisms: one developed into constricting rings and the other developed into adhesive traps. Among adhesive trapping devices, the adhesive network separated from the others early and evolved at a steady and gentle speed. The adhesive knob evolved through stalk elongation, with a final development of nonconstricting rings. Our data suggest that the derived adhesive traps are at a highly differentiated stage. The development of trapping devices is felicitous proof of adaptive evolution.

EVALUATION OF THE "MOST PROBABLE NUMBER" (MPN) AND WET-SIEVING METHODS FOR DETERMINING SOIL-BORNE POPULATIONS OF ENDOGONACEOUS MYCORRHIZAL FUNGI

The community of endogonaceous mycorrhizal fungi present in plots with two different cropping histories in a western Kentucky soybean field was analyzed by wet-sieving of spores from field soil sam...

Generation and selection of novel fully human monoclonal antibodies that neutralize Dickkopf-1 (DKK1) inhibitory function in vitro and increase bone mass in vivo

Wnt/LRP5 signaling is a central regulatory component of bone formative and resorptive activities, and the pathway inhibitor DKK1 is a suppressor of bone formation and bone mass accrual in mice. In addition, augmented DKK1 levels are associated with high bone turnover in diverse low bone mass states in rodent models and disease etiologies in human. However, examination of the precise role of DKK1 in the normal skeleton and in higher species requires the development of refined DKK1-specific pharmacological tools. Here, we report the strategy resulting in isolation of a panel of fully human anti-DKK1 antibodies applicable to studies interrogating the roles of mouse, rhesus, and human DKK1. Selected anti-DKK1 antibodies bind primate and human DKK-1 with picomolar affinities yet do not appreciably bind to DKK2 or DKK4. Epitopes mapped within the DKK1 C-terminal domain necessary for interaction with LRP5/6 and consequently effectively neutralized DKK1 function in vitro. When introduced into naïve normal growing female mice, IgGs significantly improved trabecular bone volume and structure and increased both trabecular and cortical bone mineral densities in a dose-related fashion. Furthermore, fully human DKK1-IgG displayed favorable pharmacokinetic parameters in non-human primates. In summary, we demonstrate here a rate-limiting function of physiologic DKK1 levels in the regulation of bone mass in intact female mice, amendable to specific pharmacologic neutralization by newly identified DKK1-IgGs. Importantly the fully human IgGs display a profile of attributes that recommends their testing in higher species and their use in evaluating DKK1 function in relevant disease models.

Pentameric complex of viral glycoprotein H is the primary target for potent neutralization by a human cytomegalovirus vaccine

Significance Congenital human cytomegalovirus (HCMV) infection is an important cause of newborn disability, and developing a vaccine against congenital HCMV is a top priority. However, despite decades of efforts, a vaccine remains elusive. Previous vaccines lacked an antigen called pentameric glycoprotein H (gH) complex, essential for the virus to infect epithelial/endothelial cells, and these vaccines induced poor neutralizing antibodies. To support a unique vaccine concept featuring the pentameric gH complex, we established 45 mAbs from a rabbit immunized with an experimental vaccine. Over 50% of the mAbs have antiviral activity, and potent clones target the pentameric gH complex, thus establishing this antigen as the key for potent antiviral antibodies by vaccination. Our result contributes to the understanding of immune attributes of an effective vaccine against HCMV. Human cytomegalovirus (HCMV) can cause serious morbidity/mortality in transplant patients, and congenital HCMV infection can lead to birth defects. Developing an effective HCMV vaccine is a high medical priority. One of the challenges to the efforts has been our limited understanding of the viral antigens important for protective antibodies. Receptor-mediated viral entry to endothelial/epithelial cells requires a glycoprotein H (gH) complex comprising five viral proteins (gH, gL, UL128, UL130, and UL131). This gH complex is notably missing from HCMV laboratory strains as well as HCMV vaccines previously evaluated in the clinic. To support a unique vaccine concept based on the pentameric gH complex, we established a panel of 45 monoclonal antibodies (mAbs) from a rabbit immunized with an experimental vaccine virus in which the expression of the pentameric gH complex was restored. Over one-half (25 of 45) of the mAbs have neutralizing activity. Interestingly, affinity for an antibody to bind virions was not correlated with its ability to neutralize the virus. Genetic analysis of the 45 mAbs based on their heavy- and light-chain sequences identified at least 26 B-cell linage groups characterized by distinct binding or neutralizing properties. Moreover, neutralizing antibodies possessed longer complementarity-determining region 3 for both heavy and light chains than those with no neutralizing activity. Importantly, potent neutralizing mAbs reacted to the pentameric gH complex but not to gB. Thus, the pentameric gH complex is the primary target for antiviral antibodies by vaccination.

The distal GATA sequences of the sid1 promoter of Ustilago maydis mediate iron repression of siderophore production and interact directly with Urbs1, a GATA family transcription factor

The sid1 and urbs1 genes encode L‐ornithine N5‐oxygenase and a GATA family transcription regulator, respectively, for siderophore biosynthesis in Ustilago maydis. The basic promoter and iron‐regulatory sequences of the U.maydis sid1 gene were defined by fusing restriction and Bal31 nuclease‐generated deletion fragments of the promoter region with the Escherichia coli β‐glucuronidase (GUS) reporter gene. Sequences required for basal expression of sid1 mapped within 1043 bp upstream of the translation start site and include the first untranslated exon and first intron. Sequences needed for iron‐regulated expression of sid1 were localized to a 306 bp region mapping 2.3 and 2.6 kb upstream of the ATG. The 306 bp region contains two G/TGATAA sequences, consensus DNA binding sites of GATA family transcription factors. Deletion or site‐directed mutation of either or both GATA sequences resulted in deregulated expression of sid1. In vitro DNA binding studies showed that Urbs1 binds to the 3′‐GATA site in the 306 bp iron‐responsive region. However, deletion of 1.1 kb between the distal GATA sites and the basal promoter region led to deregulated expression of GUS, indicating that these GATA sequences are by themselves insufficient to regulate sid1. In vitro DNA binding and in vivo reporter gene analysis revealed that siderophores are not co‐repressors of Urbs1.