Toxicology and Mycotoxin Research Unit

Athens, GA, United States

Toxicology and Mycotoxin Research Unit

Athens, GA, United States
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Schardl C.L.,University of Kentucky | Young C.A.,Samuel Roberts Noble Foundation | Hesse U.,University of Kentucky | Amyotte S.G.,University of Kentucky | And 51 more authors.
PLoS Genetics | Year: 2013

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.

Glenn A.E.,Toxicology and Mycotoxin Research Unit | Karagianni E.P.,Democritus University of Thrace | Ulndreaj A.,Democritus University of Thrace | Boukouvala S.,Democritus University of Thrace
FEBS Letters | Year: 2010

Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes characterized in several bacteria and eukaryotic organisms. We report a comprehensive phylogenetic analysis employing an exhaustive dataset of NAT-homologous sequences recovered through inspection of 2445 genomes. We describe the first NAT homologues in viruses, archaea, protists, many fungi and invertebrates, providing complete annotations in line with the consensus nomenclature. Contrary to the NAT genes of vertebrates, introns are commonly found within the homologous coding regions of lower eukaryotes. The NATs of fungi and higher animals are distinctly monophyletic, but evidence supports a mixed phylogeny of NATs among bacteria, protists and possibly some invertebrates. © 2010 Federation of European Biochemical Societies.

Glenn A.,Toxicology and Mycotoxin Research Unit | Bodri M.S.,University of North Georgia
PLoS ONE | Year: 2012

Fungal endophytes were isolated from 4 species of the carnivorous pitcher plant genus Sarracenia: S. minor, S. oreophila, S. purpurea, and S. psittacina. Twelve taxa of fungi, 8 within the Ascomycota and 4 within the Basidiomycota, were identified based on PCR amplification and sequencing of the internal transcribed spacer sequences of nuclear ribosomal DNA (ITS rDNA) with taxonomic identity assigned using the NCBI nucleotide megablast search tool. Endophytes are known to produce a large number of metabolites, some of which may contribute to the protection and survival of the host. We speculate that endophyte-infected Sarracenia may benefit from their fungal associates by their influence on nutrient availability from within pitchers and, possibly, by directly influencing the biota within pitchers.

Leyte-Lugo M.,National Autonomous University of Mexico | Figueroa M.,National Autonomous University of Mexico | Gonzalez M.D.C.,National Autonomous University of Mexico | Glenn A.E.,Toxicology and Mycotoxin Research Unit | And 2 more authors.
Phytochemistry | Year: 2013

An extract of the solid cultures of Sporormiella minimoides (Sporormiaceae) isolated as an endophytic fungus from Hintonia latiflora (Rubiaceae), yielded three polyketides, 3,6-dimethoxy-8-methyl-1H,6H-benzo[de]isochromene-1,9-dione, 3-hydroxy-1,6,10-trimethoxy-8-methyl-1H,3H-benzo[de]isochromen-9-one, and 5-hydroxy-2,7-dimethoxy-8-methylnaphthoquinone, along with three known compounds, corymbiferone, ziganein, and brocaenol B. Their structures were characterized by spectrometric and spectroscopic methods. So as to be consistent the literature reports, 3,6-dimethoxy-8-methyl-1H,6H-benzo[de]isochromene-1,9- dione and 3-hydroxy-1,6,10-trimethoxy-8-methyl-1H,3H-benzo[de]isochromen-9-one were given the trivial names of corymbiferone C and corymbiferan lactone E, respectively. All isolates were tested as potential human calmodulin (hCaM) inhibitors using the fluorescent biosensor hCaM V91C-mBBr, but only 5-hydroxy-2,7-dimethoxy-8-methylnaphthoquinone quenched significantly the extrinsic fluorescence of this biosensor, with a dissociation constant (K d) value of 1.55 μM. Refined docking analysis predicted that 5-hydroxy-2,7-dimethoxy-8-methylnaphthoquinone could also be bound to hCaM at site I displaying hydrophobic interactions with Phe19 and 68, Met51, 71, and 72, and Ile52 and 63 residues.© 2013 Elsevier Ltd. All rights reserved.

Bacon C.W.,Toxicology and Mycotoxin Research Unit | Hinton D.M.,Toxicology and Mycotoxin Research Unit
Canadian Journal of Microbiology | Year: 2011

Maize (Zea mays L.) is susceptible to infection by Fusarium verticillioides through autoinfection and alloinfection, resulting in diseases and contamination of maize kernels with the fumonisin mycotoxins. Attempts at controlling this fungus are currently being done with biocontrol agents such as bacteria, and this includes bacterial endophytes, such as Bacillus mojavensis. In addition to producing fumonisins, which are phytotoxic and mycotoxic, F. verticillioides also produces fusaric acid, which acts both as a phytotoxin and as an antibiotic. The question now is Can B. mojavensis reduce lesion development in maize during the alloinfection process, simulated by internode injection of the fungus? Mutant strains of B. mojavensis that tolerate fusaric acid were used in a growth room study to determine the development of stalk lesions, indicative of maize seedling blight, by co-inoculations with a wild-type strain of F. verticillioides and with non-fusaric acid producing mutants of F. verticillioides. Lesions were measured on 14-day-old maize stalks consisting of treatment groups inoculated with and without mutants and wild-type strains of bacteria and fungi. The results indicate that the fusaric-acidtolerant B. mojavensis mutant reduced stalk lesions, suggesting an in planta role for this substance as an antibiotic. Further, lesion development occurred in maize infected with F. verticillioides mutants that do not produce fusaric acid, indicating a role for other phytotoxins, such as the fumonisins. Thus, additional pathological components should be examined before strains of B. mojavensis can be identified as being effective as a biocontrol agent, particularly for the control of seedling disease of maize.

PubMed | Toxicology and Mycotoxin Research Unit and Creighton University
Type: Journal Article | Journal: Toxicological sciences : an official journal of the Society of Toxicology | Year: 2016

FTY720 (fingolimod) is a U.S. Food and Drug Administration-approved drug to treat relapsing remitting multiple sclerosis. FTY720 treatment in pregnant inbred LM/Bc mice results in approximately 60% of embryos having a neural tube defect (NTD). Sphingosine kinases (Sphk1, Sphk2) phosphorylate FTY720 invivo to form the bioactive metabolite FTY720-1-phosphate (FTY720-P). Cytoplasmic FTY720-P is an agonist for 4 of the 5 sphingosine-1-phosphate (S1P) receptors (S1P1, 3-5) and can also act as a functional antagonist of S1P1, whereas FTY720-P generated in the nucleus inhibits histone deacetylases (HDACs), leading to increased histone acetylation. This study demonstrates that treatment of LM/Bc mouse embryonic fibroblasts (MEFs) with FTY720 results in a significant accumulation of FTY720-P in both the cytoplasmic and nuclear compartments. Elevated nuclear FTY720-P is associated with decreased HDAC activity and increased histone acetylation at H3K18 and H3K23 in LM/Bc MEFs. Treatment of LM/Bc MEFs with FTY720 and a selective Sphk2 inhibitor, ABC294640, significantly reduces the amount of FTY720-P that accumulates in the nucleus. The data provide insight into the relative amounts of FTY720-P generated in the nuclear versus cytoplasmic subcellular compartments after FTY720 treatment and the specific Sphk isoforms involved. The results of this study suggest that FTY720-induced NTDs may involve multiple mechanisms, including: (1) sustained and/or altered S1P receptor activation and signaling by FTY720-P produced in the cytoplasm and (2) HDAC inhibition and histone hyperacetylation by FTY720-P generated in the nucleus that could lead to epigenetic changes in gene regulation.

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