Browsing by Author "Smith, ME"
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Item Open Access Association between cell-mediated demyelination and astrocyte stimulation.(Prog Brain Res, 1992) Smith, ME; Sommer, MAItem Open Access EAE cerebrospinal fluid augments in vitro phagocytosis and metabolism of CNS myelin by macrophages.(J Neurosci Res, 1992-07) Sommer, MA; Forno, LS; Smith, MEPrevious studies from this laboratory have shown that CNS myelin is phagocytized and metabolized by cultured rat macrophages to a much larger extent when myelin is pretreated with serum containing antibodies to myelin constituents than when it is left untreated or pretreated with non-specific serum. In this study the effect of cerebrospinal fluid (CSF) from rabbits with experimental allergic encephalomyelitis (EAE) in promoting myelin phagocytosis was examined. Fourteen rabbits were immunized with purified myelin in Freund's complete adjuvant, seven of which developed clinical EAE symptoms. Serum and CSF were collected from EAE and control rabbits, and the CSF was centrifuged to remove cells. Sera and CSF from these rabbits and from Freund's adjuvant-immunized controls and untreated controls were measured for IgG content by radial diffusion assay, their myelin antibody characteristics were analyzed by immunoblots, and the ability of these serum and CSF samples to promote myelin phagocytosis when used for myelin opsonization was examined. The ability of a CSF sample to enhance radioactive myelin uptake and phagocytosis by cultured macrophages as measured by the appearance of radioactive cholesterol ester was linearly proportional to its total IgG titer, and correlated approximately both with clinical symptoms of the animal and the presence of antibody against the myelin constituents myelin basic protein, proteolipid protein, and galactocerebroside. The cholesterol esterification activities of EAE sera correlated to a lesser extent with IgG levels and clinical symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)Item Open Access Guyanagaster, a New Wood-Decaying Sequestrate Fungal Genus Related to Armillaria (Physalacriaceae, Agaricales, Basidiomycota)(2010) Henkel, TW; Smith, ME; Aime, MCPremise of the study : Sequestrate basidiomycete fungi (e. g. "gasteromycetes") have foregone ballistospory and evolved alternative, often elaborate mechanisms of basidiospore dispersal with highly altered basidioma morphology. Sequestrate fungi have independently evolved in numerous Agaricomycete lineages, confounding taxonomic arrangements of these fungi for decades. Understanding the multiple origins and taxonomic affinities of sequestrate fungi provides insight into the evolutionary forces that can drastically alter basidioma morphology. In the neotropical rainforests of the Guiana Shield, we encountered a remarkable sequestrate fungus fruiting directly on decaying hardwood roots. The fungus 'singular combination of traits include a wood-decaying habit; black, verrucose peridium; reduced stipe; and gelatinized basidiospore mass. Methods : Guyanagaster necrorhiza gen. et sp. nov. is described. Macro-and micromorphological characters were assessed and compared to most similar taxa. To determine the phylogenetic affinities of the fungus, DNA sequence data were obtained for the 18S, ITS, and 28S rDNA, RBP2, and EF1 alpha regions and subjected to single-and multi-gene analyses. DNA sequences from fungal vegetative organs growing on decaying woody roots confirmed the wood-inhabiting lifestyle of Guyanagaster. Key results : Guyanagaster is morphologically unique among sequestrate fungi worldwide. Phylogenetic evidence places Guyanagaster in close relation to the wood-decaying mushroom genus Armillaria in the Physalacriaceae (Agaricales, Agaricomycetes, Basidiomycota). Conclusions : Guyanagaster represents an independently evolved sequestrate form within the Physalacriaceae. Although molecular data confirm that Guyanagaster is closely related to Armillaria, the unusual features of this fungus suggest a case of radically divergent morphological evolution.Item Open Access Induction of anti-myelin antibodies in EAE and their possible role in demyelination.(J Neurosci Res, 1991-12) Sadler, RH; Sommer, MA; Forno, LS; Smith, MEExperimental allergic encephalomyelitis is characterized by invasion of lymphocytes and macrophages into the central nervous system resulting in inflammation, edema, and demyelination. Sera from Lewis rats from 7-95 days after immunization with purified guinea pig CNS myelin were examined with respect to their ability to opsonize myelin. This was correlated with the appearance of antibody components and the relative amounts of antibody to myelin basic protein (MBP) and proteolipid protein (PLP). Sera from rats 10-95 days after immunization preincubated with purified myelin induced phagocytosis of myelin by cultured macrophages with the resulting production of cholesterol ester. This opsonization activity as measured by the percentage of cholesterol esterified reached a peak at 26-27 days after immunization but remained significantly elevated up to 95 days post-immunization compared to the activity of serum from the Freund's adjuvant-injected controls. Immunoblots of the sera revealed a gradual increase in antibody activity against myelin components. ELISA assays for MBP and PLP antibody showed a similar pattern. Antibody to galactocerebroside (GC) was not detected by immunostains nor by the ELISA assay. Areas of demyelination were observed histologically by luxol-fast blue stained spinal cords up to 60 days post-immunization. These results indicate that antibodies to myelin protein when given access to myelin through or within the blood brain barrier could initiate or enhance the phagocytic response by peripheral or resident macrophages.Item Open Access Structure, function, and phylogeny of the mating locus in the Rhizopus oryzae complex.(PLoS One, 2010-12-09) Gryganskyi, AP; Lee, SC; Litvintseva, AP; Smith, ME; Bonito, G; Porter, TM; Anishchenko, IM; Heitman, J; Vilgalys, RThe Rhizopus oryzae species complex is a group of zygomycete fungi that are common, cosmopolitan saprotrophs. Some strains are used beneficially for production of Asian fermented foods but they can also act as opportunistic human pathogens. Although R. oryzae reportedly has a heterothallic (+/-) mating system, most strains have not been observed to undergo sexual reproduction and the genetic structure of its mating locus has not been characterized. Here we report on the mating behavior and genetic structure of the mating locus for 54 isolates of the R. oryzae complex. All 54 strains have a mating locus similar in overall organization to Phycomyces blakesleeanus and Mucor circinelloides (Mucoromycotina, Zygomycota). In all of these fungi, the minus (-) allele features the SexM high mobility group (HMG) gene flanked by an RNA helicase gene and a TP transporter gene (TPT). Within the R. oryzae complex, the plus (+) mating allele includes an inserted region that codes for a BTB/POZ domain gene and the SexP HMG gene. Phylogenetic analyses of multiple genes, including the mating loci (HMG, TPT, RNA helicase), ITS1-5.8S-ITS2 rDNA, RPB2, and LDH genes, identified two distinct groups of strains. These correspond to previously described sibling species R. oryzae sensu stricto and R. delemar. Within each species, discordant gene phylogenies among multiple loci suggest an outcrossing population structure. The hypothesis of random-mating is also supported by a 50:50 ratio of plus and minus mating types in both cryptic species. When crossed with tester strains of the opposite mating type, most isolates of R. delemar failed to produce zygospores, while isolates of R. oryzae produced sterile zygospores. In spite of the reluctance of most strains to mate in vitro, the conserved sex locus structure and evidence for outcrossing suggest that a normal sexual cycle occurs in both species.