Fimbriae of coprinus cinereus, schizophyllum commune and ustilago violacea = structural aspects and a role in conjugation

Surface fibrils (fimbriae) have been observed on fungi from every major group. Fimbriae are thought to be involved in the following cell to cell interactions: conjugation, flocculation and adhesion. Several higher fungi exibit two other types of interactions: hyphal fusion (anastomosis) and clamp connection formation. As a prelude to examining the role of fimbriae in these processes, the fimbriae of two fungi that undergo these fusion events were examined. Electron microscopy studies revealed that Coprinus cinereus and Schizophyllum commune are fimbriated. C. cinereus fimbriae were 5 nm in diameter and 0.5 to 20 11m in length. Fimbriae of C. cinereus oidia were more numerous and longer than those of the hyphal stage. S. commune fimbriae were also 5 nm in diameter, but were only 0.5 to 2 11m in length. There was an unequal distribution of fimbriae on the hyphal surfaces of S. commune . Fimbriae were sparsely distributed over the entire hyphal surface, with higher densities of fibrils present on the side growths of the hyphae found in the older sections of the mycelium. Antiserum raised against Ustilago violacea fimbrial protein (AU) crossreacted strongly with 37 and 39 kd C. cinereus mycelial proteins. In contrast, AU bound very weakly to 89 and 92 kd S. commune mycelial proteins. Since AU cross-reacted poorly with S. commune fimbrial proteins, it was impossible to further characterize the fimbriae of this specIes. The 37 and 39 kd C. cinereus proteins, were isolated by electroelution and were shown to be able to form fibrils the same diameter as oidial fimbriae. The 37 kd protein was shown to be composed of several proteins with isoelectric points ranging from pH 6.1 to 7.63. Furthermore, the 37 kd protein was found to be multimeric, while the 39 kd protein was not. These results strongly suggested that the 37 kd protein is the structural fimbrial protein of C. cine reus . Finally, a series of experiments were designed to determine whether fimbriae are required for conjugation in U. violacea Conjugation was inhibited significantly with AU, but not with pre-immune serum or AU preincubated with purified fimbrial protein. Thus, it was concluded that fimbriae play a central role in mating in this organism.

Avaliação química e biológica do fungo endofítico Schizophyllum commune isolado de Alchornea glandulosa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Genetic structure of a population of Ganoderma boninense on oil palm

Ganoderma boninense (the causal agent of basal stem rot of oil palm in Papua New Guinea) has a tetrapolar mating system with multiple alleles. Investigations into the population structure of G. boninense, using interfertility between isolates as a marker, revealed that the population on oil palm was comprised predominantly of genetically distinct individuals, although a number of isolates were found to share single mating alleles. No direct hereditary relationship was found between isolates on neighbouring or spatially separated diseased palms, indicating that outcrossing had probably occurred over several generations in the founder population prior to colonization of oil palm. In this study, a total of 81 A and 83 B mating type alleles (factors) were detected with 18 allelic repeats at the A locus and 17 at the B locus. Alleles appeared to be randomly dispersed throughout the population in each study block, although there was a significantly (P

Basidiomycosis: a review of the literature

The basidiomycosis, fungal infections provoked by basidiomycetes or agaric fungi have been recorded at growing frequencies in the medical literature, especially after the advent of AIDS in 1991. The basidiospores of these fungi, scattered in the atmosphere and transported by winds or air currents, reach the maxillary sinuses through the nasal route, most of the times causing signs and symptoms of chronic sinusitis. Basidiomycetes have also been isolated from sputum, especially Schizophyllum commune. Lesions of the buccal mucosa, brain abscesses, onychomycosis and endocarditis have been described, with a growing interest in this type of deep mycosis on the part of mycologists and infectologists. The present paper reports descriptions of mycetism as well as infectious processes caused by basidiomycetes, such as Schizophyllum commune, Ustilago maydis (= Ustilago zeae) and Coprinus cinereus

HYMENOMYCETES DETERIORADORES DE MADEIRA EM SERRARIAS DE MANAUS, AM, BRASIL

Do levantamento realizado com fungos (Hymenomycetes) deterioradores de madeiras em serrarias de Manaus foram encontradas as seguintes espécies: Coriolopsis occidentalis, Pleurotus ostreatus, Pycnoporus sanguineus e Schizophyllum commune. Pleurotus ostreatus foi assinalada com maior freqüência. As seis espécies de madeiras examinadas Ceiba pentandra(sumaúma), Copaifera multijuga (copaiba), Hura crepitans (assacu), Maquira coriacea (muiratinga), Pseudobombax munguba (munguba) e Virola surinamensis (virola) tiveram suas cascas e alburnos atacados. Hura crepitans foi a que apresentou maior incidência de fungos.

Poliporóides (Basidiomycota) em fragmentos de mata no perímetro urbano de São José do Rio Preto, São Paulo, Brasil

Foi realizado levantamento das espécies de fungos poliporóides que ocorrem no perímetro urbano do município de São José do Rio Preto (20º49'12" S, 49º22'44" W), Estado de São Paulo, Brasil. Foram identificadas 18 espécies pertencentes a 11 gêneros de Agaricales (Schizophyllaceae), Hymenochaetales (Hymenochaetaceae) e Polyporales (Ganodermataceae, Gloeophyllaceae, Meruliaceae e Polyporaceae): Coriolopsis floccosa (Jungh.) Ryvarden, C. polyzona (Pers.) Ryvarden, Datronia caperata (Berk.) Ryvarden, D. mollis (Somf.:Fr.) Donk., Ganoderma australe (Fr.) Pat., Gloeophyllum striatum (Sw.) Murrill, Gloeoporus thelephoroides (Hook.) G. Cunn., Hexagonia hirta (P. Beauv.) Fr., H. hydnoides (Sw.) M. Fidalgo, H. papyracea Berk., Polyporus tenuiculus (P. Beauv.) Fr., Phellinus callimorphus (Lév.) Ryvarden, P. gilvus (Schwein.) Pat., P. umbrinellus (Bres.) Herrera & Bondartseva, Pycnoporus sanguineus (L.) Murrill, Schizophyllum commune Fr., S. umbrinum Berk. e Trametes modesta (Kunze:Fr.) Ryvarden. Datronia mollis é nova citação para o Estado de São Paulo. São apresentados chave de identificação, descrições e comentários para cada táxon estudado.

Poliporóides (Basidiomycota) em fragmentos de mata no perímetro urbano de São José do Rio Preto, São Paulo, Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Screening for pectinolytic activity of wood-rotting basidiomycetes and characterization of the enzymes

Seventy-five fungal strains from different groups of basidiomycetes, newly isolated from rotten wood, were screened for pectinolytic activity. Despite the fact that basidiomycetes are scarcely referred to as pectinase producers, the polygalacturonase (PG) activity was detected in 76 % of the strains; 16 % with activity higher than 40 nkat/g, 40 % between 13.3 and 40 nkat/g, and 44 % with activity lower than 13.3 nkat/g. The highest productions were obtained among the fungi from order Aphyllophorales, family Polyporaceae. The characterization of the enzymes from the highest PG producers (Lentinus sp., Gloeophyllum striatum, Pycnoporus sanguineus, Schizophyllum commune) showed optimum temperature for catalytic activity at 60-70°C and two peaks of pH optimum (3.5-4.5 and 8.5-9.5). The enzymes exhibited high pH stability (3.0-11.0) but after incubation at 40°C for 1 h their activity dropped by 18-73 %.

Avaliação do potencial biocatalítico de fungos endófitos de espécies vegetais do Cerrado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Multiple Sex Pheromones and Receptors of a Mushroom-producing Fungus Elicit Mating in Yeast

The mushroom-producing fungus Schizophyllum commune has thousands of mating types defined, in part, by numerous lipopeptide pheromones and their G protein-linked receptors. Compatible combinations of pheromones and receptors encoded by different mating types regulate a pathway of sexual development leading to mushroom formation and meiosis. A complex set of pheromone–receptor interactions maximizes the likelihood of outbreeding; for example, a single pheromone can activate more than one receptor and a single receptor can be activated by more than one pheromone. The current study demonstrates that the sex pheromones and receptors of Schizophyllum, when expressed in Saccharomyces cerevisiae, can substitute for endogenous pheromone and receptor and induce the yeast pheromone response pathway through the yeast G protein. Secretion of active Schizophyllum pheromone requires some, but not all, of the biosynthetic machinery used by the yeast lipopeptide pheromone a-factor. The specificity of interaction among pheromone–receptor pairs in Schizophyllum was reproduced in yeast, thus providing a powerful system for exploring molecular aspects of pheromone–receptor interactions for a class of seven-transmembrane-domain receptors common to a wide range of organisms.

Molecular dynamics simulations of the hydrophobin SC3 at a hydrophobic/hydrophilic interface

Hydrophobins are small (similar to 100 aa) proteins that have an important role in the growth and development of mycelial fungi. They are surface active and, after secretion by the fungi, self-assemble into amphipathic membranes at hydrophobic/hydrophilic interfaces, reversing the hydrophobicity of the surface. In this study, molecular dynamics simulation techniques have been used to model the process by which a specific class I hydrophobin, SC3, binds to a range of hydrophobic/ hydrophilic interfaces. The structure of SC3 used in this investigation was modeled based on the crystal structure of the class II hydrophobin HFBII using the assumption that the disulfide pairings of the eight conserved cysteine residues are maintained. The proposed model for SC3 in aqueous solution is compact and globular containing primarily P-strand and coil structures. The behavior of this model of SC3 was investigated at an air/water, an oil/water, and a hydrophobic solid/water interface. It was found that SC3 preferentially binds to the interfaces via the loop region between the third and fourth cysteine residues and that binding is associated with an increase in a-helix formation in qualitative agreement with experiment. Based on a combination of the available experiment data and the current simulation studies, we propose a possible model for SC3 self-assembly on a hydrophobic solid/water interface.

Immunodéficience commune variable: ce qu'il faut savoir [Common variable immune deficiency: what you need to know].

Common variable immune deficiency is the most frequent primary immune deficiency, characterized mainly by a disorder of B lymphocytes differentiation and a deficit in immunoglobulins. The clinical manifestations include recurrent infections, non-infectious lung and digestive involvements, autoimmune diseases, and an increased susceptibility to cancers. Recent breakthroughs have been made in the understanding of some genetic mechanisms of the disease. Replacement therapy with intravenous immunoglobulins remains the treatment of choice, which allows significant improvement in the survival and quality of life. However progress should be made in the understanding of the pathophysiology and in the early detection of this disease, since a delay in the diagnosis may have harmful consequences in terms of morbidity and mortality.