DETECTION OF CELLULAR-IMMUNITY WITH THE SOLUBLE-ANTIGEN OF THE FUNGUS SPOROTHRIX-SCHENCKII IN THE SYSTEMIC FORM OF THE DISEASE

Sporothrix schenckii is the etiologic agent of sporotrichosis, a mycosis of world-wide distribution more commonly occurring in tropical regions. The immunological mechanisms involved in the prevention and control of sporotrichosis are not fully understood but apparently include both the humoral and cellular responses. In the present investigation, cellular immunity was evaluated by in vivo and in vitro tests in mice infected with yeast-like forms of S. schenckii. The disease developed systemically and cellular immunity was evaluated for a period of 10 weeks. The soluble antigen utilized in the tests was prepared from yeast form of the fungus through the sonication (20 min: 10 sonications at 50 W at 2-min intervals). Delayed hypersensitivity and lymphocyte transformation tests showed that the cellular immune response was depressed between the 4th and 6th week of infection when the animals were challenged with the soluble fungal antigen. This depression frequently indicates worsening of the disease, with greater involvement of the host. This is a promising field of research for a better understanding of the pathogeny of this mycosis.

Host organism defense by a peptide-polysaccharide extracted from the fungus Sporothrix schenckii

A peptide-polysaccharide, a peptide-rhamnomannan, was isolated from the pathogenic yeast form of the fungus Sporothrix schenckii. This substance, which may play a role in fungal virulence, was tested in an animal model of systemic disease, and depression of the immune response was observed in the animals between the 4th and 6th week of infection. Concomitantly, this compound showed mitogenic activity when challenged with normal lymphocytes and was also found to be involved in the inflammatory response. These results provide further information for the understanding of fungal implantation in tissues and of the pathogenicity of this systemic mycosis.

Aromatic compounds produced by Periconia atropurpurea, an endophytic fungus associated with Xylopia aromatica

6,8-Dimethoxy-3-(2'-oxo-propyl)-coumarin (1) and 2,4-dihydroxy-6-[(1'E,3'E)-penta-1', 3'-dienyl]-benzaldehyde (2), in addition to the known compound periconicin B (3), were isolated from the ethyl acetate extract of Periconia atropurpurea, an endophytic fungus obtained from the leaves of Xylopia aromatica, a native plant of the Brazilian Cerrado. Their chemical structures were assigned based on analyses of MS, 1D and 2D-NMR spectroscopic experiments. Biological analyses were performed using two mammalian cell lines, human cervix carcinoma (HeLa) and Chinese hamster ovary (CHO). The results showed that compound I had no effect when compared to the control group, which was treated with the vehicle (DMSO). Compound 2 was able to induce a slight increase in cell proliferation of HeLa (37% of increase) and CHO (38% of increase) cell lines. Analysis of compound 3 showed that it has potent cytotoxic activity against both cell lines, with an IC50 of 8.0 mu M. Biological analyses using the phytopathogenic fungi Cladosporium sphaerospermum and C. cladosporioides revealed that also 2 showed potent antifungal activity compared to nystatin. (c) 2006 Elsevier Ltd. All rights reserved.

Phylogeography of the Solanaceae-infecting Basidiomycota fungus Rhizoctonia solani AG-3 based on sequence analysis of two nuclear DNA loci

Background: the soil fungus Rhizoctonia solani anastomosis group 3 (AG-3) is an important pathogen of cultivated plants in the family Solanaceae. Isolates of R. solani AG-3 are taxonomically related based on the composition of cellular fatty acids, phylogenetic analysis of nuclear ribosomal DNA (rDNA) and beta-tubulin gene sequences, and somatic hyphal interactions. Despite the close genetic relationship among isolates of R. solani AG-3, field populations from potato and tobacco exhibit comparative differences in their disease biology, dispersal ecology, host specialization, genetic diversity and population structure. However, little information is available on how field populations of R. solani AG-3 on potato and tobacco are shaped by population genetic processes. In this study, two field populations of R. solani AG-3 from potato in North Carolina (NC) and the Northern USA; and two field populations from tobacco in NC and Southern Brazil were examined using sequence analysis of two cloned regions of nuclear DNA (pP42F and pP89).Results: Populations of R. solani AG-3 from potato were genetically diverse with a high frequency of heterozygosity, while limited or no genetic diversity was observed within the highly homozygous tobacco populations from NC and Brazil. Except for one isolate (TBR24), all NC and Brazilian isolates from tobacco shared the same alleles. No alleles were shared between potato and tobacco populations of R. solani AG-3, indicating no gene flow between them. To infer historical events that influenced current geographical patterns observed for populations of R. solani AG-3 from potato, we performed an analysis of molecular variance (AMOVA) and a nested clade analysis (NCA). Population differentiation was detected for locus pP89 (Phi(ST) = 0.257, significant at P < 0.05) but not for locus pP42F (Phi(ST) = 0.034, not significant). Results based on NCA of the pP89 locus suggest that historical restricted gene flow is a plausible explanation for the geographical association of clades. Coalescent-based simulations of genealogical relationships between populations of R. solani AG-3 from potato and tobacco were used to estimate the amount and directionality of historical migration patterns in time, and the ages of mutations of populations. Low rates of historical movement of genes were observed between the potato and tobacco populations of R. solani AG-3.Conclusion: the two sisters populations of the basidiomycete fungus R. solani AG-3 from potato and tobacco represent two genetically distinct and historically divergent lineages that have probably evolved within the range of their particular related Solanaceae hosts as sympatric species.

Purification and characterization of two beta-glucosidases from the thermophilic fungus Thermoascus aurantiacus

beta-Glucosidase from the fungus Thermoascus aurantiacus grown oil semi-solid fermentation medium (using ground corncob as substrate) was partially purified in 5 steps - ultrafiltration, ethanol precipitation, gel filtration and 2 anion exchange chromatography runs, and characterized. After the first anion exchange chromatography, beta-glucosidase activity was eluted in 3 peaks (Gl-1, Gl-2, Gl-3). Only the Gl-2 and Gl-3 fractions were adsorbed on the gel matrix. Gl-2 and Gl-3 exhibited optimum pH at 4.5 and 4.0, respectively. The temperature optimum of both glucosidases was at 75-80 degreesC. The pH stability of Gl-2 (4.0-9.0) was higher than Gl-3 (5.5-8.5); both enzyme activities showed similar patterns of thermostability. Under conditions of denaturing gel chromatography the molar mass of Gl-2 and Gl-3 was 175 and 157 kDa, respectively. Using 4-nitrophenyl beta-D-glucopyranoside as substrate, K-m, values of 1.17 +/- 0.35 and 1.38 +/- 0.86 mmol/L were determined for Gl-2 and Gl-3, respectively. Both enzymes were inhibited by Ag+ and stimulated by Ca2+.

Chemical Composition of Metapleural Gland Secretions of Fungus-Growing and Non-fungus-growing Ants

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

Ventilation of the giant nests of Atta leaf-cutting ants: does underground circulating air enter the fungus chambers?

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