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PubMed2006

Evidence for novel pH-dependent regulation of Candida albicans Rim101, a direct transcriptional repressor of the cell wall beta-glycosidase Phr2.

Candida albicans is a commensal fungus of mucosal surfaces that can cause disease in susceptible hosts. One aspect of the success of C. albicans as both a commensal and a pathogen is its ability to adapt to diverse environmental conditions, including dramatic variations in environmental pH. The response to a neutral-to-alkaline pH change is controlled by the Rim101 signal transduction pathway. In neutral-to-alkaline environments, the zinc finger transcription factor Rim101 is activated by the proteolytic removal of an inhibitory C-terminal domain. Upon activation, Rim101 acts to induce alkaline response gene expression and repress acidic response gene expression. Previously, recombinant Rim101 was shown to directly bind to the alkaline-pH-induced gene PHR1. Here, we demonstrate that endogenous Rim101 also directly binds to the alkaline-pH-repressed gene PHR2. Furthermore, we find that of the three putative binding sites, only the -124 site and, to a lesser extent, the -51 site play a role in vivo. In C. albicans, the predicted Rim101 binding site was thought to be CCAAGAA, divergent from the GCCAAG site defined in Aspergillus nidulans and Saccharomyces cerevisiae. Our results suggest that the Rim101 binding site in C. albicans is GCCAAGAA, but slight variations are tolerated in a context-dependent fashion. Finally, our data suggest that Rim101 activity is governed not only by proteolytic processing but also by an additional mechanism not previously described.

Binding Sites↗
PubMed1999

Interactions of Penicillium marneffei with human leukocytes in vitro.

Penicillium marneffei, a dimorphic fungus endemic in parts of Asia, causes disease in those with impaired cell-mediated immunity, especially persons with AIDS. The histopathology of penicilliosis marneffei features the intracellular infection of macrophages. We studied the interactions between human leukocytes and heat-killed yeast-phase P. marneffei. Monocyte-derived macrophages bound and internalized P. marneffei in the presence of complement-sufficient pooled human serum (PHS). Binding and phagocytosis were still seen if PHS was heat inactivated or omitted altogether. The binding of unopsonized P. marneffei to monocyte-derived macrophages occurred in the absence of divalent cations and was not affected by inhibitors of mannose and beta-glucan receptors or monoclonal antibodies directed against CD14 and CD11/CD18. Binding was profoundly inhibited by wheat germ agglutinin. A vigorous respiratory burst was seen in peripheral blood mononuclear cells (PBMC) stimulated with P. marneffei, regardless of whether the fungi were opsonized. However, tumor necrosis factor alpha (TNF-alpha) release from PBMC stimulated with P. marneffei occurred only if serum was present. These data demonstrate that (i) monocyte-derived macrophages bind and phagocytose P. marneffei even in the absence of opsonization, (ii) binding is divalent cation independent but is inhibited by wheat germ agglutinin, suggesting that the major receptor(s) recognizing P. marneffei is a glycoprotein with exposed N-acetyl-beta-D-glucosaminyl groups, (iii) P. marneffei stimulates the respiratory burst regardless of whether opsonins are present, and (iv) serum factors are required for P. marneffei to stimulate TNF-alpha release. The ability of unopsonized P. marneffei to parasitize mononuclear phagocytes without stimulating the production of TNF-alpha may be critical for the virulence of this intracellular parasite.

Adult↗
PubMed2005

Molecular mapping of QTLs for resistance to Gibberella ear rot, in corn, caused by Fusarium graminearum.

Gibberella ear rot, caused by the fungus Fusarium graminearum Schwabe, is a serious disease of corn (Zea mays) grown in northern climates. Infected corn is lower yielding and contains toxins that are dangerous to livestock and humans. Resistance to ear rot in corn is quantitative, specific to the mode of fungal entry (silk channels or kernel wounds), and highly influenced by the environment. Evaluations of ear rot resistance are complex and subjective; and they need to be repeated over several years. All of these factors have hampered attempts to develop F. graminearum resistant corn varieties. The aim of this study was to identify molecular markers linked to the genes for resistance to Gibberella ear rot. A recombinant inbred (RI) population, produced from a cross between a Gibberella ear rot resistant line (CO387) and a susceptible line (CG62), was field-inoculated and scored for Gibberella ear rot symptoms in the F4, F6, and F7 generations. The distributions of disease scores were continuous, indicating that resistance is probably conditioned by multiple loci. A molecular linkage map, based on segregation in the F5 RI population, contained 162 markers distributed over 10 linkage groups and had a total length of 2237 cM with an average distance between markers of 13.8 cM. Composite interval mapping identified 11 quantitative trait loci (QTLs) for Gibberella ear rot resistance following silk inoculation and 18 QTLs following kernel inoculation in 4 environments that accounted for 6.7%-35% of the total phenotypic variation. Only 2 QTLs (on linkage group 7) were detected in more than 1 test for silk resistance, and only 1 QTL (on linkage group 5) was detected in more than 1 test for kernel resistance, confirming the strong influence of the environment on these traits. The majority of the favorable alleles were derived from the resistant parent (CO387). The germplasm and markers for QTLs with significant phenotypic effects may be useful for marker-assisted selection to incorporate Gibberella ear rot resistance into commercial corn cultivars.

Chromosome Mapping↗
PubMed2000

HPLC analyses of cultures of Phoma spp.: differentiation among groups and species through secondary metabolite profiles.

The metabolite profiles of 26 isolates of the blackleg fungus (Leptosphaeria maculans (Desm.) Ces. et de Not., asexual stage Phoma lingam (Tode ex Fr.) Desm.), obtained from diverse parts of the world (part of the International Blackleg Crucifer Network collection), were studied utilizing specific culture conditions, HPLC analysis, and a set of chemical markers. This fungus is the causative agent of blackleg disease of brassica oilseeds; a virulent strain of the pathogen has caused significant rapeseed (Brassica napus L., and B. rapa L.) and canola (B. napus L., and B. rapa L.) losses in Canada, and is also considered a serious agricultural problem worldwide. Effective surveys of blackleg epidemics require simple and reliable analytical methodology to differentiate among the diverse groups of isolates. The chemical analysis of phytotoxins and related secondary metabolites is perhaps one of the most discriminating and the least ambiguous methods for differentiation of Phoma blackleg isolates. Following HPLC analyses, the 26 isolates could be placed in three main groups, irrespective of country of origin: isolates producing phomamide and sirodesmins, isolates producing indolyl dioxopiperazines, and isolates producing polyketides. Discussion of the implications of our findings and suggestions for species reclassification are provided.

Ascomycota↗
PubMed2001

Antifungal and airway remodeling roles for murine monocyte chemoattractant protein-1/CCL2 during pulmonary exposure to Asperigillus fumigatus conidia.

Asperigillus fumigatus spores or conidia are quickly eliminated from the airways of nonsensitized individuals but persist in individuals with allergic pulmonary responsiveness to fungus. A. fumigatus-induced allergic airway disease is characterized by persistent airway hyperreactivity, inflammation, and fibrosis. The present study explored the role of CCR2 ligands in the murine airway response to A. fumigatus conidia. Nonsensitized and A. fumigatus-sensitized CBA/J mice received an intratracheal challenge of A. fumigatus conidia, and pulmonary changes were analyzed at various times after conidia. Whole lung levels of monocyte chemoattractant protein-1 (MCP-1/CCL2), but neither MCP-3/CCL7 nor MCP-5/CCL12, were significantly elevated at days 3 and 7 after conidia in nonsensitized mice. MCP-1/CCL2 was significantly increased in lung samples from A. fumigatus-sensitized mice at days 14 and 30 after a conidia challenge. Administration of anti-MCP-1/CCL2 antiserum to nonsensitized mice for14 days after the conidia challenge attenuated the clearance of conidia and significantly increased airway hyperreactivity, eosinophilia, and peribronchial fibrosis compared with nonsensitized mice that received conidia and normal serum. Adenovirus-directed overexpression of MCP-1/CCL2 in A. fumigatus-sensitized mice markedly reduced the number of conidia, airway inflammation, and airway hyperresponsiveness at day 7 after the conidia challenge in these mice. Immunoneutralization of MCP-1/CCL2 levels in A. fumigatus-sensitized mice during days14-30 after the conidia challenge did not affect the conidia burden but significantly reduced airway hyperreactivity, lung IL-4 levels, and lymphocyte recruitment into the airways compared with the control group. These data suggest that MCP-1/CCL2 participates in the pulmonary antifungal and allergic responses to A. fumigatus conidia.

Adenoviridae↗
PubMed2003

Cloning, mapping and protein expression of wheat thaumatin protein gene (TaTLP1).

To understand wheat powdery mildew resistance mechanism, reverse-transcription polymerase chain reaction (RT-PCR) and cDNA library screening were performed to isolate the full-length cDNA of wheat thaumatin protein gene from wheat-Haynaldia villosa 6VS/6AL translocation line. The putative amino acid sequence of this gene consists of 173 amino acid residues, and is an acid polypeptide. It was highly homologous to thaumatin proteins isolated from other plants, so it is designated as TaTLP1 (GenBank accession number: AF384146). Northern blot analysis of TaTLP1 showed that the transcription difference obviously existed between resistant wheat-Haynaldia villosa 6VS/6AL translocation line and susceptible "Yangmai 5". The result of western blot showed that the protein expression product of TaTLP1 gene in wheat seedling leaf was a soluble cytoplasm protein, whose expression was induced by fungus Erysiph graminis and apparently related to disease resistance of the 6VS/6AL translocation line. Southern blot indicated that the TaTLP1 gene had 1-2 copies in wheat genome, and had been localized on the specific region of 7B and 7D chromosomes in wheat.

Amino Acid Sequence↗
PubMedDate not supplied

Molecular characterization of aspergillus fumigatus allergens.

Aspergillus fumigatus (Af) is ubiquitous saprophytic fungus associated with a broad spectrum of diseases in humans. These diseases range from benign colonization of the lung to life threatening diseases such as allergic bronchopulmonary aspergillosis (ABPA) and invasive aspergillosis. Af is the etiologic agent identified in most of the Aspergillus related human diseases and is therefore of particular clinical importance. Af induced obstructive airway diseases may be due to transient exposure to fungal spores resulting in a T helper 2 response. The IgE mediated inflammatory reaction could be due to colonization of bronchial airway epithelium by Af. Early and precise diagnosis of Aspergillus induced respiratory allergy is essential for preventing irreversible lung damages. The major problems in the diagnosis of A. fumigatus induced diseases are due to the lack of standardized and well characterized fungal extracts. The advent of molecular cloning technology and the development of phage surface display technology for cloning genes have facilitated the isolation of more relevant recombinant allergens. Using these techniques, a panel of different Af allergens having distinct IgE binding with various groups of Af sensitized patients have been cloned and characterized. These allergens can be categorized functionally as secreted and cytoplasmic proteins. The distinct IgE binding property of these purified and well characterized recombinant Af allergens may be useful for the differential diagnosis of Af related pulmonary complications.

Allergens↗
PubMed2005

[Prokaryotic expression, antiserum preparation and cytochemical analysis of TaMlo3 in wheat].

Mlo gene in wheat is critical to determine wheat broad spectrum disease resistance against the pathogenic powdery mildew fungus. According to wheat TaMlo3 cDNA sequence, the two DNA fragments encoding the intracellular loop 2 and C-terminus of wheat Mlo protein were cloned respectively into the vector pET-30a, and then the fusion polypeptides were expressed in E. coli BL21. The recombinant proteins were purified by Ni2+ -NTA agarose column, and then were used to immunize the rabbits respectively. Two polyclonal antisera were obtained and they could be specifically bound on the extrahaustorial membrane and extrahaustorial matrix of the powdery mildew fungus by immuno-gold labeling.

Animals↗
PubMed1979

Histoplasmosis: clinical syndromes and management.

The fungus Histoplasma capsulatum produces a spectrum of disease forms ranging from a benign self-limited illness to progressive disseminated disease with a 50 percent mortality rate. The drug of choice, amphotericin B, must be given intravenously over a prolonged course and carries a high incidence of toxicity. Thus, optimal managment of serious forms of histoplasmosis requires considerable clinical judgment.

Acute Disease↗
PubMed1976

[Results and progress of scanning- and analytical electron microscopy in dermatology].

This is a review of the achievements of scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and ultrastructural x-ray microanalysis in Dermatology. Eight years after its introduction, the scanning electron microscope opened new possibilities for qualitative and semi-quantitative ultrastructural analysis of human skin, nails and hairs and provided new valuable information in clinical dermatology and dermatopathology. Considerable work has been done on the spatial architecture of normal skin, hair, hyperkeratotic conditions, psoriasis, hair abnormalities, fungus infections, dermal collagen in normal and diseased skin, and the surfaces of cutaneous vascular endothelia. Recently, x-ray microanalysis has been applied for the first time in dermatological research. Subcellular particles, the products of cytochemical reactions and tracer substances, such as heavy metals, can now be analyzed by SEM and STEM techniques. Keratohyaline granules do show a sulfur peak by means of this technique and lipoid droplets fail to demonstrate the peaks of sulfur and chloride. X-ray-microanalysis of ATPase and AChE-reactions in human skin facilitates the indentification and the localization of the reaction product in tissue, whereas the penetration of mercury compounds can be followed more precisely by this technique.

Chemistry Techniques, Analytical↗
PubMed1993

[Septicemic cutaneous localization of cryptococcosis following renal transplantation in a female].

Cryptococcosis is a systemic disease caused by the yeast-like fungus Cryptococcus neoformans. Cutaneous manifestations, although rare, may precede other organ involvements. A case of cutaneous cryptococcosis is described herein. The skin lesions in our patient (a 47-year old female with renal transplant) consisted of acute cellulitis over her left and right thighs, revealing a septicemic infection. The patient received immunosuppressive drugs (prednisone, azathioprine). Clinical, mycological and histopathological data are described in details. Amphotericin B and fluconazole were initially successful, but a relapse with Cryptococcus meningitis required the adjunction of itraconazole to treatment. This case report underlines the insufficient effectiveness of fluconazole and the success of itraconazole.

Antifungal Agents↗
PubMed2000

Origin and spread of allergic fungal disease of the nose and paranasal sinuses.

Although expansion of bony walls occurs in allergic fungal disease of the nose and paranasal sinuses by increased mucus secretion and fungal growth, the latter is apparently confined to the lumen and does not invade the tissues. Nevertheless, spread of the disease process from paranasal sinuses to orbit, cheek and intracranial cavity is well described. An imaging and histopathological study was carried out in 16 cases to determine how the disease originates and spreads. The infection starts in the nasal cavity, the lumen of a sinus or in a seromucinous gland or duct. A thin vascular zone of intense allergic inflammation surrounds the infected mucin. Erosion of bone takes place focally, probably by substances produced by the inflammatory tissue, allowing intromission by the thin vascular layer together with its underlying fungus-containing mucus and so extension of the disease process through the eroded bone.

Adult↗
PubMed1994

Hyperimmune serum modulates allergic response to spores in a murine model of allergic aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) is a disease in atopic asthmatics characterized by eosinophilia and elevated levels of immunoglobulin E (IgE) and IgG antibodies to the ubiquitous fungus Aspergillus fumigatus (Af). The role of specific antibodies in the disease process is not clear. In this study, BALB/c mice were injected with hyperimmune serum from syngeneic mice exposed to soluble antigen of Af. These mice were then exposed to either Af spores or soluble antigen. Total IgE, Af-specific IgG1 (enzyme-linked immunosorbent assay) in serum, and eosinophils (eosinophil peroxidase assay) in lungs and bone marrow were measured. Histologic sections of lungs were examined for cellular infiltration and morphologic changes. Results indicate a suppression of increase in levels of antibodies and eosinophilia in mice receiving immune serum and exposed to spores compared with controls receiving phosphate-buffered saline treatment. Spores being the primary source of exposure to Af in ABPA, these results are significant in understanding the role of preexisting specific antibodies in patients.

Animals↗
PubMed2006

Apparent absence of Pneumocystis jirovecii in healthy subjects.

We prospectively investigated 30 healthy subjects with normal CD4+ T cell counts in blood and normal findings of spirometry and chest radiography for the presence of Pneumocystis jirovecii, by performing polymerase chain reaction on sputum specimens. Fifty patients with chronic obstructive pulmonary disease were investigated at the same time in the same manner; this group was used as controls for the diagnosis of pulmonary colonization with P. jirovecii. None of the healthy subjects had positive test results, whereas the fungus was detected in 8 patients with chronic obstructive pulmonary disease. The results suggest that in our region (Amiens, France), P. jirovecii is apparently uncommon in healthy subjects and that this population, therefore, plays a minor role in circulation of the fungus within human communities.

Adult↗
PubMedDate not supplied

Arthroconidia in coccidioidoma: case report and literature review.

Coccidioides immitis is a dimorphic fungus capable of causing a diverse spectrum of disease in humans. Although the diagnostic pathologic finding in tissue is a mature endosporulating spherule, hyphal structures can also be found in over 50% of pathologic specimens. This report presents a case of coccidioidomycosis in which there were no intact spherules, but characteristic barrel shaped arthrospores present in tissue and cultures positively identified the organism as C. immitis. This case was further complicated by presentation in a nonendemic area for the fungus. Coccidioides immitis is a soil fungus with two distinct phases: the saprophytic and the parasitic. This biphasic life cycle was first described by Ophöls,1 and more fully characterized by Baker and colleagues. The saprophytic stage occurs in the environment with the organism existing in a mycelial state. As the mold matures, barrel-shaped arthroconidia form and alternate with empty cells. The arthroconidia subsequently fracture from hyphae and are dispersed as an aerosol. The saprophytic cycle repeats itself upon infection of a new soil site. However, if the airborne arthroconidia are inhaled by a susceptible host, the parasitic phase is initiated. In the parasitic cycle, the arthrospore swells and becomes a rounded structure, known as a spherule. The protoplasm of the spherule divides to form large numbers of endospores. If the spherule ruptures, the endospores are released. Each endospore can develop into a new spherule, or, upon expulsion via contaminated secretions from the host, return to the environment where it transforms into its mycelial form. Although the characteristic histologic finding in coccidioidomycosis is the spherule with endospores, hyphal forms also can be found. The mycelial form of C. immitis cannot be definitively identified morphologically and requires confirmation by culture techniques or genetic probes. This report presents a pulmonary coccidioidoma in which arthroconidia were the predominant forms found in tissue.

Adult↗
PubMedDate not supplied

[Histoplasmosis: not only a tropical disease].

Histoplasmosis is a fungal infection resulting from inhalation of spores from the fungus Histoplasma capsulatum; it is known to be endemic in various parts of the world, especially in North and Latin America, and can produce a spectrum of illness, from subclinical infection to progressive disseminated disease. The majority of infected persons have an asymptomatic, self-limiting illness. Clinical pneumonia occurs in those with exposure to a large number of infecting spores. Disseminated histoplasmosis usually occurs in immunosuppressed patients or in patients with chronic illness. Diagnosis is best made by visualization of yeast in tissue or by culture. In most cases, amphotericin B is the initial drug of choice, followed by one of the azoles for lifelong maintenance therapy. Itraconazole is the drug of choice for treatment of disseminated histoplasmosis in less severe cases, while fluconazole therapy for histoplasmosis is only moderately effective.

AIDS-Related Opportunistic Infections↗