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At least 793 records · Page 44Linked to original sources
PubMed2005

Synergistic effect of entomogenous fungi on some insecticides against Bihar hairy caterpillar Spilarctia obliqua (Lepidoptera: Arctiidae).

A number of fungal parasites infect a wide range of insects and cause epizootics from time to time. Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin are two of the major disease-causing fungi in insects. Investigations were carried out to study the effect of these fungi on the toxicity of endosulfan, imidacloprid, lufenuron, diflubenzuron, dimethoate and oxydemeton methyl against 10-11 days old larvae of Spilarctia obliqua (Walker). For some products the combination treatments showed higher dose mortality response than the sole treatment of fungal conidia or the insecticide. The combination of insecticides with B. bassiana showed 1.26-35.8 fold increase in toxicity of insecticides over sole treatment, while the increase was 1.05-72.0 fold in case of M. anisopliae. Imidacloprid 17.8 SL and oxydemeton methyl 25EC may be used in combination with these fungi for management of S. obliqua.

Animals↗
PubMed2006

Fungi and fungal toxins as weapons.

Recent aggressive attacks on innocent citizens have resulted in governments increasing security. However, there is a good case for prevention rather than reaction. Bioweapons, mycotoxins, fungal biocontrol agents (FBCA), and even pharmaceuticals contain, or are, toxins and need to be considered in the context of the new paradigm. Is it desirable to discuss such issues? None of the fungi are (a) as toxic as botulinum toxin from Clostridium botulinum, and (b) as dangerous as nuclear weapons. One toxin may be defined as a pharmaceutical and vice versa simply by a small change in concentration or a moiety. Mycotoxins are defined as naturally occurring toxic compounds obtained from fungi. They are the biggest chronic health risk when incorporated into the diet. The current list of fungal toxins as biochemical weapons is small, although awareness is growing of the threats they may pose. T-2 toxin is perhaps the biggest concern. A clear distinction is required between the biological (fungus) and chemical (toxin) aspects of the issue. There is an obvious requirement to be able to trace these fungi and compounds in the environment and to know when concentrations are abnormal. Many FBCA, produce toxins. This paper indicates how to treat mycotoxicosis and decontaminate mycotoxins. There is considerable confusion and inconsistency surrounding this topic which requires assessment in an impartial and scientific manner.

Biological Warfare↗
PubMed2004

Knocking on the heaven's wall: pathogenesis of and resistance to biotrophic fungi at the cell wall.

New findings challenge the traditional view of the plant cell wall as passive structural barrier to invasion by fungal microorganisms. A surveillance system for cell wall integrity appears to sense perturbation of the cell wall structure upon fungal attack and is interconnected with known plant defence signalling pathways. Biotrophic fungi might manipulate this surveillance system for the establishment of biotrophy. The attempts of fungi to invade also induce a sub-cellular polarisation in attacked cells, which activates an ancient vesicle-associated resistance response that possibly enables the focal transport of regulatory cargo and the secretion of toxic cargo. The underlying resistance machinery might have been subverted by biotrophic fungi for pathogenesis.

Cell Wall↗
PubMed2005

Mycotoxin-producing and other fungi isolated from grapes for wine production, with particular emphasis on ochratoxin A.

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that have been detected in food commodities, including grapes and wine. A survey was conducted to assess mycotoxin-producing fungi in grapes destined for wine production. The mycotoxigenic capacity of the isolates was tested in culture media. Grapes were analyzed by plating methods from 4 Portuguese wine-growing regions at 3 maturation stages (pea berry, early veraison and ripe berry) between 2001 and 2003. From the 10,602 strains detected and identified, the most frequent genera were Cladosporium (25%), Alternaria (24%), Botrytis (15%), Penicillium (9%) and Aspergillus (8%). Most (92.0%) were non-mycotoxigenic or produced mycotoxins of unknown relevance to health. Potential producers of ochratoxin A (OTA) (Aspergillus niger aggregate, 5.4%, Aspergillus carbonarius, 0.6%) and trichothecenes (Fusarium spp., 0.4%; Trichothecium roseum, 0.8%) were the most frequent mycotoxigenic species isolated from grapes. OTA was detected in all cultures of A. carbonarius and 4% of A. niger aggregate strains. There was potential for OTA and trichothecene production in grapes by A. carbonarius and T. roseum, respectively, prior to harvest time. Data presented herein indicate that A. carbonarius is most likely to occur in vineyards with Mediterranean climates, while T. roseum is more likely to occur in more temperate climates, and is associated with gray rot. The present work emphasizes the need to use grapes under good condition so as to reduce the risk of contamination with mycotoxigenic fungi and subsequent mycotoxin occurrence in wine.

Aspergillus↗
PubMed2005

Cadmium and zinc response of the fungi Heliscus lugdunensis and Verticillium cf. alboatrum isolated from highly polluted water.

The aquatic hyphomycete Heliscus lugdunensis and the terrestrial fungus Verticillium cf. alboatrum, both isolated from a highly polluted surface water, were investigated for their tolerance against Cd and Zn. Hl-H4 showed a 50% growth inhibition at 0.1 mM Cd, whereas at 0.7 mM Cd the growth of Va-H4 was only reduced by 30%. The fungi also showed a remarkable difference in their Zn-tolerance. The growth of Va-H4 was not inhibited at 1 mM Zn, whereas for Hl-H4 no growth occurred above 0.3 mM Zn. The biosorption and accumulation capacities for Cd or Zn of both fungi differed between the fungal species. In a 0.1 mM Cd-medium Hl-H4 biosorbed 15-fold and accumulated 39-fold more Cd than Va-H4. Exposure to 0.3 mM Zn resulted in a 13-fold higher biosorption and 11-fold higher accumulation for Hl-H4 than Va-H4. As glutathione (GSH) is known to be involved in the phytochelatin synthesis and other stress related processes we investigated its synthesis. Both fungi increased their synthesis of GSH in response to Cd. For Hl-H4 a concentration of 0.0125 mM Cd, corresponding to an intracellular Cd content of 2.1 nmol Cd mg(-1) dw, increased the GSH content, whereas Va-H4 only responded with a higher production of GSH at 1 mM Cd and a concomitant intracellular Cd content of 22.5 nmol Cd mg(-1) dw. An increased GSH synthesis under Zn-stress was only detectable for Va-H4 (20 mM).

Adsorption↗
PubMed2006

Exposure to aerosolized bacteria and fungi among collectors of commercial, mixed residential, recyclable and compostable waste.

Biological hazards associated with the collection of solid and compostable waste have not been well characterized in North America. This is an issue because workers who handle such materials may be exposed to bioaerosols (airborne bacteria and fungi) and dusts resulting in infections or allergic diseases. We conducted a personal sampling campaign for culturable bacteria and fungi in the breathing zones of waste collectors in a variety of typical work settings (scenarios) in the province of Quebec, Canada. Total culturable bacterial and fungal counts were analyzed and compared to ambient environmental levels (background) to determine the degree of incremental exposure among workers. In several scenarios, worker exposure counts were significantly (p < or = 0.05) higher than ambient levels measured upwind, with the highest personal exposures to bacteria observed for urban compostable waste collectors (median = 50,300 Colony Forming Units/m(3) of air (CFU/m(3))). On the other hand, fungal counts collected on an every-other-week cycle were highest among a group of rural compostable waste collectors (median = 101,700 CFU/m(3)). Similar exposures to culturable bacteria and fungi have been reported in European workers who showed such adverse health effects as nausea, diarrhea, upper respiratory tract irritation, and allergy. Therefore, it may be necessary to modify certain work practices in order to minimize exposure. Recommendations include automation of waste and compost collection, use of personal protective equipment including goggles, gloves, and disposable masks, and meticulous personal hygiene.

Aerosols↗
PubMed2006

Tolerance of Antarctic soil fungi to hydrocarbons.

Little is known about the effects of hydrocarbons and fuel oil on Antarctic filamentous fungi in the terrestrial Antarctic environment. Growth of fungi and bacteria from soils around Rothera Research Station (Adelaide Island, Antarctic Peninsula) was assessed in the presence of ten separate aromatic and aliphatic hydrocarbons [marine gas oil (MGO), dodecane, hexadecane, benzoic acid, p-hydroxybenzoic acid, toluene, phenol, biphenyl, naphthalene and m- and p-xylenes with ethylbenzene]. Aromatic hydrocarbons inhibited soil microbial growth more than aliphatic hydrocarbons. Soil microorganisms from a moss patch, where little previous impact or hydrocarbon contamination had occurred, were less tolerant of hydrocarbons than those from high impact sites. Fungal growth rates of Mollisia sp., Penicillium commune, Mortierella sp., Trichoderma koningii, Trichoderma sp. and Phoma herbarum were assessed in the presence of hydrocarbons. Generally, aromatic hydrocarbons inhibited or stopped hyphal extension, though growth rates increased with some aliphatic hydrocarbons. Hyphal dry weight measurements suggested that Mortierella sp. may be able to use dodecane as sole carbon and energy source. Hydrocarbon-degrading Antarctic fungi may have use in future hydrocarbon spill bioremediation.

Antarctic Regions↗
PubMed2003

Oomycetes and fungi: similar weaponry to attack plants.

Fungi and Oomycetes are the two most important groups of eukaryotic plant pathogens. Fungi form a separate kingdom and are evolutionarily related to animals. Oomycetes are classified in the kingdom Protoctista and are related to heterokont, biflagellate, golden-brown algae. Fundamental differences in physiology, biochemistry and genetics between fungi and Oomycetes have been described previously. These differences are also reflected in the large variations observed in sensitivity to conventional fungicides. Recently, more pronounced differences have been revealed by genomics approaches. However, in this review we compare the mode of colonization of the two taxonomically distinct groups and show that their strategies have much in common.

Fungi↗
PubMed2005

Endolithic fungi in marine ecosystems.

Fungi are an important constituent of microbial endolithic assemblages in marine ecosystems. As euendoliths, they penetrate limestone, mollusk shells and other carbonate substrates, where they can exploit mineralized organic matter, attack their hosts, or engage in symbiotic relationships. They leave specific boring traces, which can be identified in the fossil record and described as trace fossils. Their distribution is independent of light and extends from the intertidal ranges to abyssal oceanic depths. Important, but insufficiently studied, is the role of aggressive endolithic fungi in skeletons of corals where they are ubiquitous and globally distributed. In healthy growing reef corals, the relationship between the coral coelenterate, endolithic algae and fungi is in a state of equilibrium, but can turn detrimental to coral health when reefs are exposed to environmental stress.

Animals↗
PubMed2004

Dendritic cell-based vaccination against opportunistic fungi.

Efficient responses to the different forms of fungi require different mechanisms of immunity. Dendritic cells (DCs) are uniquely able to decode the fungus-associated information and translate it in qualitatively different T helper (Th) immune responses, in vitro and in vivo. DCs sense fungi in a morphotype-specific manner, through the engagement of distinct recognition receptors ultimately affecting cytokine production and costimulation. Adoptive transfer of different types of DCs activates protective and non-protective Th cells as well as regulatory T cells and affects the outcome of the infections. DCs transfected with fungal RNA also restore antifungal resistance in hematopoietic transplantation. Thus, the remarkable functional plasticity of DCs in response to fungi can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to fungal vaccines.

Animals↗
PubMed2006

Phylogenetic relationships and convergence of helicosporous fungi inferred from ribosomal DNA sequences.

Helicosporous fungi form elegant, coiled, and multicellular mitotic spores (conidia). In this paper, we investigate the phylogenetic relationships among helicosporous fungi in the asexual genera Helicoma, Helicomyces, Helicosporium, Helicodendron, Helicoon, and in the sexual genus Tubeufia (Tubeufiaceae, Dothideomycetes, and Ascomycota). We generated ribosomal small subunit and partial large subunit sequences from 39 fungal cultures. These and related sequences from GenBank were analyzed using parsimony, likelihood, and Bayesian analysis. Results showed that helicosporous species arose convergently from six lineages of fungi in the Ascomycota. The Tubeufiaceae s. str. formed a strongly supported monophyletic lineage comprising most species from Helicoma, Helicomyces, and Helicosporium. However, within the Tubeufiaceae, none of the asexual genera were monophyletic. Traditional generic characters, such as whether conidiophores were conspicuous or reduced, the thickness of the conidial filament, and whether or not conidia were hygroscopic, were more useful for species delimitation than for predicting higher level relationships. In spite of their distinctive, barrel-shaped spores, Helicoon species were polyphyletic and had evolved in different ascomycete orders. Helicodendron appeared to be polyphyletic although most representatives occurred within Leotiomycetes. We speculate that some of the convergent spore forms may represent adaptation to dispersal in aquatic environments.

DNA, Ribosomal↗
PubMed1990

Use of zoospore concentrations and life cycle parameters in determining the population of anaerobic fungi in the rumen ecosystem.

An indirect approach to quantification of the fibrolytic anaerobic fungi in the rumen is described. A mathematical model of the life cycle of anaerobic fungi, based upon observations of the life histories and growth kinetics of these organisms in vitro and in vivo, is constructed and solved in the steady-state to determine the population of particle-attached (substrate-associated) fungal thalli from the concentration of free-swimming zoospores in rumen liquid. The values obtained are broadly consistent with ruminal observations and with observations on faecal populations, which assume that a significant proportion of fungi leaving the rumen (as cysts or spores) can ultimately be accounted for in the faeces.

Animals↗
PubMed1997

Betaine lipids and zwitterionic phospholipids in plants and fungi.

Of spermatophytes, ferns, mosses, algae, lichens and fungi, 110 species not analysed so far were examined for diacylglyceryl-N,N,N-trimethylhomoserine (DGTS), diaclyglycerylhydroxymethyl-N,N,N-trimethyl-beta-alanine (DGTA), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) by TLC by using Dragendorff's and molybdenum-blue reagents for detection. The limit of detection was 0.5 microgram per mg or 0.05 weight % of total lipid. The results reveal that betaine lipids are present exclusively in non-flowering plants, including lichens and fungi and, hence, are produced by autotrophic, as well as heterotrophic organisms. DGTS in small amounts is typical of some Rhodophytes, and in appreciable amounts, of vascular cryptogamic plants and some higher fungi. Estimation of the amounts of DGTS and PC in 29 different species reveal that the total amount of zwitterionic lipids varies considerably amongst organisms. No general correlation could be found for the amounts of DGTS and PC, although Rhodophytes contain traces of DGTS but high amounts of PC. On the basis of these results and the presently available data, the natural distribution of the betaine lipids DGTS, DGTA and diacylglycerylcarboxy-N-hydroxymethyl-choline (DGCC) is discussed. In terms of biochemical evolution, the capacity for the formation of DGTS might have been acquired first and, in organisms of the 'DGTS branch', kept until the present time. The formation of DGTA and DGCC might have evolved at a later stage of development in organisms of the 'DGTA-DGCC branch'.

Betaine↗
PubMed1998

Naphthoquinone metabolites of the fungi.

Structures and physico-chemical properties of 100 naphthoquinone metabolites produced by filamentous fungi are reviewed. The conditions of pigment formation, biogenesis and the mechanism of biosynthesis of pigments by fungi are described. Sixty-three fungi cultures able to produce naphthoquinone are listed. The biological activities of the main pigments and the mechanism of fungal resistance to their own metabolites are described. The physiological role of the naphthoquinones in producers is discussed.

Anti-Bacterial Agents↗
PubMed2001

Biodegradation of anthracene and fluoranthene by fungi isolated from an experimental constructed wetland for wastewater treatment.

Pilot-scale constructed wetlands were used to treat water contaminated by polycyclic aromatic hydrocarbons (PAHs), particularly fluoranthene, and the possible role of fungi present in these ecosystems was investigated. A total of 40 fungal species (24 genera) were isolated and identified from samples (gravel and sediments) from a contaminated wetland and a control wetland. All of them were assayed for their ability to remove anthracene (AC) and fluoranthene (FA) from liquid medium. FA was degraded efficiently by 33 species while only 2 species were able to remove AC over 70%. A selection of 10 strains of micromycetes belonging to various taxonomic groups was further investigated for FA and AC degradation, toxicity assays and phenoloxidases (POx) detection. Interesting and not previously reported species were revealed (Absidia cylindrospora, Cladosporium sphaerospermum, and Ulocladium chartarum). They were all able to highly degrade the PAH-model compounds chosen. An interesting inducibility was noted for Ulocladium chartarum. Degradative ability of fungi was not related to their extracellular POx activity. This study may contribute to the improvement of constructed wetlands for water treatment, which may be enriched in efficient fungi.

Anthracenes↗
PubMed2004

Glutathione, altruistic metabolite in fungi.

Glutathione (GSH; gamma-L-glutamyl-L-cysteinyl-glycine), a non-protein thiol with a very low redox potential (E'0 = 240 mV for thiol-disulfide exchange), is present in high concentration up to 10 mM in yeasts and filamentous fungi. GSH is concerned with basic cellular functions as well as the maintenance of mitochondrial structure, membrane integrity, and in cell differentiation and development. GSH plays key roles in the response to several stress situations in fungi. For example, GSH is an important antioxidant molecule, which reacts non-enzymatically with a series of reactive oxygen species. In addition, the response to oxidative stress also involves GSH biosynthesis enzymes, NADPH-dependent GSH-regenerating reductase, glutathione S-transferase along with peroxide-eliminating glutathione peroxidase and glutaredoxins. Some components of the GSH-dependent antioxidative defence system confer resistance against heat shock and osmotic stress. Formation of protein-SSG mixed disulfides results in protection against desiccation-induced oxidative injuries in lichens. Intracellular GSH and GSH-derived phytochelatins hinder the progression of heavy metal-initiated cell injuries by chelating and sequestering the metal ions themselves and/or by eliminating reactive oxygen species. In fungi, GSH is mobilized to ensure cellular maintenance under sulfur or nitrogen starvation. Moreover, adaptation to carbon deprivation stress results in an increased tolerance to oxidative stress, which involves the induction of GSH-dependent elements of the antioxidant defence system. GSH-dependent detoxification processes concern the elimination of toxic endogenous metabolites, such as excess formaldehyde produced during the growth of the methylotrophic yeasts, by formaldehyde dehydrogenase and methylglyoxal, a by-product of glycolysis, by the glyoxalase pathway. Detoxification of xenobiotics, such as halogenated aromatic and alkylating agents, relies on glutathione S-transferases. In yeast, these enzymes may participate in the elimination of toxic intermediates that accumulate in stationary phase and/or act in a similar fashion as heat shock proteins. GSH S-conjugates may also form in a glutathione S-transferases-independent way, e.g. through chemical reaction between GSH and the antifugal agent Thiram. GSH-dependent detoxification of penicillin side-chain precursors was shown in Penicillium sp. GSH controls aging and autolysis in several fungal species, and possesses an anti-apoptotic feature.

Fungi↗
PubMed1999

Cellular and molecular mechanisms of sexual incompatibility in plants and fungi.

Plants and fungi show an astonishing diversity of mechanisms to promote outbreeding, the most widespread of which is sexual incompatibility. Sexual incompatibility involves molecular recognition between mating partners. In fungi and algae, highly polymorphic mating-type loci mediate mating through complementary interactions between molecules encoded or regulated by different mating-type haplotypes, whereas in flowering plants polymorphic self-incompatibility loci regulate mate recognition through oppositional interactions between molecules encoded by the same self-incompatibility haplotypes. This subtle mechanistic difference is a consequence of the different life cycles of fungi, algae, and flowering plants. Recent molecular and biochemical studies have provided fascinating insights into the mechanisms of mate recognition and are beginning to shed light on evolution and population genetics of these extraordinarily polymorphic genetic systems of incompatibility.

Amino Acid Sequence↗
PubMed2000

Keratomycosis: clinical and microbiologic experience with dematiaceous fungi.

OBJECTIVE: To assess the significance of dematiaceous fungi in the causation of keratomycosis. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Eighty-eight cases of dematiaceous fungal keratitis seen at the L. V. Prasad Eye Institute, Hyderabad, India from January 1991 through December 1996. INTERVENTION: Only culture-proven cases were analyzed. MAIN OUTCOME MEASURES: Predisposing factors, clinical characteristics, microbiology, treatment methods, and outcome. RESULTS: Of 557 cases of fungal keratitis seen during the study period, dematiaceous fungi were the etiologic agents in 88 (15.7%), after Fusarium in 210 (37.6%) and Aspergillus species in 170 cases (30.4%), respectively. Trauma was the most common predisposing factor (47.7%). Fifty-three eyes (61.3%) had the classical clinical picture of yellow-white, dry raised infiltrate with feathery hyphate edges at initial examination. The characteristic macroscopic pigmentation was seen in only 24 eyes (27.27%). Septate branching fungal filaments were identified in 78 smears (88.63%) on light microscopy, of which 5 (5.7%) also showed the presence of bacteria. Curvularia species dominated the spectrum (22.7%). Treatment was started in 48 eyes with topical antifungal agents, whereas 37 received both oral and topical antifungal agents. Outcome data were available for 68 cases. Forty-nine (72%) responded to medical therapy, whereas 13 eyes required therapeutic penetrating keratoplasty and 6 eyes had to be eviscerated. CONCLUSIONS: This is the largest series of keratitis caused by dematiaceous fungi reported to date. It clearly brings out the clinical importance of this group of corneal infections.

Adolescent↗