JOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2009
ARASH KOOCHEKI
ABSTRACT Teftoon, a flat bread made of whole wheat flour, is prepared by hand sheeting of dough, followed by baking. Different emulsifiers, like lecithin, E471 (distilled monoglyceride) and E472 (diacetylated tartaric acid esters of mono- and digelycerid of fatty acids), were added to the flour at various levels ranging between 0.25 and 1.0% w/w, and it was observed that they improved the dough characteristics. Improvement in bread quality parameters, such as force to tear and sensory acceptability, were monitored. Fungal, -amylase was also incorporated into the flour at 5,20 g/100 kg flour basis alone and in combination with the emulsifier. The force required to tear the fresh bread was decreased with emulsifier and enzyme addition; however, E472 addition at 0.75% w/w of whole wheat flour gave the softest bread. The tear force of stored bread significantly increased with storage; however, bread containing E472 showed a less increase in tear force up to a period of 3 days. The sensory acceptability was found to be higher than that of the control bread for emulsifiers, and lower for enzyme at a concentration higher than 10 g/kg flour. PRACTICAL APPLICATIONS Flat bread is normally consumed fresh, but the staling phenomenon starts immediately after baking this kind of bread. Today, large-scale production and increased consumer demands for high-quality bread with long shelf life have created the need for functional food additives such as emulsifiers and , -amylase enzyme. Incorporation of emulsifiers and enzyme decreased the hardness of Taftoon bread. Emulsifiers and , -amylase enzyme enhanced the flat bread dough quality. The sensory acceptability also improved with the addition of emulsifiers. Optimizing the amount of emulsifiers and enzyme required for reduction of bread hardness is vital because the quality and price of the final product depend on this parameter. [source]

EVIDENCE FOR LATERAL TRANSFER OF AN IE INTRON BETWEEN FUNGAL AND RED ALGAL SMALL SUBUNIT RRNA GENES,

JOURNAL OF PHYCOLOGY, Issue 2 2005
Kirsten M. Müller
A previous study of the North American biogeography of the red algal genus Hildenbrandia noted the presence of group I introns in the nuclear small subunit (SSU) rRNA gene of the marine species H. rubra (Sommerf.) Menegh. Group IC1 introns have been previously reported at positions 516 and 1506 in the nuclear SSU RNA genes in the Bangiales and Hildenbrandiales. However, the presence of an unclassified intron at position 989 in a collection of H. rubra from British Columbia was noted. This intron is a member of the IE subclass and is the first report of this intron type in the red algae. Phylogenetic analyses of the intron sequences revealed a close relationship between this IE intron inserted at position 989 and similar fungal IE introns in positions 989 and 1199. The 989 IE introns formed a moderately to well-supported clade, whereas the 1199 IE introns are weakly supported. Unique structural helices in the P13 domain of the 989 and 1199 IE introns also point to a close relationship between these two clades and provide further evidence for the value of secondary structural characteristics in identifying homologous introns in evolutionarily divergent organisms. The absence of the 989 IE intron in all other red algal nuclear SSU rRNA genes suggests that it is unlikely that this intron was vertically inherited from the common ancestor of the red algal and fungal lineages but rather is the result of lateral transfer between fungal and red algal nuclear SSU rRNA genes. [source]

EFFECT OF EMULSIFIERS AND FUNGAL , -AMYLASE ON RHEOLOGICAL CHARACTERISTICS OF WHEAT DOUGH AND QUALITY OF FLAT BREAD

Synchronization of the Fungal and the Plant Circadian Clock by Light

CHEMBIOCHEM, Issue 16 2008
László Kozma-Bognár
Abstract Circadian clocks are endogenous time keeping devices that provide temporal control of physiology in accordance with predicted daily changes in the environment. Photoentrainment is the process that synchronizes circadian clocks-and thereby clock-controlled gene expression and physiology-to the environmental day/night cycles. Light is primarily detected by specialized photoreceptors that are coupled,directly or through other signaling components,to the rhythm-generating oscillator. As a consequence, the expression, the activity or the stability of oscillator components are altered, resulting in a change of phase and/or pace of the oscillator. In this review our present knowledge about light absorption/transduction and light-induced modifications of oscillator components in Neurospora crassa and Arabidopsis thaliana is summarized. These systems provide a basis for understanding the molecular mechanisms of entrainment in the fungal and plant circadian systems. [source]

Cinnamic Acid Esters as Potent Inhibitors of Fungal 17,-Hydroxysteroid Dehydrogenase , A Model Enzyme of the Short-Chain Dehydrogenase/Reductase Superfamily

CHEMINFORM, Issue 46 2004
Stanislav Gobec
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Risk Factors for Rejection and Infection in Pediatric Liver Transplantation

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 2 2008
R. W. Shepherd
Rejection and infection are important adverse events after pediatric liver transplantation, not previously subject to concurrent risk analysis. Of 2291 children (<18 years), rejection occurred at least once in 46%, serious bacterial/fungal or viral infections in 52%. Infection caused more deaths than rejection (5.5% vs. 0.6% of patients, p < 0.001). Early rejection (<6 month) did not contribute to mortality or graft failure. Recurrent/chronic rejection was a risk in graft failure, but led to retransplant in only 1.6% of first grafts. Multivariate predictors of bacterial/fungal infection included recipient age (highest in infants), race, donor organ variants, bilirubin, anhepatic time, cyclosporin (vs. tacrolimus) and era of transplant (before 2002 vs. after 2002); serious viral infection predictors included donor organ variants, rejection, Epstein-Barr Virus (EBV) naivety and era; for rejection, predictors included age (lowest in infants), primary diagnosis, donor-recipient blood type mismatch, the use of cyclosporin (vs. tacrolimus), no induction and era. In pediatric liver transplantation, infection risk far exceeds that of rejection, which causes limited harm to the patient or graft, particularly in infants. Aggressive infection control, attention to modifiable factors such as pretransplant nutrition and donor organ options and rigorous age-specific review of the risk/benefit of choice and intensity of immunosuppressive regimes is warranted. [source]

Safety and efficacy of vaccines

DERMATOLOGIC THERAPY, Issue 2 2009
Brenda L. Bartlett
ABSTRACT For the past two centuries, vaccines have provided a safe and effective means of preventing a number of infectious diseases. Although the safety of some vaccines has been questioned in recent years, the currently available vaccines are more than a millionfold safer than the diseases they are designed to prevent. Vaccines, however, should always be used in conjunction with other public health interventions. One important intervention is education because the general public can be led to believe that vaccines are unsafe and not needed by misinformation readily available electronically and in print. Not only are some vaccines available via injection but other vaccines are also given orally or intranasally. New vaccines are being studied for topical and intravaginal use. In addition, new systems are being developed for more efficient production of vaccines, especially for influenza. Vaccines are currently available for only a limited number of viral and bacterial diseases. In the future, it is anticipated that safe and effective vaccines will be developed against a number of other viral and bacterial infections as well as fungal and protozoan diseases. [source]

Growth in relation to microclimatic conditions and physiological characteristics of four Lobaria pulmonaria populations in two contrasting habitats

ECOGRAPHY, Issue 1 2004
Gisela Gaio-Oliveira
The aim of the present study was to compare the physiological characteristics of various populations of the lichen Lobaria pulmonaria in Portugal and Sweden. For this, indirect markers of algal (photobiont) and fungal (mycobiont) activity were measured, as well as their CO2 gasexchange characteristics. Microclimatic conditions and the lichens growth performance in the two countries were compared using reciprocal transplantation. Two populations of L. pulmonaria represented each country: one collected from forest interior conditions and one from forest edge habitats. A non-transplanted "wild" population was also studied in each country, in order to evaluate any transplantation effects per se. The main hypothesis were that; 1) growth should be faster in Portugal due to higher light availability; 2) the energy use efficiency of lichen biomass gain should be similar for the native populations in their respective native habitat; 3) if the lichens were able to adapt to the environmental conditions in the foreign habitat this should be revealed as similar growth rates among all thalli transplanted at the same site, regardless of their origin. Physiologically, the Portuguese and Swedish populations were very similar, both concerning their CO2 gas exchange characteristics and distribution of resources between photo- and mycobiont tissue. Environmental conditions were more advantageous for L. pulmonaria growth in Portugal, i.e. higher photon flux densities and ambient temperatures when the lichens were wet and active, and a lower fraction of the active time occurring in darkness. However, despite similar physiological characteristics of all the studied populations, the Swedish lichens were not able to grow as well in Portugal as the native, while all populations had similarly low growth rates in Sweden. [source]

Oviposition preferences of Maculinea alcon as influenced by aphid (Aphis gentianae) and fungal (Puccinia gentianae) infestation of larval host plants

ECOLOGICAL ENTOMOLOGY, Issue 1 2009
ERVIN ÁRNYAS
Abstract 1.,The influence of infestation of the larval host plant Gentiana cruciata on the egg-laying preferences of the xerophilous ecotype of Alcon Blue butterfly (Maculinea alcon) was studied in a semi-dry grassland area (Aggtelek Karst Region, Northern Hungary). 2.,We examined whether oviposition patterns of females differed when G. cruciata stems were uninfested compared with when they were infested by an aphid (Aphis gentianae) or a rust (Puccinia gentianae) species. 3.,Females laid more than 90% of their eggs on fertile, uninfested G. cruciata stems, although these stems comprised only , 50% of the total stems available. Stems infested by aphids were similar to uninfested ones in properties that had a strong correlation with egg numbers, and yet there were significantly fewer eggs on infested stems than on intact ones. 4.,Females never laid eggs on parts of Gentiana stems infested by aphids, and the presence of Lasius paralienus ants, which have a mutualistic interaction with Aphis gentianae, did not increase the repulsive effect of aphids. Infection of Gentiana by Puccinia did not influence the egg-laying behaviour of females, even though the flowers and buds of infested stems exhibited a delayed development. 5.,Aphid infestation can influence butterfly oviposition patterns through both direct and indirect effects. The presence of aphids directly excluded oviposition, but our data also indicated the possibility of an indirect effect of aphid infestation. Stems that had no aphids at the last egg counting, but were infested prior to it, had significantly fewer eggs than those that were never infested. [source]

Can intra-specific genetic variation in arbuscular mycorrhizal fungi (Glomus etunicatum) affect a mesophyll-feeding herbivore (Tupiocoris notatus Distant)?

ECOLOGICAL ENTOMOLOGY, Issue 4 2007
STUART C. WOOLEY
Abstract 1.,Arbuscular mycorrhizal fungal (AMF) infection can have negative, positive or neutral effects on insect herbivore populations, but patterns are difficult to predict. 2.,Intra-specific genetic variation in nutrient uptake ability between fungal isolates may also have indirect effects on insect herbivores due to changes in plant quality. In preliminary studies mirid (Tupiocoris notatus) populations were significantly reduced on tobacco (Nicotiana rustica) colonised by AMF but it was unknown if same-species fungal isolates differed in their effect. 3.,An experiment was performed as a first test of the effect of intra-specific genetic variation in the mycorrhizal fungus Glomus etunicatum on mirid nymphal population structure, dynamics, and growth rate. 4.,Mirid nymphal populations were lower on mycorrhizal fungal-infected plants. Population size, however, did not differ between the mycorrhizal isolates. While no statistical difference in population between isolates was found, one isolate consistently had 1.7,2.4 times lower mirid populations compared with the controls, indicating that the magnitude of effect is different between mycorrhizal isolates. 5.,The significantly negative effect of AMF on mirid populations likely resulted from AMF-induced changes in plant quality (e.g. increased defence). This study lends further support to recent demonstrations that below-ground symbionts significantly influence above-ground processes. In addition, mycorrhizal fungi can affect insect population structure, which may have consequences for future herbivory. [source]

Extraordinarily widespread and fantastically complex: comparative biology of endosymbiotic bacterial and fungal mutualists of insects

ECOLOGY LETTERS, Issue 2 2010
Cara M. Gibson
Ecology Letters (2010) 13: 223,234 Abstract Endosymbiosis is a pervasive, powerful force in arthropod evolution. In the recent literature, bacterial symbionts of insects have been shown to function as reproductive manipulators, nutritional mutualists and as defenders of their hosts. Fungi, like bacteria, are also frequently associated with insects. Initial estimates suggest that insect,fungal endosymbionts are hyperdiverse, yet there has been comparatively little research investigating the roles that fungi play in their insect hosts. In many systems in which the bacterial symbionts are well-characterized, the possible presence of fungi has been routinely ignored. Why has there been so little research on this important group of symbionts? Here, we explore the differences between fungal and bacterial endosymbiotic insect mutualists. We make predictions about why a bacterium or fungus might be found associated with an insect host given particular ecological, physiological, or evolutionary conditions. We also touch on the various hurdles for studying fungal vs. bacterial endosymbionts and potential future research directions. [source]

Fate of microbial residues in sandy soils of the South African Highveld as influenced by prolonged arable cropping

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2002
W. Amelung
Summary Long-term cultivation of former grassland soils results in a significant decline of both living and dead microbial biomass. We evaluated the effect of duration of cropping on the preservation of fungal and bacterial residues in the coarse-textured soils of the South African Highveld. Composite samples were taken from the top 20 cm of soils (Plinthustalfs) that have been cropped for periods varying from 0 to 98 years in each of three different agro-ecosystems in the Free State Province. Amino sugars were determined as markers for the microbial residues in bulk soil and its particle-size fractions. Long-term cultivation reduced N in the soil by 55% and the contents of amino sugars by 60%. Loss rates of amino sugars followed bi-exponential functions, suggesting that they comprised both labile and stable fractions. With increased duration of cropping the amino sugars attached to silt dissipated faster than those associated with the clay. This dissipation was in part because silt was preferentially lost through erosion, while clay particles (and their associated microbial residues) remained. Erosion was not solely responsible for the reduction in amino sugar concentrations, however. Bacterial amino sugars were lost in preference to fungal ones as a result of cultivation, and this effect was evident in both silt- and clay-sized separates. This shift from fungal to bacterial residues was most pronounced within the first 20 years after converting the native grassland to arable cropland, but continued after 98 years of cultivation. [source]

Plant oxylipins: role of jasmonic acid during programmed cell death, defence and leaf senescence

FEBS JOURNAL, Issue 17 2009
Christiane Reinbothe
Plants are continuously challenged by a variety of abiotic and biotic cues. To deter feeding insects, nematodes and fungal and bacterial pathogens, plants have evolved a plethora of defence strategies. A central player in many of these defence responses is jasmonic acid. It is the aim of this minireview to summarize recent findings that highlight the role of jasmonic acid during programmed cell death, plant defence and leaf senescence. [source]

Metabolic fate of l -lactaldehyde derived from an alternative l -rhamnose pathway

FEBS JOURNAL, Issue 20 2008
Seiya Watanabe
Fungal Pichia stipitis and bacterial Azotobacter vinelandii possess an alternative pathway of l -rhamnose metabolism, which is different from the known bacterial pathway. In a previous study (Watanabe S, Saimura M & Makino K (2008) Eukaryotic and bacterial gene clusters related to an alternative pathway of non-phosphorylated l -rhamnose metabolism. J Biol Chem283, 20372,20382), we identified and characterized the gene clusters encoding the four metabolic enzymes [l -rhamnose 1-dehydrogenase (LRA1), l -rhamnono-,-lactonase (LRA2), l -rhamnonate dehydratase (LRA3) and l -2-keto-3-deoxyrhamnonate aldolase (LRA4)]. In the known and alternative l -rhamnose pathways, l -lactaldehyde is commonly produced from l -2-keto-3-deoxyrhamnonate and l -rhamnulose 1-phosphate by each specific aldolase, respectively. To estimate the metabolic fate of l -lactaldehyde in fungi, we purified l -lactaldehyde dehydrogenase (LADH) from P. stipitis cells l -rhamnose-grown to homogeneity, and identified the gene encoding this enzyme (PsLADH) by matrix-assisted laser desorption ionization-quadruple ion trap-time of flight mass spectrometry. In contrast, LADH of A. vinelandii (AvLADH) was clustered with the LRA1,4 gene on the genome. Physiological characterization using recombinant enzymes revealed that, of the tested aldehyde substrates, l -lactaldehyde is the best substrate for both PsLADH and AvLADH, and that PsLADH shows broad substrate specificity and relaxed coenzyme specificity compared with AvLADH. In the phylogenetic tree of the aldehyde dehydrogenase superfamily, PsLADH is poorly related to the known bacterial LADHs, including that of Escherichia coli (EcLADH). However, despite its involvement in different l -rhamnose metabolism, AvLADH belongs to the same subfamily as EcLADH. This suggests that the substrate specificities for l -lactaldehyde between fungal and bacterial LADHs have been acquired independently. [source]

Modeling the Qo site of crop pathogens in Saccharomyces cerevisiae cytochrome b

FEBS JOURNAL, Issue 11 2004
Nicholas Fisher
Saccharomyces cerevisiae has been used as a model system to characterize the effect of cytochrome b mutations found in fungal and oomycete plant pathogens resistant to Qo inhibitors (QoIs), including the strobilurins, now widely employed in agriculture to control such diseases. Specific residues in the Qo site of yeast cytochrome b were modified to obtain four new forms mimicking the Qo binding site of Erysiphe graminis, Venturia inaequalis, Sphaerotheca fuliginea and Phytophthora megasperma. These modified versions of cytochrome b were then used to study the impact of the introduction of the G143A mutation on bc1 complex activity. In addition, the effects of two other mutations F129L and L275F, which also confer levels of QoI insensitivity, were also studied. The G143A mutation caused a high level of resistance to QoI compounds such as myxothiazol, axoxystrobin and pyraclostrobin, but not to stigmatellin. The pattern of resistance conferred by F129L and L275F was different. Interestingly G143A had a slightly deleterious effect on the bc1 function in V. inaequalis, S. fuliginea and P. megasperma Qo site mimics but not in that for E. graminis. Thus small variations in the Qo site seem to affect the impact of the G143A mutation on bc1 activity. Based on this observation in the yeast model, it might be anticipated that the G143A mutation might affect the fitness of pathogens differentially. If so, this could contribute to observed differences in the rates of evolution of QoI resistance in fungal and oomycete pathogens. [source]

Microbial interactions and differential protein expression in Staphylococcus aureus ,Candida albicans dual-species biofilms

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2010
Brian M. Peters
Abstract The fungal species Candida albicans and the bacterial species Staphylococcus aureus are responsible for a majority of hospital-acquired infections and often coinfect critically ill patients as complicating polymicrobial biofilms. To investigate biofilm structure during polymicrobial growth, dual-species biofilms were imaged with confocal scanning laser microscopy. Analyses revealed a unique biofilm architecture where S. aureus commonly associated with the hyphal elements of C. albicans. This physical interaction may provide staphylococci with an invasion strategy because candidal hyphae can penetrate through epithelial layers. To further understand the molecular mechanisms possibly responsible for previously demonstrated amplified virulence during coinfection, protein expression studies were undertaken. Differential in-gel electrophoresis identified a total of 27 proteins to be significantly differentially produced by these organisms during coculture biofilm growth. Among the upregulated staphylococcal proteins was l -lactate dehydrogenase 1, which confers resistance to host-derived oxidative stressors. Among the downregulated proteins was the global transcriptional repressor of virulence factors, CodY. These findings demonstrate that the hyphae-mediated enhanced pathogenesis of S. aureus may not only be due to physical interactions but can also be attributed to the differential regulation of specific virulence factors induced during polymicrobial growth. Further characterization of the intricate interaction between these pathogens at the molecular level is warranted, as it may aid in the design of novel therapeutic strategies aimed at combating fungal,bacterial polymicrobial infection. [source]

Soil microbial community structure in cucumber rhizosphere of different resistance cultivars to fusarium wilt

FEMS MICROBIOLOGY ECOLOGY, Issue 3 2010
Huaiying Yao
Abstract Cucumber fusarium wilt is a common soil-borne disease. We hypothesize that there is a relationship between the severity of disease and soil microbial ecology. In this work, culturable microbial populations, lipid fatty acid and community-level physiological profiles (CLPP) from rhizosphere soils of four different cucumber cultivars were investigated. Comparatively higher actinomycetes, mycorrhizal colonization and higher ratios of bacteria to fungi were found in the two resistant cultivars compared with the two susceptible cultivars. CLPP analysis showed that catabolic diversity indices were higher in the presence of two resistant cultivars. Phospholipid fatty acid (PLFA) profiles suggested that fungal (18:2,6,9c) PLFA was enriched in the rhizosphere soils of the two susceptible cultivars, but some bacterial (16:0 and 15:0a) PLFAs were found in a lower relative abundance in these soils. The neutral lipid fatty acid 16:1,5, which is an indicator of arbuscular mycorrhizal fungi, was enriched in the rhizosphere soils of the two resistant cultivars. All the three methods suggested that plant genotype had a significant impact on the soil microbial community composition and activity, and the differences in the rhizosphere microbial community may result in the differences in the resistance to fusarium wilt. [source]

Degradation of N -acyl homoserine lactone quorum sensing signal molecules by forest root-associated fungi

FEMS MICROBIOLOGY ECOLOGY, Issue 2 2008
Stephane Uroz
Abstract A collection of mycorrhizal and nonmycorrhizal root-associated fungi coming from forest environments was screened for their ability to degrade N -acyl homoserine lactones (AHL) or to prevent AHL recognition by producing quorum sensing inhibitors (QSI). No production of QS-inhibitors or -activators was detected using the two biosensors Chromobacterium violaceum CV026 and Agrobacterium tumefaciens in the culture supernatant of these fungi. However, the ability to degrade C6- and 3O,C6-HSL was detected for three fungal isolates. Acidification assay revealed that the AHL were degraded by a lactonase activity for two of these isolates. These results demonstrated for the first time that the forest root-associated fungi are capable of degrading the AHL signal molecules. [source]

Fungal endophytes in potato roots studied by traditional isolation and cultivation-independent DNA-based methods

FEMS MICROBIOLOGY ECOLOGY, Issue 3 2006
Monika Götz
Abstract The composition and relative abundance of endophytic fungi in roots of field-grown transgenic T4-lysozyme producing potatoes and the parental line were assessed by classical isolation from root segments and cultivation-independent techniques to test the hypothesis that endophytic fungi are affected by T4-lysozyme. Fungi were isolated from the majority of root segments of both lines and at least 63 morphological groups were obtained with Verticillium dahliae, Cylindrocarpon destructans, Colletotrichum coccodes and Plectosporium tabacinum as the most frequently isolated species. Dominant bands in the fungal fingerprints obtained by denaturing gradient gel electrophoresis analysis of 18S rRNA gene fragments amplified from total community DNA corresponded to the electrophoretic mobility of the 18S rRNA gene fragments of the three most abundant fungal isolates, V. dahliae, C. destructans and Col. coccodes, but not to P. tabacinum. The assignment of the bands to these isolates was confirmed for V. dahliae and Col. coccodes by sequencing of clones. Verticillium dahliae was the most abundant endophytic fungus in the roots of healthy potato plants. Differences in the relative abundance of endophytic fungi colonizing the roots of T4-lysozyme producing potatoes and the parental line could be detected by both methods. [source]

Potentiality of the cox1 gene in the taxonomic resolution of soil fungi

FEMS MICROBIOLOGY LETTERS, Issue 1 2010
Claire Molitor
Abstract We explored the potential of the cox1 gene in the species resolution of soil fungi and compared it with the nuclear internal transcribed spacer (ITS) and small subunit (SSU)-rDNA. Conserved primers allowing the amplification of the fungal cox1 gene were designed, and a total of 47 isolates of Zygomycota and Ascomycota were investigated. The analysis revealed a lack of introns in >90% of the isolates. Comparison of the species of each of the six studied genera showed high interspecific sequence polymorphisms. Indeed, the average of nucleotide variations (4.2,11%) according to the genus, due mainly to the nucleotide substitutions, led to the taxonomic resolution of all the species studied regarding both ITS and SSU-rDNA, in which <88% were discriminated. The phylogenetic analysis performed after alignment of the cox1 gene across distant fungal species was in accordance with the well-known taxonomic position of the species studied and no overlap was observed between intra- and interspecific variations. These results clearly demonstrated that the cox1 sequences could provide good molecular markers for the determination of the species composition of environmental samples and constitute an important advance to study soil fungal biodiversity. [source]

Avirulence proteins from haustoria-forming pathogens

FEMS MICROBIOLOGY LETTERS, Issue 2 2007
Ann-Maree Catanzariti
Abstract A major insight that has emerged in the study of haustoria-forming plant pathogens over the last few years is that these eukaryotic biotrophs deliver suites of secreted proteins into host cells during infection. This insight has largely derived from successful efforts to identify avirulence (Avr) genes and their products from these pathogens. These Avr genes, identified from a rust and a powdery mildew fungus and three oomycete species, encode small proteins that are recognized by resistance proteins in the host plant cytoplasm, suggesting that they are transported inside plant cells during infection. These Avr proteins probably represent examples of fungal and oomycete effector proteins with important roles in subverting host cell biology during infection. In this respect, they represent a new opportunity to understand the basis of disease caused by these biotrophic pathogens. Elucidating how these pathogen proteins gain entry into plant cells and their biological function will be key questions for future research. [source]

Conservation and dispersion of sequence and function in fungal TRK potassium transporters: focus on Candida albicans

FEMS YEAST RESEARCH, Issue 2 2009
Manuel Miranda
Abstract TRK proteins , essential potassium (K+) transporters in fungi and bacteria, as well as in plants , are generally absent from animal cells, which makes them potential targets for selective drug action. Indeed, in the human pathogen Candida albicans, the single TRK isoform (CaTrk1p) has recently been demonstrated to be required for activity of histidine-rich salivary antimicrobial peptides (histatins). Background for a detailed molecular investigation of TRK-protein design and function is provided here in sequence analysis and quantitative functional comparison of CaTrk1p with its better-known homologues from Saccharomyces cerevisiae. Among C. albicans strains (ATCC 10261, SC5314, WO-1), the DNA sequence is essentially devoid of single nucleotide polymorphisms in regions coding for evolutionarily conserved segments of the protein, meaning the four intramembranal [membrane,pore,membrane (MPM)] segments thought to be involved directly with the conduction of K+ ions. Among 48 fungal (ascomycete) TRK homologues now described by complete sequences, clades (but not the detailed order within clades) appear conserved for all four MPM segments, independently assessed. The primary function of TRK proteins, ,active' transport of K+ ions, is quantitatively conserved between C. albicans and S. cerevisiae. However, the secondary function, chloride efflux channeling, is present but poorly conserved between the two species, being highly variant with respect to activation velocity, amplitude, flickering (channel-like) behavior, pH dependence, and inhibitor sensitivity. [source]

Associations between Pityogenes bidentatus and fungi in young managed Scots pine stands in Poland

FOREST PATHOLOGY, Issue 3 2008
R. Jankowiak
Summary The association between Pityogenes bidentatus and fungi was studied in young, managed Pinus sylvestris stands in Poland. Fungi were isolated from emerged adults and their galleries collected from four populations. In total, 2089 fungal isolates including 42 species, were obtained. Penicillium sp. 1 and Geosmithia sp. 1 were the most commonly isolated fungi from beetles (49% and 41% of beetles respectively). Geosmithia sp. 1 species was the dominant species in P. bidentatus galleries with a frequency of occurrence of 57.9%. Hormonema dematioides was the second most abundant fungus in gallery systems (17.1% of wood samples). Two of the isolated Geosmithia species were previously undescribed. Pityogenes bidentatus also vectored three ophiostomatoid species: Ophiostoma minus, O. piceae and Graphium sp. ,W'. These species were occasionally isolated from beetles and their galleries, suggesting a non-specific relationship. [source]

Direct genotyping of the poplar leaf rust fungus, Melampsora medusae f. sp. deltoidae, using codominant PCR-SSCP markers

FOREST PATHOLOGY, Issue 4 2005
M. Bourassa
Summary Two anonymous DNA markers that are revealed by single-strand conformational polymorphism (SSCP) analysis were developed for detection of polymorphisms in Melampsora medusae f. sp. deltoidae (Mmd). Mono-uredinial isolates of Mmd were first obtained, DNA was extracted from urediniospores and random amplified polymorphic DNA (RAPD) products of eight mono-uredinial isolates were separated on a SSCP gel to identify differences among them. Bands representing putative polymorphic loci among the eight isolates tested were excised from the SSCP gel and re-amplified by polymerase chain reaction (PCR), and then cloned and sequenced. A primer pair was designed to amplify a DNA fragment of a size suitable for SSCP analysis (<600 bp) for two out of three DNA fragments sequenced. Each set of primers amplified a PCR product for all eight isolates that were initially used to generate them and the resulting PCR products were analysed by SSCP. Polymorphisms among isolates were identified for both putative loci. The two primer pairs amplified a PCR product of the expected size on an additional 32 mono-uredinial isolates of Mmd tested. From the overall 40 mono-uredinial isolates tested, 5 and 11 alleles were detected, and 12 and 34 isolates showed to be heterozygous, as indicated by the presence of more than two bands on the SSCP gel, at loci A and B, respectively. The primer pairs were tested for specificity against 106 fungal isolates belonging to various taxa, including other rusts, and against DNA extracted from greenhouse-grown healthy poplar leaves. DNA amplification products of the expected size were obtained only when Mmd DNA was present. Optimization of PCR conditions with these two primer pairs allowed genotyping directly from single uredinia extracted from infected leaves, thus alleviating the need to culture the fungus to characterize individuals, hence making it possible to process large numbers of samples for population studies. Résumé Deux marqueurs génétiques anonymes, révélés par analyse SSCP (Single-Strand Conformational Polymorphism) ont été développés afin de détecter des polymorphismes génétiques chez le Melampsora medusae f. sp. deltoidae (Mmd). Dans un premier temps, des isolats mono-urédiniaux ont été obtenus, puis l'ADN a été extrait à partir des urédiniospores, les produits d'amplification RAPD (Random Amplified Polymorphic DNA) ont été générés à partir de huit de ces isolats mono-urédiniaux et les résultats d'amplification ont par la suite été séparés sur gel SSCP afin d'identifier des polymorphismes entre les isolats. Les bandes sur gel SSCP représentant des loci polymorphiques putatifs entre les isolats ont été prélevées du gel, ré-amplifiées par la technique d'amplification PCR (Polymerase Chain Reaction), clonées, puis séquencées. Pour deux fragments d'ADN séquencés sur un total de trois, une paire d'amorces a été développée afin de permettre l'amplification d'un fragment de taille adéquate pour analyse SSCP (<600 pb). Chaque paire d'amorces a produit un signal d'amplification positif pour chacun des huit isolats à l'origine de ces nouvelles amorces; les produits PCR ont ensuite été analysés par la technique SSCP. Les deux loci putatifs ont révélé des polymorphismes génétiques entre les isolats. Les deux paires d'amorces ont produit un fragment d'amplification de la taille attendue pour chacun des 32 isolats mono-urédiniaux supplémentaires testés. Des 40 isolats testés, 5 et 11 allèles ont été détectés, alors que 12 et 34 isolats se sont révélés hétérozygotes (tel qu'indiqué par la présence de plus de deux bandes sur gel SSCP) pour les loci A et B, respectivement. La spécificité des deux paires d'amorces a été testée à partir de 106 isolats fongiques appartenant à différents groupes taxonomiques, incluant d'autres rouilles, de même qu'à partir de l'ADN extrait de feuilles de peupliers cultivés en serre. Un signal d'amplification positif n'a été obtenu qu'en présence d'ADN du Mmd. Les conditions d'amplification PCR ont été optimisées pour les deux paires d'amorces développées afin de permettre le génotypage directement à partir d'urédinies individuelles prélevées sur des feuilles de peuplier infectées. La possibilité de génotyper directement des urédinies individuelles permet d'éviter l'obligation de cultiver le champignon pour génotyper les individus, ce qui représente un avantage important des marqueurs génétiques développés ici, puisqu'il devient dès lors possible de traiter un grand nombre d'échantillons lors de la réalisation d'études de populations. Zusammenfassung Zum Nachweis von Polymorphismen bei Melampsora medusae f. sp. deltoidae wurden zwei anonyme DNA Marker aus einer SSCP-Analyse entwickelt. Zunächst wurden Isolate aus einzelnen Uredinien gewonnen, die DNA wurde aus den Uredosporen extrahiert und polymorphe RAPD, Amplifikationsprodukte von acht Mono-Uredinium-Isolaten wurden auf einem SSCP-Gel getrennt, um Unterschiede zwischen ihnen nachzuweisen. Banden, die bei den acht geprüften Isolaten mögliche polymorphe Loci darstellten, wurden aus dem SSCP-Gel ausgeschnitten und mit PCR reamplifiziert, dann geklont und sequenziert. Für zwei von insgesamt drei sequenzierten DNA-Fragmenten wurde ein Primerpaar entwickelt, um ein in der Grösse für die SSCP-Analyse (<600 bp) geeignetes DNA-Fragment zu amplifizieren. Jedes Primerpaar amplifizierte bei allen acht ursprünglich für ihre Entwicklung verwendeten Isolaten ein PCR-Produkt, und diese wurden anschliessend mit SSCP analysiert. Für beide putativen Loci wurden bei den Isolaten Polymorphismen festgestellt. Die beiden Primerpaare amplifizierten ein PCR-Produkt der erwarteten Grösse bei allen 32 zusätzlich geprüften Mono-Uredinium-Isolaten des Pilzes. Bei den insgesamt 40 geprüften Mono-Uredinium-Isolaten wurden für die Loci A und B 5 bzw. 11 Allele gefunden, und 12 bzw. 34 Isolate erwiesen sich als heterozygot, was durch mehr als zwei Banden auf den SSCP-Gelen angezeigt wurde. Die Spezifität der Primerpaare wurden mit 106 Pilzisolaten aus verschiedenen Taxa geprüft, darunter andere Roste sowie DNA aus gesunden Pappelblättern aus Gewächshauskulturen. DNA-Amplifikationsprodukte der erwarteten Grösse wurden nur erhalten, wenn DNA von Melampsora medusae f. sp. deltoidae präsent war. Die PCR-Amplifikations-Bedingungen mit diesen beiden Primerpaaren wurde so optimiert, dass ein Genotyping direkt bei einzelnen von infizierten Blättern entnommenen Uredinien erfolgen kann und somit eine Pilzkultur zur Charakterisierung von Individuen entfällt. Dies ermöglicht grosse Probenzahlen in Populationsstudien. [source]

Effects of drying regime on microbial colonization and shredder preference in seasonal woodland wetlands

FRESHWATER BIOLOGY, Issue 3 2008
MARTYN D. INKLEY
Summary 1. Energy budgets of wetlands in temperate deciduous forests are dominated by terrestrially derived leaf litter that decays under different drying conditions depending on autumn precipitation. We compared decay rates and microbial colonization of maple leaves under different inundation schedules in a field experiment, and then conducted a laboratory study on shredder preference. In the field, litter bags either remained submerged (permanent), were moved to a dried part of the basin once and then returned (semi-permanent), or were alternated between wet and dry conditions for 8 weeks (temporary). 2. There was no difference in decay rates among treatments, but leaves incubated under permanent and semi-permanent conditions had higher fungal and bacterial biomass, and lower C : N ratios than those incubated under alternating drying and wetting conditions. 3. To determine the effects of these differences in litter nutritional quality on shredder preference, we conducted a laboratory preference test with larvae of leaf-shredding caddisflies that inhabit the wetland. Caddisflies spent twice as much time foraging on permanent and semi-permanent litter than on litter incubated under temporary conditions. 4. There is considerable variation among previous studies in how basin drying affects litter breakdown in wetlands, and no previous information on shredder preference. We found that frequent drying in a shallow wetland reduces the nutritional quality of leaf litter (lower microbial biomass and nitrogen content), and therefore preference by invertebrate shredders. These results suggest that inter-annual shifts in drying regime should alter detritus processing rates, and hence the mobilization of the energy and nutrients in leaf litter to the wetland food web. [source]

Adaptation of soil microbial communities to temperature: comparison of fungi and bacteria in a laboratory experiment

GLOBAL CHANGE BIOLOGY, Issue 12 2009
GEMA BÁRCENAS-MORENO
Abstract Temperature not only has direct effects on microbial activity, but can also affect activity indirectly by changing the temperature dependency of the community. This would result in communities performing better over time in response to increased temperatures. We have for the first time studied the effect of soil temperature (5,50 °C) on the community adaptation of both bacterial (leucine incorporation) and fungal growth (acetate-in-ergosterol incorporation). Growth at different temperatures was estimated after about a month using a short-term assay to avoid confounding the effects of temperature on substrate availability. Before the experiment started, fungal and bacterial growth was optimal around 30 °C. Increasing soil temperature above this resulted in an increase in the optimum for bacterial growth, correlated to soil temperature, with parallel shifts in the total response curve. Below the optimum, soil temperature had only minor effects, although lower temperatures selected for communities growing better at the lowest temperature. Fungi were affected in the same way as bacteria, with large shifts in temperature tolerance at soil temperatures above that of optimum for growth. A simplified technique, only comparing growth at two contrasting temperatures, gave similar results as using a complete temperature curve, allowing for large scale measurements also in field situations with small differences in temperature. [source]

Impact of elevated carbon dioxide on the rhizosphere communities of Carex arenaria and Festuca rubra

GLOBAL CHANGE BIOLOGY, Issue 11 2007
BARBARA DRIGO
Abstract The increase in atmospheric carbon dioxide (CO2) levels is predicted to stimulate plant carbon (C) fixation, potentially influencing the size, structure and function of micro- and mesofaunal communities inhabiting the rhizosphere. To assess the effects of increased atmospheric CO2 on bacterial, fungal and nematode communities in the rhizosphere, Carex arenaria (a nonmycorrhizal plant species) and Festuca rubra (a mycorrhizal plant species) were grown in three dune soils under controlled soil temperature and moisture conditions, while subjecting the aboveground compartment to defined atmospheric conditions differing in CO2 concentrations (350 and 700 ,L L,1). Real-time polymerase chain reaction (PCR) and PCR-denaturing gradient gel electrophoresis methods were used to examine effects on the size and structure of rhizosphere communities. Multivariate analysis of community profiles showed that bacteria were most affected by elevated CO2, and fungi and nematodes to a lesser extent. The influence of elevated CO2 was plant dependent, with the mycorrhizal plant (F. rubra) exerting a greater influence on bacterial and fungal communities. Biomarker data indicated that arbuscular mycorrhizal fungi (AMF) may play an important role in the observed soil community responses. Effects of elevated CO2 were also soil dependent, with greater influence observed in the more organic-rich soils, which also supported higher levels of AMF colonization. These results indicate that responses of soil-borne communities to elevated CO2 are different for bacteria, fungi and nematodes and dependent on the plant type and soil nutrient availability. [source]

Host's innate immune response to fungal and bacterial agents in vitro: up-regulation of interleukin-15 gene expression resulting in enhanced natural killer cell activity

IMMUNOLOGY, Issue 2 2003
Phay Tran
Summary Natural killer (NK) cells play an important role in the first line of defence against viral infections. We have shown earlier that exposure of human peripheral blood mononuclear cells (PBMC) to viruses results in rapid up-regulation of NK cell activity via interleukin-15 (IL-15) induction, and that this mechanism curtails viral infection in vitro. By using Candida albicans, Escherichia coli and Staphylococcus aureus, we now show here that exposure of PBMC to fungi and bacteria also results in an immediate increase of NK cytotoxicity. Reverse transcriptase,polymerase chain reaction and Western blot analyses as well as the use of antibodies against different cytokines revealed that IL-15 induction played a predominant role in this NK activation. These results indicate that IL-15 is also involved in the innate immune response against fungal and bacterial agents. [source]

Asthma and respiratory symptoms in hospital workers related to dampness and biological contaminants

INDOOR AIR, Issue 4 2009
J. M. Cox-Ganser
Abstract, The National Institute for Occupational Safety and Health investigated respiratory symptoms and asthma in relation to damp indoor environments in employees of two hospitals. A cluster of six work-related asthma cases from one hospital department, whose symptoms arose during a time of significant water incursions, led us to conduct a survey of respiratory health in 1171/1834 employees working in the sentinel cases hospital and a nearby hospital without known indoor environmental concerns. We carried out observational assessment of dampness, air, chair, and floor dust sampling for biological contaminants, and investigation of exposure-response associations for about 500 participants. Many participants with post-hire onset asthma reported diagnosis dates in a period of water incursions and renovations. Post-hire asthma and work-related lower respiratory symptoms were positively associated with the dampness score. Work-related lower respiratory symptoms showed monotonically increasing odds ratios with ergosterol, a marker of fungal biomass. Other fungal and bacterial indices, particle counts, cat allergen and latex allergen were associated with respiratory symptoms. Our data imply new-onset of asthma in relation to water damage, and indicate that work-related respiratory symptoms in hospital workers may be associated with diverse biological contaminants. [source]

Suspected white-tail spider bite and necrotic ulcers

INTERNAL MEDICINE JOURNAL, Issue 1-2 2004
G. K. Isbister
Abstract Aim: To describe the clinical features, investigation, diagnosis and treatment of ulcers attributed to white-tail (WT) spider bites or necrotic arachnidism. Methods: The study was a prospective case series of patients referred to the Hunter Area Toxicology Service (a tertiary referral toxicology unit servicing a population of 500 000) with an ulcer or skin lesion that had been attributed to either a suspected WT spider bite or necrotic arachnidism. Eleven patients with skin lesions or necrotic ulcers were referred between January 2000 and June 2002. Results: In two patients that were inpatients in other hospitals, investigation and follow up was not possible. In both cases there was no history of spider bite and Staphylococcus aureus was cultured. In nine patients, a diagnosis other than spider bite was made following appropriate investigation and follow up, including: (i) two cases of dermatophytoses, (ii) three staphylococcal infections, (iii) one case of pyoderma gangrenosum, (iv) one case of cutaneous polyarteritis nodosa, (v) one case of Nocardia braziliensis and (vi) one infected diabetic ulcer. There was only one case where the person recalled seeing a spider bite them, but the patient did not collect the spider for identification. The median time to diagnosis was 3 weeks (interquartile range: 3,9 weeks) and 3.5 years in one case. Appropriate treatment was initiated once the correct diagnosis was made and all cases resolved. Conclusions:, In this series, all cases initially referred as WT spider bites or necrotic arachnidism were found to have alternative diagnoses with appropriate investigations. This demonstrates that spider bites are an unlikely cause of necrotic ulcers and that all ulcers should be properly investigated with bacterial, fungal and mycobacterial cultures and skin biopsy for histopathology. (Intern Med J 2004; 34: 38,44) [source]