Home About us Contact
|
Home About us Contact | ||
|
|
||
Hyphae
Kinds of Hyphae Selected AbstractsVolatile organic compounds: a potential direct long-distance mechanism for antagonistic action of Fusarium oxysporum strain MSA 35ENVIRONMENTAL MICROBIOLOGY, Issue 4 2009Daniela Minerdi Summary Fusarium oxysporum MSA 35 [wild-type (WT) strain] is an antagonistic Fusarium that lives in association with a consortium of bacteria belonging to the genera Serratia, Achromobacter, Bacillus and Stenotrophomonas in an Italian soil suppressive to Fusarium wilt. Typing experiments and virulence tests provided evidence that the F. oxysporum isolate when cured of the bacterial symbionts [the cured (CU) form], is pathogenic, causing wilt symptoms identical to those caused by F. oxysporum f. sp. lactucae. Here, we demonstrate that small volatile organic compounds (VOCs) emitted from the WT strain negatively influence the mycelial growth of different formae speciales of F. oxysporum. Furthermore, these VOCs repress gene expression of two putative virulence genes in F. oxysporum lactucae strain Fuslat10, a fungus against which the WT strain MSA 35 has antagonistic activity. The VOC profile of the WT and CU fungus shows different compositions. Sesquiterpenes, mainly caryophyllene, were present in the headspace only of WT MSA 35. No sesquiterpenes were found in the volatiles of ectosymbiotic Serratia sp. strain DM1 and Achromobacter sp. strain MM1. Bacterial volatiles had no effects on the growth of the different ff. spp. of F. oxysporum examined. Hyphae grown with VOC from WT F. oxysporum f. sp. lactucae strain MSA 35 were hydrophobic whereas those grown without VOCs were not, suggesting a correlation between the presence of volatiles in the atmosphere and the phenotype of the mycelium. This is the first report of VOC production by antagonistic F. oxysporum MSA 35 and their effects on pathogenic F. oxysporum. The results obtained in this work led us to propose a new potential direct long-distance mechanism for antagonism by F. oxysporum MSA 35 mediated by VOCs. Antagonism could be the consequence of both reduction of pathogen mycelial growth and inhibition of pathogen virulence gene expression. [source] Hereditary palmoplantar keratoderma (four cases in three generations)INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 2 2001Virendra N. Sehgal MD A 39-year-old man reported with progressive thickening of the skin of the hands and feet and an inability to flex his hand. It was largely asymptomatic; however, brisk walking caused excessive sweating, pain, and widening of the fissures on the soles of the feet. He was unable to walk barefooted. According to his mother, the first episode presented with blistering at 7 days of age. Ever since, the condition has steadily worsened to acquire the current status. He was married at the age of 18 years, and had a stillborn child 18 months afterwards. Presently, he has three children, two girls aged 14 and 12 years and a son aged 10 years. Both the daughters are similarly affected. While cataloguing the details of the pattern of inheritance, the mother of the index case was also found to be affected (Fig. 1). The natural history of the disease was identical. Figure 1. Palmoplantar keratoderma: pattern of inheritance; black indicates affected individuals Examination of the palms was marked by pronounced thickening of the skin resulting in the masking of palmar creases. The thickening was well demarcated and its margins were prominent and surrounded by an erythematous halo. The color of the skin was yellow and waxy (Fig. 2a). Contractures were present on all the fingers; nevertheless, the deformity of the middle and distal interphalangeal joints of the little finger was prominent. The soles of the feet had a similar morphology. In addition, marked fissuring was obvious (Fig. 2b). His daughters had an identical affliction of the palms and soles. The texture and morphology of the nails were normal. Light microscopy performed on scrapings from the fissures, mounted on 10% potassium hydroxide, revealed mycelia (hyphae) and spores. Figure 2. Well-demarcated hyperkeratosis depicting the yellow, waxy color of the palms, with masking of creases (a). Marked fissuring on the soles was prominent (b) Hematoxylin and eosin-stained microsections from the palms and soles showed exquisite changes in the epidermis characterized by considerable uniform orthohyperkeratosis. Hypergranulosis and acanthosis were other associated changes. In addition, perinuclear vacuolization and keratohyalin granules of varying sizes and shapes were located at the periphery of the cells. A sparse mononuclear infiltrate was located at the dermo-epidermal junction. Hyphae and spores of fungi were also identified in the stratum corneum (Fig. 3). Figure 3. Orthohyperkeratosis, hypergranulosis, and acanthosis. Perinuclear vacuolization and keratohyalin granules at the periphery of the cells; a sparse mononuclear infiltrate was also present (hematoxylin and eosin, ×,40 (a), ×,400 (b)) Itraconazole, 400 mg/day in two equally divided doses, was administered with major meals for 7 days. In addition, high doses of vitamin A (100,000 IU) were given daily for 2 weeks, supplemented by 12% salicylic acid (Salicylix SF12) ointment for daytime application and an ointment containing 6% coal tar and 3% salicylic acid (Salytar) for night-time application. This treatment is useful in recalcitrant cases. [source] Onychomycosis in primary school children: association with socioeconomic conditionsMYCOSES, Issue 5 2006Turan Gunduz Summary Onychomycosis in childhood is reported to be unusual. The aim of this study was to determine the prevalence of onychomycosis in primary school children and to make comparison between different socioeconomic status in the rural and urban areas of the city. Hand and foot nails of 23235 children aged 7,14 were examined. Onychomycosis was suspected and nail scrapings for mycological examination were taken in 116 of them. Hyphae or spores were seen in 41 (0.18%) by direct microscopic examination, and mycological cultures were positive in 24 (0.1%) of them. Toenails were affected in all of the fungal culture positive cases. Trichosporon spp, Trichophyton rubrum, Candida albicans and Candida glabrata grew in 11, 6, 5 and 2 of the cultures repectively. Onychomycosis prevalence was significantly higher in the children living in the rural areas (p = 0.016) [Odds ratio = 3.43 (%95 CI 1.11 Leaf, floret and seed infection of wheat by Pyrenophora semeniperdaPLANT PATHOLOGY, Issue 4 2003M. A. Campbell Infection processes of Pyrenophora semeniperda on seedling and adult wheat leaves and wheat ears were investigated. Almost 100% germination of conidia occurred on seedling leaves, compared with 20,30% on adult leaves. Appressoria formed over the anticlinal epidermal cell walls and haloes always accompanied infection. Sometimes papillae formed within the leaves as a resistance mechanism. Infection hyphae ramified through the intercellular spaces of the mesophyll resulting in cellular disruption. The infection processes on floral tissues were similar to those observed on leaves; however, no infection occurred on anther, stigmatic or stylar tissues. Infection of ovarian tissue occurred both with and without appressoria formation. Hyphae grew mainly in the epidermal layers and appeared unable to breach the integumental layer as no growth was observed in endosperm or embryo tissues. The optimum dew period temperature for conidial germination was 23·6°C, compared with 19·9°C for lesion development, 20·4°C for the production of infection structures on seedling leaves and 23·7°C for floret infection. Leaf disease development occurred in a logistic manner in response to dew period, with maximum infection observed after 21 h compared with > 48 h in seeds. An initial dark phase during the dew period was necessary for infection and temperature after the dew period had an effect, with significantly more numerous and larger lesions being formed at 15°C compared with 30°C. Seedling leaves were found to be more susceptible than older leaves, under both field and controlled environment conditions. Infection of wheat seeds following inoculation of ears, or after harvest burial of inoculated disease-free seeds, was demonstrated. In the latter, 3-week-old seedlings were slightly stunted, whereas older plants were unaffected. The apparent unimportance of this plant pathogen as a cause of leaf disease in relation to its poor adaptation to dew periods and dew period temperature is discussed, along with the importance of its seed borne characteristics. [source] Infection and colonization of bean leaf by Phaeoisariopsis griseolaPLANT PATHOLOGY, Issue 1 2001E. O. Monda Infection and spread of Phaeoisariopsis griseola in the leaf of bean (Phaseolus vulgaris) were investigated by scanning and transmission electron microscopy. Conidia of P. griseola germinated by releasing a germ tube either at one end of the conidia or both ends. The germ-tube growth followed the contours of epidermal cells. The fungus entered the leaf through the stomata and grew mainly intercellularly between mesophyll and palisade cells. The chloroplast envelope and plasma membrane of adjacent cells disintegrated, lost structural integrity and dried out. Hyphae did not penetrate host cells. A stroma subsequently formed on the leaf surface. Conidiophores elongated under favourable conditions forming synnemata with conidia at the tips of conidiophores. Conidiophores also emerged through stomata. [source] Contributions of hyphae and hypha-co-regulated genes to Candida albicans virulenceCELLULAR MICROBIOLOGY, Issue 11 2005Carol A. Kumamoto Summary The fascinating ability of Candida albicans to undergo dramatic changes in cellular morphology has invited speculation that this plasticity in form contributes to the virulence of the organism. Molecular genetic analyses have confirmed this hypothesis and further demonstrated that genes that govern cellular morphology are co-regulated with genes encoding conventional virulence factors such as proteases and adhesins. The transcriptional regulatory networks of C. albicans thus ensure that hyphae are produced concomitantly with virulence factors, resulting in cells that are adapted for invading the tissues of an immunocompromised host. Hyphae are able to exert mechanical force, aiding penetration of epithelial surfaces, and hyphae damage endothelial cells, aiding escape of C. albicans from the host bloodstream into deeper tissue. Hyphal morphogenesis is thus an integral part of the overall virulence strategy of C. albicans. [source] Polymicrobial lung infection in postrenal transplant recipient diagnosed by fine-needle aspiration cytologyDIAGNOSTIC CYTOPATHOLOGY, Issue 4 2010Rajan Duggal M.D. Abstract Tuberculous and fungal infections are among the non-neoplastic lesions of the lung, in which fine-needle aspiration cytology (FNAC) has proven to be a useful technique in both immunocompromised and immunocompetent patients. The presence of polymicrobial infection in a renal transplant recipient is documented in the literature, but has rarely been diagnosed on cytology. We report a case of concomitant pulmonary cryptococcosis, aspergillosis, and tuberculosis in a renal transplant recipient diagnosed on FNAC. A 50-year-old renal transplant recipient, asymptomatic for 3 year, presented with intermittent low-grade fever associated with cough, expectoration, and a newly developed cavitatory lesion in the left lung on chest X-ray. Computed tomography-guided FNAC performed on the lung lesion showed fungal profiles with septate hyphae and acute-angled branching consistent with morphology of Aspergillus. In addition, numerous yeast forms of cryptococcus and a few acid-fast mycobacterial tubercle bacilli were seen. Guided FNAC is a useful and reliable technique for the diagnosis of pulmonary infection. One should always keep in mind the possibility of polymicrobial infections especially inimmunocompromised patients. Diagn. Cytopathol. 2010. © 2009 Wiley-Liss, Inc. [source] Symptomatic candidiasis: Using self sampled vaginal smears to establish the presence of Candida, lactobacilli, and Gardnerella vaginalisDIAGNOSTIC CYTOPATHOLOGY, Issue 10 2007M. K. Engberts M.D. Abstract In a prospective cohort study, 10 symptomatic women with recurrent vulvovaginal candidiasis were taught how to prepare vaginal smears of their own vaginal fluids on days 7, 14, 21, and 28. The 40 smears were stained with the PAS-method and examined by three different cytopathologists for presence of Candida. Thereafter, the smears were restained with Giemsa-stain to determine presence of lactobacilli, Gardnerella vaginalis ("clue cells") and neutrophils. All three cytopathologists unequivocally established Candida blastospores and (pseudo)hyphae in 27 out of the 40 PAS-stained vaginal smears, whereas in the remaining 13 smears Candida was not found. All 10 patients had Candida in their smears during the second half of their menstrual cycle. Self sampled smears prove to be reliable for establishing the presence of Candida in symptomatic patients with candidiasis. Candida is associated with a lactobacillus -predominated vaginal flora, but with the absence of Gardnerella vaginalis. Further studies may be directed towards the interaction between the various members of the vaginal flora. This study should open molecular methodology for determining the possible interactions of lactobacilli and Candida. Diagn. Cytopathol. 2007;35:635,639. © 2007 Wiley-Liss, Inc. [source] Impact of Collimonas bacteria on community composition of soil fungiENVIRONMENTAL MICROBIOLOGY, Issue 6 2009Sachie Höppener-Ogawa Summary The genus Collimonas consists of soil bacteria that have the potential to grow at the expense of living fungal hyphae. However, the consequences of this mycophagous ability for soil fungi are unknown. Here we report on the development of fungal communities after introduction of collimonads in a soil that had a low abundance of indigenous collimonads. Development of fungal communities was stimulated by addition of cellulose or by introducing plants (Plantago lanceolata). Community composition of total fungi in soil and rhizosphere and of arbuscular mycorrhizal fungi in roots was examined by PCR-DGGE. The introduction of collimonads altered the composition of all fungal communities studied but had no effects on fungal biomass increase, cellulose degrading activity or plant performance. The most likely explanation for these results is that differences in sensitivity of fungal species to the presence of collimonads result in competitive replacement of species. The lab and greenhouse experiments were complemented with a field experiment. Mesh bags containing sterile sand with or without collimonads were buried in an ex-arable field and a forest. The presence of collimonads had an effect on the composition of fungi invading these bags in the ex-arable site but not in the forest site. [source] Two similar enhanced root-colonizing Pseudomonas strains differ largely in their colonization strategies of avocado roots and Rosellinia necatrix hyphaeENVIRONMENTAL MICROBIOLOGY, Issue 12 2008Clara Pliego Summary Pseudomonas alcaligenes AVO73 and Pseudomonas pseudoalcaligenes AVO110 were selected previously as efficient avocado root tip colonizers, displaying in vitro antagonism towards Rosellinia necatrix, causal agent of avocado white root rot. Despite the higher number of antagonistic properties shown in vitro by AVO73, only AVO110 demonstrated significant protection against avocado white root rot. As both strains are enhanced root colonizers, and as colonization is crucial for the most likely biocontrol mechanisms used by these strains, namely production of non-antibiotic antifungal compounds and competition for nutrients and niches, we decided to compare the interactions of the bacterial strains with avocado roots as well as with R. necatrix hyphae. The results indicate that strain AVO110 is superior in biocontrol trait swimming motility and establishes on the root tip of avocado plants faster than AVO73. Visualization studies, using Gfp-labelled derivatives of these strains, showed that AVO110, in contrast to AVO73, colonizes intercellular crevices between neighbouring plant root epidermal cells, a microhabitat of enhanced exudation. Moreover, AVO110, but not AVO73, also colonizes root wounds, described to be preferential penetration sites for R. necatrix infection. This result strongly suggests that AVO110 meets, and can attack, the pathogen on the root. Finally, when co-inoculated with the pathogen, AVO110 utilizes hyphal exudates more efficiently for proliferation than AVO73 does, and colonizes the hyphae more abundantly than AVO73. We conclude that the differences between the strains in colonization levels and strategies are likely to contribute to, and even can explain, the difference in disease-controlling abilities between the strains. This is the first report that shows that two similar bacterial strains, selected by their ability to colonize avocado root, use strongly different root colonization strategies and suggests that in addition to the total bacterial root colonization level, the sites occupied on the root are important for biocontrol. [source] Phenazines and biosurfactants interact in the biological control of soil-borne diseases caused by Pythium spp.ENVIRONMENTAL MICROBIOLOGY, Issue 3 2008Maaike Perneel Summary In this study, the putative role of phenazines and rhamnolipid-biosurfactants, antagonistic metabolites produced by Pseudomonas aeruginosa PNA1, was tested in the biological control of Pythium splendens on bean (Phaseolus vulgaris L) and Pythium myriotylum on cocoyam (Xanthosoma sagittifolium L Schott). A rhamnolipid-deficient and a phenazine-deficient mutant of PNA1 were used either separately or jointly in plant experiments. When the mutants were applied separately, no disease-suppressive effect was observed, although both mutants still produced one of the antagonistic compounds (phenazines or rhamnolipids). When the mutants were concurrently introduced in the soil, the biocontrol activity was restored to wild-type levels. Bean seeds developed significantly less pre-emergence damping-off caused by P. splendens when treated with a mixture of purified phenazine-1-carboxamide and rhamnolipids than with any of the chemicals alone. When phenazines and rhamnolipids were combined at concentrations that had no observable effects when the metabolites were applied separately, mycelial growth of P. myriotylum was significantly reduced. In addition, microscopic analysis revealed substantial vacuolization and disintegration of Pythium hyphae after incubation in liquid medium amended with both metabolites. Results of this study indicate that phenazines and biosurfactants are acting synergistically in the control of Pythium spp. [source] Clinical findings and outcomes of ulcerative keratomycosis in 30 horses in the mid-Atlantic United States (2006,2007)EQUINE VETERINARY EDUCATION, Issue 1 2010M. E. Utter Summary The purpose of this study was to determine the clinical course and outcome associated with keratomycosis in horses in the mid-Atlantic USA. Records of horses diagnosed with keratomycosis at New Bolton Center from November 2006 to November 2007 with positive fungal culture were retrospectively studied. Neither horses with ulcerative keratitis and a negative fungal culture nor those with stromal abscesses were included. Subject details, history, clinical findings, therapy and outcome were recorded. Thirty horses fitted both inclusion criteria (diagnosis of keratomycosis and positive corneal fungal culture). Fourteen of 30 cases occurred during summer. Aspergillus was the most commonly cultured fungal genus (17/30, or 57%) followed by Alternaria (4/30). Seventeen horses had positive bacterial and fungal cultures. Fifteen of 30 horses were treated surgically by a keratectomy and amnion (8) or conjunctival (7) graft. Itraconazole was the most common topical anti-fungal therapy and was utilised in 25/30 horses. Globe survival was 97% (29/30). All surviving globes had a positive menace response and were visual at the last examination. It was concluded that in the mid-Atlantic USA, fungal keratitis is common, has the highest incidence in summer, and is usually associated with a positive outcome. Aspergillus may be a relatively more common corneal pathogen in this region than elsewhere in the USA. Surgical cases were more likely to have fungal hyphae identified on cytology and tended to be hospitalised longer than medical cases. There was no apparent association between surgical disease and all other patient, organism and treatment variables. [source] Early diagnosis of rhinocerebral mucormycosis by cerebrospinal fluid analysis and determination of 16s rRNA gene sequenceEUROPEAN JOURNAL OF NEUROLOGY, Issue 9 2007D. Bengel A 40-year-old diabetic woman was diagnosed with rhinocerebral mucormycosis. Cerebral mucormycosis is an acute life-threatening disease, which is caused by fungi of the class Phycomycetae. Clinical suspicion and detection of the fungal hyphae in cerebrospinal fluid (CSF) led to early diagnosis, subsequently confirmed by immunohistochemistry and molecular analysis of fungal RNA. Early infiltration of the infectious agent into the central nervous system resulted in septic thrombosis of the cavernous sinus, mycotic meningoencephalitis, brain infarctions as well as intracerebral and subarachnoidal hemorrhages. Despite immediate high-dose antimycotic treatment, surgical debridement of necrotic tissue, and control of diabetes as a predisposing factor, the woman died 2 weeks after admission. Although fungal organisms are rarely detectable in CSF specimens from patients with mycotic infections of the central nervous system, comprehensive CSF examination is beneficial in the diagnosis of rhinocerebral mucormycosis. Furthermore, a concerted team approach, systemic antifungal agents and early surgical intervention seem to be crucial for preventing rapid disease progression. [source] Microbial interactions and differential protein expression in Staphylococcus aureus ,Candida albicans dual-species biofilmsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2010Brian 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] Ericoid mycorrhizal fungi are common root inhabitants of non- Ericaceae plants in a south-eastern Australian sclerophyll forestFEMS MICROBIOLOGY ECOLOGY, Issue 2 2008Susan M. Chambers Abstract Fungi were isolated from the roots of 17 plant species from the families Apiaceae, Cunoniaceae, Cyperaceae, Droseraceae, Fabaceae-Mimosoideae, Lomandraceae, Myrtaceae, Pittosporaceae, Proteaceae and Stylidiaceae at a sclerophyll forest site in New South Wales, Australia. Internal transcribed spacer (ITS) restriction fragment length polymorphism (RFLP) and sequence comparisons indicated that the isolated fungi had affinities to a range of ascomycetes, basidiomycetes and zygomycetes. Four RFLP types had closest affinities to previously identified Helotiales ericoid mycorrhizal (ERM) or Oidiodendron spp. Isolates representing six RFLP types, which were variously isolated from all 17 plant species, formed ERM coils in hair root epidermal cells of Woollsia pungens (Ericaceae) under gnotobiotic conditions. Three of these isolates formed intercellular hyphae, intracellular hyphae and/or microsclerotia, which are typical of dark septate endophyte infection, in roots of Stylidium productum (Stylidiaceae), indicating an ability to form different types of association with roots of different hosts. Overall the data indicate that a broad range of plant taxa may act as repositories for ERM fungi in sclerophyll forest soil. [source] Adhesion and development of the root rot fungus (Heterobasidion annosum) on conifer tissues: effects of spore and host surface constituentsFEMS MICROBIOLOGY ECOLOGY, Issue 2 2000Frederick O Asiegbu Abstract The objective of this study was to correlate the occurrence of particular root and woody stump surface components with the ability of spores of the root rot fungus (Heterobasidion annosum) to adhere, germinate and establish on conifer tissues. With the aid of high performance liquid chromatography, several sugars (pinitol, xylitol, dulcitol, mannitol, D -glucose, mannose, fructose) were detected on both stump and fine root surfaces of Scots pine and Norway spruce. Of all the sugars observed, xylose and arabinose were poorly utilized for initiation of germ tube growth whereas spore germination was enhanced in the presence of D -glucose, mannose or fructose. Oxidation of these sugars by pretreatment of wood discs or roots with periodic acid abolished the ability of the spores to germinate. Non-sugar components such as long chain fatty acids on spores and root surfaces as detected with nuclear magnetic resonance were found to have a significant influence on adhesion and initiation of germ tube development. Removal of these aliphatic compounds from the root surface increased spore germination by 2-fold, whereas similar treatment on spores led to a 5-fold decrease in adhesiveness to root material. In vitro studies revealed that the di-ethyl ether extract from the roots had no long term adverse effect on spore germination which suggests that the fungus may possess the capability to detoxify this substance. Similarly, adhesion of spores was affected by low and freezing temperatures. The role of significant levels of mannitol and trehalose accumulated in spores and hyphae of the fungi on viability, survival and tolerance to adverse conditions such as oxidative stress, freezing and desiccation are discussed. [source] Deprogrammed sporulation in StreptomycesFEMS MICROBIOLOGY LETTERS, Issue 1 2002Yasuo Ohnishi Abstract The bacterial genus Streptomyces forms chains of spores by septation at intervals in aerial hyphae and subsequent maturation on solid medium. Substrate hyphae undergo extensive lysis, liberating nutrients on which aerial hyphae develop. Some mutant strains, however, ectopically form spores by septation in substrate hyphae on solid medium or in vegetative hyphae in liquid medium, which suggests that all hyphae have the potential to differentiate into spores. A Streptomyces griseus mutant strain NP4, which has a mutation in the regulatory system for an ATP-binding cassette (ABC) transporter gene, forms ectopic spores in substrate hyphae only on glucose-containing medium. In addition, overexpression of a substrate-binding protein of the ABC transporter in the wild-type strain causes ectopic septation in very young substrate hyphae and subsequent sporulation in response to glucose. These ectopic spores germinate normally. The ectopic sporulation is independent of A-factor, a microbial hormone that determines the timing of aerial mycelium formation during normal development. Thus, substrate hyphae of Streptomyces have a potential to develop into spores without formation of aerial hyphae. For programmed development, therefore, the strict repression of septum formation in substrate mycelium should be necessary, as well as the positive signal relay leading to aerial mycelium formation followed by septation and sporulation. [source] The evolution of development in Streptomyces analysed by genome comparisonsFEMS MICROBIOLOGY REVIEWS, Issue 5 2006Keith F. Chater Abstract There is considerable information about the genetic control of the processes by which mycelial Streptomyces bacteria form spore-bearing aerial hyphae. The recent acquisition of genome sequences for 16 species of actinobacteria, including two streptomycetes, makes it possible to try to reconstruct the evolution of Streptomyces differentiation by a comparative genomic approach, and to place the results in the context of current views on the evolution of bacteria. Most of the developmental genes evaluated are found only in actinobacteria that form sporulating aerial hyphae, with several being peculiar to streptomycetes. Only four (whiA, whiB, whiD, crgA) are generally present in nondifferentiating actinobacteria, and only two (whiA, whiG) are found in other bacteria, where they are widespread. Thus, the evolution of Streptomyces development has probably involved the stepwise acquisition of laterally transferred DNA, each successive acquisition giving rise either to regulatory changes that affect the conditions under which development is initiated, or to changes in cellular structure or morphology. [source] Identification of salivary components that induce transition of hyphae to yeast in Candida albicansFEMS YEAST RESEARCH, Issue 7 2009Jelani T.D. Leito Abstract Candida albicans, the major human fungal pathogen, undergoes a reversible morphological transition from single yeast cells to pseudohyphae and hyphae filaments. The hyphae form is considered the most invasive form of the fungus. The purpose of this study is to investigate the effect of saliva on hyphae growth of C. albicans. Candida albicans hyphae were inoculated in Roswell Park Memorial Institute medium with whole saliva, parotid saliva or buffer mimicking the saliva ion composition, and cultured for 18 h at 37 °C under aerobic conditions with 5% CO2. Whole saliva and parotid saliva induced transition to yeast growth, whereas the culture with buffer remained in the hyphae form. Parotid saliva was fractionated on a reverse-phase C8 column and each fraction was tested for inducing transition to yeast growth. By immunoblotting, the salivary component in the active fraction was identified as statherin, a phosphoprotein of 43 amino acids that has been implicated in remineralization of the teeth. Synthetically made statherin induced transition of hyphae to yeast. By deletion of five amino acids at the negatively charged N-terminal site (DpSpSEE), yeast-inducing activity and binding to C. albicans were increased. In conclusion, statherin induces transition to yeast of C. albicans hyphae and may thus contribute to the oral defense against candidiasis. [source] Candida albicans ABG1 gene is involved in endocytosisFEMS YEAST RESEARCH, Issue 2 2009Verónica Veses Abstract The human fungal pathogen Candida albicans undergoes reversible morphogenetic transitions between yeast, hyphal and pseudohyphal forms. The fungal vacuole actively participates in differentiation processes and plays a key role supporting hyphal growth. The ABG1 gene of C. albicans encodes an essential protein located in the vacuolar membranes of both yeast and hyphae. Using fluorescence microscopy of a green fluorescent protein-tagged version of Abg1p, a fraction of the protein was detected in hyphal tips, not associated with vacuolar membranes. Live cell imaging of emerging germ tubes showed that Abg1p migrated to the polarized growth site and colocalized with endocytic vesicles. Phenotypic analysis of a methionine-regulated conditional mutant confirmed that Abg1p is involved in endocytosis. [source] Aspergillus oryzae in solid-state and submerged fermentationsFEMS YEAST RESEARCH, Issue 2 2002Progress report on a multi-disciplinary project Abstract We report the progress of a multi-disciplinary research project on solid-state fermentation (SSF) of the filamentous fungus Aspergillus oryzae. The molecular and physiological aspects of the fungus in submerged fermentation (SmF) and SSF are compared and we observe a number of differences correlated with the different growth conditions. First, the aerial hyphae which occur only in SSFs are mainly responsible for oxygen uptake. Second, SSF is characterised by gradients in temperature, water activity and nutrient concentration, and inside the hyphae different polyols are accumulating. Third, pelleted growth in SmF and mycelial growth in SSF show different gene expression and protein secretion patterns. With this approach we aim to expand our knowledge of mechanisms of fungal growth on solid substrates and to exploit the biotechnological applications. [source] Phosphorus uptake, not carbon transfer, explains arbuscular mycorrhizal enhancement of Centaurea maculosa in the presence of native grassland speciesFUNCTIONAL ECOLOGY, Issue 6 2002C. A. Zabinski Summary 1Previous studies have shown that arbuscular mycorrhizas (AM) enhance the growth of the invasive forb Centaurea maculosa when growing with native grass species. Using 13CO2, we tested the hypothesis that this enhancement is explained by carbon transfer from native species to C. maculosa via mycorrhizal hyphal linkages. 2A C. maculosa plant was paired with one of five native species , three grasses (Festuca idahoensis, Koeleria cristata and Pseudoroegneria spicata) and two forbs (Achillea millefolium and Gaillardia aristata) , in pots that separated the plants with either a mesh barrier (28 µm, excludes fine roots but not hyphae) or a membrane barrier (0·45 µm, excludes roots and hyphae). 313CO2 was added to the atmosphere of either Centaurea or the native species after 20 weeks' growth. A 25 min pulse application was followed by 7 days' growth and subsequent harvest. 4The biomass response of C. maculosa was consistent with previous experiments: C. maculosa was larger when growing in mesh barrier pots, when hyphae were able to access the opposite side of the pot; in mesh barrier pots only, biomass varied with neighbouring species. Native plant biomass did not vary between mesh- vs membrane-barrier pots. 5There was no evidence of carbon transfer, either from the native plant to C. maculosa or in the reverse direction. 6Centaurea maculosa contained significantly more phosphorus in mesh-divided pots, but this depended on the neighbouring plant. The P concentration in C. maculosa was significantly higher in mesh-divided pots when growing with a grass and not a forb. Native species contained more P in mesh-divided pots than membrane-divided pots, and P concentration differed between species (higher in forbs than grasses), but did not vary between mesh- and membrane-divided pots. 7Our study suggests that C. maculosa is able to exploit its mycorrhizal symbiosis more effectively than the native grassland species. The mechanism for this appears to be luxury consumption of P through efficient utilization of extra-radical hyphae, but that effect is dependent on neighbouring species, and occurs when growing with a grass neighbour. 8Although no single study can disprove the carbon-transfer hypothesis, our work suggests that AM-mediated neighbour effects are the result of mycorrhizal networks that increase species' access to P. Whether the synergistic effects of neighbours are due to complementarity of AM fungal symbionts utilized by different plant species, or have to do with the structure of AM networks that develop more extensively with multiple host plants, remains to be investigated. [source] Nutrition-Driven Assembly of Colloidal Nanoparticles: Growing Fungi Assemble Gold Nanoparticles as Microwires,ADVANCED MATERIALS, Issue 1 2007A. Sugunan The use of a living fungus to ,actively' assemble presynthesized gold nanoparticles over its hyphae, resulting in conducting microstructures (see figure), is reported. This physiologically (nutrition) driven process of colloidal self-organization avoids the need for sophisticated DNA/protein chemistry for facilitating interfacing with biological surfaces. The obtained gold-laden microstructures can be modified into flat ribbonlike or tubular morphologies by simple post-formation processing. [source] Disseminated cutaneous Fusarium moniliforme infections in a leukemic childINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 5 2007Ching-Chi Chi MD A 5-year-old boy had a 10-month remission of acute lymphocytic leukemia (ALL) after chemotherapy. Re-induction chemotherapy was performed for relapse of ALL. Thereafter, he suffered from an episode of neutropenic fever with pneumonia. One week following control of the condition with antibiotics, a 1 × 1-cm, red, painful nodule appeared on the left thigh, which was initially suspected to be Pseudomonas infection. Parenteral ceftazidime and amikacin were administered, but persistent high fever, mild cough, and a few painful erythematous papulonodules on the face and lower extremities appeared several days later (Fig. 1). These lesions increased insidiously in diameter up to 2,5 cm with central necrosis. Hemogram showed neutropenia with a shift to the left [white blood cell (WBC) count, 2.1 × 109/L; neutrophil count, 0.21 × 109/L]. A skin biopsy showed heavy growth of hyaline branching septate hyphae in the deep dermis and subcutis, together with fat necrosis (Fig. 2). Invasion of molds into vessels and sweat glands was also seen. A culture from a lesion yielded Fusarium moniliforme, but no fungi were isolated from blood specimens. Only mild infiltrations on bilateral lower lung fields were detected by chest roentgenography. The skin lesions gradually healed and the fever subsided 2 weeks after the initiation of therapy with amphotericin B 30 mg and itraconazole 200 mg daily. Figure 1. A few painful erythematous papulonodules appeared on the face and lower extremities Figure 2. Skin biopsy showed heavy growth of hyaline branching septate hyphae in the deep dermis and subcutis along with fat necrosis (hematoxylin and eosin, ×400) Meanwhile, relapse of leukemia was detected by hemogram showing atypical leukocytosis (WBC count of 24,400 × 109/L, with blast cells representing 78%). A course of chemotherapy with cytarabine, mitoxantrone, and VP-16 was prescribed, subsequently resulting in neutropenia (WBC count, < 0.1 × 109/L; neutrophil count, 0/L) and spiking fever. Although the aforementioned antifungal therapy was continued, the centers of the originally healed lesions turned dusky red, swollen, necrotic, and ulcerative. There were more than 10 such ecthymiform lesions. After administration for 22 days, itraconazole was discontinued because of no appreciable effects. Granulocyte colony-stimulating factor (G-CSF) salvage was used, and the neutropenia gradually subsided 20 days later. In addition, the ecthymiform lesions gradually resolved. Amphotericin B was discontinued 1 week following neutrophil recovery. The patient died of Acinetobacter baumannii and Stenotrophomonas maltophilia sepsis 8 months later. [source] Solitary embolic cutaneous aspergillosis in the immunocompromised patient with acute myelogenous leukemia , a propos another case caused by Aspergillus flavusINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 12 2003Aleksandar L. Krunic MD A 68-year-old male with acute myelogenous leukemia was admitted for consolidation chemotherapy. The in-hospital course was complicated by neutropenia, fever and nodular pulmonary opacities suggestive of multifocal pneumonia. The patient subsequently developed a single, solitary necrotic crusted nodule on the right cheek. Skin biopsy demonstrated embolic vascular invasion with septate hyphae, dichotomous branching and minimal inflammation. Tissue culture revealed Aspergillus flavus. Despite systemic antifungal therapy with amphotericin B and granulocyte transfusions, the patient developed respiratory failure and died of disseminated aspergillosis, sepsis and renal failure. The clinical presentation of disseminated infection with Aspergillus flavus as a solitary embolic cutaneous lesion is extremely rare. We have reviewed other cases described in the literature and suggest this pattern of cutaneous involvement as more typical of disseminated infection with Aspergillus flavus. [source] Hereditary palmoplantar keratoderma (four cases in three generations)INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 2 2001Virendra N. Sehgal MD A 39-year-old man reported with progressive thickening of the skin of the hands and feet and an inability to flex his hand. It was largely asymptomatic; however, brisk walking caused excessive sweating, pain, and widening of the fissures on the soles of the feet. He was unable to walk barefooted. According to his mother, the first episode presented with blistering at 7 days of age. Ever since, the condition has steadily worsened to acquire the current status. He was married at the age of 18 years, and had a stillborn child 18 months afterwards. Presently, he has three children, two girls aged 14 and 12 years and a son aged 10 years. Both the daughters are similarly affected. While cataloguing the details of the pattern of inheritance, the mother of the index case was also found to be affected (Fig. 1). The natural history of the disease was identical. Figure 1. Palmoplantar keratoderma: pattern of inheritance; black indicates affected individuals Examination of the palms was marked by pronounced thickening of the skin resulting in the masking of palmar creases. The thickening was well demarcated and its margins were prominent and surrounded by an erythematous halo. The color of the skin was yellow and waxy (Fig. 2a). Contractures were present on all the fingers; nevertheless, the deformity of the middle and distal interphalangeal joints of the little finger was prominent. The soles of the feet had a similar morphology. In addition, marked fissuring was obvious (Fig. 2b). His daughters had an identical affliction of the palms and soles. The texture and morphology of the nails were normal. Light microscopy performed on scrapings from the fissures, mounted on 10% potassium hydroxide, revealed mycelia (hyphae) and spores. Figure 2. Well-demarcated hyperkeratosis depicting the yellow, waxy color of the palms, with masking of creases (a). Marked fissuring on the soles was prominent (b) Hematoxylin and eosin-stained microsections from the palms and soles showed exquisite changes in the epidermis characterized by considerable uniform orthohyperkeratosis. Hypergranulosis and acanthosis were other associated changes. In addition, perinuclear vacuolization and keratohyalin granules of varying sizes and shapes were located at the periphery of the cells. A sparse mononuclear infiltrate was located at the dermo-epidermal junction. Hyphae and spores of fungi were also identified in the stratum corneum (Fig. 3). Figure 3. Orthohyperkeratosis, hypergranulosis, and acanthosis. Perinuclear vacuolization and keratohyalin granules at the periphery of the cells; a sparse mononuclear infiltrate was also present (hematoxylin and eosin, ×,40 (a), ×,400 (b)) Itraconazole, 400 mg/day in two equally divided doses, was administered with major meals for 7 days. In addition, high doses of vitamin A (100,000 IU) were given daily for 2 weeks, supplemented by 12% salicylic acid (Salicylix SF12) ointment for daytime application and an ointment containing 6% coal tar and 3% salicylic acid (Salytar) for night-time application. This treatment is useful in recalcitrant cases. [source] Mucous membrane pemphigoid, thymoma, and myasthenia gravisINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 9 2000Haideh Yazdani Sabet In November 1997, approximately 1 year before being evaluated at the Mayo Clinic, Rochester, a 63-year-old woman presented with erosive tongue lesions that were diagnosed by her physician as oral lichen planus. The lesions responded well to 3 months of treatment with systemic and topical corticosteroids and topical antiyeast medication. She stopped taking the medications and had a relapse. A few months after the oral lesions developed, her left eyelid became ptotic. Results of magnetic resonance imaging of her brain were normal, and the ptosis resolved spontaneously after 2 weeks. One year later, her right eyelid began to droop, and the results of edrophonium testing were positive. She was prescribed prednisone, 30 mg daily, and pyridostigmine, as needed. The ptosis improved, but never fully resolved. Radiography revealed a left ,,thyroid nodule,'' but computed tomography did not show a mediastinal mass. She was advised to have the ,,nodule'' removed surgically and came to the Mayo Clinic, Rochester, for a second opinion. Her medical history was significant for the following: tinnitus, glaucoma, early bilateral cataracts, and long-standing hypertension, for which she took losartan, 50 mg twice daily. Other medications included: prednisone, 30 mg daily; pyridostigmine as needed; famotidine, 40 mg daily; and eyedrops for glaucoma. She denied any history of hyperthyroidism or hypothyroidism, head and neck irradiation, family history of thyroid disease, or diplopia. Hepatitis serologic studies revealed hepatitis B exposure and recovery, hepatitis C immunity, and a previous hepatitis A viral infection. On examination at the Mayo Clinic, Rochester, an erosive hypertrophic plaque was noted on the posterior dorsal half of the tongue, and vesicles and erythematous erosions on the hard and soft palates ( Fig. 1a). A lace-like white pattern was seen on the buccal mucosa bilaterally, and a small erosive patch on the left buccal mucosa ( Fig. 1b). Ocular and nasal mucous membranes were normal in appearance, and there were no pertinent skin findings. Dermatopathologic examination of an excisional biopsy specimen from the left dorsum of the tongue demonstrated an ulcer with epitheliomatous hyperplasia and a granulomatous reaction, presumably due to yeast infection. Silver staining showed hyphae and yeast at the base of the tongue ulcer. The results of the direct immunofluorescence study were negative and revealed no lichenoid changes on hematoxylin and eosin staining. Indirect immunofluorescence testing of the serum revealed a 1 : 80 titer of basement membrane zone antibodies, reflecting pemphigoid. This test was positive on repeat study. Salt-split skin on monkey esophagus revealed an epidermal pattern of basement membrane zone antibodies. Treatment included fluocinonide gel applied to the involved areas four times daily and oral antiyeast therapy (fluconazole, 200 mg once daily by mouth) while the rest of the evaluation was being completed. Figure 1(a). Erosive hypertrophic tongue plaque. Figure (b) ,. Erosive patch on the buccal mucosa. As part of the evaluation of the ptosis, a myasthenia gravis antibody panel was performed. It revealed the following abnormalities: striated muscle antibody at 1 : 480 (reference range, <1 : 60), acetylcholine receptor binding antibody at 6.33 nmol/L (reference range, ,,0.02 nmol/L), acetylcholine receptor blocking antibody at 31% (reference range, 0,25%), and acetylcholine receptor modulating antibody at 100% (reference range, 0,20%), suggesting thymoma. Treatment included pyridostigmine, 30,45 mg 3,4 times daily, to control the myasthenia symptoms, while the ill-defined neck mass was being evaluated. A mildly enlarged thyroid was noted on physical examination. Hematology panel revealed thyroid-stimulating hormone (TSH) levels in the low normal range; the thyroid microsomal antibody was normal. Chest radiography showed minor tracheal deviation, and a previous computed tomogram showed what appeared to be a 3-cm enlarged mass in the thyroid. Ultrasonographically guided thyroid biopsy did not show malignancy, but a benign mesenchymal-type tumor was found and surgical excision was planned. Intraoperatively, a thymoma of the left cervical thymic tongue was found. At 6 months' follow-up, the ptosis and oral mucosal lesions had improved significantly, although she continued topical corticosteroid therapy intermittently for minor erosive oral disease. [source] Majocchi's granuloma trichophyticum in an immunocompromised patientINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 2 2000Somesh Gupta MD A 40-year-old man with alcoholic liver disease was referred to the dermatology clinic for asymptomatic papulonodular lesions over the face of 15 days' duration. Cutaneous examination revealed multiple, dusky red to yellow, follicular as well as perifollicular papulonodular lesions, varying in size from 0.5 to 2 cm ( Fig. 1). They were distributed over the forehead, cheeks, eyelids, nose, chin, beard area, retroauricular area, and neck. Careful examination revealed well-defined scaly margins on the back of the pinna ( Fig. 2). KOH examination of a scraping from the neck revealed nonpigmented septate hyphae. Histopathologic examination of the excised nodule revealed epitheloid cell granulomas with neutrophilic microabscesses surrounding the hair follicles. Periodic acid,Schiff stain was noncontributory. Culture of an excised nodule on Sabouraud's agar showed growth of Trichophyton rubrum. Considering his liver disease, the patient was initially treated with topical terbinafine. Because of a lack of a satisfactory response this was changed to oral terbinafine 250 mg/day. There was marked regression of the lesions by the sixth day. Unfortunately, the patient succumbed to complications relating to his liver disease. Figure 1. Follicular and perifollicular lesions of Majocchi's granuloma Figure 2. A well-defined scaly margin of tinea on the back of the pina [source] Effect of physical, chemical and environmental characteristics on arbuscular mycorrhizal fungi in Brachiaria decumbens (Stapf) pasturesJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2008R.H. Posada Abstract Aim:, To evaluate the effects of soil physical and chemical factors (pH, conductivity, humidity, available phosphorus and organic matter) and environmental factors (temperature, relative air humidity, altitude and atmospheric pressure) on arbuscular mycorrhizal fungi (AMF),Brachiaria decumbens grass relationship. Furthermore to establish patterns of microbiological responses that allow to differentiate the study sites in two relief types. Methods and Results:, Mycorrhizal characteristics (spore density, external hyphae and root colonizations by hyphae, vesicles and arbuscules), physical and chemical factors in soil and environmental factors were measured. Conclusions:, The effect of physical, chemical and environmental factors on microbiological variables was related to the type of relief ,valley and hilly terrain'; the AMF behaviour was affected only over narrower ranges of evaluated variables. Similarly, the colonization of B. decumbens roots by AMF hyphae, vesicles and the mycorrhizal spore density follow different patterns according to the relief type. Significance and Impact of the Study:, The type of relief is one of the factors to be taken into consideration to evaluate the AMF inoculum and root colonization of these pastures, because of the influence of slope , as physical property of soil , on AMF. [source] Characterization of the Mucor circinelloides life cycle by on-line image analysisJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003T.L. Lübbehüsen Abstract Aims: The life cycle of the dimorphic fungus Mucor circinelloides was studied in a temperature-controlled flow-through cell, which constitutes an ideal tool when following the development of individual cells, with a view to understanding the growth and differentiation processes occurring in and between the different morphological forms of the organism. Methods and Results: Mycelial growth and the transformation of hyphae into chains of arthrospores were characterized by image analysis techniques and described quantitatively. The influence of the nature (glucose and xylose) and concentration of the carbon source on specific growth rate and hyphal growth unit length were studied. The organism branched more profusely on xylose than on glucose while the specific growth rates determined were rather similar. Methods were developed to study the yeast-like growth phase of M. circinelloides in the flow-through cell, and combined with fluorescent microscopy which allowed new insights to bud formation. Additionally, numbers and distribution of nuclei in arthrospores, hyphae and yeasts were studied. Conclusions: The results give essential information on the morphological development of the organism. Significance and Impact of Study: Development of any industrial process utilizing this organism will be dependent on the information obtained here for effective process optimization. [source]
| | |||||||||||||||||||||||||||||||||||||||