Budding Forms Research Articles

Morphological specificity of yeast and filamentous Candida albicans forms on surface properties

Physicochemical surface properties of Candida albicans were assessed from microbial adhesion to human epithelial cells and to octane droplets. The adherence of cells demonstrated the occurrence of morphological specificity for these adhesion assays. Filamentous forms exhibited adherence third times higher compared to budding forms, while their electrophoretic mobilities were comparable. Force measurements performed on filamentous form by AFM demonstrated that such adhesion was associated with microfibrillar surface structure. To cite this article: A. Kriznik et al., C. R. Biologies 328 (2005).

Separation of the filamentous and cellular yeast forms of C. albicans following serum induction

Following serum induction of filamentous structures in Candida albicans, the budding and filamentous forms of the organism are separated and the total protein in each form is determined. The method is useful for testing potential chemotherapeutics aimed at interference with the formation of the pathogenic, filamentous form of C. albicans.

The effects of carnitine on distally-burned dorsal skin flap: an experimental study in rats

Objective: In ischemia and burn injuries, there are major alterations threatening tissue survival. Increased energy flow requirements are among the major problems in these disorders. Carnitine is an endogenous cofactor, which has a regulatory action on the energy flow from different oxidative sources. The purpose of this study was to determine the effects of carnitine in an experimental flap model. Biochemically, nitric oxide (NO), malondialdehyde (MDA), and acetylcholinesterase levels, and histopathologically tissue examination under light microscope were studied. Methods: In the rat dorsal skin, a 10 cm×3 cm flap was marked. The most distal 3 cm×3 cm of the flap was burned to full-thickness. The dorsal flap was elevated, and sutured back to its original site. Sixteen rats were divided into two groups (a control (1) and a study group (2)), consisting of eight rats in each. While the animals in the control group were just followed, the animals in the study group were administrated carnitine with a dose of 100 mg/kg per day for 7 days. Results: At the end of the experiment: the mean surviving areas of the flaps were 15.22 cm 2 (50.73%) in group 1, 20.53 cm 2 (68.43%) in group 2, and the difference was statistically significant ( P=0.008). In the analysis of blood samples; the mean levels of NO were 22.63 and 40.78 μmol/l; of MDA were 6.74 and 3.79 ng/ml; and of acetylcholinesterase were 136.14 and 222.85 U/l in groups 1 and 2, respectively. The differences in the levels of NO ( P=0.001), MDA (0.027) and acetylcholinesterase ( P=0.006) were statistically significant. Histopathological examination revealed a full-thickness muscle necrosis in addition to skin tissue in the control group, while healing tissue was present with marked cellularity including mixed inflammatory cells and fibroblast proliferation with an increased vascularity in the form of capillary budding in the study group. Conclusion: Carnitine has a positive effect in such a model, particularly in preventing the progressive effect of burn, and limiting the necrosis in the full-thickness burned part.

The role of chlamydospores of Paracoccidioides brasiliensis.

The role of chlamydospores in the conversion process from a mycelial-to-yeast form using the slide culture method was studied. Three clinical isolates and two other isolates from armadillo, belonging to the fungal species Paracoccidioides brasiliensis, were cultured on Sabouraud dextrose agar (SDA), potato dextrose agar (PDA) and brain heart infusion dextrose agar (BHIDA). Initially, the mycelial forms of each isolate were grown at 25 degrees C for 7, 14, 30 or 60 days on slide cultures and then the temperature was shifted to 35 degrees C. Interestingly, the slide cultures of all the isolates at 25 degrees C formed chlamydospores on either SDA or BHIDA, whereas, on PDA medium, aleurioconidia were formed. If the slide cultures on BHIDA were incubated at 35 degrees C for 7 to 14 days, multiple budding forms could be observed. This phenomenon was not evident in the slide cultures of SDA or PDA. The results of this morphological study indicate that in P. brasiliensis, chlamydospores may play an important role in the conversion process from a mycelial-to-yeast form.

Sequential fractionation and two-dimensional gel analysis unravels the complexity of the dimorphic fungus Candida albicans cell wall proteome.

The cell wall proteins of Candida albicans play a key role in morphogenesis and pathogenesis and might be potential target sites for new specific antifungal drugs. However, these proteins are difficult to analyze because of their high heterogeneity, interconnections with wall polysaccharides (mannan, glucan, and chitin), low abundance, low solubility, and hydrophobic nature. Here we report a subproteomic approach for the study of the cell wall proteins (CWPs) from C. albicans yeast and hyphal forms. Most of the mannoproteins present in this compartment were extracted by cell wall fractionation according to the type of interactions that they establish with other structural components. CWPs were solubilized from isolated cell walls by hot SDS and dithiothreitol treatment followed by extraction either by mild alkali conditions or by enzymatic treatment with glucanases and chitinases. These highly enriched cell wall fractions were analyzed by two-dimensional PAGE, showing that a large number of proteins are involved in cell wall construction and that the wall remodeling that occurs during germ tube formation is related to changes in the composition of CWPs. We suggest that the CWP-chitin linkage is an important retention mechanism of CWPs in C. albicans mycelial forms. This article also highlights the usefulness of the combination of sequential fractionation and two-dimensional PAGE followed by Western blotting using specific antibodies against known CWPs in the characterization of incorporation mechanisms of such CWPs into the cell wall and of their interactions with other wall components. Mass spectrometry analyses have allowed the identification of several cell surface proteins classically associated with both the cell wall and other compartments. The physiological significance of the dual location of these moonlighting proteins is also discussed. This approach is therefore a powerful tool for obtaining a comprehensive and integrated view of the cell wall proteome.

Isolation and preliminary characterization of a large Babesia sp. from sheep and goats in the eastern part of Gansu Province, China.

Two species of Babesia were isolated from naturally infected sheep in the eastern part of Gansu province. One of the species was identified as B. ovis, while the another one seems as yet to be an unidentified Babesia species. The latter could be transmitted transovarially by Haemaphysalis longicornis. It was shown that larvae and nymphs transmit the organism to sheep and goats with a prepatent period of 5-28 days. As the carrier period of B. ovis is longer than that of the larger species and the prepatent period of the larger Babesia is shorter than that of B. ovis, it was possible to isolate the unidentified larger species. The larger Babesia is polymorphic, including double pyriform, single pyriform, ring-form, rod-like, three-leafed and budding forms. The size of typical paired pyriforms was 1.8-2.5 microm x 0.9-1.8 microm, with mean dimensions of 2.21 +/- 0.12 microm x 1.17 +/- 0.18 microm. The parasite causes a severe course of infection associated with a parasitaemia as high as 23.7% and with a high mortality rate in both sheep and goats, being very marked in lambs and imported small ruminants.

Switching fungi

The human pathogenic fungus Candida albicans can undergo transitions between budding and filamentous forms, as well as another morphogenetic process termed phenotypic switching. Phenotypic switching occurs spontaneously in the absence of environmental signals and can give rise to several different colony morphologies. The molecular mechanism of phenotypic switching in C. albicans is not well understood. The role of genomic rearrangements has been the primary focus of molecular switching models. Recently, however, epigenetic mechanisms have been considered, based on observations of heritable genetic changes in Saccharomyces cerevisiae. Many of these epigenetic changes are controlled by the SIR2 (silent information regulator) gene. It now appears that epigenetic mechanisms might play a role in regulating morphogenesis in C. albicans1 Perez-Martin J. et al. Phenotypic switching in Candida albicans is controlled by a SIR2 gene. EMBO J. 1999; 18: 2580-2592 Crossref PubMed Scopus (112) Google Scholar .

Brefeldin A and monensin arrest cell surface expression of membrane glycoproteins and release of rubella virus.

The maturation of rubella virus (RV) glycoproteins E2 and E1 was examined by using brefeldin A (BFA) and monensin. BFA, which induces the rapid redistribution of Golgi enzymes residing in the Golgi complex into the endoplasmic reticulum (ER), was used to locate the intracellular site for the modification of carbohydrate side-chains on RV E1 and E2 proteins. The monovalent ionophore monensin, which inhibits intracellular transport of proteins through the ER-Golgi complex, was used to block the transport of E1 and E2 glycoproteins through the Golgi complex. BFA and monensin effectively blocked the cell surface expression of RV E2 and E1 proteins, secretion of an anchor-free form of E2 and budding of RV from the plasma membrane. For O-linked glycosylation, addition of N-acetylgalactosamine and galactose to E2 protein was found to take place in the medial to the trans Golgi. A dramatic change in the intracellular distribution of RV structural proteins was observed when transfected COS cells were treated with BFA or monensin, although the proteolytic processing of RV structural protein precursor was not affected. In the presence of BFA or monensin, virus release from infected Vero cells was only 0.1% of the intracellular virus, and the intracellular virus titre decreased as well. Our results suggest that O-linked glycosylation on the E2 protein occurred in the post-ER region and the transport of RV structural proteins to the Golgi complex and post-Golgi compartment may be a rate-limiting step in RV assembly and budding.

Multiple Modes of Asexual Reproduction by Tropical and Subtropical Sea Star Larvae: an Unusual Adaptation for Genet Dispersal and Survival.

Sea star larvae (Echinodermata: Asteroidea), collected from the subtropical Northwest Atlantic Ocean, exhibited three distinct modes of asexual reproduction. A number of different bipinnariae and brachiolariae reproduced by paratomous cloning of the posterolateral arms. This morphogenesis was identical to that of larvae assignable to the genus Luidia. A second mode of asexual reproduction involves the autotomization of an anterior portion of the preoral lobe. Primary larvae with preoral lobes of varying sizes and free-swimming preoral lobes of various stages of morphological development were simultaneously collected. The free-swimming preoral lobes developed complete digestive systems and ultimately assumed the form of typical bipinnaria larvae. Asexual reproduction by larvae may also take the form of budding. The released individual is either a blastula- or gastrulastage embryo. Subsequent development to a bipinnariastage secondary larva, with the possible exception of coelom formation, appears to occur through the events associated with normal larval development. These diverse methods of asexual propagation provide a common mechanism to increase the length of larval life and amplify the number of individuals. Thus asexual reproduction by larvae should increase the likelihood of genet representation in the next generation.

The relationship between the glucose uptake system and growth cessation in Candida albicans.

It is thought that dimorphic Candida albicans undergoes changes in its intracellular metabolic state prior to yeast-mycelial transformation. Cells grown in budding form to mid-exponential phase could not be induced to form germ tubes when grown in glucose medium. However, cells in which growth was initially inhibited by either starvation or inhibitors (0.1% hydroxyurea, 4% sodium malonate or 4% 2-deoxy-D-glucose) could be induced to form germ tubes in the same medium. The effects of these initial treatments on the intracellular state in mid-exponential phase cells were analysed by measuring the kinetics of D-glucose uptake. D-glucose uptake in mid-exponential phase and stationary phase cells was measured. The untreated mid-exponential phase cells exhibited only a high Km (6.9 mM). However, mid-exponential phase cells, in which growth was initially inhibited, exhibited both a high Km (3.2-6.2 mM) and a low Km (0.40-0.78 mM) simultaneously. In addition, the stationary phase cells exhibited both a high Km (5.6 mM) and a low Km (0.56 mM). These results suggest that there are two kinetically distinct systems of glucose transport in C. albicans and that changes in the glucose uptake system in C. albicans may be related to intracellular changes prior to transition from the budding to the mycelial form.

Regulation of phase-specific genes in the more general switching system ofCandida albicansstrain 3153A

It was previously demonstrated that the genes PEP1 and Op4 are selectively transcribed in the opaque phase of the white-opaque transition in Candida albicans strain WO-1, and that the gene Wh11 is selectively transcribed in the white phase. However, the white-opaque transition occurs in only a minority of C. albicans strains and the opaque cell phenotype is highly specialized. To test whether these genes are regulated in more mainstream switching systems in C. albicans, their expression was analysed in the switching system of the laboratory strain 3153A. Both PEP1 and Op4 are not expressed in the basic smooth phenotype of 3153A, but they are expressed in switch phenotypes. However, expression is dissociated. Op4 is expressed in irregular wrinkle, star and revertant-smooth cells, while PEP1 is expressed only in star cells. Wh11 is expressed in the basic smooth and three tested variant phenotypes and is again associated with growth in a round budding form. The results support the general conclusion that PEP1 and Op4 are under the strict regulation of switching in C. albicans.

Variants selected by treatment of human immunodeficiency virus-infected cells with an immunotoxin.

An immunotoxin has been made by coupling anti-human immunodeficiency virus (HIV) envelope antibody 907 to ricin A chain (907-RAC). 907 recognizes an epitope within the immunodominant PB-1 loop of gp120. Variant cells were selected by cloning persistently infected H9/human T lymphocyte virus IIIB cells in the presence of the immunotoxin. Clones resistant to 907-RAC arose at a frequency of 0.1-1.0%. Seven clones were selected for intensive analysis. When studied, these clones fell into two distinct groups, members of which appeared to be identical, suggesting that the variation arose before the selection process. In contrast to the parent cells, none of the cloned variants produced infectious HIV. The first set of clones, designated the "E" variants, expressed decreased levels of the HIV envelope on the cell surface. However, levels of intracellular HIV antigens and reverse transcriptase were equal to or greater than that of the parental cell line. Radioimmunoprecipitation demonstrated that the gp160 was truncated to 145 kD (gp120 was normal length), capable of binding to CD4, and, unlike normal gp160, was released in its unprocessed form into the cellular supernatant. Sequence analysis demonstrated that a deletion at codon 687 of the envelope gene resulted in the production of this truncated protein. Ultrastructural analysis of E variants demonstrated some budding forms of virus, but also large numbers of HIV within intracellular vesicles. The second set of variants, the "F" series, produced no HIV antigens, reverse transcriptase, nor was there ultrastructural evidence of virus. However, proviral DNA was present. Virus could not be induced with agents known to activate latent HIV. These cells also lacked cell surface CD4 and could not be infected with HIV. These studies demonstrate that variation in HIV can affect the phenotype of the cells carrying the altered virus, allowing for escape from immunologic destruction. The E variants may serve as prototypes for attenuated HIV, which could be used as a vaccine. We have reconstructed the mutation found in the E variants within the infectious HIV clone HXB-2 and demonstrated that the resulting virus retains its noninfectious phenotype.

An Electrophoretic Karyotype Comparison of the Yeast Genera Dipodascopsis Batra et Millner, Lipomyces Lodder et Kreger-van Rij, Myxozyma van der Walt et von Arx

The chromosomal DNA banding patterns of twenty-nine strains representing the family Lipomycetaceae and the associated anamorph genus Myxozyma, were determined by orthogonal-field-alternation gel electrophoresis (OFAGE). In order to evaluate this genomic character, the results obtained were compared with carbon source utilization and coenzyme Q systems. Species within a genus produced the same number of chromosomal bands but not necessarily the same chromosome sizes, except for members of the anamorph genus Myxozyma, which produced different numbers of DNA bands. On the basis of the chromosomal DNA band number, it was possible to distinguish between the genera Dipodascopsis (one DNA band), Lipomyces and Waltomyces (two DNA bands), Zygozyma (three DNA bands) and Myxozyma (five DNA bands and more). It was however impossible to differentiate between the representative species of Dipodascopsis, Lipomyces or Myxozyma, on this basis. We found that the more complex hyphal species (characterized by the utilization of a large amount of carbon sources and the presence of a CoQ9 system) produced only one heavy DNA band, while the less complex budding forms (characterized by the utilization of a small amount of carbon sources and the presence of a CoQ8 system) produced five or more smaller chromosomal bands. No teleomorph/anamorph relations between the genus Myxozyma and the genera Dipodascopsis, Lipomyces and Waltomyces were found on the basis of OFAGE, CoQ system or physiological characteristics.

Identification of a black yeast isolated from oak bark as belonging to the genus Phaeococcomyces sp. Analysis of melanin produced by the yeast

A black fungus isolated from oak bark was identified as a member of the yeast-like genus Phaeococcomyces. While no sexual reproduction was observed, the isolate showed characteristics associated with basidiomycetous yeasts: it was non-fermentative, produced extracellular urease, was positive with the diazonium blue B colony colour test, and had an enteroblastic form of budding. The isolate produced a black pigment constitutively which was shown to be a melanin. Production of the pigment was inhibited by the incorporation of low levels of the fungicide tricyclazole in growth media, inidicating that it was a pentaketide melanin. Pigmentation mutants were produced. Albino mutants did not produce melanin. Diffusion mutants accumulated the pentaketide melanin pathway oxidation products flaviolin and 2-hydroxyjuglone in culture media. Cross-feeder mutants accumulated scytalone, a pentaketide melanin pathway intermediate, in culture media, and caused albino mutants to melanize when grown in proximity to them on agar plates. A single mutant was isolated which excreted 1,8-dihydroxy naphthalene, the end product of the pathway. Broth cultures of Phaeococcomyces sp. in stationary growth phase released melanin in the form of granules, with an average diameter of 30 nm.Key words: black yeast, melanin production, Phaeococcomyces sp.

Morphologic study of Staphylococcus aureus L-form, reverting, and intermediate colonies in situ.

Staphylococcus aureus strains of bovine origin were induced to L-form by exposure to 100 U of penicillin in brain heart infusion broth supplemented with 5% NaCl, 5% sucrose, and 10% horse serum. L-forms were cultured on similarly supplemented brain heart infusion agar containing no antibiotic. Light and electron microscopic examination of plastic-embedded L-form colonies revealed a variety of morphologic types. The primary site of growth appeared to be the core area below the agar surface, consisting mainly of pleomorphic budding forms. At the surface, these forms gave rise to large spherules with a gradation from smaller to larger spherules toward the periphery of the colony. Some colonies progressed to reverting forms with the growth of bacterial cells containing cell wall. In addition to L-forms, intermediate colony forms were observed that lacked typical L-form morphology and progressed rapidly to the parent cell form on subculture to bovine blood agar. Description of these forms will be used in the search for similar morphologic types in vivo during antibiotic treatment of chronic S. aureus bovine mastitis.

Ultrastructural study of budding and mycelial forms of Candida albicans

Biology of the CellVolume 63, Issue S1 p. 21-21a Ultrastructural study of budding and mycelial forms of Candida albicans Helene Bobichon, Helene Bobichon Laboratoire de Biologie Vegetale et de Cryptogamie, 51 rue Cognacq-Jay, 51100 Reims (France).Search for more papers by this authorPhilippe Bouchet, Philippe Bouchet Laboratoire de Biologie Vegetale et de Cryptogamie, 51 rue Cognacq-Jay, 51100 Reims (France).Search for more papers by this author Helene Bobichon, Helene Bobichon Laboratoire de Biologie Vegetale et de Cryptogamie, 51 rue Cognacq-Jay, 51100 Reims (France).Search for more papers by this authorPhilippe Bouchet, Philippe Bouchet Laboratoire de Biologie Vegetale et de Cryptogamie, 51 rue Cognacq-Jay, 51100 Reims (France).Search for more papers by this author First published: 1988 https://doi.org/10.1016/0248-4900(88)90187-6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume63, IssueS11988Pages 21-21a RelatedInformation

Variability in beech : budding, height growth and tree form

Trois caracteres du hetre : la tardivete du debourrement vegetatif, la vigueur exprimee par la croissance en hauteur et la fourchaison des plants ont ete etudies pour 7 provenances forestieres en France. On a pris comme facteurs la variabilite genetique et l'âge de la plante

Three-dimensional reconstruction of a peroxisomal reticulum in regenerating rat liver: evidence of interconnections between heterogeneous segments.

The three-dimensional (3-D) form and the interrelationship of peroxisomes (Po) in the model of regenerating rat liver after partial hepatectomy were studied by computer-assisted 3-D reconstruction of serial ultrathin sections. Po were labeled cytochemically for either catalase, which stains them all uniformly, or for D-amino acid oxidase (DAA-OX), which gives a heterogeneous reaction with lightly and darkly stained PO. In regenerating rat liver, Po exhibit marked pleomorphism with some budding forms and dumbbell-shaped ones. The 3-D reconstruction revealed many single spherical Po measuring 0.15-0.8 micron in diameter. In addition, two to five Po were found interconnected with each other via narrow 30-50-nm hourglass-shaped bridges forming a reticulum. Such aggregates of Po measured 1.5-2.5 microns across. Whereas all segments of this reticulum stained homogeneously for catalase, they exhibited a marked difference in the intensity of the DAA-OX reaction. These observations are consistent with the view of peroxisomal proliferation by budding or fragmentation from preexisting ones. Under such conditions of rapid growth as in regenerating liver, Po may be interconnected forming a reticulum. The interconnections between Po with differing DAA-OX activities suggest that they originate from the same parent organelle.

Ultrastructure and Immunoelectron Microscopy of Human T-cell Leukaemia Virus Type I-producing Lymphoid and Non-lymphoid Human Tumour Cells

The ultrastructure and distribution of some viral and cellular antigens was examined in lymphoid C91/PL and fibroblastic HOS/PL cells infected with human T-cell leukaemia virus type I. Tubuloreticular structures in the endoplasmic reticulum, characteristic of virus-infected or interferon-treated cells, were found in both cell types. Virions were observed particularly in the HOS/PL cells in budding and mature forms and in coated pits, coated vesicles and lysosomes, indicative of receptor-mediated endocytosis. Using immunogold indirect labelling, viral antigens, recognized by sera of infected patients and by monoclonal antibody, were detected in patches on the cell surface and in material loosely attached to the envelope of some virions. Beta 2-microglobulin was associated with virion envelopes from C91/PL and HOS/PL cells, but major histocompatibility complex class 1 (HLA) antigens were not associated with virions even when produced by HLA-positive HOS/PL cells.

Morphogenesis of Berne virus (proposed family Toroviridae).

In equine dermis cells infected with Berne virus particles were first detected 10 h after infection. Virions were encountered in all parts of the Golgi system and, infrequently, in the rough endoplasmic reticulum. A unique form of budding of preassembled rigid tubular nucleocapsids was demonstrated. Masses of tubular nucleocapsids of a lesser diameter and electron density were prominent in the cytoplasm and the nucleus of infected cells. Within the Golgi system and cytoplasmic cisternae virions appeared as straight or slightly curved rods. Extremely long, aberrant virions (250 nm) were occasionally seen. The proper torovirion morphology was observed in extracellular particles and in vacuoles near the cell surface.