Primary fluorescence (Autofluorescence) of fruiting bodies of the wood-rotting fungusFomes fomentarius

Effect of metal ions on autofluorescence of the dry rot fungus Serpula lacrymans grown on spruce wood

This work describes autofluorescence of the mycelium of the dry rot fungus Serpula lacrymans grown on spruce wood blocks impregnated with various metals. Live mycelium, as opposed to dead mycelium, exhibited yellow autofluorescence upon blue excitation, blue fluorescence with ultraviolet (UV) excitation, orange-red and light-blue fluorescence with violet excitation, and red fluorescence with green excitation. Distinctive autofluorescence was observed in the fungal cell wall and in granula localized in the cytoplasm. In dead mycelium, the intensity of autofluorescence decreased and the signal was diffused throughout the cytoplasm. Metal treatment affected both the color and intensity of autofluorescence and also the morphology of the mycelium. The strongest yellow signal was observed with blue excitation in Cd-treated samples, in conjunction with increased branching and the formation of mycelial loops and protrusions. For the first time, we describe pink autofluorescence that was observed in Mn-, Zn-, and Cu-treated samples with UV, violet or. blue excitation. The lowest signals were obtained in Cu- and Fe-treated samples. Chitin, an important part of the fungal cell wall exhibited intensive primary fluorescence with UV, violet, blue, and green excitation.

pFPL Vectors for High-Throughput Protein Localization in Fungi: Detecting Cytoplasmic Accumulation of Putative Effector Proteins

As part of a large-scale project whose goal was to identify candidate effector proteins in Magnaporthe oryzae, we developed a suite of vectors that facilitate high-throughput protein localization experiments in fungi. These vectors utilize Gateway recombinational cloning to place a gene's promoter and coding sequences upstream and in frame with enhanced cyan fluorescent protein, green fluorescent protein (GFP), monomeric red fluorescence protein (mRFP), and yellow fluorescent protein or a nucleus-targeted mCHERRY variant. The respective Gateway cassettes were incorporated into Agrobacterium-based plasmids to allow efficient fungal transformation using hygromycin or geneticin resistance selection. mRFP proved to be more sensitive than the GFP spectral variants for monitoring proteins secreted in planta; and extensive testing showed that Gateway-derived fusion proteins produced localization patterns identical to their "directly fused" counterparts. Use of plasmid for fungal protein localization (pFPL) vectors with two different selectable markers provided a convenient way to label fungal cells with different fluorescent proteins. We demonstrate the utility of the pFPL vectors for identifying candidate effector proteins and we highlight a number of important factors that must be taken into consideration when screening for proteins that are translocated across the host plasma membrane.

Extracellular enzymes of the white-rot fungus Fomes fomentarius and purification of 1,4-β-glucosidase

Production of the lignocellulose-degrading enzymes endo-1,4-β-glucanase, 1,4-β-glucosidase, cellobiohydrolase, endo-1,4-β-xylanase, 1,4-β-xylosidase, Mn peroxidase, and laccase was characterized in a common wood-rotting fungus Fomes fomentarius, a species able to efficiently decompose dead wood, and compared to the production in eight other fungal species. The main aim of this study was to characterize the 1,4-β-glucosidase produced by F. fomentarius that was produced in high quantities in liquid stationary culture (25.9 U ml(-1)), at least threefold compared to other saprotrophic basidiomycetes, such as Rhodocollybia butyracea, Hypholoma fasciculare, Irpex lacteus, Fomitopsis pinicola, Pleurotus ostreatus, Piptoporus betulinus, and Gymnopus sp. (between 0.7 and 7.9 U ml(-1)). The 1,4-β-glucosidase enzyme was purified to electrophoretic homogeneity by both anion-exchange and size-exclusion chromatography. A single 1,4-β-glucosidase was found to have an apparent molecular mass of 58 kDa and a pI of 6.7. The enzyme exhibited high thermotolerance with an optimum temperature of 60 °C. Maximal activity was found in the pH range of 4.5-5.0, and K (M) and V (max) values were 62 μM and 15.8 μmol min(-1) l(-1), respectively, when p-nitrophenylglucoside was used as a substrate. The enzyme was competitively inhibited by glucose with a K (i) of 3.37 mM. The enzyme also acted on p-nitrophenylxyloside, p-nitrophenylcellobioside, p-nitrophenylgalactoside, and p-nitrophenylmannoside with optimal pH values of 6.0, 3.5, 5.0, and 4.0-6.0, respectively. The combination of relatively low molecular mass and low K (M) value make the 1,4-β-glucosidase a promising enzyme for biotechnological applications.

Vital Autofluorescence: Application to the Study of Plant Living Cells

The application of various microscopy methods such as luminescence microscopy, microspectrofluorimetry and laser-scanning confocal microscopy has been considered as an approach to study the autofluorescence of plant living cells—from cell diagnostics up to modelling the cell-cell contacts and cell interactions with fluorescent biologically active substances. It bases on the direct observations of secretions released from allelopathic and medicinal species and the cell-donor interactions with cell-acceptors as biosensors (unicellular plant generative and vegetative microspores). Special attention was paid to the interactions with pigmented and fluorescing components of the secretions released by the cells-donors from plant species. Colored components of secretions are considered as histochemical dyes for the analysis of cellular mechanisms at the cell-cell contacts and modelling of cell-cell interactions. The fluorescence of plant biosensors was also recommended for the testing of natural plant excretions as medical drugs.

Bi-fluorescence imaging for estimating accurately the nuclear condition of Rhizoctonia spp

AIMS

To simplify the determination of the nuclear condition of the pathogenic Rhizoctonia, which currently needs to be performed either using two fluorescent dyes, thus more costly and time-consuming, or using only one fluorescent dye, thus less accurate.

METHODS AND RESULTS

A red primary fluorescence (autofluorescence) of the hyphal cell walls and septa of Rhizoctonia spp. with green excitation is evidenced in Rhizoctonia spp. This property is exploited and combined for the first time with a conventional DAPI fluorescence to accurately determine the nuclear condition of Rhizoctonia. This bi-fluorescence imaging strategy depicted the nuclear condition in Rhizoctonia spp. more accurately than the conventional DAPI fluorescence used alone and was validated against isolates previously genotyped by DNA sequencing.

CONCLUSIONS

We demonstrated that the bi-fluorescence imaging strategy was safe, accurate and simple to perform and interpret.

SIGNIFICANCE AND IMPACT OF THE STUDY

The developed bi-fluorescence imaging strategy provides a sensitive tool for determining the nuclear condition of Rhizoctonia strains. Its simplicity is a key advantage when there are numerous cultures to be examined.

Autofluorescence of the fungus Morchella conica var. rigida

Autofluorescence (primary fluorescence (AF)) of fruiting bodies and stems of the fungus Morchella conica var. rigida was studied by fluorescence microscopy including sporangia and ascospores. The ascospores were characterized by a weak green-yellow AF at blue excitation. Using a green excitation, no AF was observed. The hyphae located under the layer of asci with ascospores exhibited a higher primary fluorescence, namely their walls that had green-yellow color at blue excitation. Also, their red AF observed when a green excitation was used was significant. Similarly, the hyphae located in the fungal stem exhibited a significant AF, especially their walls when the blue light was used for excitation. In addition, large, yellow-to-yellow/green, oval-to-round bodies with strong fluorescence were detected whose morphological equivalents were not clearly visible in the white halogen light. The AF of the fungus M. conica var. rigida was lower compared with the other higher fungi studied so far.

Enhancement of autofluorescence of the brown-rot fungus Piptoporus betulinus by metal ions

The autofluorescence (primary fluorescence, AF) of agar cultures of the brown-rot fungus Piptoporus betulinus was investigated in Zeiss Jenalumar and Nikon Eclipse 8201 fluorescence microscopes at various excitations. The strongest AF of hyphae was found in minimal medium with glucose, where the hyphae exhibited green AF at violet (450 nm) excitation and red AF at green (570 nm) excitation. Addition of metals to cultivation media led to enhanced white-blue AF in the presence of Co (at 450 nm) and yellow to yellow-brown AF at 510 nm. When cultivated with Mn and Zn, enhanced AF of intracellular content was observed. Only a weak signal was found in the presence of Cu and Fe.

New microscope produced by Lambda Praha Co. applicable to field studies of microorganisms

A new microscope produced by the company Lambda Praha, applicable to field studies, was used for the observation of biofilms growing on stones and rocks of the Red Sea beach at Sharm El Sheikh resort in Egypt. The microscope was equipped with a novel LED illumination system, independent of sunlight as the light source, and an attachable mechanical stage making possible a precise and systematic observation of the preparation. Using this device, black biofilms of cyanobacteria and green biofilms of algae were studied; characteristic sheaths protecting the cells against the intense sunlight were found in cyanobacteria belonging to the genus Lyngbya. Trichomes on phylloids consisting of 3 to 4 cells were observed in algae belonging to the genus Padina, whose nuclei were degraded as a result of apoptosis, which is in contrast to the species Padina pavonia containing visible nuclear residues observed on the shore of the Mediterranean Sea near Lastovo island in Croatia in 2007.

Autofluorescence of the fruiting body of the fungus Macrolepiota rhacodes

The autofluorescence (primary fluorescence, AF) of the freshly collected fruiting bodies of the fungus Macrolepiota rhacodes was studied in a Zeiss Jenalumar fluorescence microscope at a blue and a green excitation. The strongest yellow AF at blue excitation was displayed by irregular granules on the surface of the fungal pileus. A weaker yellow-green AF was exhibited by spherical cells and hyphae in the central part of the pileus while basidiospores emitted somewhat stronger AF. At green excitation, a considerable red AF was emitted only by basidiospores, other parts of the pileus showing a very weak red AF. M. rhacodes AF is much weaker than the AF of wood-rotting fungi, such as Fomes fomentarius, Daedalea quercina, Piptoporus betulinus, Fomitopsis pinicola and others.