Splash and grab: Biomechanics of peridiole ejection and function of the funicular cord in bird's nest fungi

The bird's nest fungi (Basidiomycota, Agaricales) package millions of spores into peridioles that are splashed from their basidiomata by the impact of raindrops. In this study we report new information on the discharge mechanism in Crucibulum and Cyathus species revealed with high-speed video. Peridioles were ejected at speeds of 1–5 m per second utilizing less than 2 % of the kinetic energy in falling raindrops. Raindrops that hit the rim of the basidiome were most effective at ejecting peridioles. The mean angle of ejection varied from 67 to 73° and the peridioles travelled over an estimated maximum horizontal distance of 1 m. Each peridiole carried a cord or funiculus that remained in a condensed form during flight. The cord unravelled when its adhesive surface stuck to a surrounding obstacle and acted as a brake that quickly reduced the velocity of the projectile. In nature, this elaborate mechanism tethers peridioles to vegetation in a perfect location for browsing by herbivores.     

Ultrastructure of Ascodichaena rugosa on beech bark

Ascodichaena rugosa Butin is a corkinhabiting fungus, found frequently on the bark of Fagus sylvatica L. The hyphae of the fungus are distributed solely in the phellem cells, stopping their growth in the last-formed cork cell layer. The cell to cell invasion is effected by penetration hyphae, causing no extensive dissolution of the cork wall. Electron microscopical observations revealed fine structural details of the fruit bodies and of the intracellular hyphae. Of special interest were the finger-like hyaline hyphae in the last-formed layer of cork cells, which are interpreted as haustoria on the basis of the fine structure both of hyphae and host cells. This situation is considered as reflecting a parasitic relationship of Ascodichaena to beech bark. The activity of the fungus led also to the increased production of cork cells, perhaps related to the nutrient supply of the fungus.     

A taxonomic study of the subantarctic Piptoporus (Polyporaceae, Basidiomycetes) I

Ryvardenia gen. nov. is proposed to accommodate Polyporus cretaceus (as type species) and Polyporus campylus . The new genus is characterized by: medium to large fruit bodies that may be solitary or imbricate; monomitic context with clamped generative hyphae with thin to thickened walls that are not metachromatic in cresylblue; dimitic dissepiments with unbranched skeletal hyphae; obovate or broad-ellipsoid, uninucleated, thick walled spores; bipolar sexuality; astatocoenocytic nuclear behavior and simple-septated generative hyphae in the advancing mycelium in culture. Mating tests between specimens from Australia/New Zealand and Argentina of R. cretacea and R. campyla are presented. Tyromyces falcatus is considered a synonym of R. campyla only differing in the greater amount of sclerified generative hyphae and skeletal hyphae present in the fruit bodies.     

Ultrastructure of Fomes igniarius mycelium

The mycelium is composed of thin-walled hyphae, fiber hyphae and cuticular cells, the modified cells developing from the thin-walled hyphae with a dolipore septum at the differentiation point. The cell wall is usually triplelayered. occasionally, multilayered. Cell organelles such as endoplasmic reticulum, mitochondria and vesicles are found in abundance in thin-walled hyphae. Characteristic features of this fungus are the concentric membrane systems from which vesicles arise, the membrane-enclosed osmophilic bodies in vacuoles and the dense bodies in the cytoplasm. As the fiber hyphae and cuticular cells develop, the innermost layer of the wall thickens and the cell contents become disorganized so that, at the maturity of these cells, there is a reduced amount of diffuse cytoplasm, or none in the lumen.The study formed part of a doctoral dissertation submitted by the author to the University of Alberta, Edmonton, Alberta, Canada, 1971.     

Genetic evidence for somatic haploidization in developing fruit bodies of Armillaria tabescens

Armillaria spp. have vegetative hyphae with diploid uninucleate cells, but the fruit bodies of many species contain clamped dikaryotic hyphae. Earlier observations suggest that somatic haploidization takes place in developing fruit bodies. To verify this, a uninucleate diploid cell was isolated from each of the 49 mating combinations between single-spore isolates of Armillaria tabescens and they were fruited. Twenty-four isolates produced fruit bodies with at least a partially dikaryotic subhymenium. Dikaryotic hyphae were isolated from fruit-body primordia and homokaryons were obtained by micromanipulation or by protoplasting. Approximately half of the isolates proved to represent recombinant mating types in respect to parent homokaryons, and most of them contained recombinant haploid DNA, based on random-amplified microsatellite markers. The results show that the nuclei in dikaryotic hyphae found in fruit bodies result from somatic haploidization. The mechanism of haploidization remains unclear.     

Lysophosphatidylcholine derived from deer antler extract suppresses hyphal transition in Candida albicans through MAP kinase pathway

A family of 2-lysophosphatidylcholines (lyso-PCs) was isolated from deer antler extract, guided exclusively by hyphal transition inhibitory activity in Candida albicans. Structural determination of the isolated lyso-PCs by spectroscopic methods, including infrared spectroscopy, 1H nuclear magnetic resonance (NMR), 13C NMR, 2D correlation spectroscopy NMR, fast atom bombardment mass spectrometry and tandem mass spectrometry, confirmed that the natural products were composed of at least four different lyso-PCs varying in fatty acid moiety at the sn-1 position of the glycerol backbone. The major lyso-PCs were confirmed as 1-stearoyl-, 1-oleoyl-, 1-linoleoyl- and 1-palmitoyl-2-lyso-sn-glycero-3-phosphatidylcholines. Lyso-PC specifically suppressed the morphogenic transition from yeast to hyphae in C. albicans, without affecting the growth of either yeast or hyphae. Lyso-PC exerted hyphal transition that suppressed activity in the broad spectrum of the Candida species, such as C. albicans, Candida krusei, Candida guilliermondii and Candida parapsilosis. Northern analysis indicated that the suppression was mediated through the mitogen-activated protein kinase pathway.     

Trifluoromethanesulfonic acid-based proteomic analysis of cell wall and secreted proteins of the ascomycetous fungi Neurospora crassa and Candida albicans

Cell wall proteins from purified Candida albicans and Neurospora crassa cell walls were released using trifluoromethanesulfonic acid (TFMS) which cleaves the cell wall glucan/chitin matrix and deglycosylates the proteins. The cell wall proteins were then characterized by SDS–PAGE and identified by proteomic analysis. The analyses for C. albicans identified 15 cell wall proteins and six secreted proteins. For N. crassa, the analyses identified 26 cell wall proteins and nine secreted proteins. Most of the C. albicans cell wall proteins are found in the cell walls of both yeast and hyphae cells, but some cell type-specific cell wall proteins were observed. The analyses showed that the pattern of cell wall proteins present in N. crassa vegetative hyphae and conidia (asexual spores) are quite different. Almost all of the cell wall proteins identified in N. crassa have close homologs in the sequenced fungal genomes, suggesting that these proteins have important conserved functions within the cell wall.     

Ultrastructure of hyphae and ascospores in the genus Eremascus eidam

Hyphae and ascospores of Eremascus fertilis and E. albus were studied in ultrathin sections. The lateral wall of the hyphae had a thick electron-light inner layer and a thin dark outer layer. The septa had a simple central pore with or without a plug, and there were Woronin bodies in the vicinity. The wall of the ascospores of E. fertilis showed a thick light inner layer and a thin dark outer layer. In the wall of the spores of E. albus a dark fibrillar layer was present between the light inner layer and the dark outer layer. The spores of this species germinated with a tube the wall of which was continuous with a newly formed layer inside the spore wall.This investigation was supported by the Netherlands Organization for the Advancement of Pure Research (Z. W. O.)     

Comparative analysis of the binding of antibodies prepared against the insect Spodoptera exigua and against the mycopathogen Nomuraea rileyi

Polyclonal antibodies were produced in mice against Spodoptera exigua (beet armyworm) larval hemolymph and hemocytes and against cell wall surfaces of hyphal bodies and hyphae of the entomopathogenic hyphomycete Nomuraea rileyi. In addition to exhibiting strong activity against their original antigenic substrates, all of the antibodies cross-react extensively with other substrates. The hemolymph antibody binds to hemocytes and vice versa, and both antibodies cross-react to the insect fat body basement membrane (extracellular matrix (ECM) and to N. rileyi and Beauveria bassiana (another entomopathogenic fungus) cell wall surfaces (ECM). Likewise, the anti-fungal antibodies cross-react with S. exigua hemolymph and hemocytes, especially the granules that may contain ECM components, and with fat body basement membrane. These cross-reactivities are specific as indicated by negative controls in the microscopy and Western blotting assays. Parallel labeling experiments using Con A suggest that the reactive epitopes contain mannose; however, none of the antibodies bind to mannose residues of nonentomopathogenic Candida albicans or Saccharomyces cerevisiae yeast cells. Thus, these cross-reactivities suggest that the host mimicry expressed by surface components of entomopathogenic fungi represents an important pathogenic determinant.     

Three new species of anamorphic yeasts phenotypically and phylogenetically related toCandida mesenterica: The description ofCandida fungicola sp. nov.,Candida sagamina sp. nov., andCandida fukazawae sp. nov. isolated from fruit bodies of mushrooms

Four strains of anamorphic yeasts isolated from fruit bodies of mushrooms collected in Japan were found to represent three new species of the genusCandida. These species resembleCandida mesenterica in characteristics commonly employed in the classification of yeasts. On the basis of DNA-DNA reassociation, however, they were clearly distinguished fromC. mesenterica and from one another. Three new species,Candida fungicola, Candida sagamina, andCandida fukazawae, are proposed for these yeasts. The analysis of SSU rDNA sequences suggested that these three species were closely related to each other and toC. mesenterica andC. suecica.     

Microscopic observations of the early development of Pleurotus pulmonarius fruit bodies

From observations made by light microscopy, transmission electron microscopy, environmental-scanning and cryoscanning electron microscopy we conclude that the expansion of the young fruit body of Pleurotus pulmonarius involves considerable vacuolation of hyphae but no marked inflation of cell dimensions. There is evidence for an extensive extracellular matrix (ECM), the components of which must be under the control of the hyphae which the ECM surrounds. However the ECM in these fruit bodies is a dilute material. It is easily lost during specimen preparation and is evident only when certain techniques are used to preserve the fluid surface of the hyphae. Observations of the hyphal and fruit body structures with a range of conventional microscopic techniques are crucial to complement the information obtained through physiological and molecular studies for understanding the cellular changes that occur during mushroom development.     

Electron microscopy of vesicular-arbuscular mycorrhizae of yellow poplar. II. Intracellular hyphae and vesicles.

Intracellular hyphae and vesicles in mycorrhizal roots of yellow poplar were examined by electron microscopy. An investing layer of host wall material and cytoplasm enclosed the endophyte within the cells. Young developing hyphae contained abundant cytoplasm and few vacuoles. As hyphae matured, they became highly vacuolated and accumulated carbohydrate (glycogen) and lipid reserves. Mature vesicles were engorged with lipid droplets, possessed a trilaminate wall and were also enclosed by host wall material and cytoplasm. Compared with uninfected cells, infected cortical cells showed an increase in cytoplasmic volume, enlarged nuclei, and a reduction of starch reserves. Host nuclei were always proximal to the hyphae during hyphal development and deterioration. While other cytoplasmic components of infected and uninfected cells were comparable large electron-dense bodies occurred in vacuoles of most cells containing hyphae. Deterioration of intracellular hyphae occurred throughout the samples examined. Septa separated functional and degenerating portions of the hyphae. Hyphal deterioration involved degeneration and ultimate disappearance of fungal cytoplasm as well as collapse of hyphal walls. Based on these observations, the authors hypothesize that deterioration of the endophyte may release significant quantities of mineral nutrients, via hyphal contents, which are absorbed by the host.     

Verticillium disease or "dry bubble" of cultivated mushrooms: the Agaricus bisporus lectin recognizes and binds the Verticillium fungicola cell wall glucogalactomannan

The step of recognition and (or) binding for the development of the disease of the cultivated mushroom Agaricus bisporus by the mycoparasite Verticillium fungicola was studied by several approaches: agglutination of V. fungicola germinated spores by an A. bisporus extract from fruit body cell walls, immunofluorescence microscopy of A. bisporus hyphae from fruit bodies and vegetative mycelia pretreated with purified V. fungicola cell wall glucogalactomannan, and finally, by hemagglutination experiments carried out with an A. bisporus fruit body lectin in the presence and absence of the same glucogalactomannan. Hemagglutinating activity of the purified A. bisporus fruit body lectin was clearly inhibited by the V. fungicola glucogalactomannan, whereas in the A. bisporus vegetative mycelium such lectin was not encountered. All the results obtained make evident the recognition and binding of the A. bisporus fruit body lectin to the V. fungicola cell wall glucogalactomannan, clarifying why the mushrooms, but not the vegetative mycelium, become diseased.     

葡萄座腔菌Botryosphaeria dothidea侵染及其对苹果果实影响的组织细胞学研究

利用光镜和电镜技术系统研究了苹果轮纹病菌葡萄座腔菌在成熟果实上的侵染扩展过程及其细胞学特征。扫描电镜观察发现,接种后3h位于皮孔处的分生孢子开始萌发,萌发后的孢子从一端或两端产生芽管直接侵入皮孔细胞,接种后9h完成侵入。30d后果面接种部位表现症状,45d后产生子实体。对接种部位取样进行光镜和透射电镜观察发现,病菌菌丝主要存在于寄主细胞壁、细胞内、细胞间隙及细胞壁与细胞膜之间。菌丝呈丝状,分枝,具隔膜。菌丝细胞内含有细胞核、线粒体、液泡等细胞器;菌丝外散发出一些高电子密度的颗粒物质,这些物质以菌丝为中心,呈放射状分布。病菌在果肉细胞生长扩展过程中,果肉细胞发生一系列变化。果肉细胞壁膨胀、变形,胞间层分离、破裂。与菌丝接触或相邻的果肉细胞细胞壁电子致密度降低,被降解成为如散发状的胞壁纤维束丝。果肉细胞的液泡破裂,质壁分离,细胞质凝结坏死并沉积于细胞壁周围,或通过受损的细胞壁胞间连丝从一个细胞转移到另一个细胞。后期菌丝在表皮下聚集生长、发育成分生孢子器。分生孢子器内壁细胞排列紧密,细胞中含有由数条丝状物平行排列而成的细胞器。该细胞器形状多样,周围总是分布着丰富的脂肪粒,推测可能与营养的运输与积累有关。     

STARCH IN FUNGI. II. INDUCTION OF AMYLOIDITY IN MEMBERS OF DIVERSE GENERA

Nonamyloid hyphae from fungal fruit bodies which normally produce amyloid structures can be induced to produce starch molecules when incubated in glucose-1-phosphate solution. Hyphae from fruit bodies without natural amyloid structures could not be induced to produce starch. The genes for the starch-synthesizing enzymes are apparently activated when fruit body formation is initiated.     

Simple staining detects ultrastructural and biochemical differentiation of vegetative hyphae and fruit body initials in colonies of Pleurotus pulmonarius

AIMS: To know the ultrastructural and biochemical differences of vegetative hyphae and fruit body initials in colonies of Pleurotus pulmonarius. METHODS AND RESULTS: Feulgen reagent was used to detects differentiation of hyphae. The intracellular laccases, proteases and beta-1,3-glucanases activity, content of cytoplasmic protein, glycogen and glucans in the cell wall were evaluated in hyphae of fruit body initials and in vegetative hyphae. The thickness of hyphal walls of the vegetative hyphae was also evaluated. Substantial biochemical changes were observed in hyphae of different zones of the fruiting colony. Hyphae at the periphery had thinner walls than in the centre of the colony. CONCLUSION, SIGNIFICANCE AND IMPACT OF THE STUDY: Staining correlated with the enzymatic activity, protein, glycogen and glucans, in mycelium and in fruit body initials. The implications are that hyphal maturity in P. pulmonarius involves storage of glucans, in part at least, in the form of a thickened hyphal wall.     

Aspects of the dimorphism of Histoplasma farciminosum: a light and electron microscopic study.

Within 48h following the induction of mycelial to yeast-like phase conversion of Histoplasma farcininosum, randomly occurring hyphal cells were observed to contain multiple nuclei and markedly increased numbers of mitochondria. Yeast-like cells arose as buds from swollen tips of terminal hyphae, as sessile buds along the hyphae, and as buds from chlamydospores. Yeast-like cells were characterized by the presence of numerous buds over the surface of the mother cell. Bud scars were evident in the cell wall of the mother cell following abscission of the bud cell. Little similarity was noted between the fine structure of yeast-like H. farciminosum and that reported for H. capsulatum. The yeast-like cells of H. frciminosum underwent rapid transformation to the mycelial phase at 25 degrees C. The hyphal cell wall originated from the inner layer of cell wall of the yeast-like form. The cytoplasm of the hyphal cell usually contained a single nucleus, scattered mitochondria and occasional lipid storage bodies. Occasionally, Woronin bodies were observed at the septal pore.     

Ultrastructure at the Host-Parasite Interface of Phytophthora capsici in Roots and Stems of Capsicum annuum

The infecting hyphae of Phytophthora capsici grew intercellularly in infected tissues of roots and stems of pepper (Capsicum annuum). The vascular tissues were not markedly disorganized even when heavily infected. Intercellularly growing hyphae penetrated the host cells by forming haustorium-like bodies. The consistent features of ultrastructural changes in infected tissues of pepper roots and stems were degeneration of cell organelles and dissolution of host cell walls. The cytoplasm detached from the cell wall aggregated abundantly around some haustorium-like bodies or the penetration sites of fungal hyphae. The host cell walls were palely stained, thinned and swollen, possibly being biochemically altered by the action of fungal macerating enzymes. Electron-dense, wall-like material was apposed on the outer wall of xylem vessel contacted by fungal hyphae. The infecting hyphae were also surrounded by granular, dark-staining cytoplasm. Characteristics of host cell responses to the invading P. capsici were the deposition of papilla-like material on host cell walls next to hyphae and the encasement of haustorium-like bodies with wall appositions.     

Elastic properties of the cell wall of Aspergillus nidulans studied with atomic force microscopy

Currently, little is known about the mechanical properties of filamentous fungal hyphae. To study this topic, atomic force microscopy (AFM) was used to measure cell wall mechanical properties of the model fungus Aspergillus nidulans. Wild type and a mutant strain (deltacsmA), lacking one of the chitin synthase genes, were grown in shake flasks. Hyphae were immobilized on polylysine-coated coverslips and AFM force--displacement curves were collected. When grown in complete medium, wild-type hyphae had a cell wall spring constant of 0.29 +/- 0.02 N/m. When wild-type and mutant hyphae were grown in the same medium with added KCl (0.6 M), hyphae were significantly less rigid with spring constants of 0.17 +/- 0.01 and 0.18 +/- 0.02 N/m, respectively. Electron microscopy was used to measure the cell wall thickness and hyphal radius. By use of finite element analysis (FEMLAB v 3.0, Burlington, MA) to simulate AFM indentation, the elastic modulus of wild-type hyphae grown in complete medium was determined to be 110 +/- 10 MPa. This decreased to 64 +/- 4 MPa for hyphae grown in 0.6 M KCl, implying growth medium osmotic conditions have significant effects on cell wall elasticity. Mutant hyphae grown in KCl-supplemented medium were found to have an elastic modulus of 67 +/- 6 MPa. These values are comparable with other microbial systems (e.g., yeast and bacteria). It was also found that under these growth conditions axial variation in elastic modulus along fungal hyphae was small. To determine the relationship between composition and mechanical properties, cell wall composition was measured by anion-exchange liquid chromatography and pulsed electrochemical detection. Results show similar composition between wild-type and mutant strains. Together, these data imply differences in mechanical properties may be dependent on varying molecular structure of hyphal cell walls as opposed to wall composition.     

彩绒革盖菌超微结构的研究

利用电子显微镜对彩绒革盖菌[Coriolus versicolor(L.:Fr.)Quél.],俗名云芝的人工培养的菌丝和野生的子实体进行超微结构的研究。结果表明:子实体由三种类型的菌丝(生殖菌丝、骨架菌丝、联络菌丝)组成。菌丝和子实体菌丝的细胞壁由两层结构组成。担子和担孢子的细胞壁由多层结构组成,至少有三层。菌丝顶端细胞的细胞质中有顶泡复合体(AVC)和顶体。菌丝细胞和子实体菌丝细胞都有桶状隔膜,在细胞质中有丰富的糖原贮存。担孢子与担子的小梗连接处出现初生壁溶化现象。