Mycelium

About: Mycelium is a research topic. Over the lifetime, 8923 publications have been published within this topic receiving 170993 citations.

Continuous imaging of amino-acid translocation in intact mycelia of Phanerochaete velutina reveals rapid, pulsatile fluxes

Abstract: Summary • Nitrogen translocation by woodland fungi is ecologically important, however, techniques to study long-distance amino-acid transport in mycelia currently have limited spatial and temporal resolution. We report a new continuous, noninvasive imaging technique for β-emitters that operates with submillimetre spatial resolution and a practical sampling interval of 10–60 min. • Transport of the nonmetabolized, 14C-labelled amino-acid analogue, α-aminoisobutyric acid (AIB) was imaged using a photon-counting camera as it was transported in foraging mycelium of the cord-forming woodland fungus, Phanerochaete velutina, grown over an intensifying screen in microcosms. • The maximum acropetal transport velocity of 14C-AIB to the colony margin was 50 mm h−1 (average 23 mm h−1), with a mass transfer of 4.6–51.5 pmol 14C-AIB h−1 per cord. Transport in cords had a pulsatile component with a period of 11–12 h. • Transport was significantly faster than diffusion, consistent with rapid cycling of nutrients throughout the mycelium between loading and sink regions. The increased spatial and temporal resolution of this method also revealed the rhythmic nature of transport in this fungus for the first time.

Formation and properties of protoplasts from antibiotic-producing strains of Penicillium chrysogenum and Cephalosporium acremonium.

Abstract: SUMMARY: Osmotically fragile protoplasts have been prepared by the action of lytic enzymes on the mycelium of Penicillium chrysogenum and Cephalosporium acremonium. The yield of protoplasts, based on DNA content, was up to 18 %. Pretreatment of the mycelium with a thiol compound was necessary with Cephalosporium but not with Penicillium. Electron micrographs indicated that the protoplasts contained all the intracellular organelles of the mycelium and were bounded only by a cytoplasmic membrane. The metabolic activity of the protoplasts, as measured by their respiration, ability to maintain intracellular amino-acid pools, and antibiotic production, was similar to that of control mycelium. l-Valine and l-α-aminoadipic acid, which are precursors of penicillin N and cephalosporin C, were taken up and concentrated by the protoplasts of C. acremonium, although the latter transported l-valine less rapidly than did the corresponding mycelium. Protoplasts of P. chrysogenum took up l-valine but not l-α-aminoadipic acid or its δ-ester. There was little or no transport of the corresponding d-amino acids by protoplasts of either organism.

On the taxonomy of Monilia roreri, an important pathogen of Theobroma cacao in South America

Abstract: Monilia roreri Cif., the causal agent of an important pod rot of cocoa in South America, is redescribed and illustrated. The presence of dolipore septa in the vegetative mycelium indicating basidio...

The influence of external nitrogen on carbon allocation to Glomus intraradices in monoxenic arbuscular mycorrhiza.

Abstract: The influence of external nitrogen (N) on carbon (C) allocation and processes related to phosphorus (P) metabolism were studied in monoxenic arbuscular mycorrhiza (AM) cultures of Daucus carota. Fungal hyphae of Glomus intraradices proliferated from colonized roots growing on solid medium into C-free liquid minimal medium with two different N and P levels. Furthermore, we exposed the colonized roots to high or low N availability and then studied the mycelial development. Roots were provided with C-13-glucose in order to follow the C allocation. The mycelium was analysed for phosphatase activity and transcription levels of two nutrient regulated genes. High N availability to the monoxenic AM root reduced the C allocation to the AM fungus while N availability to the mycelium was important for the upregulation of the fungal inorganic phosphorus (Pi)-transporter GiPT. We found that N availability can regulate nutritional processes in arbuscular mycorrhiza. We conclude that negative impacts of N on AM abundance are caused by reduced C allocation from the plant. Upregulation of the fungal Pi-transporter GiPT indicated that increased N availability might induce P limitation in the mycelium.

Ultrastructure of Dimorphic Transformation in Paracoccidioides brasiliensis

Abstract: The fine structure of Paracoccidioides brasiliensis undergoing temperature-dependent transformation from mycelium to yeast and vice versa (M right harpoon over left harpoon Y) was studied. The transitional form to mycelium from the yeast appears as an elongated bud that extends from the yeast and which has a mixture of characteristics from both the yeast and the mycelium. The transitional form to yeast from the mycelium starts with enlargement of the interseptal spaces and cracking of the outer electron-dense layer of the cell wall of the hypha. Later the interseptal spaces tend to become round and separate. In M --> Y only few interseptal spaces seem to transform. The yeast is produced by self-transformation of the hypha. In Y --> M a new structure is formed and the yeast dies. Intrahyphal hyphae are observed during the transformation from M --> Y, and intrayeast hyphae during the Y --> M. Due to the high mortality and breakage observed in both types of transformations, we believe that wound of the yeast or the mycelium could elicit this phenomenon.