Cytology and Morphology

"Wood fungi" are eukaryotic and carbon-heterotrophic (free from chlorophyll) organisms with chitin in the cell wall, reproduce asexually and/or sexually by non-flagellate spores, filamentous, immovable and mostly land inhabiting. Damage to wood in water by fungi is described by Jones and Irvine , Jones and Kim and Singh . Soft-rot fungi belonging to the Ascomycetes and Deuteromycetes destroy wood with high moisture content in water or soil (e.g., Findlay and Savory 1954; Liese 1955). Fungi associated with leaf litter in a woodland stream were treated by Suberkropp .

In this book, a fungal cell, the hypha, is defined as one individual cell of mostly tubular shape that consists of a cell wall, contains a protoplasm with a nucleus and other organelles, and is in the "higher fungi" separated from its one or two neighbors by a transverse wall, the septum . In analogy to the "higher plants", where nearly every living cell is connected to its neighbors by cytoplasmic channels, the plasmodesmata, which pass through the intervening cell walls, also the protoplasms of neighbored hyphae are connected with each other through the pore or dolipore system . This basic hypha is termed "vegetative hypha" in this book. This definition contrasts to others where one hypha, also termed generative hypha, is a more or less long filament consisting of several hyphal "compartments", a definition that is hazy because the transition to the next higher unit, the mycelium, is flowing. The mycelium is thus the filamentous lining up of hyphae, consisting in young mycelia of only a few vegetative hyphae and in older ones of several and branched hyphae. shows septate hyphae as they occur in the wood-inhabiting Deuteromycetes, Ascomycetes, and Basidiomycetes.

The diameter of hyphae reaches from 0.1-0.4 p.m for the microhyphae of Phellinus pini (Liese and Schmid 1966) to 60 pm for the vessel hyphae in the mycelia/ strand (cord) of the True dry rot fungus, Serpula lacrymans, with an vegetative (S. lacy mans: 311m: Seehann average for hyphae of about 2-7 pm th reaches from about and v. Riebesell 1988). Their leng 5 pm for round/oval irometers. The size of many bacteria is between cells (spores) up to several mc 0.4 and 5pm.

Due to the smallness of the individual hypha and the use of microscopic and microbiological methods, fungi are microorganisms. This attachment does not contrast to the fact that fungi can form large and firm structures such as fruit bodies of decimeters in size like in the Tinder fungus, Fomes fomentarius .

Vegetative hyphae. C coencytic hyphae, S septate hyphae

Those fruit bodies are, however, also composed of single hyphae. The main argument is, however, that the "actual fungus" is the vegetative hyphal system that can grow unlimited by simple mitotic reproduction without ever fruiting if fresh nutrients (wood, soil, agar) are available, and if growth in a certain biotope is not inhibited by the own or foreign metabolic products.

Fungi are scientifically examined in microbiological or medical institutes (predominantly Deuteromycetes and Ascomycetes) and often in botanical in-stitutes. They do, however, no longer rank among the plants. In multi-kingdom systems (Whittaker 1969), the "higher fungi" (Ascomycetes, Basidiomycetes) form the distinct group of fungi beside the Prokaryotes (Bacteria), Protista (eukaryotic single-celled organisms: slime fungi and "lower fungi"), plants, and animals (Muller and Loeffler 1992). Based on rDNA sequences, Woese and Fox (1977) divided the Prokaryotes into the kingdoms Eubacteria and Archae-bacteria and later emphasized three domains, which were renamed Bacteria, Archaea, and Eucarya

The hyphal wall defines the shape of the hypha and provides the mechan-ical strength to resist the internal turgor pressure. The wall consists of var-ious carbohydrates. Some yeast has mannan-J3-glucans, while Ascomycetes, Deuteromycetes, and Basidiomycetes possess chitin-f3-glucans, never cellulose. Chitin f poly-f3(1-4)-N-acetoamido-2-deoxy-D-glucopyranosel, which occurs except in fungi also in the exoskeleton of arthropods and crustaceans, and in some mollusks, is a macromolecule made of p-1,4-glycosidically linked N-acetylglucosamine units.

Chitin synthases (CHS; EC 2.4.1.16) catalyze the formation of chitin from the precursor UDP-N-acetylglucosamine. In the yeast Saccharomyces cerevisiae, CHS I acts as a repair enzyme and is involved in the chitin synthesis at the point where the daughter and mother cells separate. CHS II participates in septa formation and CHS III in chitin synthesis of the cell wall (Robson 1999). Ascomycetes have two-layered cell walls, while walls of Ba-sidiomycetes are multilamellar. The entire structure of the cell wall including extracellular layers is complex (Toft 1992; Robson 1999):

The wall of filamentous fungi may consist for example of an inner wall of about 10 -20 nm composed of chitin microfibrils and an outer wall composed of a protein layer (about 10 nm), a layer of glycoprotein (about 50 nm), and a slime layer, also termed mucilage layer, sheath, extracellular matrix or mycofibrils (about 75-100 rim). Slime layers are common to fungi and have been found in blue stain, white, brown, and soft-rot fungi. They are composed of protein, lipid and carbohy-drate containing material (a-glucan, /3-1,3 and /3-1,6-glucan) or of crystalline to membranous and fibrillar structures (Liese and Schmid 1.963; Schmid and Liese 1965; Schmid and Baldermann 1967; Holdenrieder 1982; Green et al. 1989). Various functions have been suggested for the slime layer (Schmid and Liese 1966; Sutter et al. 1984; Green et al. 1991b; Kim 1991; Abu Ali et al. 1997; Messner et al. 2003; Table 2.1).

In Phanerochaete chrysosporium, the slime layer is composed of equal amounts of carbohydrates, lipids, and proteins, includ-ing five fractions with molecular weights between 30 and 200 kDa (cf. Messner et al. 2003). Production of the slime layer was influenced by iron, manganese and nitrogen concentration, temperature, and pH value (Jellison et al. 1997). Hyphae may be encrusted and covered with resinous material, oil drops, and calcium oxalate crystals (e.g., Holdenrieder 1982).

The hyphal wall encloses the cytoplasm with its outer boundary, the plas-malemma. In the majority of fungi, ergosterol is the chief sterol in the plasma membrane and is used for fungal quantification . Some antifungals like polyene and triazole act on this ergosterol (Robson 1999). The cytoplasm principally resembles that one of plants. There is one too many relatively small nuclei. Plastides are absent. Growing hyphae of Ascomycetes and Basi-diomycetes show at the hyphal apex a mass of small vesicles, the "SpitzenkOr-per".

The tonoplast encloses a vacuolar system. Carbon is stored in glycogen vesicles and lipid vacuoles. Nitrogen is deposited as amino acids in the vacuo-lar system or as protein. Phosphorus is condensed as polyphosphate in volutin grana, often in vacuoles. Some yeast contains starch.

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Reproduction of Deuteromycetes

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Red Streaking

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Ecosia ; Ecology Search

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Bioenergetics

T housands of chemical reactions occur throughout the body during each minute of the day. Collec-tively, these reactions are called metabolism. Metab-olism includes chemical pathways that result in the synthesis of molecules (anabolic reactions) as well as the breakdown of molecules (catabolic reactions). Since energy is required by all cells, it is not sur-prising that cells possess chemical pathways that are capable of converting foodstuffs (i.e., fats, proteins, carbohydrates) into a biologically usable form of energy . This metabolic process is termed bioenergetics. In order for you to run, jump, or swim, skeletal muscle cells must be able to continuously extract energy from food nutrients. In fact, the inability to transform energy contained in foodstuffs into usable biological energy would limit performance in endurance activities. The explanation for this is simple. To continue to contract, muscle cells must have a continuous source of energy. When energy is not rea

White Rot

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Soft Rot

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