Brown Rot

Brown Rot is caused by Basidiomvcetes, which metabolize the carbohydrates cellulose and hemicelluloses of the woody cell wall by non-enzymatic and enzymatic action and leave the lignin almost unaltered , whereby the brown color develops.

Brown-rot fungi do not produce lignin-degrading enzymes. There are how-ever reports of lignin peroxidase and manganese peroxidase in some brown-rot fungi, and lignin loss or metabolization by brown-rot fungi have been reported. Particularly in later stages of decay, the highly lignified middle lamella/primary walls were observed to undergo attack. Also, the penetration of the wood cell wall by bore holes removes lignin in the process, all suggesting that low molec-ular weight lignin degrading agents and potentially even lignin degrading enzymes max occur in some brown-rot fungi, at least with localized activity (Goodell 2003).

Laccase activity was also found in Coniophora puteana (Lee et. al. 2004), and in Glocophyllum trabeum and Oligoporus placenta (Goodell 2003). Non-enzymatic, low molecular agents produced by the brown-rot fungi are responsible for initial stages of cell wall attack (Goodell 2003; Chap. 4). Of about 1,700 wood-degrading Basidiomycetes in North America, only 120 species (7%) caused brown rot, and of these 79 (65%) were polypores (Eriksson et al. 1990; Ryvarden and Gilbertson 1993). White-rot fungi distribute broader over the different basidiomycetous groups and some belong to the Ascomycetes (Rayner and Boddy 1988). Most brown-rot fungi affect conifers (Ryvarden and Gilbertson 1993), while white-rot fungi occur more frequently on hardwoods.

Brown rot occurs in standing trees, felled and processed wood as well as in sapwood and heartwood. In the northern hemisphere, the majority of timber used in construction is from conifers. Thus, a large part of wood in outdoor and indoor service is destructed due to the action of brown-rot fungi. Brown rot is usually uniformly distributed over the substrate. A brown cubical pocket rot is caused by Laurelia taxodii in cypress and by Oligoporus amarus in incense cedar. Decay pockets are localized and surrounded by firm wood (Zabel and Morrell 1992).

A woody substrate both may show brown rot and white rot; a standing tree of Picea engelmannii exhibited "white pocket rot" by Phellinus pini in the heartwood , and after wind throw the healthy areas became brown-rotten (Blanchette 1983). Brown-rot wood debris is extremely stable due to its content of slightly modified lignin and has remained unaltered in the soil for centuries. In conifers forests, this humic material may comprise up to 30 vol % in the upper layers (Swift 1982; Ryvarden and Gilbertson 1993).

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Reproduction of Deuteromycetes

F ungi that reproduce asexually (anamorphic fungi ) are either yeasts or Deu-teromycetes. The term "yeast" is descriptive and stands for any fungus that reproduces by budding. Deuteromycetes (Fungi imperfecti, colloquially: molds) is an artificial as-semblage of fungi that reproduce asexually by conidia (conidiospores), either as the only form for propagation (imperfect fungi) or additionally (anamorph) to a sexual reproduction (teleomorph). When both the anamorph and the teleo-morph are known, the fungus is called a holomorph (the whole fungus). The teleomorph may have one (mono-anamorphic) or many (pleo-anamorphic) asexual stages. In other words: Deuteromycetes are the conidia-producing forms of a fungus and may or may not be associated with a teleomorph. Many Deuteromycetes are supposed to have a teleomorph in the Ascomycetes, but they may also have basidiomycetous affinity. Also in the wood-inhabiting Deuteromycetes, the teleomorph often is of ascomycetous a

What shapes the peer review landscape in ecology?

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Islands

H ow often have you seen those wonderful advertisements inviting you to have a holiday on a tropical island ( Fig. )What is it about islands, whether in the tropics or polar regions, that suggests romance, excitement and adventure? Is it because of a sense of escape from the pressures and stress of a bustling way of life, or the opportunity to savour sun-soaked beaches, or the adventure of rocky unexplored shores, or perhaps the chance of seeing unique island wildlife? It is for all these reasons that there is a growing tourist industry for many islands around the world. The wildlife of islands, especially oceanic islands , has long been of special significance in biology , ecology , conservation and biogeography. Studies of island species have also been of historical significance for evolutionary biology. Many of the world's islands have high levels of endemic flora and fauna; that is, taxa found only on a particular island and no other place. Island biota has o

Red Streaking

Red Streaking Red-streaking discoloration (known as "Rotstreifigkeit" in Germany) is one of the most common and important damage in seasoning logs and sawn lumber, occurring only in conifers (spruce, pine, fir) and recognized as a distinct con-dition in continental Europe. The stripe-shaped to spotted yellow to reddish-brown discoloration extends in logs from both their bark-covered faces and from their cut ends (Butin 1995; Baum and Bariska 2002) . Stems that are not debarked show a rather flat discoloration and debarked stems exhibit a streakier staining (v. Pechmann et al. 1967). Causal agents are several white-rot Basidiomycetes, in spruce particularly Stereum sanguinolentum (Kleist and Seehann 1997) and Amylostereum areola-turn. In south Germany, Amylostereum chailettii is common (Zycha and Knopf 1963; v. Pechmann et al. 1967). In pine, red streaking is mainly due to Trichap-turn abietinum (Butin 1995). According to Kreisel (1961), S. sanguinolentum and T

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

W hite-rot research has been reviewed by Ericksson et al. (1990) and Mess-ner et al. (2003). White rot means the degradation of cellulose, hemicellu-loses, and lignin usually by Basidiomycetes and rarely by Ascomycetes, e.g., Kretzschmaria deusta and Xylaria hypoxylon. White rot has been classified by macroscopic characteristics into white-pocket, white-mottled, and white-stringy, the different types being affected by the fungal species, wood species, and ecological conditions. From microscopic and ultrastructural investiga-tions, two main types of white rot have been distinguished (Liese 1970). In the simultaneous white rot ("corrosion rot"), carbohydrates and lignin are almost uniformly degraded at the same time and at a similar rate during all decay stages. Typical fungi with simultaneous white rot are Fomes fomentar-ws, Phellinus igniarius, Phellinus robustus, and Trametes versicolor in standing trees and stored hardwoods (Blanchette 1984a). Wood decay

Soft Rot

The term " soft rot " was originally used by Findlay and Savory (1954) to describe a specific type of wood decay caused by Ascomycetes and Deuteromycetes which typically produce chains of cavities within the S2 layer of soft- and hardwoods in terrestrial and aquatic environments (Liese 1955), for example when the wood-fill in cooling towers became destroyed despite water saturation, and when poles broke, although they were protected against Basidiomvcetes. About 300 species (Seehann et al. 1975) to some 1,600 examples of ascomvcete and deuteromvcete fungi (Eaton and Hale 1993) cause soft rot, e.g., Chaeromium globosurn (Takahashi 1978), Hurnicola spp., Lecythophora hoffrnannii, Monodictys putredinis, Paecilornyces spp., and Thielavia terrestris. Soft-rot fungi differ from brown-rot and white-rot Basidiomycetes by grow-ing mainly inside the woody cell wall trate, starting from the tracheidal lumina., by means of thin perforation hyphae of less than 0.5 pm thickne

Antagonists, Synergists, and Succession

Interactions (reciprocal effects) between wood fungi have been early investi-gated e.g., by Oppermann (1951) and Leslie et al. (1976), and were described in detail by Rayner and Boddy (1988). Antagonism (competitive reciprocal effect), the mutual inhibition and in a broader sense the inhibition of one organism by others, is based on the pro-duction of toxic metabolites, on mycoparasitism, and on nutrient competition. Antagonisms are investigated as alternative to the chemical protection against tree fungi ("biological forest protection") and against fungi on wood in service ("biological wood protection") (Walchli 1982; Bruce 1992; Holdenrieder and Greig 1998; Phillips-Laing et al. 2003). As early as 1934, Weindling showed the inhibiting effect of Trichoderma species on several fungi. Bjerkandera adusta and Ganoderma species were antagonistic against the causing agent of Plane canker stain disease (Grosclaude et al. 1990). Also, v. Aufseg (197

Sexual Reproduction

A specific feature of the sexual reproduction of Ascomycetes and Basid-iomycetes is that plasmogamy of haploid cells and karyogamy of two nuclei (n) to form a diploid nucleus (2n) are separated from each other temporally as well spatially by the dikaryophase (two-nuclei phase, dikaryon, n + n, ===) (Fig.1). A dikaryotic hypha is one with two nuclei that derive from two haploid hyphae, but in which the nuclei are not yet fused by karyogamy. Particularly in Basidiomycetes, the dikaryotic phase is considerably ex-tended. By conjugated division of the two nuclei (conjugated mitosis), by division of the dikaryotic hypha, and by means of a special nucleus migration connested with camp formation both daughter cells become again dikaryotic. Ascomycetes The life cycle of a typical ascomycete is shown in Fig.1 (also Muller and Loeffler 1992; Eaton and Hale 1993; Schwantes 1996; Jennings and Lysek 1999). Haploid (n) spores (A, ascospores or conidia from an anamorph) germi-nate

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