Light and Force of Gravity

At first sight, light might have no significance for fungi, because fungi are carbon-heterotrophic. The vegetative mycelium including the rhizomorphs of Armillaria species and the strands of house-rot fungi grow in nature in the absence of light, namely in the soil and within trees or timber (substrate mycelium), or in buildings hidden behind wall coverings and in the subfloor area.

The growth within the substrate might be rather due to hygro-, hydro-, geo- and chemotropisms than to negative phototropism (Muller and Loeffler 1992). Surface and aerial mycelia also grow in the dark like during the routine fungal culturing in the laboratory or at low light intensity like in the indoor polypores and Serpula lacrymans in buildings.

A requirement for light occurs particularly with respect to the initiation of reproduction and the ripening of the fruit bodies. Light is the signal that the mycelium has reached the (irradiated) surface, where there the spores can be produced in an environment suitable for spore release (Jennings and Lysek 1999). For fungi, light in the short wavelengths, blue light, is effective, while light with longer wavelengths is ineffective. The light acceptor of the photons hitting the mycelium is riboflavin, which then reduces a cytochrome. The required light quantities are low, below those of the full moonlight at a clear sky (0.23 pW cm-2).

During the cultivation of Lentinula edodes on wood , the col-onized wood substrate was exposed to light for 8-15 h/day (Schmidt 1990). In the dark, the primordia did not develop further or abnormal fruit bodies occurred. Particularly suitable are wavelengths from 370-420 nm and from 620-680 nm. Daedalea quercina, Gloeophyllum abietinum, Lentinus lepideus, Payilhic nammides and some other fungi develop abnormal and frequently

The Deuteromycetes Aspergillus niger and Paecilomyces variotii develop conidia both with light and in the dark, likewise the ascomycete Chaetomium globosum forms fertile cleistothecia. In other Ascomycetes, conidia formation is induced by light, while in darkness ascospores develop (Reif3 1997). Light-dark cycles lead to a rhythmic change of growth and reproduction of Peni-cillium species and other Deuteromycetes. When the hyphae are irradiated, their growth rate is reduced to differentiation into conidia.

Concentric rings develop on agar plates from the inoculum in periodically repeated distances (Schwantes 1996; Reif 1997; Jennings and Lysek 1999). Some fungi can grow permanently on sites exposed to light, e.g., fungi growing on plant surfaces (leaves, phylloplane). Typical phylloplane fungi are Alternaria, Aureobasidium and Cladosporium species (Jennings and Lysek 1999). Some of them are potential parasites, but also effect blue stain of timber as saprobionts. UV light, particularly 254 nm, has a lethal and mutagenic effect. Nucleic acids are damaged by UV -B of 260 nm by the photochemical induction of cy-anscription and reduplication clobutan dimers, which prevents the correct transcription of DNA (panten et al. 1996).

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Reproduction of Deuteromycetes

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What shapes the peer review landscape in ecology?

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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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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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