Wednesday, December 24, 2008

Chytridiomycota


Chytridiomycota or chytrids is a division of the Fungi kingdom. The name is derived from the Greek chytridion, meaning "little pot": the structure containing unreleased spores. In older classifications, chytrids (except the recently established order Spizellomycetales) were placed in the Class Phycomycetes under the subdivision Myxomycophyta of the Kingdom Fungi. Also, in an older and more restricted sense (not used here), the term "chytrids" referred just to those fungi in the order Chytridiales.

The chytrids are the most primitive of the fungi and are mostly saprobic (degrading chitin and keratin). Many chytrids are aquatic (mostly found in fresh water). There are approximately 1,000 chytrid species, in 127 genera, distributed among 5 orders.
Both zoospores and gametes of the chytrids are mobile by their flagella, one whiplash per individual. The thalli are coenocytic and usually form no true mycelium (having rhizoids instead). Some species are unicellular. Like other fungi, the cell wall in chytrids is composed of chitin.

Discolored skin, be sloughing (The dead outer skin shed by a reptile or amphibian),or peeling the outside layers of its skin. This can vary from obvious peeling of skin (particularly on the feet), to a roughness of the frog's skin that you can barely see, sit out in the open, not protecting itself by hiding, be sluggish, and have no appetite, have its legs spread slightly away from itself, rather than keeping them tucked close to its body. In more extreme cases, the frog's body will be rigid, and its back legs will trail behind it.

Despite rumors of Chloramphenicol as a possible cure for this fatal frog disease, repeated trials have unfortunately shown the compound to be no more effective at conferring resistance than previously-known antifungal agents.

The chytrid Batrachochytrium dendrobatidis is responsible for a recently discovered disease of amphibians, chytridiomycosis. Discovered in 1998 in Australia and Panama this disease is known to kill amphibians in large numbers, and has been suggested as a principal cause for the world-wide amphibian decline. The actual process leading to mortality is, however, unknown.
Chytrids may also infect plant species; in particular, maize-attacking and alfalfa-attacking species have been described. Synchytrium endobioticum is an important potato pathogen.

The earliest fossils of chytrids are from the Scottish Rhynie chert, a Devonian-age locality with anatomical preservation of plants and fungi. Among the microfossils are chytrids preserved as parasites on rhyniophytes. These fossils closely resemble the genus Allomyces.

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