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| ==Processes involved== | ==Processes involved== | ||
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| + | '''Asexual Reproduction''' | ||
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| + | Chytrids have a simple thallus and motile zoospores, making them distinct form other fungi. The structure is very simple and consists of a single cell, which consists of rhizoids that help to anchor it onto a substrate. Motile zoopsores are produced by the chytrids in order for asexual reproduction to occur. The zoospores have a single, posterior flagellum in sporangia. Chytrids are normally holocarpic meaning that the entire thallus functions as sporangium. A holocarpic chytrid has a thallus that consists of only one cell with rhizoids. They are usually parasitic on aquatic plants or fish. The fungus "feeds" from its substrate directly through the rhizoids. A holocarpic chytrid's entire cell content will convert to motile zoospores. | ||
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| + | '''Sexual Reproduction''' | ||
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| + | Diploid spore production after the fusion of two different mating types is how sexual reproduction may occur in some members of the chytrids. A diploid mycelium or haploid mycelium may be produced. The spore may germinate to produce a diploid vegetative mycelium, or a haploid mycelium may be produced through meitotic division. Another way for a haploid vegetative mycelium to be produced is through having resting sporangia undergo meiosis. Then, the haploid zoospres may germinate to produce haploid mycelium. | ||
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| + | [[Image:http://www.microbiologybytes.com/introduction/graphics/2-6.jpg]] | ||
| ==History of Chytrids== | ==History of Chytrids== | ||
Revision as of 22:11, 15 March 2013
Contents |
Chytrids and their role in the food web
Introduction
Chytrids play an important role in the food web, especially in fresh water ecosystems. The five main roles of chytrids as described by Gleason et al. (2008) are as follows: chytrid zoospores are a good food source for zooplankton, chytrids decompose particulate organic matter, chytrids are parasites of aquatic plants, chytrids are parasites of aquatic animals, and chytrids convert inorganic compounds into organic compounds. These are important factors as each of these specific situations affect the ecosystem greatly. Chytrid zoospores are a great source of nutrition and are a good size (2-3 μm in diameter) for feeding zooplankton (Gleason et al. 2008). They also contain some organic compounds such as nitrogen, phosphorous, and sulphur, important for supplying vitamins to the zooplankton. As the chytrid zoospores are ingested, their nutrients are transferred up the food chain to higher trophic levels. Chytrids are able to decompose particulate organic matter such as chitin, cellulose, and protein found in snake and hair (Gleason et al. 2008). This is important because these molecules are hard to digest or virtually indigestible by other organisms. With the help of chytrids, these molecules can become dissolved organic matter and thus be taken up by organisms higher up the trophic levels. Chytrids can be parasites of both phytoplankton and vascular plants. They help control seasonal successions of phytoplankton species (Gleason et al. 2008). Chytrids are also parasites of aquatic invertebrates such as rotifers, nematodes, and mites. They help with the regulation of populations in these environments. The fact that chytrids can convert inorganic compounds into organic compounds is essential in the food chain because some of these inorganic compounds are not usable in their inorganic state. For example, there are insoluble states of phosphorous that need to be broken down by chytrids before they can be absorbed. Organic compounds made by chytrids are then able to be used by other organisms in the ecosystem. After introducing the five main roles of chytrids and their importance in the food web, the processes they are involved in, their variety of species, and their evolutionary history will be further discussed in more detail.
Chytrid Life Cycle
Species involved
Processes involved
Asexual Reproduction
Chytrids have a simple thallus and motile zoospores, making them distinct form other fungi. The structure is very simple and consists of a single cell, which consists of rhizoids that help to anchor it onto a substrate. Motile zoopsores are produced by the chytrids in order for asexual reproduction to occur. The zoospores have a single, posterior flagellum in sporangia. Chytrids are normally holocarpic meaning that the entire thallus functions as sporangium. A holocarpic chytrid has a thallus that consists of only one cell with rhizoids. They are usually parasitic on aquatic plants or fish. The fungus "feeds" from its substrate directly through the rhizoids. A holocarpic chytrid's entire cell content will convert to motile zoospores.
Sexual Reproduction
Diploid spore production after the fusion of two different mating types is how sexual reproduction may occur in some members of the chytrids. A diploid mycelium or haploid mycelium may be produced. The spore may germinate to produce a diploid vegetative mycelium, or a haploid mycelium may be produced through meitotic division. Another way for a haploid vegetative mycelium to be produced is through having resting sporangia undergo meiosis. Then, the haploid zoospres may germinate to produce haploid mycelium.
Image:Http://www.microbiologybytes.com/introduction/graphics/2-6.jpg
History of Chytrids
References
Gleason, F., Kagami, M., Lefevre, E., Sime-Ngando, T. 2008. The Ecology of Chytrids in Aquatic Ecosystems: Roles in Food Web Dynamics. Fungal Biology Reviews. 22: 17-25
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