Science Fair Project Encyclopedia
Acytostelium The dictyostelids are a group of cellular slime moulds. When food is readily available they take the form of individual amoebae, which feed and divide normally. However, when the food supply is exhausted, they aggregate together to form a multicellular assembly, called a pseudoplasmodium or slug. This has a definite anterior and migrates to a new location, and under the correct circumstances matures to form a fruiting body, supporting one or more balls of spores. These spores are inactive cells protected by resistant cell walls, and become new amoebae once food is available.
In Acytostelium, the fruiting body is supported by a stalk composed of cellulose, but in other dictyostelids the stalk is composed of cells, sometimes taking up the majority of the original amoebae. With a few exceptions, these cells die once the stalk has been formed, and there is a definite correspondence between parts of the slug and parts of the fruiting body. Aggregation of amoebae generally takes place in converging streams. The amoebae move using filose pseudopods, and are attracted to chemicals produced by other amoebae. In Dictyostelium, aggregation is signalled by cAMP, but others use different chemicals.
- dictyBase Online Informatics Resource for Dictyostelium
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