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Dictyosteliida

Dictyosteliids
Scientific classification
Kingdom:Protista
Taxon:Ramicristates
Order:Dictyosteliida
Families & genera
Dictyosteliidae
    Dictyostelium
    Polysphondylium
    Coenonia
Actyosteliidae
    Acytostelium

The dictyosteliids are a group of cellular slime molds. When food is readily available, they take the form of individual amoebae, which feed and divide normally. However, when the food supply is exhausted, these aggregate in merging streams to form a pseudoplasmodium or slug. This may be dissolved by shaking it in water, upon which the amoebae resume individual function, but has a distinct anterior and posterior, and after some time differentiates to form a stalk. The cells in the stalk secrete cellulose and die, after which the other cells migrate to the top and form a sporangium, which produces spores.

There is a definite correspondence between different parts of the slug and parts of the final stalked sporangium. As such, dictyostelids have been of interest to those studying cellular communication and differentiation. Aggregation takes place by chemotaxis to chemicals produced by other amoebae, notably cAMP. Dictyosteliid amoebae move using filose pseudopods, and appear particularly closely related to the Acanthamoebida[?] and Stereomyxida[?].



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