The role of the nucleus in the cell functions of amoebae

Becker, E.R.

Biol Bull Marine Biol Lab 50(5): 382-392

1926


Accession: 025927052

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Abstract
Amoeba dubia (proteus type) was used to determine the effect of the removal of the portion of protoplasm containing the nucleus. If the operation is carefully done, streaming continues for a few minutes in the enucleated fragment. Then it ceases, and the fragment becomes a wrinkled sphere, suggesting a reduction of osmotic pressure within the protoplasm. At this time the contractile vacuole disappears. After a few hours, streaming is resumed, the outline of the protoplasm is not so wrinkled, and the contractile vacuole reappears. Streaming of an enucleated fragment is usually of a modified limax type, although it may approximate the normal. Enucleated amoebae often attach themselves to the substratum quite as firmly as those with a nucleus. Normal amoebae react to violent mechanical agitation by assuming a stellate shape, which is maintained for some time. Enucleated amoebae react similarly at first but cannot sustain the protoplasmic projections, and soon become wrinkled spheres. A few hours after cutting, however, they lose the property of giving even the initial normal response, and react simply by withdrawing the pseudopods and contracting into a wrinkled sphere. Food organisms (Euglena sp?) found within the protoplasm of enucleated amoebae are digested. Such amoebae were never seen to ingest food by their own efforts. An Euglena was observed to force its way into an amoeba by a "battering ram" process. An occasional enucleated amoeba divided. One enucleated amoeba was observed in the act of division, which was accomplished by the appearance of 2 opposing streaming systems.