what will happen when if the nucleus from another amoeba is transplanted in an eucleated amoeba
Answers
Cells of different Amoeba proteus strains (C, B and L) lose their ability to attach to the substratum 5, 6 and 7 d, resp., after enucleation. During the first day the attachment rates of enucleated amoebae and anucleate cell fragments are lower than those of whole intact amoebae and nucleate fragments. However, 2 d after the operation, the former ones do not differ in this respect from the latter ones. The comparison of amoebae treated with actinomycin D (1 mg/ml) or puromycin (100μg/ml) and of enucleated cells shows that protein synthesis plays an important role in maintaining the ability of these protozoans to attach to the substratum. Between 30 min and 4 h after enucleation, the attachment rates of whole enucleated amoebae B and C exceed those of the respective anucleate fragments due to a different behaviour of “anterior” (pre-nuclear) and “posterior” (post-nuclear) anucleate fragments, the attachment rate of the former being significantly higher. However, the “anterior” and “posterior” fragments of L amoebae 2 h after enucleation attach to the substratum with similar rates. 1 d after the operation, “anterior” and “posterior” fragments of amoebae B do not differ in their attachment rates from each other and from whole enucleated amoebae; in strain C, the attachment rate of “posterior” anucleate fragments still remains somewhat lower than that of “anterior” ones. It may be suggested that the role of the cell nucleus in the attachment of amoebae to the substratum comes, f
Answer:
1. A description is given of a method for replacing the original nucleus of an amoeba by a nucleus from another amoeba. This method has been used to study transfers of nuclei within a species (homotransfers) and between species (heterotransfers). The species used were A. proteus and A. discoides.
2. Removal of the nucleus from an amoeba inactivates the animal, so that movement is sporadic and unco-ordinated, digestion ineffective, and death results after 10-20 days.
3. Renucleation results in reactivation with both homo- and heterotransfers. Reactivated homotransfers normally are able to divide and form mass cultures. Heterotransfers are less often able to divide and very seldom form mass cultures.
4. Amoebae taken at random from a mass culture divide after an interval which appears to be composed of a lag tl in which the processes leading to division are inactive, followed by an interdivision period td during which preparation for division is active. Experiments are given showing the effect of nuclear transfer on tl and td.
5. After heterotransfer nuclei of either species may grow and divide in foreign cytoplasm. Before the first division after heterotransfer a cytoplasmic effect on nuclear size is observable, and after the first division the cytoplasm has a dominant effect in determining nuclear diameter.
6. When curves are plotted of the frequency of occurrence of nuclei of various diameters in pure cultures, maxima are found in the curves characteristic of the species. After nuclear transfer the cytoplasm and nucleus both have a strong influence in determining the position of the maxima.
7. Studies of the form assumed by heterotransfers show that, although there is a measurable influence of the nucleus on the form soon after transfer, this influence disappears almost entirely in 6-12 days, after which the determination of form is almost entirely cytoplasmic.
8. The results given under points 4, 5, 6, and 7 are based on the study of animals immediately after transfer and for the subsequent two divisions only. Longer-term effects will be discussed in another paper.
Explanation: