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Biol Bull 85: 164-178. (October 1943)
© 1943 Marine Biological Laboratory
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A QUANTITATIVE STUDY OF ANAPHASE MOVEMENT IN THE APHID TAMALIA

HANS RIS 1

1 Department of Biology, The Johns Hopkins University, Baltimore, and the Marine Biological Laboratory, Woods Hole

1. The movement of chromosomes at anaphase was measured in living cells of Tamalia, Protenor and Thelia. The distance between the separating chromosomes plotted against time produces curves which describe accurately the chromosome movement. In embryonic cells and secondary spermatocytes of Tamalia, spermatogonia and primary spermatocytes of Protenor, and a primary spermatocyte of Thelia the curves consist of two S-shaped components separated by a plateau. The second part of the movement coincides with the elongation of the cell.

2. In stained sections the length of chromosomal fibers and the spindle was measured at various stages of chromosome separation. A comparison with the data from living cells shows that in the first part of anaphase the chromosomal fibers shorten, i.e., the chromosomes approach the poles. In the second part the spindle elongates and thus produces a further movement of the chromosomes.

3. The chromosome movement in the otherwise exceptional anaphase of primary spermatocytes in Tamalia is characterized by a simple unbroken curve. Measurements on stained cells demonstrate that the movement is due entirely to spindle elongation. The chromosomal fibers remain constant in length and the chromosomes therefore do not approach the poles.

4. Since the double curve was found in all Hemiptera and Homoptera studied but not in the grasshopper (unpublished results) this type of anaphase movement is probably related to the diffuse spindle attachment found in these insects. This points out the functional significance of structural variations.

5. The curves for the primary spermatocyte of Protenor show that the lagging of the daughter chromosomes of the univalent X chromosome is due to an abnormal first part of the movement. This indicates some impairment in the functioning of their chromosomal fibers. The exceptional behavior of a chromosome can thus be traced to one particular factor of the anaphase movement.




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P. J. Wilson, A. Forer, and D. Wise
Microtubule distribution during meiosis I in flea-beetle [Alagoasa (Oedionychus)] spermatocytes: evidence for direct connections between unpaired sex chromosomes
J. Cell Sci., April 1, 2003; 116(7): 1235 - 1247.
[Abstract] [Full Text] [PDF]


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