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. 1965 Apr 1;25(1):119–135. doi: 10.1083/jcb.25.1.119

CHROMOSOME VELOCITY DURING MITOSIS AS A FUNCTION OF CHROMOSOME SIZE AND POSITION

R Bruce Nicklas 1
PMCID: PMC2106602  PMID: 14342826

Abstract

Chromosome velocity has been studied in living Melanoplus differentialis spermatocytes by phase contrast cinemicrography. Melanoplus chromosomes (and bivalents) differ in length by as much as 1:3.5. As expected, no size-dependent velocity differences were detected in anaphase, and this is also shown to be true for the less predictable movements during prometaphase congression. The size of the X chromosome can change during observation following x-irradiation, but this is equally without influence on velocity. However, an effect of position on velocity is found in both prometaphase and in anaphase: the chromosomes furthest from the central interpolar axis move 25 per cent faster than more central chromosomes. A simple mechanical model relating frictional resistance and mitotic forces to chromosome velocity is discussed in detail. Calculations from the model suggest that a significant difference in the force acting on a large, as compared with a small chromosome is necessary to account for the observed similarity in velocity. Therefore, it is concluded that the mitotic forces are so organized or regulated that velocity is, within limits, independent of load. The implications of velocity-load independence in relation to the molecular origin of mitotic forces are discussed.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. AMOORE J. E. NON-IDENTICAL MECHANISMS OF MITOTIC ARREST BY RESPIRATORY INHIBITORS IN PEA ROOT TIPS AND SEA URCHIN EGGS. J Cell Biol. 1963 Sep;18:555–567. doi: 10.1083/jcb.18.3.555. [DOI] [PMC free article] [PubMed] [Google Scholar]
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