, Volume 41, Issue 1, pp 231–256 | Cite as

Meiosis VII: “Detorsive bending” as a basis for geometric shapes of late prophase bivalents

  • L. T. Douglas


A new model depending on mechanical properties of chromosomes is adduced as a basis for diplotene opening-out and for curvature occurring in grasshopper bivalents, during and subsequent to diplotene. Conditions underlying the model are: (1) rigid physical binding exists between sister chromatids, (2) each chromatid remains free of torsional strain if its pairing face is straight, i.e. the chromatid is bilaterally symmetrical, (3) reciprocal exchange together with stiff binding between sisters produces twist in each chromated before diplotene begins, (4) stiffening of the bivalent during late meiotic prophase removes the twist resulting from reciprocal exchange, (5) since sister binding prevents untwisting of chromatids about their long axes, untwisting would be achieved only in conjunction withbending of each chromated. It is shown that this bending, called “detorsive bending”, automatically produces opening out, not only in bivalents with one chiasma but also in those with more than one, especially if the chiasmata are interstitial.

In bivalonts with two chiasmata, classes of curvature resulting when both chiasmata are interstitial (II), when one is interstitial and one terminal (IT) and when both are terminal (TT) are attributed to differences in strength of opening out at interstitial and at terminal chiasmata respectively. It is postulated that mechanisms responsible for opening out at terminal chiasmata are basically different from those at interstitial chiasmata.

A theoretical basis of a method for cytological detection of chromatid interference is outlined and arguments are presented against the electrostatic hypothesis.


Mechanical Property Chromated Theoretical Basis Geometric Shape Sister Chromatid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. Anderson N. G. (1965). Cell division, part one, A theoretical approach to the primeval mechanism, the initiation of cell division and chromosomal condensation.Quart. Rev. Biol. 31: 169–199.Google Scholar
  2. Battaglia E. & J. W. Boyes (1956). Post-reductional meiosis: its mechanism and causes.Caryologia 8: 87–134.Google Scholar
  3. Darlington C. D. (1965). Cytology. J. & A. Churchill Ltd., London.Google Scholar
  4. Douglas L. T. (1966). Meiosis, I: Association of non-homologous bivalents during spermatogenesis in white mice.Genetica 37: 466–480.Google Scholar
  5. Douglas L. T. (1968a). Meiosis, III: The elastica and Markov segregation as basis for distributive pairing inDrosophila.Genetica 39: 289–328.Google Scholar
  6. Douglas L. T. (1968b). Meiosis IV: Segregation from interchange multivalents as a Markov process.Genetica 39: 429–255.Google Scholar
  7. Douglas L. T. (1968c). Meiosis, V: Matric and path coefficient solutions of tri-and quadrivalents.Genetica 39: 456–496.Google Scholar
  8. Douglas, L. T. (1970a). Correlation between terminal chiasma frequency and bivalent length inLocusta migratoria. (manuscript).Google Scholar
  9. Douglas, L. T. (1970b) Curvature in bivalent loops of the grasshopper,Locusta migratoria (manuscript).Google Scholar
  10. Douglas L. T. & S. J. Geerts (1966). Meiosis, II: A modified affinity model in mice.Genetica 37: 411–542.Google Scholar
  11. Douglas L. T. & H. W. Krors (1969). Meiosis VI: A reinterpretation of tritium thymidine labelling of meiotie chromosomes, supporting the chiasmatype hypothesis,Genetica 40: 503–507.Google Scholar
  12. Fagerlind F. (1960). The mechanism of chiasma formation and crossingover.Acta Horti Bergiani 19: 249–385.Google Scholar
  13. Greenhill A. (1892). The applications of elliptic funetions. Dover, New York.Google Scholar
  14. Haga T. (1944). Meiosis inParis I. Mechanism of chiasma formation.J. Fac. Sci. Hokkaido Univ. Ser. V.5: 121–198.Google Scholar
  15. Henderson S. A. & R. G. Edwards (1968). Chiasma frequency and maternal age in mammals.Nature 218: 22–28.Google Scholar
  16. King, R. C. (1969). The meiotic behavior of theDrosophila oocyte. International Review of Cytology (in press).Google Scholar
  17. Lillie R. S. (1905). On the conditions determining the disposition of the chromatic filaments and chromosomes in mitosis.Biol. Bull. 8: 193–204.Google Scholar
  18. Lima-De Faria A. (1956). The role of the kinetochore in chromosome organization.Hereditas 42: 85–160.Google Scholar
  19. Linden, A. V. D. (1969). Personal communcation.Google Scholar
  20. Lindsley, D. L. & E. H. Grell (1967). Genetic variation ofDrosophila melanogaster, Carnegie Inst. of Wash. Publ. No.627.Google Scholar
  21. Mather K. (1935). Reductional and equational separation of the chromosomes in bivalents and multivalents.J. Genet. 30: 53–78.Google Scholar
  22. Matsuura, H. (1937). Chaomosome studies onTrillium kamtsehaticum Pall, V. Abnormal meiotic divisions due to high temperature.Cytologia, Fujil jub. vol.: 20–35.Google Scholar
  23. Matsuura H. (1938). Chromosome studies onTrillium kamtsehaticum. Pall. VII. Additional evidence for the neo-two-plane theory of biyalent constitution.Cytologia 9: 78–87.Google Scholar
  24. Nicklas R. B. (1966). A note on orientation in mitosis and meiosis.J. Theoret. Biol. 12: 147–150.Google Scholar
  25. Nicklas R. B. (1968). Chromosome segregation: an explanation of kinetochore reorientation.Genetics 20: 207–208.Google Scholar
  26. Noda S. (1968). Achiasmate bivalent formation by parallel pairing in PMC's ofFritillaria amabilis.Bot. Mag. (Tokyo)81: 344–345.Google Scholar
  27. Östergren G. (1943). Elastic chromosome repulsions.Hereditas 29: 444–450.Google Scholar
  28. Southwell R. (1941). An introduction to the theory of clasticity, Oxford Univ. Press., London.Google Scholar
  29. Swanson C. P. (1942). Some considerations on the phenomenon of chiasma terminalization.Am. Nat. 76: 593–610.Google Scholar
  30. Swanson C. P. (1957). Cytology and cytogenetics. Prentice Hall, Inc. Englewood Cliffs, New Jersey.Google Scholar
  31. Swanson C. P., T. Merz & W. J. Young (1967). Cytogenetics. Prentice-Hall, Inc., Englewood Cliffs, New Jersey.Google Scholar
  32. Sybenga J. (1965). The quantitative analysis of chromosome pairing and chiasma formation based on relative frequencies of MI configurations. I Introduction: normal diploids.Genetica 36: 243–252.Google Scholar
  33. Taylor J. H. (1965). Distribution of tritium thymidine DNA among chromosomes during meiosis I: Spermatogenesis in the grasshopper.J. Cell. Biol. 25: 57–67.Google Scholar
  34. Wolf B. E. (1950). Die Chromosomen in der Spermatogeneso der DipterenPhryne undMycelobia.Chromosoma 4: 148–204.Google Scholar

Copyright information

© Martinus Nijhoff 1970

Authors and Affiliations

  • L. T. Douglas
    • 1
  1. 1.Department of GeneticsUniversity of NijmegenThe Netherlands

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