Presumptive X-Autosome Translocation in a Cow : Preferential Inactivation of the Normal X Chromosome

Abstract

THE Lyon hypothesis1 was constructed on genetical evidence derived from observations of sex-linked variegation of coat colour in the mouse. Within the framework of this hypothesis, late DNA synthesis and genetic inactivity of the same X chromosome are considered strictly related phenomena. Thus information about the chronology of DNA replication in structurally abnormal X chromosomes is relevant to the study of the genetic activity of mammalian sex chromosomes. So far, such information is available only for two mammalian species, mouse and man. In human females, structurally abnormal X chromosomes, such as deficiencies, duplication/deficiencies or rings, were found to be consistently late-replicating compared with the normal X chromosome2. The same applies to a presumptive X-autosome translocation3. In the mouse, two cases of X-autosome translocations have been studied cytogenetically, with contrasting results. In females heterozygous for Searle's translocation (T16H), in which part of the X chromosome is translocated on to an unidentified autosome, the sex-linked variegation is suppressed. Lyon et al.4, by the appropriate genetic tests, showed that the translocated X was consistently active while the normal X was inactive in all cells. Ohno and Lyon5 later reported that the normal X of heterozygous females carrying the translocation showed positive heteropycnosis in 90 per cent of somatic prophases.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1

    Lyon, M. F., Nature, 190, 372 (1961); Russel, L. B., Science, 133, 1795 (1961); Gruneberg, H., J. Embryol. Exp. Morphol., 16, 569 (1966).

  2. 2

    Fraccaro, M., and Lindsten, J., in Cytogenetics of Cells in Culture (edit. by Harris, R. J. C.) (Academic Press, New York, 1964).

  3. 3

    Mukerjee, D., and Burdette, W. J., Nature, 212, 153 (1966).

  4. 4

    Lyon, M. F., Searle, A. G., Ford, C. E., and Ohno, S., Cytogenetics, 3, 306 (1964).

  5. 5

    Ohno, S., and Lyon, M. F., Chromosoma, 16, 90 (1965).

  6. 6

    Ohno, S., and Cattanach, B. M., Cytogenetics, 1, 129 (1962).

  7. 7

    Cattanach, B. M., and Isaacson, J. H., Genetics, 57, 331 (1967).

  8. 8

    Evans, H. J., Ford, C. E., Lyon, M. F., and Gray, J., Nature, 206, 900 (1965).

  9. 9

    Mukherjee, B. B., and Sinha, A. K., Canad. J. Genet. Cytol., 5, 490 (1963); Gartler, S. M., and Burt, B., Cytogenetics, 3, 135 (1964).

  10. 10

    Gustavsson, I., Nature, 211, 865 (1966).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

GUSTAVSSON, I., FRACCARO, M., TIEPOLO, L. et al. Presumptive X-Autosome Translocation in a Cow : Preferential Inactivation of the Normal X Chromosome. Nature 218, 183–184 (1968) doi:10.1038/218183a0

Download citation

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.