Lampbrush chromosome

Lampbrush chromosome from the cell nucleus of an ovarial egg from Triton sp., a salamander.

Lampbrush chromosomes are a special form of chromosome found in the growing oocytes (immature eggs) of most animals, except mammals. They were first described by Walther Flemming in 1882.[1] Lampbrush chromosomes of tailed and tailless amphibians, birds and insects are described best of all.[2][3][4] Chromosomes transform into the lampbrush form during the diplotene stage of meiotic prophase I due to an active transcription of many genes. They are highly extended meiotic half-bivalents, each consisting of 2 sister chromatids. Lampbrush chromosomes are clearly visible even in the light microscope, where they are seen to be organized into a series of chromomeres with large chromatin loops extended laterally. Amphibian and avian lampbrush chromosomes can be microsurgically isolated from oocyte nucleus (germinal vesicle) with either forceps or needles.[5][6]

Each lateral loop contains one or several transcription units with polarized RNP-matrix coating the DNA axis of the loop.[7][8][9]

Giant chromosomes in the lampbrush form are useful model for studying chromosome organization, genome function and gene expression during meiotic prophase, since they allow the individual transcription units to be visualized.[10] Moreover, lampbrush chromosomes are widely used for high-resolution mapping of DNA sequences and construction of detail cytological maps of individual chromosomes.[11]


Notes

  1. ↑ Flemming W (1882) Zellsubstanz, Kern- und Zelltheilung. Vogel, Leipzig.
  2. ↑ Callan HG (1986) Lampbrush Chromosomes. Springer-Verlag, Berlin, Heidelberg. 252pp.
  3. ↑ Morgan, G.T. (2002) Lampbrush chromosomes and associated bodies: new insights into principles of nuclear structure and function. Chromosome Research. 10: 177 - 200.
  4. ↑ Gaginskaya E, Kulikova T, Krasikova A (2009) Avian Lampbrush Chromosomes: a Powerful Tool for Exploration of Genome Expression. Cytogenet Genome Res. V.124. P.251-267.
  5. ↑ Gall JG (1966) Techniques for the study of lampbrush chromosomes. In: Prescott DM (ed) Methods in cell physiology, vol II. Academic Press, London New York, pp 37-60.
  6. ↑ Macgregor HC, Varley J (1988) Working with Animal Chromosomes. 2nd edition. John Wiley & Sons.
  7. ↑ Macgregor HC (1984) Lampbrush chromosomes and gene utilisation in meiotic prophase. In: Controlling Events in Meiosis, W. Evans and H.G.Dickinson (Editors). The Company of Biologists. P 333-348.
  8. ↑ Morgan, G.T. (2002) Lampbrush chromosomes and associated bodies: new insights into principles of nuclear structure and function. Chromosome Research. 10: 177 - 200.
  9. ↑ Gaginskaya E, Kulikova T, Krasikova A (2009) Avian Lampbrush Chromosomes: a Powerful Tool for Exploration of Genome Expression. Cytogenet Genome Res. V.124. P.251-267.
  10. ↑ Morgan, G.T. (2002) Lampbrush chromosomes and associated bodies: new insights into principles of nuclear structure and function. Chromosome Research. 10: 177 - 200.
  11. ↑ Gaginskaya E, Kulikova T, Krasikova A (2009) Avian Lampbrush Chromosomes: a Powerful Tool for Exploration of Genome Expression. Cytogenet Genome Res. V.124. P.251-267.

it is present in humans and rodent oocytes. Humans are also mammals then why in upper portion it is written that it is present in animals except mammals

References

Flemming W (1882) Zellsubstanz, Kern- und Zelltheilung. Vogel, Leipzig.
Rückert J (1892) Zur Entwicklungsgeschichte des Ovarialeies bei Selachiern. Anat Anz 7: 107-158.
Gall JG (1966) Techniques for the study of lampbrush chromosomes. In: Prescott DM (ed) Methods in cell physiology, vol II. Academic Press, London New York, pp 37–60.
Callan HG (1986) Lampbrush Chromosomes. Springer-Verlag, Berlin, Heidelberg. 252pp.
Macgregor HC (1984) Lampbrush chromosomes and gene utilisation in meiotic prophase. In: Controlling Events in Meiosis, W. Evans and H.G.Dickinson (Editors). The Company of Biologists. P 333-348.
Macgregor HC, Varley J (1988) Working with Animal Chromosomes. 2nd edition. John Wiley & Sons.
Morgan, G.T. (2002) Lampbrush chromosomes and associated bodies: new insights into principles of nuclear structure and function. Chromosome Research. 10: 177 - 200.
Alberts, Johnson, Lewis, Raff, Roberts, Walter (2008), "Molecular biology of the cell" 5th edition. (p234-235).
Gaginskaya E, Kulikova T, Krasikova A (2009) Avian Lampbrush Chromosomes: a Powerful Tool for Exploration of Genome Expression. Cytogenet Genome Res. V.124. P.251-267.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.