Preprophase band

Source: Wikipedia, the free encyclopedia.
The preprophase band predicts the cell division plane: 1) Preprophase band formation during preprophase. 2) Metaphase spindle orients with the equator along the plane marked by preprophase band. 3) Phragmoplast and cell plate form along the plane marked by preprophase band. 4) The new cell wall of the daughter cells connects with the parent cell wall along the line of the former preprophase band location.

The preprophase band is a

Cambridge University in 1966.[1]

Just before mitosis starts, the preprophase band forms as a dense band of microtubules around the phragmosome and the future division plane just below the

mitotic spindle when dividing cells enter the G2 phase of the cell cycle after DNA replication is complete. The preprophase band consists mainly of microtubules and microfilaments (actin) and is generally 2-3 µm wide. When stained with fluorescent markers, it can be seen as two bright spots close to the cell wall
on either side of the nucleus.

Plant cells lack centrosomes as microtubule organizing centers. Instead, the microtubules of the mitotic spindle aggregate on the nuclear surface and are reoriented to form the spindle at the end of prophase. The preprophase band also functions in properly orienting the mitotic spindle, and contributes to efficient spindle formation during prometaphase [2]

The preprophase band disappears as soon as the nuclear envelope breaks down and the mitotic spindle forms, leaving behind an actin-depleted zone. However, its position marks the future fusion sites for the new cell plate with the existing cell wall during telophase. When mitosis is completed, the cell plate and new cell wall form starting from the center along the plane occupied by the phragmosome. The cell plate grows outwards until it fuses with the cell wall of the dividing cell at exactly the spots predicted by the position of the preprophase band.

Bibliography

  • P.H. Raven, R.F. Evert, S.E. Eichhorn (2005): Biology of Plants, 7th Edition, W.H. Freeman and Company Publishers, New York, NY,
    ISBN 0-7167-1007-2
  • L. Taiz, E. Zeiger (2006): Plant Physiology, 4th Edition, Sinauer Associates, Inc., Publishers, Sunderland, MA,
    ISBN 0-87893-856-7

Notes and references

  1. PMID 5929804
    .
  2. PMID 19825595
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=Preprophase_band&oldid=1092356473"