Membrane Growth (1):
Figure: Electron Micrograph of a growing Prospore Membrane (PrM) engulfing a nuclear lobe (N)
Figure.
The localization of the septin-associated protein Gip1p (in green) as cells
progress through Meiosis II. Chromatin is shown by the DAPI stain in blue.
Septins. The septins are a conserved family of cytoskeletal proteins found in fungi and metazoans. In vegetatively growing yeast they from a ring at the neck of the bud which serves as a barrier to distinguish mother cell from the bud. In sporulating yeast, the behavior of septins is more dynamic. The septins appear in early Meiosis II as rings surrounding the position of the Spindle Pole Body. As Meiosis II progresses the septins resolve into pairs of parallel sheets that run from the leading edge of the prospore membrane back towards the spindle pole. Finally, after membrane closure the septins redistribute around the periphery of the spore. In addition to five septin proteins at least two other proteins Gip1p and Glc7p localize in these sheets during Meiosis II.
for movie click here
Movie: A 3-D reconstruction of Gip1p localization in a Meiosis II cell reveals that the Gip1p and the septins are organized into parallel sheets.
The Septin sheets may aid in the proper extension of the prospore membrane.
| For More Details on our work in this area see reference # 7 |
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Additional reading: Fares, H., Goetsch, L., & J.R. Pringle (1996) Identification of a developmentally regulated septin and involvement of the septins in spore formation in Saccharomyces cerevisiae. J. Cell Biol. 132:399-411. [PubMed] DeVirgilio, C., DeMarini, D.J., & J. R. Pringle (1996) SPR28 a sixth member of the septin gene family in Saccharomyces cerevisiae that is expressed specifically in sporulating cells. Microbiology 142:2897-2905. [PubMed] |