BACKGROUND: In Saccharomyces cerevisiae, nutrient limitation stimulates diploid 
cells to undergo DNA replication and meiosis, followed by the formation of four 
haploid spores. Septins are a family of proteins that assemble a ring structure 
at the mother-daughter neck during vegetative growth, where they control 
cytokinesis. In sporulating cells, the septin ring disassembles and septins 
relocalize to the prospore membrane.
RESULTS: Here, we demonstrate that nutrient limitation triggers a change in the 
localization of at least two vegetative septins (Cdc10 and Cdc11) from the bud 
neck to the microtubules. The association of Cdc10 and Cdc11 with microtubules 
persists into meiosis, and they are found associated with the meiotic spindle 
until the end of meiosis II. In addition, the meiosis-specific septin Spr28 
displays similar behavior, suggesting that this is a common feature of septins. 
Septin association to microtubules is a consequence of the nutrient limitation 
signal, since it is also observed when haploid cells are incubated in 
sporulation medium and when haploid or diploid cells are grown in medium 
containing non-fermentable carbon sources. Moreover, during meiosis II, when the 
nascent prospore membrane is formed, septins moved from the microtubules to this 
membrane. Proper organization of the septins on the membrane requires the 
sporulation-specific septins Spr3 and Spr28.
CONCLUSION: Nutrient limitation in S. cerevisiae triggers the sporulation 
process, but it also induces the disassembly of the septin bud neck ring and 
relocalization of the septin subunits to the nucleus. Septins remain associated 
with microtubules during the meiotic divisions and later, during spore 
morphogenesis, they are detected associated to the nascent prospore membranes 
surrounding each nuclear lobe. Septin association to microtubules also occurs 
during growth in non-fermentable carbon sources.