No abstract

We have investigated the effects that iron limitation provokes in Saccharomyces cerevisiae exponential cultures. We have demonstrated that one primary response is the induction of bulk autophagy mediated by TORC1. Coherently, Atg13 became dephosphorylated whereas Atg1 appeared phosphorylated. The signal of iron deprivation requires Tor2/Ypk1 activity and the inactivation of Tor1 leading to Atg13 dephosphorylation, thus triggering the autophagy process. Iron replenishment in its turn, reduces autophagy flux through the AMPK Snf1 and the subsequent activity of the iron responsive transcription factor, Aft1. This signalling converges in Atg13 phosphorylation mediated by Tor1. Iron limitation promotes accumulation of trehalose and the increase in stress resistance leading to a quiescent state in cells. All these effects contribute to the extension of the chronological life, in a manner totally dependent on autophagy activation.

No abstract

We investigated, to determine whether disruption of lipid rafts would influence the effect of three selected strains of Lactobacillus on TNF-alpha production by peripheral blood mononuclear cells. Two strains increased TNF-alpha production; and the third one reduced cytokine levels. Disruption of rafts changed the immunomodulatory effect of the three strains. This is the first report on a potential role of rafts in lactobacilli-cell interaction.