JM43_Galactose_N2_AntimycinA

In previous temporal studies, we found the anaerobic response was biphasic when cells growing in galactose medium were shifted from aerobiosis to anaerobiosis, consisting of an acute, transitory phase (<60 min) followed by a more chronic but delayed phase (> 1 generation), but largely monophasic (delayed, chronic phase only) when cells were shifted in glucose medium. Gene network and functional analyses revealed the acute phase was comprised of genes associated with the retooling of metabolism (respiro-fermentative to strictly fermentative) and balancing energy supply and demand. A similar pattern of gene expression is seen when cells encounter other “environmentally stressful” conditions. However, cells shifted to anaerobiosis on glucose, in which no catabolic rearrangement is required nor change in growth rate observed, do not exhibit this pattern, suggesting the “stress” encountered is one associated with the abrupt cessation of galactose-dependent respiration and slowing of growth, not oxygen deprivation per se. In order to test this hypothesis, we added the respiratory inhibitor, antimycin A, under aerobiosis for three generations then shifted to anaerobiosis, which no catabolic rearrangement is required. Keywords: time course Sparged, fermentor cultures of a wild-type yeast strain (JM43) were aerobically grown on galactose medium (SSG-TEA) in the presence of Antimycin A for three generations. After three generations, the sparge gas was switched from air to O2-free N2 and samples were harvested after 0.04, 0.08, 0.13, 0.19, 0.25, 0.38, 0.5, 1, 2, and 3 generations of anaerobic growth in the presence of Antimycin A. Total RNA was reverse transcribed (Cy3) and hybridized against a reference (Cy5). The full time series was repeated in triplicate.