| dc.description.abstract | Yeasts preferentially use glucose as their carbon source via fermentation for growth. When glucose in the environment is exhausted, yeasts will adjust their metabolisms though Mig1 in order to use other carbon sources via non-fermentation processes for growth. However, the regulation of MIG1 expression remains unclear. Previous studies have indicated that four nucleotides, at positions -151, -152, -174 and -498, in the promoter region might control MIG1 expression levels, and the nucleotide located at -498 may play a key role in regulating MIG1 expressions. Therefore, we constructed a single nucleotide mutant strain by swapping to determine whether the nucleotide at position -498 is the only key regulatory.
Based on our results, we found out that GYL43-1 at the ninth hour（T9） and GYL43-2、GYL43-3 at the thirteenth hour（T13） time point were diuxic shift. But the MIG1 expression of GYL43-3 was opposite to the previous study results, and we inferred that our adenine concentrations were highly variable in YPAD media.
Based our pyrosequencing results, we found out that gDNA ratios （BY:RM） were not 1:1 in the experimental group, GYL49. The ratios of GYL49 gDNA were 1:2 to 1:2.5, therefore we could not compare the gene expression levels with the wild-type group, GYL43, to determine whether the nucleotide at position -498 is the only key regulatory. We inferred when we changed the promoter sequence after the first swapping, making the MIG1 expression level lower than normal, and during the second swapping, the BY strain inserted the wild-type RM strain`s MIG1 gene fragments into the chromosome at other sites. Therefore the MIG1 gene expression level of RM was higher than the one of BY in the experimental group, GYL49. | en_US |