Table 3.

Main differences reported hitherto between K. lactis and S. cerevisiae, two alternative unicellular eukaryote models for hypoxic and oxidative stress responses.

	K. lactis	S. cerevisiae
Crabtree effect	Negative	Positive
Glucose catabolism in aerobic conditions	Mainly respiratory	Mainly fermentative
Ratio PPP/glycolysis for glucose catabolism	High	Low
Reoxidation of NADPH from PPP	Mainly by mitochondrial alternative external dehydrogenases	Mainly by cytosolic NADPH oxidoreductases
Catabolic repression of respiration	Low	High
Respiratory capacity	Unlimited	Limited
Petite phenotype	Positive in specific mutant genetic backgrounds	Positive
Caloric restriction increases longevity	No	Yes
Aerobic/hypoxic gene pairs	Absent	Present
Upregulated by hypoxia	Genes related to ergosterol synthesis, cell wall composition, and glycolytic genes. OS genes: CUP1 and CUP2, HSP12, FMP46 and GRE1, and SOD1.	Genes from the heme biosynthetic pathway, pyruvate decarboxylase, and lipid biosynthesis. OS genes: KlOYE2, KlGSH1. This response is highly dependent on the relative flux of glucose through glycolysis or PPP
Transcriptional regulators Hap1 and Rox1	Not related to heme-mediated oxygen response	Related to heme-mediated oxygen response