The UPC2 deletion strain is hypersusceptible to GdA and impairs ascorbic acid-associated blockage of the elongated cell shape. (A) The UPC2 deletion strain is hypersusceptible to GdA. The upc2Δ/upc2Δ (D-6) strain was tested for its hypersusceptibility to GdA by treating it with 4 μM GdA, a concentration that is unable to induce elongated growth in the corresponding wild type. The UPC2 reintegrant strain (EC-7) (upc2Δ/upc2Δ + UPC2) displays a phenotype similar to that of the wild type. The images were taken after 8 h of growth at 30°C in YPD medium. (B) Deletion of UPC2 impairs ascorbic acid-associated blockage of the elongated cell shape. Deletion strains were grown at 30°C in YPD rich medium supplemented with either 10 μM GdA, 2.5 mM l-ascorbic acid, or a combination of the two. While ascorbic acid blocks the GdA-induced filamentation of the wild-type strain, it is unable to do so in the upc2Δ/upc2Δ mutants D-6 and TF077, while the reconstitution of UPC2 restores the yeast growth response. The images were taken after 8 h.