Consequences of the overexpression of PAB3 in the nab2-1 mutant background. (A) A comparison of the poly(A) tail phenotypes of the nab2-21 (left) and nab2-1, as well as nab2-1 strain overexpressing PAB3 or Pab1p (right) at normal (30°C) and low (14 or 18°C, as indicated) temperatures. Total poly(A) tail length distributions in the YRH201c cells, in which Nab2p is expressed from GAL promoter, on galactose, and after the shift into glucose medium are also shown (left). A 36-nucleotide long DNA oligonucleotide was used as a size marker. (B) Phenotypic rescue of the cold sensitivity of the nab2-1 mutant by overexpression of Pab1p or PAB3. The strains shown above the respective panels were streaked onto the selective synthetic medium and incubated at 18°C for 12 d. (C) FISH with the (dT)70 probe of the nab2-1 mutant cells transformed with the 2μ/PAB3 construct or an empty 2μ vector, as indicated, after the shift to the nonpermissive temperature (18°C) for 16 h. Staining for nuclei with DAPI is shown in the two right panels.
