FIG. 1.

Analysis of a diploid S. pombe strain heterozygous for the uaf2::LEU2 deletion-replacement allele. (A) Genomic Southern blot of DNA from SpCW1 (see Materials and Methods) and its parent strain, SpDS3. The probe was pBSK⁺, containing the 5.1-kb XbaI fragment labeled by random priming. In SpCW1, replacement of one copy of the uaf2⁺ gene with LEU2 increases the size of the endogenous XbaI fragment (5.1 kb) by 1.4 kb, producing a 6.5-kb fragment containing the uaf2::LEU2 null allele. The second allele of uaf2⁺ remains a 5.1-kb fragment. In the parental diploid SpDS3 (3), both copies migrate at 5.1 kb. (B) Schematic representations of the wild-type and deletion-replacement alleles of uaf2⁺. (C) Plate assay demonstrating complementation of the fission yeast small-subunit null allele by plasmids expressing either S. pombe or human U2AF³⁵. Empty vector was used as a negative control. A, adenine; L, leucine. See the legend to Table 2 for details.