Figure 2.

The pal-1(e2091) mutation is a point mutation within a conserved intronic sequence. (A) Complementation rescue experiments defining the gene segment containing the mutation. Two genomic DNA fragments were amplified from either wild type or pal-1(e2091) as shown, ligated at the NcoI site in either homologous or heterologous combinations, and injected into pal-1(e2091); him-5 hermaphrodites. Only the 3′ fragment from pal-1(e2091) failed to support rescue. Nucleotide positions are in cosmid C38D4. Likewise, the genomic-cDNA hybrid construct pSC16, which lacks the last intron of pal-1, failed to support rescue. (B) The two sequence differences between pal-1(e2091) and wild type. The sequence of the pal-1(e2091) coding region, including all introns, plus 1 kb of 3′ UTR was determined. One of the two mutations was reverted in the intragenic revertant pal-1(e2091 bx89), thus identifying T24264→C as the pal-1(e2091) mutation. (C) Alignment of part of the last intronic sequence of C. elegans and C. briggsae pal-1, showing the conserved region containing the pal-1(e2091) mutation.