Expression and splicing of tagged Zorro 3 RNA. (A) Map of tagged Zorro3 element showing primer locations. URNAR2 straddles the intron insertion site. (B) RT-PCR of tagged Zorro3 RNA. Genomic DNA and total RNA were separately extracted from a C. albicans CAI4 derivative stably transformed with a plasmid carrying a marked Zorro3 element. The RNA was reverse transcribed using oligonucleotide ZRNAR2 as a primer. PCRs were then performed using oligonucleotides URNAR1 and ZRNAR1 as primers. Templates in the reactions were as follows: lane 1, total RNA reverse transcribed with primer ZRNAR2; lane 2, total RNA not reverse transcribed; lane 3, genomic DNA; lane 4, no template. The intron-containing PCR amplicon obtained using primers URNAR1 and ZRNAR1 would be 364 bp long. Amplification of reverse transcribed RNA from which the intron had been precisely spliced would produce an amplicon of 280 bp. Primer URNAR2 was used (in combination with ZRNAR1) to quantify the tagged Zorro3 RNA (see text).