This is a follow up to the previous project on the intron retention of yellow fin tuna and albacore (see report for ASP Spring 2001). Since there was a lack of a sufficient clone for DNA sequencing in the previous study, a new methodology was used in the present study. Further, three different species of fish were chosen to ascertain whether the phenomonon of intron retention is broadly found. The three species used were: tuna, roosterfish, and zebra fish. The second focus of the project was the caharcterization of exon/intron boundaries of the slow-twitch RyR1 isoform and determining if the intron is predisposed for retention.