Temporal expression profiles of the expL3 gene. A: Developmental time course of expL3 splicing detected by semi-quantitative RT-PCR. Total RNA was extracted from Ax2 cells every 3 h and used as a template for the amplification of a specific expL3 to detect DNA fragments with or without an intron. The image shows the RT-PCR results for expL3 after 30 cycles of amplification. Note that after 30 cycles of amplification, the band intensity was almost saturated between 12–21 h. The band of approximately 200 bp contained an intron whereas the band of approximately 100 bp did not. The stages are loose aggregate (6 h), mound (9 h), tipped aggregate (12 h), slug (15 h), Mexican hat (18 h), culminant (21 h), and mature fruiting body (24 h), respectively. B: Expression profiles of the expL3 gene during multicellular developmental stages. The upper row shows the RT-PCR results for expL3 after 27 cycles of amplification before the PCR reaction saturated. IG7 was detected using the same cDNA as a normalization control. The IG7 DNA product (lower row) was detectable after 17 cycles of amplification.