Fig. 3

Temporal expression pattern of zebrafish follistatin and noggin. (A) Developmental RT-PCR analysis for follistatin, noggin, and the ef1α (control). Neither noggin nor follistatin transcripts are detected before 80% epiboly. noggin signals are weak during late gastrulation and segmentation stages, but much stronger during primordia stages, with a maximum at day 2. follistatin signals are of comparable strength throughout all investigated stages from 80% epiboly onward, with a slight maximum at the 8- and 15-somite stages. (B) Developmental Northern blot hybridized with follistatin probe. Ten micrograms of stage-specific total RNA was loaded per lane and stained with ethidium bromide as a loading control. Consistent with the results of RT-PCR, expression is first detectable at 80% epiboly, reaches a maximum at day 1 of development, and then declines. Note the two transcripts of follistatin. The larger transcript is 3.5 kb, the shorter transcript approximately 2.4 kb.