Fig. 2. RNase protection assays show that SpGsc transcripts accumulate at mesenchyme blastula (MB), gastrula (G) and pluteus (P) stages. A negative control is provided by hybridization to yeast tRNA (ytRNA). Unhybridized probe (P), egg (E), 16-cell stage (16-c), VEB (very early blastula, 150 cells). The arrow indicates the band produced by the hybridized probe; trace amounts of undigested probe persist in some of the samples.