Fig. 7.

Northern blots showing the expression of a BgPGRP-LAs, b BgPGRP-SA, and c BgGNBP in M line and BS-90 snails (6–9 mm) exposed to E. paraensei or S. mansoni. For M line snails, lanes 1 and 2 show mRNA from snails at 12 and 17 dpe to E. paraensei. Lanes 3 to 5 show the expression level of three genes in snails that were not exposed (lane 3) or were exposed for 2 days to E. paraensei (lane 4) or to S. mansoni (lane 5). For BS-90 snails, lanes 1 to 3 show mRNA abundance of the three genes from snails that were not exposed (lane 1) or that were exposed for 2 days to E. paraensei (lane 2) or to S. mansoni (lane 3). Please note that the BgGNBP band is faint because the membrane had been stripped three times. Other Northern blots revealed that if the membrane was first probed by BgGNBP, it showed high expression level in all RNA samples, and differential expression was not observed (data not shown). In the case of BgPGRP-SA, the bands were intense, even though the membrane may have been previously stripped (the one shown here was stripped three times). For BgPGRP-LAs, the bands were always faint even on new membranes. Among the three genes, expression from lowest to highest was BgPGRP-LAs, BgGNBP, and BgPGRP-SA