Figure 7.

Expression of the M. spretus transgene in H19 deletion maternal heterozygotes. (A) A female heterozygous for a deletion of the H19 gene region (23) and carrying the M. spretus transgene was crossed to a B6(CAST-H19) male. Total liver RNA was prepared from the progeny and analyzed for the expression of Igf-2 RNA using an allele-specific RNase protection assay that distinguishes M. castaneus Igf-2 RNA (+^C) from that of M. domesticus (+^D). Littermates were genotyped for the presence of the wild-type (+) or mutant (−) endogenous H19 gene (H19 genotype) and the presence (+) or absence (−) of the transgene (Tg). P, probe; M, markers. (B) The same RNAs were analyzed for the expression of the M. spretus H19 gene. The multiple bands in the + Tg lanes are the result of the fact that the probe (P) was derived from the M. castaneus gene.