Figure 2.

Maternal-specific expression of the M. spretus H19 transgene. (A) M. spretus H19 transgenic founders of lines 21 and 25 were crossed to DBA/2J mice. Male and female transgenic progeny were backcrossed to DBA/2J and their transgenic (+) and nontransgenic (−) progeny assayed for expression of the transgene. The parental origin of the transgenes are indicated. Five micrograms of total RNA from neonatal livers was assayed by an RNase protection assay (22). Digestion conditions that allow one to distinguish transgene-specific products (arrows) also result in partial digestion of the endogenous RNA. The full-length endogenous H19 RNA is indicated by the closed circle. (B) Male and female siblings of pups inheriting the transgene through the paternal germ line were backcrossed to DBA/2J and RNAs from neonatal livers assayed as described above. Lane and protected fragment designations are as described for A.