S1 nuclease protection assay of human ɛ and Aγ transgene expression during mouse development in mice carrying HS2ɛγ and HS3ɛγ constructs. (A) Human ɛ transgene expression data from HS2ɛγ lines 187 (top panel) and 166 (bottom panel). Phosphorimager scans of S1 protection assays analyzing human ɛ transgene (hɛ) and mouse  gene (m) expression are shown from two embryos or fetuses at each time point. The band protected by the mouse ζ probe is not shown but was included in the calculations in Table 2. Y = yolk sac; L = fetal liver; 4WB = blood from 4-week old pups. (B) Human ɛ transgene expression data from HS3ɛγ lines 2649 (top panel) and 2564 (bottom panel). The band protected by the mouse ζ probe is not shown but was included in the calculations in Table 1. (C) Human Aγ transgene expression in HS2ɛγ lines. Samples are from line 192 (top panel) and 186 (bottom panel). (D) Human Aγ transgene expression in HS3ɛγ lines. Samples are from line 150 (top panel) and 155 (bottom panel).