FIGURE 7.

Analysis of concatemeric structure of the transgene and the junction sequence of transgenes in hTG mice. Southern blot analysis with either the 0.6-kb or the 1.1-kb probe indicated (as shown in Fig. 6) two DNA bands of about 5.8 and 5.1 kb in the hTG mice SP-A1(6A⁴) and SP-A2(1A³). These two bands are probably the result of a concatemer structure of the transgene. One 0.9-kb PCR DNA fragment could be generated with primers 1636 (sense) and 1634 (antisense) (data not shown). Because the sense primer 1636 is located in the 3′-UTR of the human SP-A gene and the antisense primer 1634 is on the flanking region of the human SP-C promoter, only a concatemer structure can produce the 0.9-kb PCR product. Sequencing analysis of the 0.9-kb PCR product revealed that two copies of the transgene form a concatemer structure. The junction sequence of the two copies of the transgene consists of a 3′-sequence (GCGGCC) of the first copy and a 5′-sequence (CATATG) of the second copy shown here. One additional base (G, shown in boldface type) was found between the two copies of the transgene.