Figure 7. Fluorescent in situ hybridization (FISH) analysis. A: Relative positions of the SSGP-11A1 and SSGP-11C1 genes. BAC clones 3k23 (containing SSGP-11A1) and 8p1 (containing SSGP-11C1 and -11C2) were labeled with red and green fluorescent dyes, respectively, and hybridized to polytene chromosomes prepared from larval salivary glands. A yellow image was observed in the overlapping region, indicating that these two BACs were located next to each other. In addition to a strong image at the distal region of chromosome A1 with the 3k23 (red) probe, a weak image was also detected in the proximal region of the same chromosome. This weak image appeared to be in the same region where the SSGP-11B gene family (see panel B), and might be caused by related hybridization. B: Relative positions of the SSGP-11B1 and SSGP-11C1 genes. BAC clones 8p24 (containing SSGP-11B1) and 8p1 (containing SSGP-11C1 and -11C2) were labeled with green and red fluorescent dyes, respectively, and hybridized to polytene chromosomes prepared from larval salivary glands. A single location for each BAC probe was observed in the Hessian fly genome. C: A physical map of the three SSGP genes. A map was constructed to show the relative chromosomal localization of the SSGP-11A1, SSGP-11B1, and SSGP-11C1 (and -11C2) genes according to the FISH analysis.