Fig. 4.

Use of whole-chromosome paints to characterize chromosomal aberrations. (A) Labeled libraries of chromosomes 1 (green) and 5 (red) were applied to homozygous material of reciprocal translocation T1-5 (8041). The centromere satellite, CentC, is labeled in white. Previous studies have demonstrated that the set of centromere sequences present at the translocation breakpoint is inactive (37). The reciprocally exchanged chromosomes are labeled T1-5 and T5-1. (B) Reciprocal translocation T5-9d was probed with the two respectively labeled libraries (5, green; 9, red). (C) Reciprocal translocation T7-9 (4363) was probed with the two respectively labeled libraries (7, green; 9, red). (Inset) Enlarged image of a T7-9 homolog from a different metaphase spread shows the breakpoint in the short arm of chromosome 7. The arrowheads at the constriction denote the position of the centromere. (D) Chromosome painting of homozygous material of T1La-B-10L18, which is a chromosome with a B centromere that has the long arm of chromosome 1 joined together with the long arm of chromosome 10, which was recovered in a test for recombination in the B chromosome (40) as described in the text. Chromosome 1 is labeled in green, and chromosome 10 in red. The T1L-B-10L chromosome is the recombinant with red and green in the opposite arms. The B chromosome centromere-specific sequence is labeled in yellow on this chromosome (Materials and Methods). The homologs of the reciprocal product of TB-1La, labeled T1-B, consist of a portion of the long arm of the B chromosome exchanged near the centromere within 1L and an intact short arm of chromosome 1. The homologs of the reciprocal product of TB-10L18, labeled T10-B, consist of the short arm of the B chromosome exchanged near the centromere in the long arm of chromosome 10 and an intact short arm. The T1-B and T10-B chromosomes have portions that are not labeled by chromosome paints because they are derived from the B chromosome. (E) Heterozygous material of transposition Tp1L-3L was labeled with paints of chromosomes 1 (green) and 3 (red). The chromosome 3 carrying a small interstitial segment of 1L is labeled Tp1L-3L. The normal chromosome 1 is labeled 1N, and normal chromosome 3 is labeled 3N. (F) Heterozygous material of Tp3L-9S was probed with labeled libraries for chromosomes 3 (red) and 9 (green). The transposition chromosome is labeled Tp3L-9S, and the normal chromosomes are labeled 9N and 3N. The Insets show a magnified region of the 3L transposition with label and in grayscale. (Scale bar, 5 µm.)