Of the seven translocations, only one (TB-10L16) has a break in the proximal euchromatic region, at the fourth chromomere (Fig.1B). Six others (TB-10L13, TB-10L20, TB-10L32, TB-10L34, TB-10L36 and TB-10L38) have breakpoints in the distal heterochromatic region: TB-10L34 and TB-10L38 at the junction of H1 and H2 (Fig.1C and 1D), TB-10L32 in H3 close to the junction of H2 and H3 (Fig.1E) and TB-10L13 at the junction of H2 and H3 (Fig.1F). TB-10L20 and TB-10L36 break in H3 (Fig.1G and1H), consistent with Linís earlier observation (Genetics 90: 613-627, 1978). The breakpoint of TB-10L36 is distal but close to that of TB-10L20. The results are summarized in Figure 2.
Figure 1. A-H Pachytene figure of the B chromosome and seven B-10 chromosomes. (A) B chromosome. (B) TB-10L16. (C) TB-10L34. (D) TB-10L38. (E) TB-10L32. (F) TB-10L13. (G) TB-10L20. (H) TB-10L36. The breakpoints are marked with an arrow.
2. B-breakpoints of seven B-10L translocations.
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