Table 2 Breakpoints on 2nd chromosome balancers
Balancer(s)Component aberrationPolytene breakpoint1Proximal breakpoint coordinateDistal breakpoint coordinateDuplication (+) or deletion (–)Predicted band2Disrupts
SM1, SM5, SM6a, CyOIn(2L)Cy22D1–2Unknown3Unknown3Unknown22D1CG11723, TBCD, or AIF4
33F5–34A1Unknown5Unknown5Unknown33F4MRP
SM1, SM5, SM6a, CyOIn(2R)Cy42A2–32R:6,012,4592R:6,012,739+28042A75′ of Src42A
58A4–58B12R:21,971,9182R:21,972,072−15358A4
SM1, SM5, SM6aIn(2LR)SM122A3–22B12L:1,586,8452L:1,586,840−422A3haf, CG10869
60B–60C2R:24,117,0462R:24,117,059−1260B11CG3257
SM6a, CyOIn(2LR)O30E–30F2L:9,805,5752L:9,805,567−730D1nAChRα6
50C10–50D12R:14,067,7712R:14,067,782−1050D4Prosap
SM5In(2L)SM5-1621D1–22L:675,1872L:675,190+421E2ds
36C2L:16,995,3372L:16,995,336+236B6
SM5In(2L)SM5-2629C–29EUnknown7Unknown7Unknown29D5–E48Unknown
40FUnknownUnknownUnknownUnknownUnknown
SM5Dp(2;2)SM5642DUnknown96,917,406Unknown42E1CG3015810
53C2R:16,682,3512R:16,682,827−47553D1CG30463
58F2R:22,689,9622R:22,689,962059A2CR4476311
  • 1 Breakpoint observed in polytene chromosome preparations (Lindsley and Zimm 1992).

  • 2 Breakpoint position predicted from genomic coordinate using FlyBase correlation table.

  • 3 Breakpoint mapped to the interval 2L:2,146,403–2,156,403.

  • 4 One or none of these three genes may be affected by the breakpoint.

  • 5 Breakpoint mapped to the interval 2L:12,726,221–12,736,221.

  • 6 Because SM5 arose from SM1 through two inversions (In(2L)SM5-1 followed by In(2L)SM5-2) and a complex rearrangement, we have given symbols to these component aberrations to replace the single aberration In(2LR)SM5. The symbol Dp(2;2)SM5 was chosen for the complex rearrangement to emphasize the duplicated segment from the progenitor over the inverted segment.

  • 7 This breakpoint could not be localized molecularly, but recessive lethality presumably associated with the breakpoint was mapped to the interval 2L:8,529,124–8,700,124 by complementation tests with molecularly defined chromosomal deletions.

  • 8 Bands corresponding to the 2L:8,529,124–8,700,124 interval defined by chromosomal deletions.

  • 9 The proximal side of the breakpoint is present in two presumably identical copies juxtaposed to low-complexity sequence and maps to the 2L:6,916,809–6,917,405 interval.

  • 10 The sequence on the distal side of the breakpoint suggests this gene is disrupted.

  • 11 A second, intact copy of this gene is present elsewhere on SM5.