Ultrastructure of E_{1 + 2 + 9 + 12} inversion breakpoints in Drosophila subobscura

Abstract

Summary— The ultrastructure of the Drosophila subobscura chromosome regions around the breakpoints of the complex E1 + 2 + 9 + 12 gene arrangement was analyzed. This overlapping inversion is formed by the association of the E1, E2, E9, and E12 simple inversions. Ultrastructure of sections involving 58D/59A, 61C/D, 62D/63A, 64B/C, 67A/B, and 68B/C breakpoints on Est chromosomes were compared with the ultrastructure of sections involving 58D/68B, 62D/64C, 59A/63A, 64B/68C, 67B/61C, and 67A/61B breakpoints on E1 + 2 + 9 + 12 chromosomes. No detectable changes of structural organization on banding patterns induced by the E1 + 2 + 9 + 12 inversion were found. Ultrastructural analysis of the two E12 breakpoints has, however, facilitated the analysis of the left boundary of E12 inversion. Accordingly, we propose 61B/C as a new breakpoint instead of 61C/D.

The origin of chromosomal inversions as a source of segmental duplications in the Sophophora subgenus of Drosophila

“…At the cytological level and according to the Kunze-Mühl and Müller 24 map for the E st arrangement, the E 12 inversion breakpoints would be located at sections 61C/61D and 67A/67B for the proximal and distal breakpoint, respectively. However, a later comparison of the banding pattern of chromosomal arrangements E st and E 1+2+9+12 led Cuenca et al 25 to propose section 61B/61C as the proximal breakpoint.…”