Figure 6.—
Biorientation and segregation failure in incenp mutant oocytes. (A–C) FISH analysis of chromosome orientation. In contrast to the biorientation observed for the X bivalent (green FISH signal) in the w1118 control (A), in incenpQA26 Df(2L)Exel7049/incenpQA26 mutant oocytes the X bivalent (green) is monooriented (B and C). In these oocytes the fourth chromosomes (red) are bioriented. (D and E) Staining for MEI-S332 (red), spindle (green), and DNA (blue). MEI-S332 localizes to chromosomes in incenp mutant oocytes. Although it can localize in a pattern consistent with centromere localization (arrow in D), extra foci frequently are observed (E). (F and G) FISH analysis of chromosomes. Bivalents fail to biorient in incenpQA26 ord10/incenpQA26 oocytes. In F, the X chromosomes are bioriented (green) but the fourth chromosomes (red) monooriented, whereas the opposite is observed in G. Bars are indicated in each panel.