Dynamics and control of sister kinetochore behavior during the meiotic divisions in Drosophila spermatocytes
Fig 6
Sister KTs separation and bi-orientation during M II.
(A) Sister KT behavior during progression through the meiotic divisions as observed by time lapse imaging with spermatocytes expressing Cid-EGFP and His2Av-mRFP is illustrated by representative still frames displaying the Cid-EGFP signal associated with one pair of sister KTs (except for telophase II where a single sister KT is shown). Sister KTs are detected as a single Cid-EGFP dots (yellow circle) from NEBD I to NEBD II until unequivocal separation in metaphase II (yellow arrows). (B) Time lapse imaging revealed occasional transient splitting of Cid-EGFP dots (white arrows), as illustrated with an event during IK. Time (seconds) is indicated. Scale bar = 2 μm. The scatter plot describes separation width and duration of such events in the indicated genotypes (n = 13 in controls, n = 36 after Spc105 RNAi). (C-E) KTs in spermatocytes expressing His2Av-mRFP and Mis12-EGFP were tracked during M II followed by plotting of VKT (C), AKT (D) and DKT (E) over time. Black dotted lines mark the onset of the indicated division phases. (F) Spermatocytes expressing Mis12-EGFP and His2Av-mRFP were used for time lapse imaging of M II in the absence (control) and presence of colcemid. Inter sister KT distances (DKT) were measured at the indicated time points (minutes after NEBD II) and plotted with averages (+/- s.d.). (G) Separation of a sister KT pair during prometaphase II is documented with high magnification views (top) and a graph (bottom) of the distance between the two sister KTs (yellow line in stills) at the indicated time points (seconds after NEBD II). A track overlay in the top panel describes the displacement of one sister KT from the preceding to the displayed time point. Track color indicates VKT from slow (blue) to fast (red). Spindle axis is vertical. After 620 sec, the sister KT pair remained stably bi-oriented during congression into the metaphase plate (located at the upper edge of the images) until anaphase. Scale bar = 0.7 μm.