Fig. 6

Cell division does not completely stop in spr mutants; however, each allele has a unique phenotype. (A) Illustration of lineage tracing analysis for EVL cells in wild-type and mutant embryos. (B) Average number of cell divisions in a clone between the time marked and 24 h or 36 h. Each point is based on 3 or more clones. After tailbud, EVL cells cease to divide in the spr^ro1 mutant. (C) Frames from a time-lapse recording, showing cell divisions still occur at 24 h in the EVL of wild-type embryos (top panel) and spr^tu21 mutants (bottom panel). The Dual FUCCI transgene reports cells in the S/G2/early M phase of the cell cycle (blue) or in the G1 (G0) phase of cell cycle (red). Wild-type cells take approximately 20 minutes to go from metaphase to the next S-phase; whereas mutants take about 1 hour. Scale bar is 10 μm. (D) Frames from a time-lapse recording, showing that deep cells continue to divide at 5-somites (11.5 h) in wild-type embryos (top panel) and spr^ro1 mutants (bottom panel) using H2B-RFP mRNA (pseudo colored in green) shows that wild-type cells take approximately 15 minutes to get through mitosis, whereas mutants take about 35 minutes. Scale bar is 5 μm.