Fig. 4. Abnormal expression of Cyclin A in larval brains of dally mutants. Lateral views of LPCs and lamina (LA) of dally heterozygous (dallyP2/TM6B, A-C) or homozygous (dallyP2/dallyP2, D-F) larval brains stained with anti-cyclin A antibody (red, A,D) and propidium iodide (gray tones, B,E). C and F show merged images of A and B, and D and E, respectively. The numbers 1 and 2 in A mark the two consecutive LPC divisions that occur in front of and immediately posterior to the lamina furrow in a wild-type brain, respectively. The arrow marks a dividing cell in the first LPC division where loss of Cyclin A immunoreactivity is associated with entry into M phase, as shown by the condensed state of the chromosomes (A,B). The second LPC division cycle is completely absent in the dally mutant brain lobe, as shown by the lack of Cyclin A expression posterior to the lamina furrow. Arrows in D-F indicate cells in dally mutant brains that show condensed chromosomes, yet retain high levels of Cyclin A immunoreactivity.
