mahj1 homozygotes and mahj1/Df(2R)XE-2900 transheterozygotes exhibit signs of quiescence in the larval brain: neuroblasts show a significant decrease in cell divisions (DNA replication/EdU staining); are significantly decreased in number; and frequently show a primary cellular process, whereas control neuroblasts show a typically rounded morphology. In agreement, mahj1 homozygous larvae exhibit a small brain, as compared to controls.
Like in controls, mushroom body neuroblast lineages in mahj1 homozygous larvae are able to under cell division (DNA replication/EdU staining).
Homozygous and mahj1/Df(2R)XE-2900 animals develop more slowly than normal.
Homozygous larvae do not have any detectable morphological defects.
Analysis of homozygous clones in the wing disc shows that 72 hours after clone induction, both homozygous and wild-type sibling clones are readily detected. However, at 96 hours after clone induction, the homozygous clones are smaller than the sibling clones, and by 120 hours after clone induction, most of the homozygous clones have disappeared from the wing disc epithelium. Homozygous cells adjacent to wild type or heterozygous cells frequently undergo apoptosis, whereas homozygous cells that are not adjacent to wild type or heterozygous cells rarely undergo apoptosis. The majority of apoptotic cells are basally extruded from the disc epithelium, but some remain within the epithelial layer. Basally extruded homozygous cells which are not apoptotic are also sometimes seen.