Misexpression of labial does, however, result in axonal projections defects in central brain lineages.
The brain lineages have been named by various groups in the past.
Nevertheless, some of the brain lineages also appear to be simple, rather homogeneous collections of neurons and we would expect these to also represent parallel processing units.
Thus, while labial misexpression does not appear to affect neuroblast survival, it can result in aberrant secondary axon tract projection patterns in central brain lineages during postembryonic development.
The recent characterization of lineages in the fly brain (Ito et al., 2013; Yu et al., 2013) shows many brain lineages that contain a greater diversity of cell types than we see for the VNS hemilineages.
As most postembryonic lineages have now been identified in both the larval and adult brains, such molecular genetic analyses can now be extended to other brain lineages (Ito et al., 2013; Lovick et al., 2013; Wong et al., 2013; Yu et al., 2013).
Since both clonal cell death block and clonal labial inactivation result in the formation of the same two ectopic neuroblast lineages, these findings imply that labial is required in these two postembryonic brain neuroblast lineages for termination of proliferation through programmed cell death.
Furthermore, it has been recently shown that the missexpression of PROS at high level suppresses proliferation in type II larval brain NBs lineages without apparent change in their identity [47].
Development, morphogenesis, and differential Otd expression in two identified central brain neuroblast lineages, LALv1 and ALad1.
The main event in this first phase is the proliferation of neuronal progenitors followed by the establishment and maturation of the 2 main brain cell lineages (neurons and glia).
To determine if the Hox gene labial is also able to induce programmed cell death in central brain neuroblast lineages other than Ect1 and Ect2, we performed a clonal MARCM misexpression assay of labial.
