Glial Precursor (GP)

LINEAGE: Unlike other neuroblasts, the glial precursor (sometimes known as the glioblast) does not divide to make GMC's or neurons. The GP divides roughly symmetrically during stage 11 to produce two cells which eventually divide to generate six longitudinal glia. These cells migrate from their birthplace laterally to prefigure the position of the longitudinal axon connectives. At stage 16, the longitudinal glia are positioned on the dorsal side of the nerve cord, dorsal to the longitudinal axon tracts. These cells have been proposed to function as a substrate for longitudinal axon guidance. ( Jacobs and Goodman, 1989, Jacobs et al., 1989).

GENE EXPRESSION: At formation at stage 10, the GP expresses fushi-tarazu ( Doe et al., 1988), mirror-lacZ (Broadus et al., 1995), and repo/RK2 (Xiong et al., 1994; Campbell et al., 1994; Halter et al., 1995). The expression of mirror-lacZ and repo/RK2 is maintained in the longitudinal glia at stage 16. ftz is not maintained, though a few ftz-lacZ lines do maintain expression in these cells. prospero found in the nuclei of the longitudinal glia. (Those are the green cells in the splash picture of the lab home page). orthodentical (otd) protein was thought to be expressed in the longitudinal glia, however this expression was found to be a cross-reactivity of that particular antibody to the repo/RK2 protein (E.P. Spana, unpublished).. There are a variety of enhancer trap lines that express in the longitudinal glia including: r56, KZ663, 566-Gal4, etc.

GENE FUNCTION: repo/RK2 mutants generate less longitudinal glia cells. They have less pros positive cells per segment (usually 1 or 2 instead of 6), and have faciculation defects in the longitudinal tracts ( Campbell et al., 1994). The longitudinal glia do not differentiate and enwrap the axons in pros mutants (Jacobs et al., 1993).

Go back.