NB 5-6 details
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NB 5-6 delaminates in the lateral column at S1.
No information about the lineage derived from NB 5-6 is available from other insects.
At S1, NB 5-6 expressies wingless (wg) and gooseberry-distal (gsb-d) (Chu-LaGraff and Doe, 1993; Doe 1992; Skeath et al, 1995; Broadus et al, 1995). At S3 it adds seven-up-lacZ (svp-lacZ) and Klumpfuss (Klu) expression (Broadus et al, 1995; Yang et al, 1997). By S5 it adds castor (cas) expression (Cui and Doe, 1992, 1995).
The NB 5-6 lineage was described by Schmidt et al. (1997) as containing 10-14 local interneurons and a variable number of glial cells in thoracic segments, with fewer interneurons in abdominal segments.
A. Interneurons
The local interneurons have four distinct axon trajectories: (1) anterior in the ipsilateral connective; (2) briefly posterior in the ipsilateral connective before reversing and projecting anterior (see Fig. 5-6C, asterisk and movies); (3) posterior in the ipsilateral connective; and (4) across the anterior commissure then extending anterior in the contralateral connective. Most interneurons are relatively large (5.2 um; n=8) but 2-3 cells are lateral, ventral, and smaller (3.2 um; n=7). The stage 17 clone spans the lateral half of the hemisegment (see Fig. 5-6).
B. Glia
We detect dorsal, medial and lateral sub-perineural glia with equal probabilities, but find it impossible to distinguish these cells except by position, which is greatly variable (Ito et al., 1995). We also observe (putative) medial-most cell body glia (Fig. 5-6C)in thoracic segments and occasionally see ventral sub-perineural glial cells (n=2).
References:
Broadus, J., Skeath, J. B., Spana, E. P., Bossing, T., Technau, G. M., and Doe, C. Q. (1995). New neuroblast markers and the origin of the aCC/pCC neurons in the Drosophila central nervous system. Mech Dev 53: 393-402.
Chu-LaGraff, Q., and Doe, C.Q. (1993). Neuroblast specification and formation regulated by wingless in the Drosophila CNS. Science 261(5128): 1594-7.
Cui, X., and Doe, C.Q. (1992). ming is expressed in neuroblast sublineages and regulates gene expression in the Drosophila central nervous system. Development 116(4): 943-52.
Cui, X., and Doe, C.Q. (1995). The role of the cell cycle and cytokinesis in regulating neuroblast sublineage gene expression in the Drosophila CNS. Development 121(10): 3233-43
Doe, C. Q. (1992) Molecular markers for identified neuroblasts and ganglion mother cells in the Drosophila central nervous system. Development 116: 855-863.
Ito, K., Urban, J., and Technau G. M. (1995). Distribution, Classification and Development of Drosophila glial cells in the late emrbyonic and early larval ventral nerve cord. RouxÕs Arch Dev Biol 204: 284-307.
Schmidt, H., Rickert, C., Bossing, T., Vef, O., Urban, J., and Technau, G. M. (1997). The embryonic Central Nervous System lineages of Drosophila melanogaster II. Neuroblast lineages derived from the dorsal part of the neurectoderm. Dev Biol 189: 186-204.
Skeath, J. B., Zhang, Y., Holmgren, R., Carroll, S. B., and Doe, C. Q. (1995). Specification of neuroblast identity in the Drosophila embryonic central nervous system by gooseberry-distal. Nature 376: 427-430.
Yang, X., Bahri, S., Klein, T., and Chia, W. (1997). Klumpfuss, a putative Drosophila zinc finger transcription factor, acts to differentiate between the identities of two secondary precursor cells within one neuroblast lineage. Genes Dev 11(11):1396-1408.