NB 7-2 details
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NB 7-2 delaminates at S2 in the intermediate column.
No information about the lineage derived from NB 7-2 is available from other insects.
NB 7-2 expresses intermediate neuroblast defective (ind), seven-up-lacZ (svp-lacZ) and engrailed (en) as it delaminates (Weiss et al, 1999; Doe, 1992; Broadus et al, 1995). At S3 ind is lost and at S4, castor (cas) and Klumpfuss (Klu) expression are added (Cui and Doe, 1992, 1995; Yang et al, 1997).
Bossing et al. (1996) described its lineage as containing 8-14 interneurons that project either contralaterally in the posterior commissure, or ipsilaterally posterior.
A.Interneurons:
There are ~8 intersegmental interneurons with two distinct projection patterns: 1) ipsilateral posterior for at least three segments, and 2) contralateral across the posterior commissure and then posterior. The contralateral projection is shorter and contains fewer axons than the ipsilateral projection (Fig. 7-2C). There are ~4 local interneurons that project anteriorly in both ipsilateral and contralateral connectives. The clone contains large oval presumptive intersegmental interneurons (7 x 4.2 um; n=16), and smaller presumptive local interneurons (4.1 um; n=10). NB 7-2 is the only lineage generating ipsilateral posterior intersegmental interneurons by stage 17.
References
Bossing, T., Udolph, G., Doe, C. Q., and Technau, G. M. (1996). The Embryonic CNS lineages of Drosophila melanogaster I. Neuroblast lineages derived from the ventral half of the neurectoderm. Dev Biol 179: 41-64.
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.
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.
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.
Weiss, J., VonOhlen, T., Mellerick, D., Dressler, G., Doe, C. Q., and Scott, M.P. (1998). Dorsoventral patterning in the Drosophila central nervous system: the intermediate neuroblasts defective homeobox gene specifies intermediate column identity. Genes Dev 12:3591-3602.
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.