NB 5-5 details
Video
NB 5-5 delaminates at S5.
In Grasshopper, NB 5-5 generates the first and third common inhibitory motoneurons, CI1 and CI3 (Hale and Burrows, 1985), as well as intersegmental interneurons with GABA-like immunoreactivity (Burrows, 1996).
In Drosophila, NB 5-5 expresses wingless (wg), gooseberry distal (gsb-d), seven-up-lacZ (svp-lacZ), huckebein (hkb), Klumpfuss (Klu), and unplugged (upg) as it forms (Doe 1992; Chu-LaGraff et al, 1993, 1995; Skeath et al, 1995; Broadus et al, 1995; Yang et al, 1997; Chiang et al, 1995).
Schmidt et al (1997) did not report a lineage for NB 5-5. They did report clone Y however, which they did not attribute to a neuroblast. They observe Clone Y to consist of 6-9 interneurons, and a motorneuron that extends through the median nerve and exits the CNS via the Transverse Nerve. They observed a number of other complex projections associated with this clone as well. We conclude that clone "y" is produced by NB 5-5 and that the reported motoneuron is likely to be a neurosecretory cell.
A. Neurosecretory Cells
Both thoracic and abdominal clones contain a ventral cell that migrates to the midline and has a rhomboidal-shape (10 x 7.5 um at stage 17; n=2). It extends two bifurcating projections laterally before joining the TN nerve (Fig. 5-5, broken circles). This putative neurosecretory cell is similar to the description of the Manduca Va neurosecretory cell in shape and ganglionic position (OÕBrien and Taghert, 1989; Carr and Taghert, 1988 a,b). Its position is also similar to that of the medial CCAP-positive cell previously observed in Drosophila and Manduca (Broadie et al., 1990; Tublitz and Sylwester, 1990). Finally, we cannot completely rule out the possibility that this cell is a TN motoneuron, as postulated by Schmidt et al. (1997), because its mature endings may form post-embryonically.
B. Interneurons
Most of the clone consists of local interneurons that project either across the posterior commissure or posteriorly in the ipsilateral connective. Both interneuronal projections are at the dorsal surface of the CNS.
References:
Broadie, K., Sylwester, A., Bate, M., and Tublitz, N. J. (1990). Immunological, biochemical and physiological analyses of cardioacceleratory peptide 2 (CAP2) activity in the embryo of the tobacco hawkmoth, Manduca sexta. Development 108: 59-71.
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.
Carr, J.N., and Taghert, P. H. (1988a). Formation of the Transverse Nerve in moth embryos: I. A scaffold of non-neuronal cells prefigures the nerve. Dev Biol 130: 487-99.
Carr, J.N., and Taghert, P. H. (1988b). Formation of the Transverse Nerve in moth embryos. II. Stereotyped growth by the axons of identified neuroendocrine neurons. Dev Biol 130: 500-512.
Chiang, C., Young, K.E., and Beachy, P.A. (1995). Control of Drosophila tracheal branching by the novel homeoomain gene unplugged, a regulatory target for genes of the bithorax complex. Development 121(11):3901-12.
Chu-LaGraff, Q., and Doe, C.Q. (1993). Neuroblast specification and formation regulated by wingless in the Drosophila CNS. Science 261(5128): 1594-7.
Chu-LaGraff, Q., Schmid, A., Leidel, J., Broenner, G., Jaeckle, H., and Doe, C. Q. (1995). huckebein specifies aspects of CNS precursor identity required for motoneuron axon pathfinding. Neuron 15: 1041-1051.
Doe, C. Q. (1992) Molecular markers for identified neuroblasts and ganglion mother cells in the Drosophila central nervous system. Development 116: 855-863.
Hale, J. P., and Burrows, M. (1985). Innervation patterns of inhibitory motor neurons in the thorax of the locust. J. Exp Biol 117: 401-413.
OÕBrien, M. A., and Taghert, P. H. (1989). A peritracheal neuropeptide system in insects: release of myomodulin-like peptides at ecdysis. J. Exp Biology 201: 193-209.
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.
Tublitz, N. J., and Sylwester, A. W. (1990). Postembryonic alteration of transmitter phenotype in individually identified peptidergic neurons. J. Neurosci 10(1): 161-8.
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.