Expression: prospero (pros) is expressed in the CNS, PNS, midgut primordia (Adult midgut precursors?), and Garland gland in the embryo. In the PNS, pros is cortical in the SOP for ES organ, asymmetrically localized to the progeny B cell where it translocates into the nucleus. It is then nuclear in the B cell progeny neuron and glia. It is repressed in the neuron and maintained in the glia through stage 16. It is also maintained in the scalopale cell of the chordotonal organ.

In the CNS, pros protein is nuclear in MP2 and MNB, but cortical in all others. See Map. pros RNA is transcribed in all neuroblasts, but the protein is localized to the neuroblast cortex in a cell-cycle dependent manner. The protein is then asymmetrically localized to the GMC at mitosis where it resides on the cortex for a short time after cytokinesis before being translocated into the nucleus. pros remains nuclear through the next mitosis where it is equally distributed to the two progeny neurons. It remains in the neurons for a period of time (we don't know exactly how long after mitosis each neuron turns off). pros is maintained in the nuclei of the six longitudinal glia and a small cluster of nuclei on the lateral side of the nerve cord.

There are changes in gene expression in the GMCs. The expression of eve and ftz is reduced and the anterior compartment engrailed positive neurons are missing. Genes expressed in neuroblasts but not GMCs are maintained into the GMCs: deadpan, asense and the posterior compartment engrailed neurons. There are massive defects in axonogenesis. The anterior and posterior commisures do not separate and the longitudinal connectives do not form (Doe et al., 1991; Vaessin et al., 1991). Motorneuron outgrowth is severely delayed/retarded (Broadie and Bate, 1993). Condensation of the nerve cord is defective in both the A/P and mediolateral directions. Severe gaps are found in the midline of the nerve cord (Doe et al., 1991). The longitudinal glia do not differentiate (Jacobs, 1993).

In the PNS, there are severe axonal defects but no changes in gene expression noted, yet. So far, there has been no phenotype identified in the gut and Garland gland.

Other remarks
In the third-instar larvae, pros expression is about the same in the CNS. pros is not expressed in the optic lobe precursors, though. Disk expression looks like it is probably confined to PNS organs, except the eye disk. In the eye, pros is nuclear in the "R7 equivalence group" (R7 and cone cells) from the time of their determination. At midpupal stage pros is only in R7 and the bristle organ glia. (No, pros isn't required for R7 formation, we did look).

Homologs for prospero have been identified in mouse and C. elegans. (Oliver et al., 1993; Burglin, 1994). Protein expression in these organisms is unknown.

References: The FlyBase entry for prospero gives alot of useful info. You can access DNA and protein sequences and various references from there. The following references give the gist of pros expression in CNS.

Originally identified in: Doe,C.Q., Chu-LaGraff,Q., Wright,D.M. and Scott,M.P. Cell 65, 451-464, 1991.

Initial GMC protein localization in: Vaessin, H., Grell, E., Wolff, E., Bier, E., Jan, L. Y. and Jan, Y. N. Cell 67, 941-953, 1991.

Additional protein localization in: Matsuzaki, F., Koizumi, K., Hama, C., Yoshioka, T. and Nabeshima, Y. Biochemical and Biophysical Research Communications 182, 1326-1332, 1992.

More info: Chu-Lagraff, Q., Wright, D.M., McNeil, L.K. and Doe, C.Q. Development Supplement 2, 79-85, 1991.

Asymmetric protein localization in neuroblasts: Spana, E. and Doe, C. Q. Development, in press, 1995.

pros protein expression in the longitudinal glia shown in: Campbell, G., Goring, H., Lin, T., Spana, E, Andersson, S., Doe, C.Q. and Tomlinson, A. Development 120, 2957-2966, 1994.

pros interaction with abl: Gertler, F.B., Hill, K.K., Clark, M. J. and Hoffmann, F.M. Genes and Development 7, 441-453, 1993.

C. elegans pros: Burglin, T.R. Trends in Biochemical Sciences 19, 70-71, 1994.

Mouse pros, Prox1: Oliver, G., Sosa-Pineda, B., Geisendorf, S., Spana, E.P., Doe, C.Q. and Gruss, P. Mechanisms of Development 44, 3-16, 1993.

Motor axon defects: Broadie, K. and Bate, M. Nature 361, 350-353, 1993.

Longitudinal Glia defects: Jacobs, J.R. Journal of Neurobiology 24, 611-626, 1993.

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