Figure 1.

The fly Pss gene: structure and expression pattern

(A) PS synthesis in mammalian cell and Drosophila. Drosophila PSS is the only PS synthase in Drosophila.

(B) Homology between Drosophila PSS and human PSS1 and PSS2.

(C) Pss mutant alleles. Three P element insertions are clustered in a small region of the 5′ UTR. Pss^Δ1 is a deletion mutation in the second exon, which causes a frameshift in the ORF.

(D) Complementation tests. The trans-heterozygous mutants are in the same w⁺ background as we used the Pss³² line to collect virgins for crosses. With the ubiquitous overexpression of Pss, the viabilities of trans-heterozygous mutants were increased up to 139% of expected flies. Numbers indicate the ratio of observed/expected flies.

(E) Identification of cell types expressing Pss in the larval CNS and adult brain. mCherry expression by Pss-GAL4 (Pss>mCherry.nls) in the third instar larval (a', c') ventral nerve cord (VNC) and (b', d') brain, and (e', f') adult brain. (a", b", e") Glial cells were labeled by anti-Repo and (c", d", f") neuronal cells by anti-Elav. (a-f) Merged image of Pss>mCherry.nls with either anti-Repo or anti-Elav. Scale bar, 25 μm in a-d, 100 μm in e-f.