Both long and short pnr
transcript isoforms are expressed at the dorsal-most region of the wing disc.
After germband retraction, pnr
transcript is expressed just below the amnioserosa, and adjacent and dorsal to the ectodermal expression domain of ara
At stage 4 of embryogenesis, pnr
transcript is detected dorsally at 35-60% of egg length, in cells which will give rise to the amnioserosa and the dorsal ectoderm. pnr
is expressed in the amnioserosa until stage 9 of embryogenesis, and expression in the dorsal epidermis continues through dorsal closure.
In late third instar larvae, pnr
transcript is detected in a restricted pattern in the thoracic region of the dorsal mesothoracic (wing) disc. pnr
transcript levels are highest in the dorsal-most thoracic region, especially where the dorsocentral and scutellar bristles will arise, and decrease gradually over the thoracic epithelial region. pnr
transcript is also detected in a restricted pattern in the dorsal-most edge of the eye-antennal disc, in the region where postvertical and anterior vertical bristles will arise.
Northern blot analysis reveals that pnr
is expressed at high levels in embryos 2-12 hours post-fertilization. Using whole mount embryo in situ hybridization, pnr
transcript is detected as early as stage 5, in 5 stripes. At stage 5, which corresponds to cellularization, the pnr
transcript is present at 20-60% egg length, in a region which will give rise to the dorsal ectoderm and the amnioserosa. Early in stage 8, pnr
is expressed in the dorsal section of the embryo, in a region delineated by the cephalic furrow and the proctodeum. By mid-stage 8, during germband extension, pnr
transcripts begin to concentrate in the dorsal ectoderm, but some transcripts are still detected in the amnioserosa. In stage 11 embryos, pnr
expression is only seen in the epidermis dorsal to the tracheal pit. By stage 13, when germ band shortening is complete, pnr
transcripts are still present in the dorsal epidermis, but additional signal is detected in the posterior spiracles. At dorsal closure at stage 15, pnr
is expressed in a single cell layer on either side of the midline, and in an anterior cluster of epidermal cells.