As deduced from GFP labeled nos
transcripts in early egg chambers nos
transcript localizes to the posterior of the oocyte. There is a transient redistribution to an anterior ring at the margin of the oocyte during stages 8 and 9. nos
transcript is no longer detected in the oocyte at stage 10. At stage 10b nurse cell dumping is initiated and by stage 11 nos
transcript can be detected in the posterior cortex of the oocyte with a punctate distribution. Cooccurence with vas
protein suggests that nos
transcript associates with the germ plasm. Maximum accumulation of nos
transcript is observed at stage 13/14.
in situ hybridization detects a localized nos
transcript at the posterior pole in embryos, however, northern blot analysis detects high transcript levels in both anterior and posterior embryo halves, indicating that transcript is expressed uniformly, and subsequently localized to the posterior pole.
During oogenesis, nos
transcipt is first clearly detected at stage S5, in both nurse cells and oocytes. At stage S7-8, nos
transcript transiently localizes to the anterior margin of the oocyte. At stage S10, a high level of nos
transcript is present in oocytes; this transcript subsequently dumped into the oocyte. By stage S12, nos
transcript begins to accumulate at the posterior pole of the oocyte, and is localized to the posterior pole of the oocyte at the later stages of oogenesis. In embryos, nos
transcript is undetectable after germ band extension.
In wild type and in pum
mutant embryos, nos
RNA is localized to the posterior pole plasm.
Wild type nos
transcripts are expressed in a wild type pattern at the posterior pole in nosbcd.3UTR
embryos. wild type nos
transcripts are absent in nosbcd.3UTR
embryos from osk1
transcripts containing a bcd
3'UTR are localized at the anterior end of embryos in a distributionresembling the wild type bcd
The 2.4 kb nos
transcript is detected at high levels in ovaries and in 0-2 hour embryos, and at much lower levels in 2-8 hour embryos. This transcript is not detected in older embryos, larvae, or pupae. The nos
transcript localizes to the posterior pole of stage 1-2 embryos. The levels of nos
transcript in pole cells are high at stage 3 and 4, and have declined dramatically by early germ band extension (stage 8), with no pole cell-specific staining detected after stage 10.