transcript expression was assayed at 20o
C from embryonic time 0 to 7.25 hours. The authors stated that this was a temperature correction factor of 1.7, therefore, corresponding to 0-3.25 hours of development at 25o
C. At time 0 prior to egg activation bcd
transcript lacks a poly-A tail. Upon activation the transcript is rapidly poly-adenylated. Maximal polyadenylation corresponds to maximal translation of the bcd
protein. At approximately 2 hours post activation at 25o
C significant deadenylation is observed which leads to reduced translation of bcd
protein and subsequent degradation of bcd
Following injection of the full length S35
transcript, the transcript becomes tightly localized to the anterior cortex of the embryo, reaching between 5-10% egg length.
transcripts localize as an anterior cap in mature oocytes and are found in a characteristic patchy pattern in nurse cells.
transcript accumulation occurs in 4 phases during oogenesis. Between stages S6 and S9, transcripts accumulate as a ring at the anterior end of the oocyte. In stages S9-S10a follicles, they localize to the apical region of nurse cells. As nurse cells contract in stages S10b-S11, all bcd
transcripts localize to the cortex at the anterior end of the oocyte. Between stage S12 and egg deposition they become localized to a spherical dorsally located region at the anterior pole. The distribution of bcd
transcripts in nurse cells and the oocyte is altered in exu
mutants. In early embryos, bcd
transcripts are restricted to the anterior pole. exu
mutations lead to nearly uniform distribution of bcd
RNA in the early embryo while stau
mutations produce a gradient of expression at the anterior pole of the embryo.
transcript is expressed at very low levels through all stages of development.
During oogenesis bcd
transcript is localized to the anterior edges of the oocyte and remains localized throughout oocyte development. bcd
transcript is also detected surrounding the nurse cell nuclei. In early embryos bcd
transcript is detected in an "anterior cap", with strong signal present in the most anterior part of the embryo. Lower levels of bcd
transcript are detected in a gradient up to 80% egg length.
is detected at high levels in nurse cells and in the anterior of oocytes. In embryos undergoing cleavage, an anterior-posterior gradient of bcd
expression is apparent. Expression levels subsequently decline, and are undectectable after the cellular blastoderm stage.