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Fig. 1. Development of the GF system. (A) GF development. The timing of events is
based on the work presented in the present paper as well as the dye injection
work of Jacobs et al. (Jacobs et al.,
2000). The time line is recorded as percent of pupal development
with time zero according to Bainbridge and Bounds (Bainbridge and Bounds,
1981). The phases indicated below the time line were determined experimentally
in the present work. The time of dye coupling was determined by Jacobs et al.
(Jacobs et al., 2000). t1, t2
and t3: first, second and third thoracic neuromere. (B) Expression patterns of
the three Gal4 constructs. (B1) Simultaneous staining of the GF (with c17) and
the TTMn (with shakB-Gal4) at 33% of pupal development. In this
particular specimen, the left GF has reached the TTMn and the right GF has
not. (B2) When driven by shakB-Gal4, lacZ is expressed in
the postsynaptic motoneurons and TTMn exhibits the strongest staining. (B3)
The P[Gal4]a307 enhancer is expressed strongly in the GF and more weakly in
the postsynaptic cells. In this specimen both GFs are labeled and the
dendrites of the left TTMn are revealed. (B4) The P[Gal4]-c17 enhancer is
expressed in the GF but not in the motoneurons. The developmental stage of
each specimen is indicated in the lower right of each panel. Scale bar: 20
µm.