The International Journal of Developmental Biology

Int. J. Dev. Biol. 54: 1251 - 1258 (2010)

Vol 54, Issue 8-9

Drosophila castor is regulated negatively by the Ubx and abdA genes, but positively by the AbdB gene

Original Article | Published: 18 May 2010

Ju-Hyun Ahn1, Siuk Yoo2, Hyun-Joo Park2, Keuk-Il Jung1, Sang-Hee Kim3 and Sang-Hak Jeon*,1

1Department of Biology Education, Seoul National University, Seoul, 2Department of Biology, Yeungnam University, Gyeongsan and 3Department of Chemistry, Konkuk University, Seoul, Korea


The ventral nerve cord (VNC) of Drosophila exhibits significant segmental-specific characteristics during embryonic development. Homeotic genes are expressed over long periods of time and confer identity to the different segments. castor (cas) is one of the genes which are expressed in neuroblasts along the VNC. However, at late embryonic stages, cas transcripts are found only in head and thoracic segments and terminal abdominal segments, while Cas protein lasts longer in all segments. In this study, we investigated the regulation of temporal and spatial expression of cas by the bithorax complex genes. In the loss-of-function mutants of Ultrabithorax (Ubx) and abdominal-A (abdA), cas transcripts were ectopically expressed in abdominal segments at late embryonic stage. However, unlike in Ubx and abdA mutants, in Abdominal-B (AbdB) loss-of-function mutant embryos, cas disappeared in the terminal region. Ectopic Ubx and abdA suppressed cas expression, but ectopic AbdB activated cas expression in most abdominal segments. Moreover, cas was co-expressed in the cells in which AbdB was normally expressed, and overexpressed in the ectopically expressed AbdB embryos. These results suggest that the expression of cas is segment-specifically regulated negatively by Ubx and abdA genes, but positively by the AbdB gene.


Ubx, abdA, AbdB, castor, neuroblast

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