QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 3 July 2006
doi: 10.1242/dev.02451

This Article Summary Full Text Full Text (PDF) Supplementary Material Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mihaly, J. Articles by Karch, F. Search for Related Content PubMed PubMed Citation Articles by Mihaly, J. Articles by Karch, F. Social Bookmarking                         What's this?

Dissecting the regulatory landscape of the Abd-B gene of the bithorax complex

¹ Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, 6723 Szeged, Hungary.
² Department of Zoology and Animal Biology and National Research Centre `Frontiers in Genetics', University of Geneva, 30 quai E. Ansermet, 1211 Geneva-4, Switzerland.
³ Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.

View larger version (26K): [in a new window]   Fig. 1. Regulatory landscape of the Abd-B gene of the BX-C. (A) Genomic map of the 3' cis-regulatory region of the Abd-B gene. The proximal and distal arrows point towards the centromere and telomere, respectively. The black numbers above the DNA line correspond to the nucleotide sequence marked in kb (SEQ89E) (Martin et al., 1995). The exons of the Abd-B transcription unit encoding the m variant are shown below the DNA line. The extent of the iab-5, 6 and 7 cis-regulatory domains are indicated by brackets, with the domain boundaries in between shown by gray circles. The red boxes on the DNA line mark the IAB5, IAB6, IAB7a, IAB7b and IAB8 initiator elements (from proximal to distal, respectively). The extent of the deletions analyzed are shown below the DNA line, in black for deletions associated with loss-of-function of phenotypes and in red for gain-of-function phenotypes. (B) The DNA line with the scales as in A is drawn again. The extent of the different restriction fragments used in transgenic constructs are shown below, with the initiator fragments drawn in red. The expression patterns directed by these initiator fragments are presented in C-F, which show embryos at the extended germ band stage, doubled stained with antibodies directed against Engrailed (brown) and the ß-Galactosidase (in blue). The parasegmental anterior border of lacZ expression (indicated by an arrow) shifts one parasegment posterior in each panel from left to right

View larger version (91K): [in a new window]   Fig. 2. Homeotic transformations in adult male. Male abdomens were cut along the dorsal midline and flattened on a slide. The dorsal surface of each abdominal segment has a rectangular plate of hard cuticle called the tergite. Only half of the tergites of the 4th, 5th and 6th abdominal segments (numbered) are visible, as well as the genitalia at the bottom. (A) In wild type, the 5th and 6th tergites are pigmented. The ventral surface of abdominal segments is composed of soft cuticle called the pleura. On the ventral midline of the pleura, there are small plates of harder cuticle called sternites. In wild type, the 6th sternite (shown by arrows) can easily be distinguished from the more anterior sternites by its different shape and by the absence of bristles. In wild-type males, the 7th abdominal segment present in embryos and larvae does not contribute to any adult structures after metamorphosis. (B) iab-7280males harbor a complete transformation of A7 into A6, as revealed by the presence of a large 7th tergite and sternites (arrows). (C) In iab-7R73 males, however, there is only a weak transformation of A7 into A6, as revealed by the small 7th tergite and the absence of a 7th sternite on the ventral side. (D) In iab-6,7IH, A6 is completely transformed into a copy of A5. However, A7 is only partially transformed into a segment of intermediate identity between A5 and A6, as seen by the shape of the 7th sternite, which resembles the 6th, but harbors a few bristles (A5 character). This indicates that in iab-6,7IH, iab-7 is not completely inactivated (E)In iab-5,6J82, both A5 and A6 are transformed into a copy of A4. (F) In iab-5,6J81 the residual pigmentation on the 6th tergite, as well as the shape of the 6th sternite show that A6 is not fully transformed into A4, but instead, into a mixture of identity between A4 and A6, suggesting that the iab-6 domain is not completely inactivated by the deletion. (G) In iab-4,5,6DB, A5 is transformed into A3. However, as in iab-5,6J81, the 6th segment harbors features of A6, suggesting that iab-6 is also not completely inactivated by the deletion.

View larger version (66K): [in a new window]   Fig. 3. Abd-B expression pattern in wild type and deficiency mutants. HRP staining with antibodies against Abd-B. After staining, the central nervous systems were dissected out from 12 hour-old embryos. In wild type, the typical Abd-B expression pattern is characterized by an anterior-to-posterior gradient from PS10 to 13 in the number of expressing nuclei per parasegment, as well as by the intensity in each nucleus. See text for the description of the expression patterns in the different mutants.

View larger version (87K): [in a new window]   Fig. 4. Mutations associated with gain-of-function phenotype. (A-C) Cuticles from adult males of homozygous Fab-3,5DV, wild type and Fab-6,71. See text and the legend of Fig. 2 for descriptions. (D-F) The corresponding Abd-B expression patterns in the CNS of 12-hour-old embryos (refer to legend of Fig. 3).

View larger version (19K): [in a new window]   Fig. 5. Initiators control the activity of whole domains. Two adjacent domains are drawn, as well as the target Abd-B gene further to the right. The thick blue rectangles symbolize silencing by the Pc-G complex(es). The example on the left shows an initiation domain, while the example on the right shows a non-initiated domain.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter