Hox genes regulate muscle founder cell pattern autonomously and regulate morphogenesis through motor neurons.

The differentiation of myoblasts to form functional muscle fibers is a consequence of interactions between the mesoderm and ectoderm. The authors examine the role of segment identity in directing these interactions by studying the role of Hox genes in patterning adult muscles in Drosophila. Using the 'four-winged fly' to remove Ultrabithorax function in the developing adult, the authors alter the identity of the ectoderm of the third thoracic segment towards the second and show that this is sufficient to inductively alter most properties of the mesoderm-myoblast number, molecular diversity, and migration pattern-to that of the second thoracic segment.

Developmental genetics of Drosophila.

Drosophila melanogaster is one of the most valuable organisms in biological research, particularly in the areas of genetics and developmental biology. Drosophila has been used as a model organism in research for almost a century. The organism is easy to breed and has a short life cycle, making it ideal for the study of genetic mutations.

Characterization of the intergenic RNA profile at abdominal-A and Abdominal-B in the Drosophila bithorax complex.

The correct spatial expression of two Drosophila bithorax complex (BX-C) genes, abdominal-A (abdA) and Abdominal-B (AbdB), is dependent on the 100-kb intergenic infraabdominal (iab) region. The iab region is known to contain a number of different domains (iab2 through iab8) that harbor cis-regulatory elements responsible for directing expression of abdA and AbdB in the second through eighth abdominal segments. Here, we use in situ hybridization to perform high-resolution mapping of the transcriptional activity in the iab control regions.

Transcription defines the embryonic domains of cis-regulatory activity at the Drosophila bithorax complex.

The extensive infraabdominal (iab) region contains a number of cis-regulatory elements, including enhancers, silencers, and insulators responsible for directing the developmental expression of the abdominal-A and Abdominal-B homeotic genes at the Drosophila bithorax complex. It is unclear how these regulatory elements are primed for activity early in embryogenesis, but the 100-kb intergenic region is subject to a complex transcriptional program. Here, we use molecular and genetic methods to examine the functional activity of the RNAs produced from this region and their role in cis regulation.

The function ofbithorax genes in the abdominal central nervous system ofDrosophila.

We have analysed the influence of the bithorax gene complex (BX-C) on two segment-specific features of the central nervous system ofDrosophila larvae: the "presumptive leg neuromeres" (PLN), which are present only in the thoracic ganglia of the larva and develop into the leg neuromeres of the adult fly during metamorphosis; and the "lateral dots" (LD) which are found in the first abdominal as well as thoracic ganglia. We show in both cases that consecutive BX-C genes can suppress the development of these structures. We also show that each gene is expressed in several consecutive segments, leading to an apparent redundancy of the suppression in posterior segments.