ABSTRACT Homeotic genes confer identity to the different segments of Drosophila. These are expressed in many cell types over long periods time. To determine when homeotic required for specific developmental events we have Ultrabithorax, abdominal-A and Abdominal-Bm proteins at times during development using GAL4 targeting technique. We find that early transient gene expression has no lasting effects on differentiation larval epidermis, but it switches fate other irreversibly (e.g. spiracle...

In Drosophila, the Hox gene Ultrabithorax (Ubx) specifies development of two different metameres--parasegment 5, which is entirely thoracic, and parasegment 6, includes most first abdominal segment. Here we investigate how a single can specify such morphologies. We show that, in early embryo, cells respond similarly to UBX protein both parasegments. The differences between parasegments 5 6 be explained by spatial temporal pattern expression these metameres. find no evidence for multiple...

During development, small RhoGTPases control the precise cell shape changes and movements that underlie morphogenesis. Their activity must be tightly regulated in time space, but little is known about how Rho regulators (RhoGEFs RhoGAPs) perform this function embryo. Taking advantage of a new probe allows visualisation RhoGTPase Drosophila, we present evidence Rho1 apically activated essential for epithelial invagination, common morphogenetic movement during embryogenesis. In posterior...

ABSTRACT Comparisons between Hox genes in different arthropods suggest that the diversity of Antennapedia-class homeotic present modern insects had already arisen before divergence and crustaceans, probably during Cambrian. gene duplications are therefore unlikely to have occurred concomitantly with trunk segment diversification lineage leading insects. Available data domains expression also generally conserved among insects, but changes regulation may played a significant role...

Abstract Hox proteins belong to a family of transcription factors with similar DNA binding specificities that control animal differentiation along the antero-posterior body axis. are expressed in partially overlapping regions where each one is responsible for formation particular organs and structures through regulation specific direct downstream targets. Thus, explaining how protein can selectively its targets from those another fundamental understand development. Here we analyse cis...

Members of the Rho family small GTPases are required for many morphogenetic processes to shape animal body. The activity this is regulated in part by a class proteins known as RhoGTPase Activating Proteins (RhoGAPs) that catalyse conversion RhoGTPases their inactive state. In our search genes regulate Drosophila morphogenesis, we have isolated several lethal alleles crossveinless-c (cv-c). Molecular characterisation reveals cv-c encodes RhoGAP protein RhoGAP88C. During embryonic development,...

Extradenticle (Exd) and Homothorax (Hth) function as positive transcriptional cofactors of Hox proteins, helping them to bind specifically their direct targets. The posterior protein Abdominal-B (Abd-B) does not require Exd/Hth DNA; and, during embryogenesis, Abd-B represses hth exd transcription. Here we show that this repression is necessary for function, maintained expression results in transformations similar those observed loss-of-function mutants. We characterize the cis regulatory...

ABSTRACT The genetic mechanisms controlling organ shape are largely unknown. We show that the Drosophila grain gene is required during development for shaping adult legs and larval posterior spiracles. Mutant short wide rather than long thin, while spiracles flat instead of dome-shaped. demonstrate encodes GATAc transcription factor. Analysis loss- of-function mutations at cellular level indicates affects by locally cell rearrangement. Ectopic expression causes major morphogenetic movements,...

It is commonly accepted that activation of most signalling pathways induced by ligand receptor dimerisation. This belief has been challenged for some vertebrate cytokine receptors the JAK/STAT pathway. Here we study whether DOME, Drosophila pathway, can dimerise and if dimerisation ligand-dependent. To analyse DOME homo-dimerisation, have applied a β-gal complementation technique allows detection protein interactions in situ. used previously cell culture but this first time it to whole...

The re-use of genes in new organs forms the base many evolutionary novelties. A well-characterised case is recruitment posterior spiracle gene network to Drosophila male genitalia. Here we find that this has also been co-opted testis mesoderm where required for sperm liberation, providing an example sequentially repeated developmental co-options. Associated co-option event, expression novelty appeared, activation segment determinant Engrailed anterior A8 controlled by common and regulatory...

Abstract The gonad is formed from two populations of cells originating at different locations: the primordial germ (PGCs), giving rise to either sperm or oocytes, and somatic gonadal mesoderm precursors (SGPs), which support development gametes. Following PGCs' migration during gastrulation, these meet, forming immature gonad. We present evidence that embryonic development, PGCs require canonical JAK/STAT signalling cascade migrate efficiently towards SGPs. Loss function for any element...

In vertebrates, seven signal transducer and activator of transcription (STAT) proteins bind to palindromic sites separated by spacers two or three nucleotides (STAT1), four (STAT6) (STAT2 STAT5a/b). This diversity binding provides specificity counter semiredundancy was thought be a recent evolutionary acquisition. Here, we examine the natural DNA‐binding single Drosophila Stat show that this is not case. Rather, Stat92E able activate target gene expression through both 3 n 4 spaced sites....

The ventral veinless (vvl) and trachealess (trh) genes are determinants of the Drosophila trachea. Early in development both independently activated tracheal primordia by signals that ill defined. Mutants blocking JAK/STAT signaling at any level do not form a tree suggesting STAT92E may be an upstream transcriptional activator early trachea determinants. To test this hypothesis we have searched for responsive enhancers activating expression vvl trh primordia. We show regulated can rapidly...

Organogenesis is controlled by gene networks activated upstream selector genes. During development the network stepwise, with a sequential deployment of successive transcription factors and signalling molecules that modify interaction elements as organ forms. Very little known about steps leading from early specification cells form primordium to moment when robust in place. Here we study detail how Hox protein induces during embryogenesis simple organogenetic cascade matures into complex...