Gain-of-function screen for genes that affect Drosophila muscle pattern formation.

This article reports the production of an EP-element insertion library with more than 3,700 unique target sites within the Drosophila melanogaster genome and its use to systematically identify genes that affect embryonic muscle pattern formation. We designed a UAS/GAL4 system to drive GAL4-responsive expression of the EP-targeted genes in developing apodeme cells to which migrating myotubes finally attach and in an intrasegmental pattern of cells that serve myotubes as a migration substrate on their way towards the apodemes. The results suggest that misexpression of more than 1.5% of the Drosophila genes can interfere with proper myotube guidance and/or muscle attachment. In addition to factors already known to participate in these processes, we identified a number of enzymes that participate in the synthesis or modification of protein carbohydrate side chains and in Ubiquitin modifications and/or the Ubiquitin-dependent degradation of proteins, suggesting that these processes are relevant for muscle pattern formation

Control of triglyceride storage by a WD40/TPR-domain protein

Obesity is a metabolic disorder related to improper control of energy uptake and expenditure, which results in excessive accumulation of body fat. Initial insights into the genetic pathways that regulate energy metabolism have been provided by a discrete number of obesity-related genes that have been identified in mammals. Here, we report the identification of the adipose (adp) gene, the mutation of which causes obesity in Drosophila. Loss of adp activity promotes increased fat storage, which extends the lifespan of mutant flies under starvation conditions. By contrast, adp gain-of-function causes a specific reduction of the fat body in Drosophila. adp encodes an evolutionarily conserved WD40/tetratricopeptide-repeat-domain protein that is likely to represent an intermediate in a novel signalling pathway

Muscle Pattern Defects in <i>esg</i> and <i>sdc</i> Mutants

<p>Muscle pattern of three segments of <i>oreR</i> (A, D, and G), <i>esg ^L2</i> (B and H), and <i>sdc ²³</i> mutant embryos (C, E, F, and I) after staining with anti-MHC antibodies or using a <i>delilah</i> transcript-specific anti-sense RNA probe (G–H). Lateral (A–C and G–I) and ventral views (D–F) of embryos at stage 14 (E) and stage 16 (A–D and F–I). <i>esg</i> mutant embryos show variable muscle pattern defects with muscles absent ([B], arrowheads). In <i>sdc</i> mutant embryos few muscles cross the ventral midline in a position dorsal to the central nervous system ([E], arrowheads), and they show disruptions of the pattern in the ventral region ([C], arrowheads). The typical “finger-type pattern” of the ventral muscles of wild-type embryos (D) is unordered in <i>sdc ²³</i> mutant embryos, with ventral muscles aligning in parallel with the anterio-posterior axis, ignoring the segment border attachment ([F], arrowheads). Also shown is the pattern of epidermal muscle attachment sites (<i>delilah</i> marker gene expression) in wild-type (G), <i>esg</i> (H), and <i>sdc</i> (I) mutant embryos. Note that the pattern is unchanged in the mutants.</p

Expression Patterns of Genes that Cause a Gain-of-Function Muscle Phenotype

<p>Lateral views of embryos at stage 11 (M), stage 13 (A, C, E, G, I, K, and N), and stage 16 (B, D, F, H, J, and L) that were stained with transcript-specific anti-sense RNA probes or with anti-Toll antibodies (A and B). Note the expression of Toll (A and B) in segment border cells, <i>sdc</i> (LD08230) (C and D) in trachea, segment border cells, and the differentiated apodemes, CG3563 (LD15689) (E and F) in the apodeme precusor cells at the segment border, CG13913 (RE53394) (G and H) and CG5008/<i>gnbp3</i> (SD21560) (I and J) in a subset of apodeme precursors and cells of the epidermis, CG14713/14714 transcripts (AT17253) (K and L) in the dorsal and ventral epidermis around the segment border, and <i>pxb</i> (SD26190) (M and N) in intrasegmental epidermal stripes.</p

Schematic Representation of the Classification of the 66 Identified Candidate Genes into Functional Groups

<p>The affiliation of the genes products is indicated by the color and the size of the fragments represents the quantitative distribution. cytsk., cytoskeleton; nucl. acid bdg., nucleic acid binding; prot. mod. + degrade., protein modification or degradation; secr. + membrane assoc., secreted or membrane-associated factors; transp. + carrier, transporter or carrier; unknown fct., unknown function.</p