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Analysis of Malpighian tubule development in Drosophila melanogaster

Milán Szuperák

The excretory and osmoregulatory functions in insects are performed by the Malpighian tubules, analogous to renal tubules in vertebrates. The Malpighian tubules of the Drosophila larva consist of two pairs of long epithelial tubes within the hemocoel, which are connected to the hindgut at the distal end by the ureter. Recently, we identified and described larval translucida (ltl), a novel gene regulating BMP signaling during wing development. Interestingly, homozygous null mutants of ltl exhibit larval lethality and a bloating phenotype suggesting excessive water retention.  This could imply an impairment of Malpighian tubule function.  Consistent with this hypothesis, ltl mutant larvae exhibit disorganization of the actin cytoskeleton in the tubules and the ureter is conspicuously enlarged.  Fluid transport in the Malpighian tubules appears to be generally normal, but our observations suggest that the enlarged ureter may be blocked by the contents of the gut.  To better understand these phenotypes, we are currently investigating the function of ltl in renal tubule development in Drosophila and whether this activity is connected to BMP signaling.

   

Studying the role of SUMOylation in the development of Drosophila imaginal discs.

 Kiki Kanakousaki

Animal development requires not only transcription and translation of thousands of important regulatory molecules, but also their modification by post-translational mechanisms such as phosphorylation, proteolytic cleavage, or ubiquitination.   SUMOylation is a post-translational protein modification proposed to impact on many cellular processes, although the role of SUMOylation at the organismal level and in broad processes like development is not well understood. In a genetic screen we found a novel mutation in a key component of the biochemical pathway of SUMO conjugation.  This mutation dramatically affected the growth of imaginal discs, although many other larval structures were unperturbed. Using genetics, biochemistry, cytometry and imaging, we analyzed the phenotype and found that mutants cells exhibit reduced levels of SUMOylation and defects in mitosis. Our goal is to understand the pathways and proteins affected by SUMOylation, leading to the observed phenotype.

Genetic control of epithelial morphogenesis in the Drosophila wing disc

Usha Nagarajan

The mechanisms that control organ size and shape are ultimately integrated with the regulation of epithelial architecture. To identify new players in both processes, we are performing a novel genetic screen for mutant cell clones that disrupt the size or shape of wing disc epithelial cells.  One candidate under investigation causes a dramatic overgrowth of mutant cell clones.

 

 


  

Genome-wide functional analysis of cyclic transcription in the Drosophila wing imaginal disc

Liang Liang

Previous studies have characterized genome-wide transcriptional oscillations associated with cell cycle progression, but insights in this area have been restricted to unicellular systems, such as yeast or tissue culture cells. In this project, we analyzed the global cell cycle-associated transcriptional oscillations of Drosophila wing imaginal disc epithelial cells, and identified over 600 cyclically expressed genes in the wing disc epithelium. Intriguingly, numerous genes were cyclically expressed in a context- and cell type-specific manner when directly compared to Drosophila S2 cells. These findings reveal a surprising degree of plasticity in the manner of cyclic transcription. We are now attempting to understand the developmental function of a few novel cyclic genes in Drosophila wing growth.