Project description:Leigh Syndrome (LS) is the most common early-onset, progressive mitochondrial encephalopathy usually leading to early death. The single most prevalent cause of LS is occurrence of mutations in the hSurf1 gene. LSSurf1 patients show a marked and specific decrease in the activity of mitochondrial respiratory chain complex IV (cytochrome c oxidase, COX). hSurf1 encodes an inner membrane mitochondrial protein involved in COX assembly. We established a D. melanogaster model of LS based on the post-transcriptional silencing of CG9943, the Drosophila homolog of hSurf1. Knock down of Surf1 was induced (i) ubiquitously, which led to larval lethality; (ii) in the mesodermal derivatives, which led to pupal lethality; (iii) in the central nervous system, which allowed survival; and (iv) at specific developmental stages. A biochemical characterization was carried out in knock down individuals, which unexpectedly revealed defects in all complexes of the mitochondrial respiratory chain (MRC) included the F-ATP synthase (complex V) in larvae, and a COX-specific impairment in adults. Silencing of Surf1 expression in Drosophila S2R+ cells led to loss of COX activity associated with decreased oxygen consumption. We conclude that Surf1 is essential for COX activity and mitochondrial function in D. melanogaster, and provide a new tool to clarify the pathogenic mechanisms of LS.
Project description:Thermal acclimation study on Drosophila melanogaster reared at 3 different temperatures (12, 25, and 31oC). The proteomic profiles of D. melanogaster under these different temperatures were analyzed and compared using label-free tandem mass spectrometry.
Project description:In Drosophila melanogaster larval hemolymph, under normal conditions, plasmatocytes and crystal cells represent respectively ~95% and ~5% of hemocytes, while lamellocytes, the third larval cell type, are absent since they are only induced after parasitoid wasp oviposition, their role being the encapsulation-melanization response to eliminate the wasp egg. However, even after induction lamellocytes number remains low, making difficult biochemical studies. Here using the D. melanogaster hopTum-l mutant that constitutively produces a high number of hemocytes, we set up a method to purify lamellocytes and analyzed their major proteins by 2D gel electrophoresis and their biotinylated plasma membrane surface proteins by 1D SDS-PAGE after affinity purification. Mass spectrometry allowed to identify 430 proteins from the 2D spots and 344 from affinity purified proteins, totalizing 639 unique proteins. Known lamellocyte markers such as PPO3 and the integrin myospheroid are among the major proteins and affinity purification led to the detection of other integrins and a large array of integrins associated proteins involved in cell-cell junction formation and function. Overall newly identified proteins indicated that these cells are highly adapted to the encapsulation process but may have also several different physiological functions. This study provides the basis for new lamellocyte studies in vivo and in vitro, and develop markers to search whether different populations coexist, establish their origins and decipher their respective roles in drosophila physiology and immunity.