Environmental and Regional Problems of Contaminated Sites

Environmental Economics and Policy, Land Economics/Use,

Drosophila mauve Mutants Reveal a Role of LYST Homologs in the Maturation of Phagosomes and Autophagosomes

Chediak-Higashi syndrome (CHS) is a lethal disease caused by mutations that inactivate the lysosomal trafficking regulator protein (LYST). Patients suffer from diverse symptoms including oculocutaneous albinism, recurrent infections, neutropenia and progressive neurodegeneration. These defects have been traced back to over-sized lysosomes and lysosome-related organelles (LROs) in different cell types. Here, we explore mutants in the Drosophila mauve gene as a new model system for CHS. The mauve gene (CG42863) encodes a large BEACH domain protein of 3535 amino acids similar to LYST. This reflects a functional homology between these proteins as mauve mutants also display enlarged LROs, such as pigment granules. This Drosophila model also replicates the enhanced susceptibility to infections and we show a defect in the cellular immune response. Early stages of phagocytosis proceed normally in mauve mutant hemocytes but, unlike in wild type, late phagosomes fuse and generate large vacuoles containing many bacteria. Autophagy is similarly affected in mauve fat bodies as starvation-induced autophagosomes grow beyond their normal size. Together these data suggest a model in which Mauve functions to restrict homotypic fusion of different pre-lysosomal organelles and LROs

Molecular Methods Used for the Identification of Potentially Probiotic Lactobacillus reuteri Strains

Forty potentially probiotic Lactobacillus strains as well as reference strains of different genera were grown under standardised conditions. Cell masses were harvested and DNA was isolated. For identification, all strains were subjected to genus-specific polymerase chain reaction (PCR), and the affiliation with the genus Lactobacillus was confirmed for all isolates. Using two species-specific primer-pairs for Lactobacillus reuteri, specific amplicons were observed for eight of the forty investigated strains. For differentiation, these eight strains as well as the reference strains of the species L. reuteri and closely related species were subjected to randomly amplified polymorphic DNA (RAPD)-PCR using fourteen arbitrary primers. Two selected strains as well as probiotic and common reference strains were further investigated applying pulsed field gel electrophoresis (PFGE). With the latter two methods, individual profiles were found for most strains, but no difference between probiotic and common strains could be made out

Wavelength Selection in Systems Far from Equilibrium

It is shown that for systems developing stationary periodic patterns there exists at most one stable wavelength state if a supercritical region is connected to a subcritical one by the imposition of a slow spatial variation of the external parameters. In nonpotential systems the selected wavelength depends on the particular combination of parameters that vary but not on the (slow) rate of spatial variation. Suitable parameter variations force the system into a dynamic state

Interaction of the HOPS complex with Syntaxin 17 mediates autophagosome clearance in Drosophila

Homotypic fusion and vacuole protein sorting (HOPS) is a tethering complex required for trafficking to the vacuole/lysosome in yeast. Specific interaction of HOPS with certain SNARE (soluble NSF attachment protein receptor) proteins ensures the fusion of appropriate vesicles. HOPS function is less well characterized in metazoans. We show that all six HOPS subunits (Vps11 [vacuolar protein sorting 11]/CG32350, Vps18/Dor, Vps16A, Vps33A/Car, Vps39/CG7146, and Vps41/Lt) are required for fusion of autophagosomes with lysosomes in Drosophila. Loss of these genes results in large-scale accumulation of autophagosomes and blocks autophagic degradation under basal, starvation-induced, and developmental conditions. We find that HOPS colocalizes and interacts with Syntaxin 17 (Syx17), the recently identified autophagosomal SNARE required for fusion in Drosophila and mammals, suggesting their association is critical during tethering and fusion of autophagosomes with lysosomes. HOPS, but not Syx17, is also required for endocytic down-regulation of Notch and Boss in developing eyes and for proper trafficking to lysosomes and eye pigment granules. We also show that the formation of autophagosomes and their fusion with lysosomes is largely unaffected in null mutants of Vps38/UVRAG (UV radiation resistance associated), a suggested binding partner of HOPS in mammals, while endocytic breakdown and lysosome biogenesis is perturbed. Our results establish the role of HOPS and its likely mechanism of action during autophagy in metazoans